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Service Tutorial 1 (C#) - Creating a Service1\CSharp
This tutorial teaches you how to:
- Create a new service.
- Start a service.
- Support an HTTP request.
- Use Control Panel.
- Stop the Service.
- Support Replace.
See Also:
Prerequisites: Create a Service
Begin by creating a new service.
Open the Start menu and choose the DSS Command Prompt command. If the command does not appear in the Start menu, choose All Programs, Microsoft Robotics Developer Studio, and then DSS Command Prompt. This opens a special Command Prompt window in the root directory of the installation path.
Change to the Samples directory and run the DssNewService tool using the parameters shown in the sample below to create your first service. Then change to the ServiceTutorial1 (ServiceTutorial<Number One>) directory. This procedure automatically creates a template to help you get started.
cd Samples dssnewservice /namespace:Robotics /service:ServiceTutorial1 cd ServiceTutorial1
At this time, a Microsoft Visual Studio Project named ServiceTutorial1.csproj is created in ServiceTutorial1 directory. You can load this Project using your C# editor (either Visual Studio or Visual Studio Express) from the command line as shown below, or locate it in Windows Explorer and double-click on it.
start ServiceTutorial1.csproj
When you edit a project that does not have a Solution file (ServiceTutorial1.sln in this case), Visual Studio will ask if you want to create a Solution file when you exit. This is the easiest way to create the Solution file. Note that you do not need a Solution file in order to compile and use the service - the Project file is sufficient.
Next, build the solution. In Visual Studio you can build the solution by clicking Build menu and then choosing Build Solution (or pressing F6). You can also compile from the DSS Command Prompt:
msbuild ServiceTutorial1.sln
The command above assumes you have created the Solution file. If not, then just build the .csproj file instead.
Lastly, note that you can also create a new service using a Wizard in Visual Studio. This is much easier and has more functionality than using the command-line tool. See Creating Service Projects for more information.
Step 2: Start a Service
Go back to the Microsoft Robotics Developer Studio (RDS) installation folder.
cd ..\..
You should now see the following files in the bin directory that were created when you built your project.
. . . ServiceTutorial1.Y2007.M07.dll ServiceTutorial1.Y2007.M07.pdb ServiceTutorial1.Y2007.M07.Proxy.dll ServiceTutorial1.Y2007.M07.Proxy.pdb ServiceTutorial1.Y2007.M07.proxy.xml ServiceTutorial1.Y2007.M07.transform.dll ServiceTutorial1.Y2007.M07.transform.pdb
To run a service, you must first run a DSS node by running the DSS hosting application DssHost.exe. DssHost can start services for you. There are 3 ways to specify which service or services DssHost should start:
- By manifest, using the command line flag /manifest
- By assembly name, using the command line flag /dll
- By contract, using the command line flag /contract
A manifest file is an XML file that contains the information needed to start a service. DssNewService automatically creates a file called ServiceTutorial1.manifest.xml which contains the information required by DssHost to start the service.
Start DssHost using the manifest already created with the following command.
dsshost /port:50000 /manifest:"samples\ServiceTutorial1\ServiceTutorial1.manifest.xml"
You should see service load outputs for the specified manifest:
. . . * Starting manifest load: .../ServiceTutorial1.manifest.xml * Service uri: ...[] * Manifest load complete ...[]
Now open your web browser and navigate to the address
An XML serialization (representation) of the newly created service, ServiceTutorial1State encapsulated in a SOAP envelope appears in the browser window.
Figure 1 - in browser shows the state of the service as a SOAP envelope.
Exit DSS host by pressing CTRL+C in the command window. "Shutdown complete" message appears and then returns to the command prompt.
Step 3: Support HTTP GET
When sending state to a web browser, the service can optionally avoid sending a SOAP envelope and instead send an XML serialization of its state as follows.
The ServiceTutorial1Types.cs file defines the Contract of the service. It includes types for contract identifier, state, operations port, operation messages, and request/response types for this service. You will learn more about the components of services as you go through these tutorials.
In the file ServiceTutorial1Types.cs, make the following changes:
First add a using directive to the top of the file to include the namespace Microsoft.Dss.Core.DsspHttp. This namespace contains the message definitions that allow a service to respond directly to requests from a standard HTTP client, such as a standard web browser.C#
using Microsoft.Dss.Core.DsspHttp;
Next, add a property to the class ServiceTutorial1State, this will allow us to see the serialized data more clearly. In Service Tutorial 6 (C#) - Retrieving State and Displaying it Using an XML Transform you will use the ServiceTutorial1State class to carry information between services.C#
private string _member = "This is my State!"; [DataMember] public string Member { get { return _member; } set { _member = value; } }
The DataContract attribute specifies that the ServiceTutorial1State class is XML serializable. Within a type marked with the DataContract attribute, you must explicitly mark individual properties and fields as XML serializable using the DataMember attribute. Only public properties and fields declared with this attribute will be serialized. Also, in order for the property members to serialize, they will need to have both the set and get methods implemented.
Now, further down in the same file, add the HttpGet message to the list of messages supported by the service's port. A port is a mechanism through which messages are communicated between services. A PortSet is just a collection of ports.C#
[ServicePort] public class ServiceTutorial1Operations : PortSet<DsspDefaultLookup, DsspDefaultDrop, Get, HttpGet> { }
In the file ServiceTutorial1.cs, add support for the HttpGet message. ServiceTutorial1.cs defines the behavior of the service.
Again add a using statement for DsspHttp.C#
using Microsoft.Dss.Core.DsspHttp;
Then in the ServiceTutorial1 class, add a message handler for the HttpGet message.C#
/// ; }
This handler sends an HttpResponseType message to the response port of the HttpGet message. The HTTP infrastructure within the DSS node will serialize the provided state to XML and set that as the body of response to the HTTP request.
IMPORTANT NOTE: This is the default behavior of a HttpGet handler. The resulting output will be an XML serialized version of the service state. If this is the behavior that you want, then there is no need to write the HttpGet code into your service because DsspServiceBase will take care of it for you if you tag your state with the ServiceState attribute.
Build and run the service (press F5 or select the Debug > Start Debugging menu command) and, while it is running, use a web browser to navigate to to view the following:
Step 4: Using Control Panel
To start your service you could also use DSS Control Panel, which is itself a DSS service. To try this, first terminate the current DSS node by pressing CTRL+C in the command prompt. Then run DssHost again without supplying a manifest.
dsshost /port:50000
Now open in the browser. When the page is loaded, in the left navigation pane click on Control Panel. A table of services recognized by the current node appears in your browser.
Each row of the table begins with the Name of a service. Following that there is a dropdown list with the list of manifests that can run the service. If there are any instances of that service which are currently running, you should see a URL for that instance under the service's Description. Each instance of a running service also includes a button in the right-hand side of the URL which allows you to Drop that service. Clicking this button sends a Drop message to the service. This message stops the service.
Scroll down the page and find the entry for ServiceTutorial1 or type the name of your service in the Search box: servicetutorial1
You will probably see two results. One of them is the Service Tutorial 1 from the completed project that comes with a DSS installation. You can distinguish them by looking at the location of manifests in the dropdown lists, however, for running this service you don't need to select a manifest and can do it by directly loading the assembly (dll file) by selecting <<Start without manifest>>. In cases where you need to run your service together with a group of partner services that are listed in the manifest, you will need to run the manifest instead.
Run the service by clicking on the Create button.
Now from the left navigation pane select Service Directory. You should see /servicetutorial1 in the list of services that are running. Notice the other services running, including /controlpanel are actually different components of the DSS runtime and are started by default when DSS environment is initialized. You can inspect the state of each service by clicking on its link or browsing directly to the service's URL.
Step 5: Stop the Service
While the service is running, open your web browser to
Find the entry for servicetutorial1 as described in the previous section.
Click the URL to inspect the state of the service, create a new instance by clicking the Create button, or stop a running iteration of the service by clicking the Drop button.
Step 6: Support Replace
A Replace message is used to replace the current state of a service. When a Replace message is sent the entire state of the service is replaced with the state object specified in the body of the Replace message. This allows initializing a service with a new state or restoring the service with a state that was previously saved, at any time during the lifetime of the service.
For our service to support replace, define the Replace type in ServiceTutorial1Types.cs.
/// <summary> /// ServiceTutorial1 Replace Operation /// </summary> /// <remarks>The Replace class is specific to a service because it uses /// the service state.</remarks> public class Replace : Replace<ServiceTutorial1State, PortSet<DefaultReplaceResponseType, Fault>> { }
Then add Replace to the port set.
/// <summary> /// ServiceTutorial1 Main Operations Port /// </summary> [ServicePort] public class ServiceTutorial1Operations : PortSet<DsspDefaultLookup, DsspDefaultDrop, Get, HttpGet, Replace> { }
In ServiceTutorial1.cs add the Replace handler.
/// <summary> /// Replace Handler /// </summary> [ServiceHandler(ServiceHandlerBehavior.Exclusive)] public IEnumerator<ITask> ReplaceHandler(Replace replace) { _state = replace.Body; replace.ResponsePort.Post(DefaultReplaceResponseType.Instance); yield break; }
In the above code the body of the replace message which is of type ServiceTutorial1State is assigned to _state of this service. Then, a success response of type DefaultReplaceResponseType is posted to the ResponsePort of the Replace message. This signals back to the sender that the state was successfully replaced.
We will use the Replace operation later to exchange values between services.
Summary
In this tutorial, you learned how to:
Appendix A: The Code
ServiceTutorial1Types.cs
The ServiceTutuorial1Types.cs file defines the service Contract. The Contract is identified by a unique text string, which is associated with a .NET CLR namespace, and a set of messages that the service supports.
This establishes the namespaces that are used in this file.
using Microsoft.Ccr.Core; using Microsoft.Dss.Core.Attributes; using Microsoft.Dss.Core.DsspHttp; using Microsoft.Dss.ServiceModel.Dssp; using System; using System.Collections.Generic; using W3C.Soap; using servicetutorial1 = RoboticsServiceTutorial1;
The Contract Class
/// <summary> /// ServiceTutorial1 Contract class /// </summary> public sealed class Contract { /// <summary> /// The Dss Service contract /// </summary> public const String Identifier = ""; }
This Contract class defines the unique string, Identifier, that is used to identify this Contract and, in general, service. We follow a convention used in XML documents of using a URI (Unique Resource Identifier) to specify a unique name. The default mechanism used is to compose the URI from a host name (provided as a parameter to DssNewService), a path (in this example empty), the year, the month and the name of the service. If the Namespace is composed from a host name and path that the service author has some level of control over (for example, the address of an account at could be used) then the composition of date elements and service name gives the user a reasonable expectation of uniqueness, with the benefit of containing a small amount of information about the service. While there is no requirement that the URI have a page behind it, there is also no reason why a service author shouldn't create a matching page.
The ServiceTutorial1State Class
/// <summary> /// The ServiceTutorial1 State /// </summary> [DataContract] public class ServiceTutorial1State { private string _member = "This is my State!"; [DataMember] public string Member { get { return _member; } set { _member = value; } } }
The ServiceTutorial1State class has one public property, Member, that is itself declared with the DataMember attribute that (as discussed above) is used to indicate that this member should be serialized. By default, a property or field that is null will not be serialized.
The ServiceTutorial1Operations Class
/// <summary> /// ServiceTutorial1 Main Operations Port /// </summary> [ServicePort] public class ServiceTutorial1Operations : PortSet<DsspDefaultLookup, DsspDefaultDrop, Get, HttpGet, Replace> { }
This class defines the public messages that the service supports.
Get and Replace are the two messages that do not have appropriate default declarations but are supported by this service.
- In the case of Get, this is because the primary response to a Get message should be the State of the service. The state type of this service, ServiceTutorial1State, is specific to this service.
- For Replace, the Body of the message is the ServiceTutorial1State of this service.
/// <summary> /// ServiceTutorial1 Get Operation /// </summary> /// <remarks>All services require their own specific Get class because /// the service state is different for every service.</remarks> public class Get : Get<GetRequestType, PortSet<ServiceTutorial1State, Fault>> { /// <summary> /// ServiceTutorial1 Get Operation /// </summary> public Get() { } /// <summary> /// ServiceTutorial1 Get Operation /// </summary> public Get(Microsoft.Dss.ServiceModel.Dssp.GetRequestType body) : base(body) { } /// <summary> /// ServiceTutorial1 Get Operation /// </summary> public Get(Microsoft.Dss.ServiceModel.Dssp.GetRequestType body, Microsoft.Ccr.Core.PortSet<ServiceTutorial1State,W3C.Soap.Fault> responsePort) : base(body, responsePort) { } } /// <summary> /// ServiceTutorial1 Replace Operation /// </summary> /// <remarks>The Replace class is specific to a service because it uses /// the service state.</remarks> public class Replace : Replace<ServiceTutorial1State, PortSet<DefaultReplaceResponseType, Fault>> { }
ServiceTutorial1.cs
The ServiceTutorial1.cs file contains the service implementation class.
using Microsoft.Ccr.Core; using Microsoft.Dss.Core; using Microsoft.Dss.Core.Attributes; using Microsoft.Dss.Core.DsspHttp; using Microsoft.Dss.ServiceModel.Dssp; using Microsoft.Dss.ServiceModel.DsspServiceBase; using System; using System.Collections.Generic; using System.ComponentModel; using System.Xml;
These are the namespaces that will be used in this class.
Service Implementation Class
This section of the code declares a class, ServiceTutorial1, derived from DsspServiceBase. All service implementation classes derive from DsspServiceBase.
/// <summary> /// Implementation class for ServiceTutorial1 /// </summary> [DisplayName("Service Tutorial 1: Creating a Service")] [Description("Demonstrates how to write a basic service.")] [Contract(Contract.Identifier)] [DssServiceDescription("")] public class ServiceTutorial1Service : DsspServiceBase {
The Contract attribute declares a direct association between this class and the Contract Identifier discussed in the previous section. The DisplayName and Description are attributes that describe the service. The DisplayName is the shorter description similar to a title. The Description is a more detailed description.
ServiceTutorial1State holds the state of the service. Every service provides messages through its operations port that allow other services to read and modify its state.
/// <summary> /// Service State /// </summary> [ServiceState] private ServiceTutorial1State _state = new ServiceTutorial1State();
In this sample, the service only supports:
Reading the entire state (Get and HttpGet), and
Replacing the entire state (Replace)
The ServicePort attribute declares that the _mainPort field is the primary service port of this service.
/// <summary> /// Main Port /// </summary> [ServicePort("/servicetutorial1", AllowMultipleInstances=false)] private ServiceTutorial1Operations _mainPort = new ServiceTutorial1Operations();
This also specifies the default path used to address this service, /servicetutorial1. It also stipulates that only one instance of this service to run at a time. If AllowMultipleInstances = true is specified, a unique suffix is appended to the path when an instance of the service is created.
Initialization
When services are created, there is a two stage creation process during which partner services are created as discussed in Service Tutorial 4 (C#) - Supporting Subscriptions and Service Tutorial 5 (C#) - Subscribing.
/// <summary> /// Default Service Constructor /// </summary> public ServiceTutorial1Service(DsspServiceCreationPort creationPort) : base(creationPort) { }
This constructor is used in the first part of the creation process and must have the form shown for the service to be created correctly.
The Start method is called as the last action of the two stage creation process.
/// <summary> /// Service Start /// </summary> protected override void Start() { base.Start(); // Add service specific initialization here. }
Calling base.Start() does three things for the service. (These steps could be done explicitly, but using base.Start() is easier).
Calls ActivateDsspOperationHandlers which causes DsspServiceBase to attach handlers to each message supported on the main service port. (This relies on ServiceHandler attributes and method signatures.)
See below for how to declare a handler.
Calls DirectoryInsert to insert the service record for this service into the directory. The directory is itself a service and this method sends an Insert message to that service.
When the DssHost is running, you can inspect the directory service by pointing your browser to.
Calls LogInfo to send an Insert message to the /console/output service (). The category of the message is Console, which causes the message to be printed to the command console. The URI of the service is automatically appended to the output.
The following code summarizes the three tasks done by base.Start() as described above. However, in most cases it is recommended to use base.Start() instead of manually initializing the service start.
// Listen on the main port for requests and call the appropriate handler. ActivateDsspOperationHandlers(); // Publish the service to the local node Directory DirectoryInsert(); // display HTTP service Uri LogInfo(LogGroups.Console, "Service uri: ");
Message Handlers
The following is the handler for the Get message. This handler simply posts the state of the service to the response port of the message.
/// <summary> /// Get Handler /// </summary> /// <param name="get"></param> /// <returns></returns> /// <remarks>This is a standard Get handler. It is not required because /// DsspServiceBase will handle it if the state is marked with [ServiceState]. /// It is included here for illustration only.</remarks> [ServiceHandler(ServiceHandlerBehavior.Concurrent)] public virtual IEnumerator<ITask> GetHandler(Get get) { get.ResponsePort.Post(_state); yield break; }
The ServiceHandler attribute is used by the method ActivateDsspOperationHandlers called in the base.Start() method to identify member functions as message handlers for messages posted to the main service port, itself identified with the ServicePort attribute. ServiceHandlerBehavior.Concurrent is used to specify that the message handler only needs Read-Only access to the state of the service. This allows message handlers that do not modify state to run concurrently.
Message handlers generally have the signature, Microsoft.Ccr.Core.IteratorHandler<T>
public delegate IEnumerator<ITask> IteratorHandler<T>(T parameter);
Using Iterators (a new feature in .NET 2.0) allows the handler to contain a sequence of asynchronous actions without blocking a thread. This is demonstrated in Service Tutorial 3 (C#) - Persisting State.
The HttpGetHandler is discussed previously in this tutorial (Step 3: Supporting HTTP GET).
/// ; }
Note that this is the default behavior for a HttpGet handler. Therefore it is not necessary to include this code in your service. It is included here so that you can see what it does. However, the DsspServiceBase class will take care of it for you and it is only necessary to declare your own handler if you want to do some service-specific processing before sending the result.
The following is the handler for the Replace message. Note that this handler is declared with ServiceHandlerBehavior.Exclusive, indicating that it will modify state. Only one Exclusive handler will execute at a time and no Concurrent handler can execute while an Exclusive handler is running.
/// <summary> /// Replace Handler /// </summary> [ServiceHandler(ServiceHandlerBehavior.Exclusive)] public IEnumerator<ITask> ReplaceHandler(Replace replace) { _state = replace.Body; replace.ResponsePort.Post(DefaultReplaceResponseType.Instance); yield break; }
.NET Framework Developer's Guide: Attributes Overview | http://msdn.microsoft.com/en-us/library/bb483064.aspx | CC-MAIN-2014-10 | en | refinedweb |
Im trying to decide which image loading library to use with OpenGL. I found several online such as DevIL and SOIL. I was wondering what everyone here is using.
Im trying to decide which image loading library to use with OpenGL. I found several online such as DevIL and SOIL. I was wondering what everyone here is using.
DevIL and SOIL are certainly a good place to start. I'm using imagemagick myself, it's cross-platform and supports virtually all file formats. On the other hand, it doesn't provide an OpenGL interface.
N.
NiCo do you have to compile imagemagick to use Magick++. I downloaded the imagemagick binary package and did not see any c++ header files.
You don't have to compile it if you installed the binary package. The header files are in c:/Program Files/ImageMagick-6.3.8-1-Q8/include
N.
ifl from Silicon Graphics is also a nice package. I found it a bit easier to use and get started with than ImageMagick.
NiCo do you know where i can find an example of how to use imagemagick with opengl.
Code :Image im; im.read("test.bmp"); int w = im.columns(); int h = im.rows(); unsigned char* data = new unsigned char[w*h]; im.write(0,0,w,h,"RGBA",CharPixel,data); ... glTexImage2D(...,GL_RGBA8,GL_UNSIGNED_BYTE,&data[0]); delete[] data;
N.
Nico thanks, I'll try it out.
NiCo I know this is not an Opengl question but can you help, I am getting link errors while compiling my code using Dev-C++. The error shows undefined reference to Magick::Image::Image() while compiling.
I include the namespace for it and (using namespace Magick
I tried linking the following files
CORE_RL_Magick++_.lib
CORE_RL_magick_.lib
CORE_RL_wand_.lib
but no luck. I also try initializing Magick++ with the following lines of code.
InitializeMagick("C://Program Files/ImageMagick-6.3.8-Q16/");
and still no luck. Any suggestion?
Why not FreeImage? Is open source but you can use It for commercial purposes, and now supports HDR images!( OpenEXR and Radiance):
Some sample code:
Code :thisIsInitGL(){ loadTexture(); } ///Now the interesting code: loadTexture(){ FREE_IMAGE_FORMAT formato = FreeImage_GetFileType(textureFile,0);//Automatocally detects the format(from over 20 formats!) FIBITMAP* imagen = FreeImage_Load(formato, textureFile); FIBITMAP* temp = imagen; imagen = FreeImage_ConvertTo32Bits(imagen); FreeImage_Unload(temp); int w = FreeImage_GetWidth(imagen); int h = FreeImage_GetHeight(imagen); cout<<"The size of the image is: "<<textureFile<<" es "<<w<<"*"<<h<<endl; //Some debugging code GLubyte* textura = new GLubyte[4*w*h]; char* pixeles = (char*)FreeImage_GetBits(imagen); //FreeImage loads in BGR format, so you need to swap some bytes(Or use GL_BGR). for(int j= 0; j<w*h; j++){ textura[j*4+0]= pixeles[j*4+2]; textura[j*4+1]= pixeles[j*4+1]; textura[j*4+2]= pixeles[j*4+0]; textura[j*4+3]= pixeles[j*4+3]; //cout<<j<<": "<<textura[j*4+0]<<"**"<<textura[j*4+1]<<"**"<<textura[j*4+2]<<"**"<<textura[j*4+3]<<endl; } //Now generate the OpenGL texture object glGenTextures(1, &texturaID); glBindTexture(GL_TEXTURE_2D, texturaID); glTexImage2D(GL_TEXTURE_2D,0,GL_RGBA, w, h, 0, GL_RGBA,GL_UNSIGNED_BYTE,(GLvoid*)textura ); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); GLenum huboError = glGetError(); if(huboError){ cout<<"There was an error loading the texture"<<endl; } } | http://www.opengl.org/discussion_boards/showthread.php/163929-image-loading?p=1158293&viewfull=1 | CC-MAIN-2014-10 | en | refinedweb |
There's a lot of good advice on how to interview here at the Monestary. Just a quick search turns up:
I have, instead, bad advice, more in the vein of How's your Perl? and How's your Perl? (II) The last time I used these questions, I asked a coworker who sat in on the interview about them. He responded by saying that if someone gets them right, you know they know Perl really well. If someone gets them wrong, however, you can't tell whether they know Perl well or not. I agree, so I'm more or less retiring them here.
How are these two different?
$self->foo();
foo($self);
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(Assume for this problem that $self is a blessed object of some kind.)
($x) = foo();
$x = foo();
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for ( @x ) { foo( $_ ) }
map { foo( $_ ) } @x;
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What does this output?
sub baz { return 11 unless shift }
print 'baz(5): ', baz(5), "\n";
print 'baz(0): ', baz(0), "\n";
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my $FOO = 'foo';
sub bar { $_[0] = 'bar' }
print $FOO, "\n";
print bar( $FOO ), "\n";
print $FOO, "\n";
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for my $s ( qw( a b c ) ) { $s =~ s/$/\n/ && print $s }
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Yes, I really did ask these questions of a candidate. In my defense, I prefaced my questions by saying that I was not very concerned with whether he got the answers right or not. These questions were meant to be "conversation pieces."
Regarding the last question and different Perl versions:
Update: corrected version number.
lodin
Maybe you need something even older?
I'm quite surprised. I used ActivePerl 5.6.0 back then, but I don't think that the distribution would make any difference. Maybe I'm just mixing this up with something closely related.
perl561delta agrees with me though that ...
Could you provide B::Deparse output of your code for 5.6.0 and 5.6.1? B::Deparse had plenty issues of its own back then, but it will probably be interesting.
I'd count that as right,
Jenda
I think your answer is correct. My own answer looks at it from the perspective of where you might notice a difference in a real program. I think your explanation says more about how that difference arises (i.e., how it all works).
if someone gets them wrong, however, you can't tell whether they know Perl well or not
I'd say the first two are important to know.
The next two fall into the "I wouldn't do that, therefore that code is suspect. I'm not sure what it does, but documentation needs to be added to explain what it's doing and/or it needs to be refactored."
The last one is just plain unimportant. The code dies quite loudly and reproduceably. A better discussion would be how to fix it.
I wouldn't do that, therefore that code is suspect.
Those two were the map vs. for and return 11 unless shift...
The last one is just plain unimportant.
I'd leave the interview with the impression that you're just trying to show the others on the interview panel how much better you were than the applicants
Mmmm .. and they'd probably be OK with that, because how you answer the answer (or walk out of the room) is part of your answer.
An interview happens on many levels -- there's the basic, "Hi, How are you, ..." level, there's the technical level, and there's also the meta-technical level. For me, the meta-technical level is the most interesting -- sure, you know how something clever works, but can you explain it to someone so that they understand? And why was it necessary to do it that way? Can you explain your thought processes out loud as you go, so that your interviewers 'get' how you approach a problem? (In my most recent interview, I proposed a solution to a regex problem, was asked to explain it, started my first sentence, said out loud -- "Wait -- that won't work", paused, then proposed a second, different solution. Apparently, that approach works.)
This meta-behavior also helps them understand how you may well behave when you get stressed our doing too many things -- My response used to be to bark at people (don't get into that habit -- it upsets them), but now I look them in the eye and say "I'm in the middle of an emergency right now -- is your problem more urgent?" and wait for them to explain. I make a point to follow up a few minutes later, once my emergency is over, and deal with their emergency.
I really don't think anyone gets the boot as a result of a code review. It has to be a combination of many factors, all pointing to the breakdown of the employer/employee relationship.
There shouldn't be any 'tricks' involved in interviews -- it's an exploration into whether there's a the basis for a good relationship, based on mutual compatibility. But if someone has (unwisely) labeled themselves as a 'Perl guru', I guess they should expect a few of these tough questions.
Alex / talexb / Toronto
"Groklaw is the open-source mentality applied to legal research" ~ Linus Torvalds
Did you read the whole post? In the interview, the questions were posed as starting points for discussion, not as a pass/fail trick quiz. And that completely changes how I for one react to them. I'd say there are plenty of valid reasons for finding out what a candidate thinks about code like these examples!
My reaction to an interview along these lines would be:
I'd make my decision on whether it was a place I wanted to work based on how the discussion went, not the questions themselves; and I'd hope the interviewer would judge me likewise.
Pass. Though I was not too sure about the "for x map" one.
Update: erm. Oops. Thanks zby, it was not supposed to be there, I just added it when testing and forgot to remove it again.
I bet a lot of people would respond that it would print three lines with formatted dates 1970-01-01 with slightly different times.
Regardless of whether the function returns a list or an array...
Can you show an example of a function that returns an array? (Not an array reference.)
sub function { return 'an array'; }
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Cheers - L~R
Can you show an example of a function that returns an array?
While you haven't said so, I'm guessing that what you have on your mind is something like what you said in Re^4: returning tied array, which is to say:
You can only return scalars and lists and (nothing) from subroutines. You can't return arrays or hashes directly, only as lists or references.
I suspect this statement is more meaningful to perl programmers than to Perl programmers. I haven't read perlguts, let alone perl source, but I'm guessing that under the covers somewhere, in the sea of C, it's really true that nothing can escape a sub besides a scalar, a list, or Nothing.
That having been said, please consider:
sub get_list { return ( 4, 5, 6 ); }
sub get_array { @x = ( 4, 5, 6 ); return @x; }
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get_list and get_array return the same collection of values in different ways. They do different things in scalar context. This is why I think there's a difference between returning a list and returning an array—they behave differently.
One might say that they both do the same thing in scalar context—return a scalar (neither list, nor array).
I think these points of view are looking at the sub from different sides of the return. This is the difference between "imply" and "infer". It's the difference between what one says and what another hears. It's the difference between expression and interpretation.
If I scream "value" into the Void, have I still said something?
I think one could correctly say that sub { @_ } returns an array. It always returns an array regardless of context. Its caller may receive from it a scalar or a list or Nothing, depending on the context it provides, but what the sub itself does is the same every time.
I have in my head a call like this:
... = get_stuff();
[download]
Inside get_stuff somewhere there's a return with some "stuff" after it. I'm guessing that perl takes that "stuff" and turns it into something that makes sense to whatever "..." is, and it does that before the "stuff" gets out of get_stuff. So what actually comes out of the sub can only be a scalar, a list, or Nothing.
I could conceive of it being implemented differently. It could pass out of the sub whatever the sub "said" it wanted to return, and then coerce it into the appropriate type once it got there.
If that were the case, would we still say that subs can only return scalars, lists, or Nothing? Would they really behave any differently? More to the point, how is any of this distinction relevant to Perl programmers?
This reads to me like it is motivated by the all-too-common and deceptively flawed meme of "an array in scalar context gives its size while a list in scalar context returns its last element". I've seen that used to justify so very many flawed conclusions. You can also use it to make flawed justifications to quite a few "correct" conclusions, but that just demonstrates how the flaws in that meme are deceptive (which is probably part of why it is still "all too common").
The subroutine does /not/ return an array that then decides to give its size when it finds itself in a scalar context. There are many other ways that thinking "this sub returns an array" will mislead people. So it is better to divorce yourself from both of these flawed ways of thinking about context in Perl.
And, no, my objections are not based on some secret knowledge on how Perl works internally. They are based on repeatedly seeing people make mistakes about how Perl scripts would behave based on these ideas. There are lots of cases where these ideas give the right answer. But the cases where they lead to the wrong answers are surely more important.
- tye
I think one could correctly say that sub { @_ } returns an array. It always returns an array regardless of context.
Try pushing on to the "array" returned from your sub then:
sub return_array { @_ }
my $new_count = push (return_array(qw( foo bar ))), 'baz';
[download]
(There's an even subtler trick related to a fundamental truth about the semantics of Perl 5 in that example, which I only realized after I chose it.)
I'm guessing that under the covers somewhere, in the sea of C, it's really true that nothing can escape a sub besides a scalar, a list, or Nothing.
The implementation is what it is to support the semantics of Perl-with-an-uppercase-P. I'm not interested in an ontological debate as to which came first, but the internals could change if p5p decided that these language semantics needed to change.
More to the point, how is any of this distinction relevant to Perl programmers?
I find that correctly understanding the semantics of a programming language has a positive effect on the quality and correctness of code written in that language.
I hate these type of technical questions... I find they are just dumb!
NO!
There is more important skills than knowing the subtle differences between coding implementations( this is especially true when you have an interpreter to check your work).
What makes a good programmer? How about,
To me these are harder to evaluate but drastically more important. It is amazing the number of problems you can avoid with a good approach. A deep knowledge of a languages quirks and behaviors will not take you very far.
I have had horrible interviews with people that decide that knowing this intimate behavior is considered a sign of a good programmer.
These people also end up writing 600 line while() loops. that no one can understand. So I have little respect for individuals who rely upon these sort of evaluations..
Nice questions.
Regarding the third question (for and map), I didn't know the answer you gave. However, there's another difference from the one you mentioned.
-sam
Rather than just asking the candidate a few questions, I prefer to give them a task and a set time to do it in. The tasks that we use here (obviously I can't tell you what they are) test that he has sufficient clue about data structures, algorithms, and the language. We do *not* expect anyone to finish any of them, but can get a great deal of information by seeing how far they got and how they approached the problem.
The code they write can often lead to some quite interesting discussions.
If and when you do that, always give the candidate a collection of language reference-texts or free-access to a web equivalent. Be sure to emphasize to them that they are free to use any of those sources entirely without penalty. If they feel that they can't do the exercise and instead want to explain to you the approach that they would take, let them do it ... without penalty nor prejudice.
A good coder is fine, but a good conceptual designer who can present his or her thoughts and ideas to you in a cohesive and understandable way is infinitely better.
Another approach is to present a candidate with a block of code and ask them to explain, in their own words, what it's doing and perhaps what its data-structures look like. Ask them if they might have any comments or suggestions about the code. The code that you select for such a purpose should be the clearest, least-obscure code that you can find.
During all the community-college courses I have ever taught, students were allowed to have a hand-prepared “cheat sheet” with them during the exams. They turned-in a copy of those cheat-sheets with the exam. You could see their depth-of-understanding from the way in which they prepared that material, and I notice that the very best sheets were rarely used during the test.
Another important courtesy that I suggest, in these days of e-mail, is to send the candidate a detailed description of exactly what you intend for them to do during the interview. Consider sending them a preliminary e-mailed interview, not from Brain-whoeveritis, asking them to return their responses via reply. I'd have no problem at all telling anyone generally “what they are,” since each ‘exam’ when I actually sent it out would be unique. I'm not trying to test a candidate's ability to react to surprises, and I don't want to re-create grammar school with all of its anxieties.
Oh.
I think that I, too, would join the “walk out of the room” group. The mere fact that I was being asked such questions would tell me a great deal about the organization, including the fact that I would not want to work there.
I've been programming for ... well, for a very long time now ... and “picking up a new language” is frankly the work of a long weekend, at most. The task of understanding an obscure language-construct is the work of fifteen-minutes on Google.
... but the experience that enables me to know not to write such code in the first place, and to know to be repelled by it and to eliminate it (like kudzu) wherever it may be found, has taken ... well, a very long time.
Therefore, I frankly do not want to work for an organization that prizes its developers' knowledge of arcane language-lore. I don't want to have to deal with their code-base or with the rash of avoidable bugs that I know it will contain. I don't want to plunge into a nest of competing egoes, because in such a nest there will be neither partnership nor communication. This will not be “a healthy place to work.” Instead, it will be a constantly-abrasive one that will grind you down, and life's too short for that. The best thing to do with such places (and they are legion...) is to avoid them at all costs.
The questions that you are asked during even the very first stages of the hiring process will tell you a great deal about what that organization values, what qualities it holds in high esteem, and how it defines its worth within the business organization in which it is situated. A company's interview process is a bright window straight into the personality and temperament of a fairly high-level manager whom you may never get to meet. They will reveal the organization's confidence (or lack thereof) in itself, and may illuminate the nature of the political image-battles which the organization fights.
I say again: interview questions are a magic mirror. A workgroup that peppers its candidates with obscure questions lacks confidence in itself, and therefore will lack confidence in you even if your name is Larry Wall. A workgroup that asks how you feel about teamwork and long-hours isn't a cohesive and well-managed team and pays for it with long hours. Per contra, a workgroup that talks about company-paid employee training early in the interview process is probably a well-run group that is on top of its game (as it should be), and confident-enough about staying there to pay attention to its members' professional growth and personal well-being.
Your reactions to being asked such questions will likewise tell you a lot about yourself. If you find that you have a visceral negative-reaction to it, do not ignore your ‘gut,’ no matter how badly you (think that you) want the job! It's tough to walk away from an interview, much less a firm offer, especially when you don't have another offer in-the-wings. But sometimes that's what you have to do. You want to “get to the ‘yes,’” but it must be the right “yes,’ and the right one might not be the first one. If you are not satisfied with your job right now ... if it did not turn out to be what you expected it to be ... then unfortunately, you made a poor selection, too.
Simply put, testing helps find out if the candidate is fibbing about their skills or not. And yes, a lot of people lie (or exaggerate if you wanna be nice about it).
I know that a fair number of candidates are fibbing lying about their past experience. They have to, as long as gatekeepers filter-out resumes based on the field-names they put into a “skills” array and the numeric value of that field.
The best solution that I have found for this phenomenon is to talk about soft skills in the job-requisition, and hope that enough of it makes it through the HR-gauntlet to be useful. Describe what the candidate will be responsible for, not in programming-terms but instead in business-terms.
A problem that you will very-frequently encounter is that candidates simply don't have “business” skills to begin with. Nothing in their formal education (that they might well have spent tens of thousands of dollars for) has prepared them for this. So they have studied “wrenches” for years, and they've maybe even torn-apart and rebuilt an engine, but if you make the mistake of asking them an abstract question you get a blank stare. But when I'm interviewing, it's those abstract questions that I want to get answers to.
One of my favorites: “In your opinion, what makes a Truly Great piece of software, and why?” Notice that there is no right answer. That throws a lot of people... I wish it didn't, and I don't mean for it to. It's another chapter of the story of folks who get out of school with a perfectly-honed ability to take tests, and no practical knowledge whatever. That's a failing of our educational and training system, not of those people.
Let me put it this way: “around here, we don't ‘write programs in Perl.’ Well, that's what we Little-D-Do. What we Big-D-Do is to build solutions to business problems for people who, quite frankly, don't want to give a damm about computers except to use them. We intend for them to find that our solutions are technically flawless (“but of course”) ... and to find that our solutions are great.”
I'll omit all mention of what programming languages we are using, if I can. The folks who don't particularly care what language we're using are the ones I want to talk to. The ones who know how to design-and-build Great Software... in anything.
It can, of course, be problematic to get these things through “the HR gauntlet,” and yet you have to work with these guys and do things their way, because they're the ones who make it their business to keep you from getting sued. “Hell hath no fury like a lover loser-candidate spurned...”
I think the value of knowing arcane language-lore is not in its utility when writing but in its utility when debugging and refactoring (i.e., when reading). Yes, you can look up some obscure construct and figure out what it does fairly quickly. On the other hand, some constructs do not appear to be obscure but can have unexpected features anyway (the map vs. for example, for instance).
Most (if not all) of the places I've worked have somewhere some old scary code written by someone who wasn't very experienced at the time. I want people who can read it and know what it really does, not just what it looks like it's doing or what the comments say it's doing.
Knowing the arcane can also reveal a passion for the subject.
Pretty much every conversation of strange constructions or obfuscated code that I've been in has included someone saying, "but writing that would be a bad idea anyway." If I'm talking to a candidate who doesn't say that, it makes me wonder. If I ever talk to a candidate who says, "I'll have to use that feature," that's almost certainly disqual).
Yes
No
A crypto-what?
Results (167 votes),
past polls | http://www.perlmonks.org/index.pl/jacques?node_id=667087 | CC-MAIN-2014-10 | en | refinedweb |
#include <db_cxx.h> int Db::set_alloc(db_malloc_fcn_type app_malloc, db_realloc_fcn_type app_realloc, db_free_fcn_type app_free);
Set the allocation functions used by the DbEnv(), DbEnv::lock_stat(), DbEnv::log_archive(), DbEnv::log_stat(), DbEnv::memp_stat(), and DbEnv::txn_stat(). There is one method
DbEnv:() method may not be called after the
Db::open() method is called.
The
Db::set_alloc()
method either returns a non-zero error value or throws an
exception that encapsulates a non-zero error value on
failure, and returns 0 on success.
The
Db::set_alloc()
method may fail and throw a DbException
exception, encapsulating one of the following non-zero errors, or return one
of the following non-zero errors:
If called in a database environment, or called after Db::open() was called; or if an invalid flag value or parameter was specified.
Database and Related Methods | http://idlebox.net/2011/apidocs/db-5.2.28.zip/api_reference/CXX/dbset_alloc.html | CC-MAIN-2014-10 | en | refinedweb |
JAXB's @XmlTransient and Property Order
Java Model
BaseThis class will serve as the root of the inheritance hierarchy. This will be a mapped class, and as such there is nothing special we need to do, to make this happen.
package blog.proporder.xmltransient; public abstract class Base { private int id; public int getId() { return id; } public void setId(int id) { this.id = id; } }Person
To exclude a class from being mapped as part of the inheritance hierarchy you simply need to annotate it with @XmlTransient. Any super classes of this class that are not annotated with @XmlTransient (i.e. Base) will still be mapped.
package blog.proporder.xmltransient; import javax.xml.bind.annotation.XmlTransient; @XmlTransient public class Person extends Base { private String name; public String getName() { return name; } public void setName(String name) { this.name = name; } }
Customer
Since the parent class (Person) has been marked @XmlTransient the name property will be treated as part of the Customer class and can be included in the propOrder. The Customer class also extends Base which was not marked @XmlTransient so the id property can not be specified in the propOrder. The propOrder setting must not include a field/property that has been annotated with @XmlTransient.
package blog.proporder.xmltransient; import java.util.List; import javax.xml.bind.annotation.*; @XmlRootElement @XmlType(propOrder = { "phoneNumbers", "name"}) public class Customer extends Person { private String password; private List<String> phoneNumbers; @XmlTransient public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } @XmlElement(name = "phone-number") public List<String> getPhoneNumbers() { return phoneNumbers; } public void setPhoneNumbers(List<String> phoneNumbers) { this.phoneNumbers = phoneNumbers; } }Demo Code
Below is the demo code that can be used to run this example:
package blog.proporder.xmltransient;("input.xml"); Customer customer = (Customer) unmarshaller.unmarshal(xml); Marshaller marshaller = jc.createMarshaller(); marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true); marshaller.marshal(customer, System.out); } }XML (input.xml/Output)
Below is the input to, and output from running the demo code. Note how the properties of classes marked with @XmlTransient are included, but properties marked @XmlTransient are not.
<?xml version="1.0" encoding="UTF-8"?> <customer> <id>123</id> <phone-number>555-1111</phone-number> <phone-number>555-2222</phone-number> <name>Jane Doe</name> </customer>
(Note: Opinions expressed in this article and its replies are the opinions of their respective authors and not those of DZone, Inc.) | http://java.dzone.com/articles/jaxbs-xmltransient-and | CC-MAIN-2014-10 | en | refinedweb |
The new tutorial series can be found here, please use KAuth when developing with KDE: it's easier, more integrated, and portable:
This is a very simple overview on .policy files that should be enough for most needs, should you need some more information, you can consult PolicyKit reference manual.
Polkit-qt is splitted into 2 libraries, one for working without GUI interaction (-core), and one for working with it (-gui). It also includes some nice additions to make working with helpers easier, as you will see in the next tutorial. Let's see how to use Polkit-qt
You will find this file into polkit-qt source. This file not only defines the dbus_add_activation_system_service macro, that will be extremely useful later, but also lets you find and link against -core, -gui or both.
Polkit-qt-core is composed by Auth and Context. The first is a namespace that lets you easily obtain and check for authorizations, while Context lets you retrieve informations about PolicyKit context. Please refer to polkit-qt docs for more details.
Polkit-qt-core is composed by Action, ActionButton and ActionButtons. They are simply wrappers around QAction and QAbstractButton that let you integrate those two elements with a PolicyKit action. The library will take care not only of obtaining and notify you upon authorization, but also to change the GUI elements (text, icon, etc...) accordingly to the result PolicyKit streams to you.
The api docs for Polkit-qt are really detailed and a strongly advised read. Even if in the next tutorial we'll show you how to use Polkit-qt in the most common case, having some more knowledge on it will surely help you in advanced uses.
In the next tutorial, we'll see how to obtain root privileges with an helper, using some of the knowledge we have gathered now | http://techbase.kde.org/index.php?title=Development/Tutorials/PolicyKit/Introduction&diff=74981&oldid=39317 | CC-MAIN-2014-10 | en | refinedweb |
Practical .NET
The IComparable interface lets you create objects that know how to sort themselves correctly. This interface also provides an example of a high-level strategy for building and extending your classes.
In my last column, I discussed how the Microsoft .NET Framework (and its compilers) use interfaces to implement behavior that crosses many different kinds of objects. My example in that column was using the IEnumerable interface in one of your classes to allow your class to work with a For...Each loop. I showed how you could use that knowledge to create a read-only collection. But I also pointed out that creating your own read-only collection was sort of pointless: The .NET Framework already provides the ReadOnlyCollectionBase class to let you create custom read-only collections, and it includes the AsReadOnly extension method for creating read-only collections from existing read-write collections.
This month, I thought I'd do something more useful: show you how to use the ICompare interface to create a class that supports sorting. However, a class that supports sorting can only support sorting one way -- the "typical" sort. I'll also show you how to support common, but not typical, sorts with your classes (and even how to apply any sort that you want to any collection), again by leveraging another .NET Framework interface.
All that will lead up to suggesting a strategy for building functionality into multiple classes in a flexible, maintainable way.
I'll start by sorting something simple: a List of strings. This code adds some strings to a List and then sorts them by calling the List's Sort method:
Dim sList As New List(of String)
sList.Add("Pat")
sList.Add("Terry")
sList.Add("Lou")
sList.Sort()
If I loop through the collection after the List's Sort method is called, I'd find "Lou" before "Pat" and "Terry" following "Pat." But there are limits to what the Sort method can do. I might have a Customer object with a constructor and three properties, like this:
Public Class Customer
Public Property ID As String
Public Property FirstName As String
Public Property LastName As String
Public Sub New()
'...code omitted...
End Sub
Public Sub New(ID As String)
'...code omitted...
End Sub
End Class
If I add multiple copies of my Customer Object to a List and try to sort it, I'll get an error:
Dim custList As New List(of Customer)
Dim cust As Customer
cust = New Customer("Q456")
custList.Add(cust)
cust = New Customer("A123")
custList.Add(cust)
cust = New Customer("0789")
custList.Add(cust)
custList.Sort()
It turns out that the Sort method requires the objects that will be sorted to have implemented the IComparable interface. The string class apparently implements this interface and my Customer class does not.
Adding Sort Support
To enhance my Customer object to support sorting, I first need to have my class implement the IComparable interface. Adding that interface will cause Visual Studio to add the one method required by that interface (called CompareTo) to my class. As part of implementing this interface, I'm going to promise that I'll only compare Customer objects to other Customer objects by using the generic version of IComparable, which forces me to specify what kind of objects I'll be comparing to. I'll end up with a class like this:
Public Class Customer
Implements IComparable(of Customer)
'...code omitted...
Public Function CompareTo(other As Customer) As Integer _
Implements IComparable(Of Customer).CompareTo
End Function
End Class
Reading the documentation on the IComparable interface tells me that the Sort method will select a Customer object from the List and call its CompareTo method, passing some other Customer object from the List. In my CompareTo method I have to indicate whether the Customer object passed to the method is to appear before or after the selected Customer object (or indicate that I don't care which Customer appears first). If the Customer passed to the method should appear before the selected Customer, then I should return 1; if the Customer passed in should appear after, I should return -1; if I don't care, I return 0.
If I assume I'll normally want to sort Customers by their ID property, I should create a CompareTo method:
Public Function CompareTo(other As Customer) As Integer _
Implements IComparable(Of Customer).CompareTo
If other.ID < Me.ID Then
Return 1
ElseIf other.ID > Me.ID Then
Return -1
Else
Return 0
End If
End Function
I can simplify this code, though. As I said earlier, the String class implements the IComparable interface, which means that any property of type String must have a CompareTo method that will return the correct value. Because my Customer's ID property is of type string, I can simplify my CompareTo method:
Public Function CompareTo(other As Customer) As Integer _
Implements IComparable(Of Customer).CompareTo
Return other.ID.CompareTo(Me.ID)
End Function
Supporting Other Sorts
This CompareTo method will work as long as users only want to sort the Customer objects by their ID property. But what if a user wants to sort Customer objects by their FirstName and LastName properties? If that request occurs often enough, I'd probably be willing to support that "common but not typical" sort by writing some code.
If you look at the Sort method on a List (or any other collection), you'll see that it will accept any object that implements not the IComparable interface, but the IComparer interface. If you pass a class that implements IComparer to the Sort method, the method will ignore the CompareTo method of the objects in the List (in fact, the objects in the List don't even have to implement the IComparable interface). One way to think of this is to consider the CompareTo method built into your class as the comparer for the "default sort" and support other sorts by creating "sorting classes" that implement IComparer.
A class that implements a version of IComparer that works with Customer objects, though without the actual sort code, looks like this (I've called this class SortByName):
Public Class SortByName
Implements IComparer(Of Customer)
Public Function Compare(x As Customer, y As Customer) As Integer _
Implements IComparer(Of Customer).Compare
End Function
End Class
The Compare method required by the IComparer interface is passed two Customer objects and must return -1 if the first object being passed should appear first, 1 if the second object should appear first, and 0 if you don't care what order the objects appear in. To support sorting Customer objects by first and last name, I should compare the LastName properties of the two objects, and when I have two Customer objects with the same LastName, compare their FirstName properties. The code in Listing 1 will do the trick (and could be simplified further, but I wanted to make the first version as obvious as possible).
Public Function Compare(x As Customer, y As Customer) As Integer _
Implements IComparer(Of Customer).Compare
If x.LastName < y.LastName Then
Return -1
ElseIf x.LastName > y.LastName Then
Return 1
ElseIf x.FirstName < y.FirstName Then
Return -1
ElseIf x.FirstName > y.FirstName Then
Return 1
Else
Return 0
End If
End Function
To use this new sort, when it comes time to call the Sort method, you would pass an instance of my SortByName class:
custList.Sort(New SortByName)
Beyond Predefined Sorts
There are additional benefits to using the IComparable interface. For instance, the List collection also has several methods for locating objects within a List, one of which (BinarySearch) requires the objects in the collection to have implemented the IComparable interface. Because I've implemented the IComparable interface with a method that tests the ID property, a developer using my Customer object could find the closest matching Customer by ID by passing a Customer object with an ID property holding the value to search for (provided that the List has been sorted):
custList.Sort()
Dim pos As Integer =
custList.BinarySearch(New Customer With {.ID = "A123"})
I can also use my IComparer object with the BinarySearch method if I want to find objects that match on the properties I used in my IComparer. This example finds Customers with a specific FirstName and LastName (again, provided the List has been sorted using those properties):
custList.Sort(New SortByName)
Dim pos As Integer = custList.BinarySearch(
New Customer With {.FirstName = "Peter",
.LastName = "Vogel"},
New SortByName)
The Sort and BinarySearch methods are defined in the List class itself. However, they could just as easily be extension methods that attach themselves to any class that implements IComparable (I discussed extension methods in last month's column).
And that brings me to my point: Using interfaces and extension methods provides a process for creating classes that can be extended in a maintainable way. First, you define an interface that's easy for developers to implement; second, you add functionality by defining extension methods that work with that interface.
For instance, this company embeds quite a lot of information in its CustomerID: as an example, customers with an ID that begins with a letter are premium customers, while the second digit in the Customer ID specifies what division supplies support for the customer ("1" for the Eastern division, "2" for the Western division and so on). Support for decoding information from the Customer ID would be easy to implement in the Customer object through methods called IsPremium, GetDivision and so on. However, the CustomerID appears in many different objects: the SalesOrder object also has a CustomerID property, as does the CustomerInvoice object. It would be useful to provide those methods on all of those objects. The process I'm recommending here would do that.
I'll begin that process by defining an interface that's easy to implement because it contains just a single property:
Public Interface ICustomerID
ReadOnly Property CustID As String
End Interface
A developer that implements this interface only has to return the Customer ID from this property:
Public Class SalesOrder
Implements ICustomerID
Public ReadOnly Property CustID As String _
Implements ICustomerID.ID
Get
Return Me.ID
End Get
End Property
Now you can incrementally add functionality to any object that implements the interface by writing extension methods that work with any class that implements the ICustomerID interface. The following code implements the IsPremium method that checks to see if the first character of the ID is a letter:
Public Module ICustIDExtensions
<Extension>
Public Function IsPremium(Cust As ICustomerID) As Boolean
Return Char.IsLetter(Cust.CustID.Substring(0, 1))
End Function
'...more methods
End Module
From the developer's point of view, adding the ICustomerID interface to their class (and implementing its one member) also adds all of the related extension methods to their class. And when a new requirement appears, you just add another extension method -- which also adds that new method to every class that implements the interface. This process also allows you to limit the potential damage of any change, because extension methods can only modify the external properties of a particular interface.
It would probably be a good idea to establish some conventions around using this process. Keeping all the extension methods in the same file (or at least in the same project) with their related interface would be a good idea. This would also simplify using the extension methods, because adding the reference that supports the interface would also add the extension method. Keeping the interface and extension methods in the same namespace -- which is easier if they're in the same file or project -- would also make life easier for developers using your interface.
One last note: The only reason that this column got written was because I was lucky enough to sit in on a class on design patterns with Greg Adams. Thanks, Greg!
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Mono 2.6.4 is a portable and open source implementation of the .NET framework for Unix, Windows, MacOS and other operating systems.
Major Highlights
Mono 2.6.4 is a bug fix release for Mono 2.6..6
Specific bug fixes include:
- 596339 - Converting double.NaN to int doesn't generate OverflowException
- 595918 - Decimal parameter stored incorrectly from sql stored procedure
- 595863 - Crash when using nhibernate with bidirectional many-to-many relation
- 594464 - SIGSEGV in ToObject
- 594110 - SSL X.509 SubjectAltNameExtension does not work with more than 1 value (breaks HttpWebRequest)
- 592981 - UnixSignal.WaitAny not interrupted when exiting
- 592711 - --debug=casts does not work for arrays
- 592215 - ** ERROR **: overrwritting old token 3
- 591800 - SIGSEGV in CustomAttributeBuilder
- 591733 - [sdb] Cannot automatically break on NullReferenceExceptions
- 591633 - Basic WebAuth fails.
- 591443 - Cloning a DataColumn with Expression result in a DataColumn in an invalid state
- 591397 - System.Data.DataTableExtensions.CopyToDataTable(Of T) returns 0 Rows
- 591000 - SUSE debuginfo script crashes on Mono AOT .so
- 590503 - GdipCloneImage does not clone PropertyItem.value
- 590488 - Not an exception when connecting to the socket.
- 590232 - DataColumn.Clone doesn't clone the extended properties
- 589482 - DataTable.Clone loses the AutoIncrement of Columns of type Decimal
- 589305 - FtpWebRequest with keepalive=false doesn't work correctly
- 589236 - StreamReader class raise IndexOutOfRangeException
- 588356 - NullReferenceException thrown System.Convert.ChangeType
- 588165 - CultureInfo for da-DK dosen't have the right format.
- 587849 - IL: Missing expected ref 'test.ThisClass`2[T,O]'
- 582667 - DirectoryInfo's property exists doesn't get updated when folder is deleted.
- 576520 - DataTable.WriteXml has a wrong behavior when using a column of type "object".
- 575941 - Mono crashes (assert) when compiling generic code in F# Interactive
- 574713 - crash if System.IO.Compression.DeflateStream.ReadZStream is called
- 567882 - abort in mono_try_assembly_resolve while JITting a verified method
- 567040 - abort in mini_emit_memcpy while JITting a verified method
- 566296 - abort in mono_local_regalloc while JITting a verified method
- 565765 - After crash, 100% cpu spin on Mac
- 565598 - abort in mono_spill_global_vars (load_opcode != OP_LOADV_MEMBASE) while JITting a verified method
- 565149 - ORACLE StoredProcedure with OracleParameter type NUMBER OutPut throw ORA-06502
- 547675 - [PATCH] DateTimeOffset fails to parse timezone fragment when its value has no separator
- 531767 - Cross compiling mono on Linux to Windows fails on Ubuntu
- 515884 - call on virtual/final property gives runtime error while callvirt works fine
- 473298 - MonoReflectionGenericParam unmanaged shadow object is not kept in sync with GenericParameterBuilder
- 440924 - Large arrays cause "mini-ppc.c:2070:ppc_patch: code should not be reached " errors
- 564408 - Worse Performance reading items selected with Linq 2 Obj
- 580736 - [Regression] System.Data failure on ClubWebSite when running on mono-2.6.3
- 567904 - RadioButton.Appearance = Appearance.Button does not work
- 575731 - Invalid RichTextBox paste behavior
- 574991 - Respect pragma warning disable on partial definitions
- 564833 - DataAdapter's fill method throws exception in connection with DbProviderFactories
- 564987 - Make check fails with compile error
- 480152 - string.Normalize() frequently produces incorrect output
- 567676 - abort in mono_class_inflate_generic_method_full while JITting a verified method
- 562155 - XML parsing fails when executing on iPhone
- 560327 - [verifier] abort in mono_class_inflate_generic_class on bad assembly
- 574434 - segment fault on System.MonoCustomAttrs.IsDefinedInternal
- 325489 - backcolor strange behaviour
- 322957 - AppDomain.TypeResolve event raised for System.Int32
- 571336 - XmlDocument XmlElement creation is broken.
- 573329 - csharp shell multi-line continuation inoperable
- 475815 - int.TryParse fails with very large numeric values.
- 489339 - ComboBox popup suggestion box does not appear on linux
- 562043 - HttpWebRequest returns 'invalid length' if kernel-mode auth is not enabled on IIS 7.0
- 566311 - Unable to open project in Xcode
- 567351 - Cannot SetValue of Nullable Property
- 574842 - DomainUnload debug events have wrong id during Domain Unload.
- 577984 - Mono AOT can not handle reference to parameter type return values.
- 385497 - Process Start doesn't handle spaces in paths
- 566057 - SetMaxThreads does not allow you to set a limit lower than its default
- 577818 - WebClient.UploadStringAsync always throws NotImplementedException
- 577891 - HttpListener incorrect headers parsing under moderate load
- 578271 - System.Net.Mail.SmtpClient ReplyTo header is incorrect
- 579146 - Disk Full Error doesn't release handle on files
- 584050 - ServerCertificateValidationCallback receives wrong certificate chain
- 586870 - Exception when serializing empty byte array generated from empty string
- 542464 - Int32.Parse doesn't respect NumberStyles.AllowExponent
- 547753 - ItemGroups seem to get corrupted/truncated after using the CallTarget task within a target
- 558739 - Invalid ResX input. at System.Resources.ResXResourceReader.LoadData ()
- 562056 - xbuild does not accept properties containing ':' passed by CLI..
- 565849 - CreateItem transformation returns wrong results
- 566087 - NoWarn ignored when TreatWarningsAsErrors is true
- 576579 - xbuild does not use default namespace as part of resource id for embedded resources
- 576589 - xbuild conditional statement 'Exists' does not seem to work
- 568989 - linq expression code causes mono_method_to_ir assertion
- 576810 - Cannot run VS packaged BlogEngine 1.5 on SLES 11 w/mono-2.6.2
- 548988 - Cannot bind Web Service Type from return XML on Monotouch
- 561962 - Cannot inspect nullable values
- 564538 - Stepping doesn't walk to previous frame
- 582460 - Multi-threaded app crashed using soft debugger
- 550968 - Inlining causes exceptions if assembly isn't available
- 560196 - [verifier] abort in get_call_info (both x86 and x86_64) while JITting a verified method
- 564695 - LLVM support: this sample generates very slow code.
- 566294 - abort in mono_type_generic_inst_is_valuetype while JITting a verified method
- 566295 - sigsegv in mono_save_args while JITting a verified method
- 566689 - Ahead of time-compiled multithreaded app fails under Mono 2.6.1
- 567084 - sigsegv in mono_method_to_ir while JITting a verified method
- 569390 - SIGSEGV Error with MarshalByRefObject implementing a generic interface
- 574819 - CRITICAL **: mono_bitset_test: assertion `pos < set->size' failed
- 576341 - Modulus on Decimal values does not work as expected
- 581950 - Using checked int64 op codes results in runtime crash
- 582322 - SIGABRT when constructing java.text.DecimalFormat (through IKVM)
- 583817 - SIGABRT (ERROR:mini-trampolines.c:183:mono_convert_imt_slot_to_vtable_slot: code should not be reached) using Saxon
- 586664 - Incorrect values in array after very basic operations
- 559990 - Microsoft.Build.BuildEngine.Engine.UnloadAllProjects() throws an exception when invoked with 1 or more projects
- 423853 - monodoc crashes on search for "()"
- 510995 - Cannot implicitly convert `string' to `object'
- 559045 - Printing an array of enum shows wrong garbage values
- 567900 - Runtime Crash in ves_icall_System_Globalization_CultureInfo_construct_internal_locale_from_specific_name
- 567944 - FirstDayOfWeek not parsed when creating culture-info-tables.h
- 573988 - Soft debugger is broken on systems not supporting MMAP_32BIT flag (Solaris, probably *BSD)
- 565547 - ObjectStateFormatter fails to convert collections from string
- 566541 - Empty HtmlForm produces JavaScript Code
- 568366 - NET_2_0 profile : BuildManagerDirectoryBuilder AddVirtualDir infinite loop
- 568441 - Web.config <location>-><authorization> tag doesn't work
- 568631 - aspx/ascx files can not be compiled when an asp:Literal-tag is embedded in another tags attribute
- 568843 - mod_mono sets max_memory on RLIMIT_DATA, which usually won't do anything
- 571365 - Incorrect JSON Responses
- 572781 - OnInit event of SqlDataSource does not fire.
- 578586 - Cannot compile ASP page using Microsoft Chart Control
- 578880 - System.Web.Hosting.HostingEnvironment's IsHosted, ApplicationID and SiteName properties not provided for a hosted environment
- 579241 - System.Web.HttpFileCollectionWrapper (System.Web.Abstractions.dll) Get method and indexer by name throw exceptions for unfound name/index
- 580086 - Running mod_mono from svn on apache gives constant "Abnormal string size" exceptions
- 580594 - System.Web.Mvc.Resources.MvcResources.resources: Could not find any resources appropriate for the specified culture or the neutral culture.
- 580692 - Treeview nodes not applying font colour correctly using stylesheet class
- 581459 - Process restarts by thread abort with AspNetForums and mono-2.6.3
- 581594 - Plus sign, +, in URLs gets messed up during MVC request handling
- 585933 - DropDownList items and GridView columns don't translate.
- 585968 - XmlDataSource does not update cache when DataFile property changes.
- 585992 - HttpUtility.HtmlDecode does not decode hexadecimal coded HTML entities
- 327053 - System.IO.MemoryStream is too eager in zeroing data
- 473725 - MessageBox.Show() makes no sound
- 505105 - Exception message uninformative (different from with MS .Net)
- 536919 - Parallel.For doesn't execute when number of iterations is fewer than number of processors
- 561239 - Monitor.Pulse() Monitor.Wait() Thread.Abort() cause mono hang
- 564095 - Construct of System.Collections.Generic.List<T>(IEnumerable<T> e) creates list with e.Count null-Elements
- 564910 - The CultureInfo class does not support the Georgian culture
- 565120 - Type.IsVisible might throw null reference exception
- 565152 - Directory.Exist should not ever throw an exception
- 565923 - runtime always SEGFAULT booc.exe upon exit and reports exit code 139
- 566106 - String.IndexOf returns incorrect value
- 567847 - Disabled GroupBox isn't grayed out (ie: looks the same as enabled)
- 567857 - DateTime.TryParseExact throws NullReferenceException on null string
- 567872 - Missing public default constructor on System.Transactions.TransactionAbortedException
- 568026 - TrackBar: Scroll event should occur BEFORE ValueChanged
- 569530 - IndexOutOfRangeException when loading RTF into RichTextBox
- 569806 - mono assumes c99 flexible array member syntax is available without testing
- 569940 - Mono crashes when using System.Drawing.Image.FromFile with a special TIF-File
- 569950 - RichTextBox Modified property not set when (Selected)Text changes
- 571226 - Regression in System.Configuration Test Suite
- 572643 - ForeColor for selected ToolStripComboBox item in ownerdraw mode should be set to highlighted text
- 572660 - mono_metadata_decode_row assertion with System.Reflection.Emit circular array field type
- 572738 - 13 Test Regressions in XmlDataDocumentTest
- 572874 - ValueType.Equals fails on structs containing nullables
- 573322 - Array.SetValue is very unreliable for arrays of Nullable types
- 573682 - segtaults when encoding/decoding non-UTF8 strings
- 575946 - Dynamically generated code doesn't initialize static values as expected
- 575955 - Accessing 2D array cells in dynamically generated code causes crash (assert)
- 575986 - Linq Where extension method fails on typeof(T) for generic method parameter
- 577029 - Can't build ironruby on mono 2.6.1 or trunk
- 579493 - System.NotSupportedException: Custom attributes on a ParamInfo with member System.Reflection.Emit.MethodOnTypeBuilderInst are not supported
- 579791 - HashSet<T> does not handle null values when using a non-default comparer
- 579984 - EMail (SmtpClient) with text and html mail with linked resources are not get generated correctly
- 582440 - ResXResourceReader does not read resource comments.
- 582691 - Return key works intermittently in TextBox
- 585017 - Path.GetTempFileName () takes 100% CPU if /tmp is not writable
- 585455 - HttpListener does not handle authentication completely
- 577090 - Intermittent threading issue with Mono 2.6.1 and SmartThreadPool
- 562320 - [verifier] SIGSEGV in set_stack_value on a bad assembly
- 564897 - [verifier] abort in mono_method_get_signature_full (2) on bad assembly
- 567548 - [verifier] SIGSEGV in mono_class_init (cmethod) on a bad assembly
- 570648 - System.IO.Packaging ZipPackage does not work due to Uri issue
- 582991 - Soft Debugger: Incorrect number or types of arguments error when calling int.Parse
- 576618 - IndexOutOfRangeException on 12 Remoting test suite tests
- 578587 - Global.asax's issue
- r148593 - Fixes the IPY+Chiron test case.
- 556884 - Shadow copies of assemblies cannot be overwritten if originating assembly files are read only
- 545417 - ListView + DataPager fails while trying to set up custom paging
- 565117 - Crash in System.MonoCustomAttrs.IsDefinedInternal
- 565127 - GetGenericParameterConstraints fails on methods in dynamic modules
- 564379 - [REGRESSION] 2.6/svn gmcs throws CS1501 on overload/explicit implementation resolution
- 565602 - string.PadRight(int, char) returns empty string.1.1.
- Verifier integration with the [[Moonlight2CoreCLR|CoreCLR Security Sandbox]: the IL verifier can be integrated by those embedding Mono with the CoreCLR security system to prevent untrusted code from using dangerous operations (like pointer access) or access to restricted APIs (for example, file access)..1.4.tar.gz $ cd libgdiplus-2.6.4 $ ./configure $ make $ make install
Then compile Mono itself:
$ tar xzf mono-2.6.4.tar.gz $ cd mono-2.6.4 $ ./configure $ make $ make install | http://www.mono-project.com/Release_Notes_Mono_2.6.4 | CC-MAIN-2014-10 | en | refinedweb |
Regular. This library became the regex library in Boost, which is accepted as part of the peer- reviewed boost library (see). In this article, I'll show how regex++ can be used to make C++ as versatile for text processing as script-based languages such as Awk and Perl.
Data Validation
One of the simplest applications of regular expressions is data-input validation. Imagine that you need to store credit-card numbers in a database. If such numbers are stored in machine-readable format they will consist of a string of either 15 or 16 digits. The regular expression:
[[:digit:]]{15,16}
can be used to verify that the number is in the correct format; here I have used the extended regular expression syntax used by egrep, Awk, and Perl. Regex++ also supports the more basic syntax used by the grep and sed utilities. However, most people find that the extended syntax is both more natural and more powerful, so that is the form I will use throughout this article. I do not intend to discuss the regular expression syntax in this article, but the syntax variations supported by regex++ are described online (). The documentation for Perl, Awk, sed, and grep are other useful sources of information, as is the Open UNIX Standard ().
To use the aforementioned expression, you will need to convert it into some kind of machine-readable form. In regex++, regular expressions are represented by the template class
reg_expression<charT, traits, Allocator>; this acts as a repository for the machine-readable expression and is responsible for parsing and validating the expression.
reg_expression is modeled closely on the standard library class
std::basic_string, and like that class, is usually used as one of two
typedefs:
typedef reg_expression<char> regex; typedef reg_expression<wchar_t> wregex;
Listing One contains some code for validating a credit-card format; in fact, this code could hardly be simpler, consisting of just two lines.
Listing One
bool validate_card_format(const std::string& s) { static const boost::regex e("\\d{15,16}"); return regex_match(s, e); }
The first line declares a static instance of
boost::regex, initialized with the regular expression string; note that I have replaced the verbose (albeit POSIX standard)
[[:digit:]] with the Perl-style shorthand
\d. Note also that the escape character has had to be doubled up to give
\\d. This is an annoying aspect of regular expressions in C/C++. Since character strings are seen by the compiler before the regular expression parser, whenever an escape character should be passed to the regular expression engine, a double backslash must be used in the C/C++ code. The second line simply calls the algorithm
regex_match to verify that the input string matches the expression. My use of a static instance of
boost::regex here is important this ensures that the expression is parsed only once (the first time that it is used) and not each time that the function is called. Although the algorithm
regex_match is defined inside namespace
boost, I haven't prefixed the usage of the algorithm with the
boost:: qualifier. This is because the Koenig lookup rules ensure that the right algorithm will be found anyway, as long as one of its arguments is a type also declared inside namespace
boost. It should be noted, however, that not all compilers currently support Koenig lookup. For these compilers, a
boost:: qualifier is required in front of the call to
regex_match. For simplicity, however, all the examples in this article assume that the Koenig lookup is supported.
Now suppose that at some point, the application using this code is converted to Unicode. Using traditional C APIs, this could be difficult, however, the library makes this trivial I just had to change
std::string to
std::wstring and
boost::regex to
boost::wregex (see Listing Two).
Listing Two
bool validate_card_format(const std::wstring& s) { static const boost::wregex e(L"\\d{15,16}"); return regex_match(s, e); }
Search and Replace
Frankly, the examples given so far are not all that interesting. One of the key features of languages such as Perl is the ability to perform simple search and replace operations on character strings. Consider the credit-card example again while it may be machine friendly to store credit-card numbers as long strings of digits, this is not very human friendly. Normally, people expect to see credit-card numbers as groups of three or four digits separated by spaces or hyphens. If you print out receipts containing the customer's card number, you would expect to see the number in a human-friendly form. Conversely, if you receive an order by e-mail, the chances are that the card number has not been typed in a machine-friendly form. Fortunately, regular expression search-and-replace comes to the rescue.
In Listing Three, I have defined a single regular expression that will match a card number in almost any format, along with two format strings that define how the reformatted text should look one for a machine-readable form and one for a standardized human-readable form. The regular expression and the format strings are used by two functions (
machine_readable_card_number and
human_readable_card_number) that perform the text reformatting by calling the algorithm
regex_merge. This algorithm searches through the input string and replaces each regular expression match with the format string. Note, however, that the format string is not treated as a string literal; instead, it acts as a template from which the actual text is generated. In this example, I've used a sed-style format string where each occurrence of
\n is replaced by what matched the
nth subexpression in the regular expression. Users of sed or Perl should be familiar with this kind of usage, and the library lets you choose which format string syntax you want to use by passing the appropriate flags to
regex_merge. By the way, the name
regex_merge comes from the idea that the algorithm merges two strings (the input text and the format string) to produce one new string.
Listing Three
// match any format with the regular expression: const boost::regex e("\\A" // asserts start of string "(\\d{3,4})[- ]?" // first group of digits "(\\d{4})[- ]?" // second group of digits "(\\d{4})[- ]?" // third group of digits "(\\d{4})" // forth group of digits "\\z"); // asserts end of string // format strings using sed syntax: const std::string machine_format("\\1\\2\\3\\4"); const std::string human_format("\\1-\\2-\\3-\\4"); std::string machine_readable_card_number(const std::string& s) { std::string result = regex_merge(s, e, machine_format, boost::match_default | boost::format_sed | boost::format_no_copy); if(result.size() == 0) throw std::runtime_error ("String is not a credit card number"); return result; } std::string human_readable_card_number(const std::string& s) { std::string result = regex_merge(s, e, human_format, boost::match_default | boost::format_sed | boost::format_no_copy); if(result.size() == 0) throw std::runtime_error ("String is not a credit card number"); return result; }
Error handling in Listing Three is quite simple by passing the flag
boost::format_no_copy to
regex_merge, sections of the input text that do not match the regular expression are ignored and do not appear in the output string. This means that if the input does not match the expression, then an empty string will be returned by
regex_merge, and the appropriate exception can be thrown. The algorithm
regex_merge will search the input for all possible matches, but in this case, it requires that the expression must match the whole of the input string or nothing at all. Therefore, the expression in Listing Three starts with
\\A and ends with
\\z. Taken together, these ensure that the expression will only match the whole of the input string and not just one part of it (these are what Perl calls "zero width assertions").
If you study the regular expression in Listing Three, you should notice one big improvement over script-based languages; C++ lets you specify a single-string literal as a series of shorter string literals. I've taken advantage of this in Listing Three to split the regular expression up into logical sections, and then to comment each section. When the compiler sees that section of code, the comments will get discarded and the strings will merge into one long-string literal. Perhaps surprisingly, this makes regular expressions much more readable in C++ than in those traditional scripting languages that require regular expressions to be specified as a single long string.
Nontrivial Search and Replace
So far, the examples have concentrated on simple search-and-replace operations that use an existing syntax (either sed or Perl) for the format string. However, it is sometimes necessary to compute the new string to be inserted. A typical example would be a web application that uses a regular expression to locate a custom HTML tag in a file, then uses the match to perform a database lookup. The output would then be another HTML file with the custom tags replaced by the current database information. Imagine that the custom tag looks something like this:
<mergedata table="tablename" item="itemname" field="fieldname"> | http://www.drdobbs.com/cpp/regular-expressions-in-c/184404797?cid=SBX_ddj_related_mostpopular_default_mobile&itc=SBX_ddj_related_mostpopular_default_mobile | CC-MAIN-2014-10 | en | refinedweb |
IRC log of webfonts on 2010-12-01
Timestamps are in UTC.
15:00:25 [RRSAgent]
RRSAgent has joined #webfonts
15:00:25 [RRSAgent]
logging to
15:00:27 [trackbot]
RRSAgent, make logs world
15:00:27 [Zakim]
Zakim has joined #webfonts
15:00:29 [trackbot]
Zakim, this will be 3668
15:00:29 [Zakim]
ok, trackbot; I see IA_Fonts()10:00AM scheduled to start now
15:00:30 [trackbot]
Meeting: WebFonts Working Group Teleconference
15:00:30 [trackbot]
Date: 01 December 2010
15:01:00 [Zakim]
IA_Fonts()10:00AM has now started
15:01:06 [Zakim]
+Tal
15:01:50 [sylvaing]
sylvaing has joined #webfonts
15:02:06 [Zakim]
+ChrisL
15:02:30 [ChrisL]
I started on a disposition of comments
15:02:31 [Zakim]
+tal.a
15:02:32 [erik]
erik has joined #webfonts
15:03:16 [Zakim]
+ +1.978.790.aaaa
15:03:39 [ChrisL]
zakim, aaaa is Vlad
15:03:39 [Zakim]
+Vlad; got it
15:04:19 [ChrisL]
zakim, who is here?
15:04:37 [Zakim]
On the phone I see Tal, ChrisL, tal.a, Vlad
15:04:51 [Zakim]
On IRC I see erik, sylvaing, Zakim, RRSAgent, tal, ChrisL, trackbot
15:05:30 [tal]
I had some phone trouble this morning, maybe zakim got confused by me calling in twice?
15:05:40 [erik]
I'm not able to call in today. I'll follow on IRC.
15:05:57 [ChrisL]
Vlad: having internet issues, will join shortly
15:07:26 [Zakim]
-Vlad
15:07:48 [Zakim]
+Vlad
15:09:11 [Vlad]
Vlad has joined #webfonts
15:10:33 [ChrisL]
Topic: epub update
15:10:43 [ChrisL]
scribenick: chrisl
15:11:16 [ChrisL]
Vlad: strong interest in woff support from many participants, but Adobe representative is against WOFF for epub
15:11:54 [ChrisL]
... if publishers want it, they will add it
15:12:50 [ChrisL]
... waiting for response from internal Adobe discussions. May be opposition was based on resource issues
15:13:13 [ChrisL]
Topic: woff metadata comments
15:14:03 [tal]
15:16:04 [ChrisL]
ChrisL: extensibility via namespaces is good for totally open extensibility
15:16:18 [ChrisL]
tal: we dont want it totally open ended
15:17:05 [ChrisL]
Vlad: want to not deviate too much from the original, and widely deployed, submission. This would be a breaking change
15:17:21 [ChrisL]
... and we do have an extensibility element
15:17:54 [ChrisL]
tal: fontshop and others are using woff with metadata - making all of those invalid is a problem
15:19:23 [ChrisL]
ChrisL: (explains last call process on getting a response back from commentor)
15:19:36 [ChrisL]
Vlad: dont like a breaking change
15:19:53 [ChrisL]
... dont want to invalidate the usage of early adopters
15:21:26 [ChrisL]
action: chris to respond to erik muller on namespaces in metadata
15:21:26 [trackbot]
Created ACTION-51 - Respond to erik muller on namespaces in metadata [on Chris Lilley - due 2010-12-08].
15:22:35 [ChrisL]
action: chris to respond to erik muller on pronunciation and sorting
15:22:35 [trackbot]
Created ACTION-52 - Respond to erik muller on pronunciation and sorting [on Chris Lilley - due 2010-12-08].
15:23:59 [ChrisL]
ChrisL: adding @url to license text elements is a good idea
15:24:54 [ChrisL]
(generally seem to be in favour of separate urls for license elements)
15:25:13 [ChrisL]
Vlad: additional metadata does not override the license
15:26:41 [ChrisL]
Vlad; link can point to a page with multiple further links
15:27:46 [ChrisL]
ChrisL: woff benefit is being explicit on license. prefer to have option for separate ones
15:27:59 [ChrisL]
Vlad: will discuss with Monotype legal
15:28:37 [ChrisL]
tal: nothing changes for existing users. it adds options
15:29:23 [ChrisL]
ChrisL: important that this is not a breaking change
15:30:21 [ChrisL]
Vlad: easier for distributors to use a single place provided by the font owner
15:31:36 [ChrisL]
tal: mentioned that url at top of license, so should allow to have no text below. some foundries want just a link, no text.
15:32:06 [ChrisL]
ChrisL: please send that as a separate comment
15:32:57 [ChrisL]
Vlad: spec is clear that the text in a license element is about the license, not a copy of the license
15:33:54 [ChrisL]
... better to have some text, for users
15:35:09 [ChrisL]
tal: made some fonts for a foundry and they said that they wanted just a url, no text
15:36:17 [ChrisL]
... spec currently says we need both
15:36:26 [ChrisL]
... should it be either/or
15:36:46 [ChrisL]
ChrisL: seems more reasonable to me
15:37:20 [ChrisL]
Topic: test plan issues
15:37:40 [ChrisL]
tal: do we neeed null bytes. some things like that came up in the test plan, they are in red
15:38:28 [ChrisL]
15:39:25 [ChrisL]
tal: in the process of doing the test plan, multiple spec read-thoughs turned up some issues.
15:39:41 [ChrisL]
... some are clear, like the file has to be long enough to contain the header
15:40:08 [ChrisL]
... if the flavour is in contradiction with the actual table data. spec is silent on that.
15:40:42 [ChrisL]
ChrisL: there are multiple flavours for truetype
15:41:16 [ChrisL]
tal: thses have caused problems for text engines before
15:41:46 [ChrisL]
Vlad: packaging mechanism is separate - if you package a broken thing, the package is not at fault
15:41:59 [ChrisL]
tal: jdaggett said list them all, so i did
15:42:24 [ChrisL]
Vlad: think that particular one is out of scope
15:43:11 [ChrisL]
tal: its additional tests
15:43:37 [ChrisL]
Vlad: may cross boundary between packaging and font sanitising
15:45:14 [ChrisL]
ChrisL: these are good for a validator, but in spme cases its not the woff spec that is violated but the OT spec
15:45:29 [ChrisL]
tal: some t=of these are crashing bugs for certain OS
15:45:59 [ChrisL]
tal: number of tables, needs to be parseable
15:46:29 [ChrisL]
tal: some are tagged as format bit also need to be UA conformance as well
15:47:27 [ChrisL]
... read the wiki pages
15:48:22 [ChrisL]
Vlad: anything here needs more discussion?
15:48:31 [ChrisL]
tal: tried to be very clear
15:49:24 [ChrisL]
Vlad: lets discuss on email and make resolutions next week on the red items
15:49:32 [ChrisL]
15:49:53 [ChrisL]
tal: have worked on infrastructure for tests
15:50:26 [ChrisL]
... have been reading the css testsuite documentation
15:51:04 [ChrisL]
adjourned
15:51:11 [ChrisL]
zakim, list attendees
15:51:11 [Zakim]
As of this point the attendees have been Tal, ChrisL, +1.978.790.aaaa, Vlad
15:51:14 [ChrisL]
chair: vlad
15:52:18 [ChrisL]
(general appreciation for tal's work)
15:52:20 [ChrisL]
rrsagent, make minutes
15:52:20 [RRSAgent]
I have made the request to generate
ChrisL
15:52:27 [Zakim]
-Tal
15:52:28 [Zakim]
-tal.a
15:52:28 [Zakim]
-ChrisL
15:52:32 [tal]
tal has left #webfonts
15:52:33 [Zakim]
-Vlad
15:52:34 [Zakim]
IA_Fonts()10:00AM has ended
15:52:36 [Zakim]
Attendees were Tal, ChrisL, +1.978.790.aaaa, Vlad
18:00:26 [Zakim]
Zakim has left #webfonts | http://www.w3.org/2010/12/01-webfonts-irc | CC-MAIN-2014-10 | en | refinedweb |
dotPeek Features
.NET assemblies to C# code.
C# code to Visual Studio projects
As soon as you've decompiled an assembly, you can save it as a Visual Studio project (.csproj).
That helps a lot if you're trying to reconstruct lost source code of an application..
Use the navigation mode drop-down in the menu bar to choose whether you only want dotPeek to decompile assemblies, or try find source code if possible.
Installer or executable
dotPeek is distributed in several ways:
- As an .msi installer for easier version management.
- As 32-bit and 64-bit .exe files if you prefer to keep tools like dotPeek in a location shared between your machines.
Open archives or folders
In addition to traditional assemblies and executables, you can have dotPeek open archives (including .zip, .vsix, and .nupkg formats) and folders. For example, when you point dotPeek at a folder, it processes all its subfolders in hunt for files that it can decompile._3<<
Rich Assembly Explorer.
Find usages of any symbol
With dotPeek, you have several options to search where code symbols are referenced.
Specifically, Find Usages displays all usages of a symbol (method, property, local variable etc.) characteristics.
Finally, Highlight Usages in File puts highlighting on usages of a symbol in the current file, depending on whether it's a write or read usage:
Context-sensitive navigation
Whenever you put a caret on a symbol in the code view area, dotPeek offers a plethora of contextual navigation options that are all available via Navigate To drop-down menu:
.
Bookmarks
If there are lines of decompiled code that you feel are important and you want to go back to them later, feel free to set bookmarks::
Perfect for ReSharper users
Long-time users of JetBrains ReSharper will feel at home working with dotPeek as it provides ReSharper-like navigation and search, code insight, and keyboard shortcuts.
Actually, if you have experience working with other intelligent developer tools from JetBrains, you'll be able to apply your habits as well.
dotPeek indexes all assemblies in your assembly list, as well as all assemblies that they reference, and provides two ReSharper-based features to quickly jump to specific code from this aggregation:
- Go to Symbol helps navigate to a specific symbol declaration, which could be a type, method, field, or property. You can use lowerCamelHumps syntax to locate types — for example, entering xmard is enough to locate and open XamlMarkupDeclaredElement.
- Go to Everything allows searching for an assembly, namespace, type or member from the same input box, and also viewing recently opened files. lowerCamelHumps syntax is supported here as well.
Overview of inheritance chains
If you're interested to navigate up and down the inheritance hierarchy from a specific type or type member, you can always lean on two contextual navigation options: Go to Base Symbols and Go to Derived Symbols.
These are extremely useful when you want to go to an inheritor or a base symbol right away.
However, if you're looking to get a visual overview of a certain inheritance chain, use Type Hierarchy instead: dotPeek will show you all types that are inherited from the selected type, as well as types that it inherits itself — as a tree view, in a separate tool window:
Show compiler-generated code
You can choose to turn off certain compiler transformations, thus making code structure that dotPeek displays very similar to what the compiler turns it to. This helps see how compiler deals with lambdas, closures, and auto-properties, among other things.
Complete keyboard support
dotPeek is a keyboard-centric application, providing keyboard shortcuts for most actions.
By default, dotPeek uses the Visual Studio keymap derived from ReSharper. dotPeek also provides another shortcut scheme familiar to ReSharper users: the IntelliJ IDEA scheme. You can switch between these schemes via Tools | Options | Environment | General. | https://www.jetbrains.com/decompiler/features/ | CC-MAIN-2014-10 | en | refinedweb |
Liquidat has posted a nice overview of the technology known as NEPOMUK, a part of KDE 4. An excerpt reads: "Nepomuk-KDE is the basis for the semantic technologies we will see in KDE 4. Sebastian Trüg, the main developer behind Nepomuk-KDE, provided me with some up2date information about the current state and future plans".
To me, the hard problem here always was how to share and transfer the metadata between users and machines. For instance, suppose I am using more than one machine; would the Nepomuk information created on one machine even make sense on the other? Would it be possible to sync the databases between machines? Is it possible to distill out a meaningful, privacy-filtered subset of the data and send that to a friend? What happens when I reorganise all of my data using non Nepomuk aware tools?
I see in the article that there are some plans to address these issues, but it seems they have not been solved so far. Any thoughts?
Just a KDE user here wanting to say that is a good question
I hadn't thought about it but the problem you bring up should be thought about. Though I don't know, I assume that any non-nepomuk enabled desktop won't support tags made with a nepomuk desktop. Perhaps if a nepomuk is brought to all of the free desktops than atleast we can be assured that it would work on all the free operating systems.
In a way, KDE is the first largescale test. If it works out, perhaps it'll be adopted elsewhere (gnome, xfce,... perhaps even a proprietary OS like OSX?).
Actually, as far as this goes, I was somewhat certain that OSX already had a framework in place for the support of arbitrary metadata. I'm not sure on details, but a friend of mine was talking about it at length one night
For Mac OS X, Apple's Spotlight system is very similar, but not exactly the same. You can write metadata importer plugins which can add, index, and search arbitrary metadata.
However, programs like Google Desktop for Mac OS X show that it's possible in some ways to integrate other systems with Apple's Spotlight metadata system....
i'm not a semantic web (SW) expert, but i had to study it for school (uni). but for all i know the SW technologies are build with exactly what both you guys ask for: distributed and sharing oriented.
SW basically allows computers to understand that something means, and how that relates to other information. it's all about describing (annotating) data in standard, computer readable way.
That sounds like pure and plain xml.
RDF/XML is one format for it. Internally, it's probably going to look more like the Notation3 (N3 format) -- just a list of "triples": lines like "uri1 relationship uri2". For instances, you might declare relationships like " photographer_of", or "googleearth://postcode location_of ipinfo://yourserver") or " manufacturer_of companyservers://missioncriticalserver1".
As an ancestor post said, this is pretty much perfect for exporting/importing/otherwise sharing info. You can easily create queries based on this data, like "? photographer_of ?", to get a list of all photographers, or "? photographer_of*" to get a list of all photos published by your company. Then, you just need to provide that list to others in some way. Depending on how its implemented, it might also be possible to mark certain namespaces as private, but make the rest available, so that anything referring to objects such as "myborrowedmp3collection://*" or "topsecretprojects://*" or just "smb://" gets filtered, but everything else is made available. Likewise, and probably more safely, the opposite could be true, with only public namespaces made available.
Interestingly, let's say you have a kde io plugin that understands URIs with unique hashes, and deferences those to the appropriate files: something like "md5://number". By publishing this on some shared site (say nepomuk_repository.kde.org), then every KDE user with that file could automatically gain all the (non-filtered, public) tags of information that any other participating KDE user contributes. So, some KDE user in taiwan might mark set a song attribute such as "amarok://performed_by amarok://artist/Sarah McLachlan", and everyone else's desktop would suddenly know this.
For general queries, let's assume Wikipedia will take up the (already very functional) Semantic MediaWiki Extension at some point. Then, it'll be possible for your desktop to ask Wikipedia for all sorts of complicated information, like "countries with a population of more than 1,000,000, but less than three internet providers", or, for a more basic Unix utility, "languages that include the characters X, Y, Z, but not A". Or, for a person in need of medical help, they might consult a national medical database, along with a blog site, asking for "doctors within coordinates A,B and C,D who specialise in earache and who no one called a sadist". Within an organisation, lots of useful queries, like "people working on project X, who work over lunch" would be possible.
No one's saying the file format (be it XML/RDF, N3, CSV, or something else) is revolutionary (although, in the relative simplicity of N3/RDF, they do make some advances, I suppose). The trick is in taking all these information sources, combining them into a huge database of triples that performs well, and designing the right queries, the right interfaces, the right amount of sharing, and the right security features, so that your desktop "knows" more than it used to, and can work with other systems that know more than they used to, without being bogged down by the terabytes of new data we're soon going to be using for this.
Of course, this all depends on your own/others' ability to organise information, but it's all coming together, from other projects online. This WILL take off, and it will almost certainly be the REAL Web 2.0, that people actually notice, like they noticed Web 1.0. KDE *must* be part of that, and I'm very glad to see it's going to be there.
I DO hope KDE's/NEPOMUK's not going to be limited to simple things like tagging and searching files though, much as I want to see KDE have those features. At the very least, I'm hoping to see what GNOME's (now abandoned, for some insane reason) hint-based system did: let applications actually share knowledge in real time, like "user is working with a document that has subject X" and "Oh, I have files related to subject X". It's unclear whether NEPOMUK will actually allow the kind of things described above. The technology certainly does, though, and Nepomuk is claiming to advance it, as I understand things.
Neopomuk cooperates with freedesktop.org, however I don't know how good this cooperation works, and what standards will be defined there or if those standards will address those issues.
On the Mandriva Club there is also an interview with nepomuk-kde developer Sebastien Trüg:
On Liqudiat's blog there is quite a lot of support for using xattributes, yet it seems like this option won't be used. Can anyone explain why?
- not all filesystems support it
- you'll need a database anyway to be able to search through it
I dunno what the performance is, either...
- not all filesystems support it.
Most of the well used ones support it.
- you'll need a database anyway to be able to search through it
Well yes, but xattributes is about making sure the tags move with the file. Not searching.
metadata you can't search is completely useless.... that's the point of nepomuk, isn't it? finding and connecting stuff through metadata. therefor you need a central index. an index scattered through the whole filesystem is useless. that's why everyone is working on something like strigi...
Sure, but you could have some kind of minimal metadata attached to the file to differentiate it from other files, and the full metadata in the index. Otherwise how would you cope with:
echo Hello > ~/myfile
# I go to Dolphin and tag myfile
cp ~/myfile ~/myfile.bak
mv ~/myotherfile ~/myfile
mv myfile.bak ~/myfile
Unless you have some way of disambiguating files *other* than their name, you're going to have issues confusing the metadata of these two different files.
Now, there are various ways you could handle this. xattrs would be the obvious one to me, but I guess you could also have others.
that only works if you want to find the metadata of a file. whats with the other way around? i want to find every file i got per mail.
its quite simple: if you move the file you break the index. the index needs to be updated everytime a file is moved.
>that only works if you want to find the metadata of a file. whats with the other way around? i want to find every file i got per mail.
That's why you have the same data stored in the file and in the database. Having the metadata in every file means that all applications automatically keep the metadata intact without modification. Having the metadata in a database allows fast searching.
>its quite simple: if you move the file you break the index. the index needs to be updated everytime a file is moved.
but the database is broken every time you move a file even if no metadata is stored in the file.
The database will have to include the location of every file so when you search for files based on metadata you probably want strigi to tell you where to find the file, this means the location of the file has to be in the database and updated every time a file moved.
Why have "files" in the first place? Why "copy/move them around"? They are just
sequences of bytes. Why should I have a file manager? Isn't that what we want to
replace? The only reason is different physical computers on a network. But we could imagine even that to be irrelevant in some, not so far, point in the future.
You have the meta-data in the file and in a database.
It goes in a file to ensure that the file keeps the correct metadata even after mv, cp, dd or being E-mailed. Etc.
It goes in a database to be searched.
> or being E-mailed ?
than the metadata needs to be stored inside the _file_. The filesystem is of no help here... or do you want to email your filesystem?
but this doesn't solve the whole problem. if you move a file you still have to change the index, otherwise you could only find the oldlocation of the file. so you don't gain much.
so if you have to change the index everytime a file moves anyway, there is no real gain from storing anything with the file.
also, you don't need a filename or an id to track files. look at modern version controll systems like monotone or git. the identity of a file isn't an id, or a name. its the content - so use a hash. that would automatically solve all copy problems.
the only remaining problem would be tools that alter the file somehow. that should be solved by nepomuk integration into all applications. for legacy apps you could store the location of a file too. so if you overwrite a file, the index should automaticaly "transfer" the metadata, if not told otherwise through the nepomuk api.
so with this in place, the only scenario that could break the data-metadata relationship would be legacy applications (apps without nepomuk support) which create "copies" of files with new content (like converting images).
but that's a case you can't do anything about.
You also have to remember that most apps move the old file to a backup file (eg. xx~) and write a new file. Unless the app knows to copy the meta data it will be lost at this point.
The filesystem _is_ a database. A metadata supporting filesystem can maintain its own indexes. Why put the file and metadata relationship on such a high level if you don't need to? There might be considerable overhead space-wise, but with 1TB harddisks getting mainstream soon this should not be a big problem.
If you put this indexing responsibility on filesystem level you get automatic, default nepomuk support for low level commands like cp and mv.
If you want this information to 'cross over' non-metadata filesystems you can use higher level tools. I could see a project like BasKet fit such a role for example.
Regarding hashes to bind relationships, I think this is not so useful on a filesystem. reading the full content of a couple of ISO files or a large mp3 collection just to get the hashes seems a little inefficient to me. And a hash still isn't as uniquely identifying as a URI.
I just started a FAQ page for Nepomuk-KDE. The first question I answer there is the xattributes one.
You can find the FAQ at:
Thanks :)
Thank you, please could you use this for the second question:
"Will my file lose the metadata associated with it if I use generic rather than Nepomuk specific tools to move files around (FTP, mv, cp, a non-kde file manager, firefox upload. etc)
I'll be curious to see how it turns out. WinFS was supposed to have a metadata based filesystem, but WinFS is vaporware at this point. If KDE beats Microsoft to the relational/metadata/integrated-search desktop, I think a lot of businesses might suddenly become interested. I haven't gotten a chance to try Nepomuk, but I really like Strigi - it's freaking fast (compared to Beagle, which I tried previously) and it doesn't have security holes like Google Desktop Search (which I haven't tried, because of the constant "A new zero-day hole has been found in Google Desktop!" stories on Slashdot).
The file system argument is a good one: Isn't is all about filesystems? I think distributors need to think more about filesystems. For our home partition a crypto file system should be standard. I don't know whether user space solutions make much sense.
I posted an italian translation of this article:... | http://dot.kde.org/comment/50627 | CC-MAIN-2014-10 | en | refinedweb |
JXMLPad is a java component for editing XML/HTML document.
Main :
Documentation :
Download :
News :
- add a DocumentInfo objet inside the current XMLContainer for improving the document action management (loading/saving with the good filter, default DTD...)
- Each time a document is updated, the cursor is located before the first tag and the current editor gets the focus
- SystemHelper for completion on comment, cdata and system part
- Document integrity available inside the XMLContainer for avoiding to save a bad XML document, or to avoid user to corrupt tags
- All default action return a boolean inside the notifyAction method showing if no error has been met
- Features have been added on actions
- A comment is removed when no content is found
- A toolkit has been added for editing easily single file (com.japisoft.xmlpad.toolkit.SingleDocumentEditor)
Bugs fixed :
- Undo was available for a new document
- Old DTD completion was reused for new document without DTD
- Syntax coloration for comments was bad for multiple empty lines
- Parsing was not validating for a document with a DTD
- Formatting could create attribute duplicata
- User could insert a comment inside a tag
Features :
* JDK 1.2 and later version compatible
* Java bean usage
* Syntax coloration (tag, string, entities...)
* Syntax completion for tag and entities
* Look-and-feel plugIn
* Customizable action toolbar
* Customizable coloration for tags, attributes,namespaces
* Syntax correction
* Template for easy creation
* Easy to integrate in your application
* Several standard action for XML usage (parsing, search, comment...)
* Standard Swing EditorKit
* Real time tree text synchronization and location
* Auto tag closing
* Customizable with a property file
* Sample for JSP/XML editing, applet and standalone usage
* Sources can be provided for the registered version
Best regards,
A.Brillant
Forum Rules | http://forums.codeguru.com/showthread.php?264543-Rules-for-the-Announcements-Forum&goto=nextnewest | CC-MAIN-2014-10 | en | refinedweb |
Fabio Luis De Paoli <[email protected]> wrote in message
news:[email protected]...
> I've searched the JTable API and the Java tutorial but I haven't been able
> to discover how to change the color of one specific JTable row.
>
You use a JTableRenderer to do that. Here's an example of one that I use:
public class IStringTableRenderer extends BNBTableRenderer implements
TableCellRenderer
{
private IString rendered;
public IStringTableRenderer(IString is) {
rendered = is;
}
public Component getTableCellRendererComponent(JTable table, Object value,
boolean isSelected, boolean hasFocus,
int row, int col) {
Component renderer = super.getTableCellRendererComponent(table, value,
isSelected, hasFocus, row, col);
if (row != 0 && rendered.isOverridden(row))
renderer.setFont(BNBUtil.boldFont);
else
renderer.setFont(BNBUtil.plainFont);
return renderer;
}
}
To have the JTable use this to render its cells, I just write
theTable.setDefaultRenderer(Object.class, new IStringTableRenderer(is));
Forum Rules
Development Centers
-- Android Development Center
-- Cloud Development Project Center
-- HTML5 Development Center
-- Windows Mobile Development Center | http://forums.devx.com/showthread.php?29429-JTable-colored-rows-how-to | CC-MAIN-2014-10 | en | refinedweb |
EA offers full PC games as demos
9th Dec 2008 | 13:23
Timed demo of Burnout Paradise launches in February
The PC version of Burnout Paradise arrives in February, with EA trialling an innovative way of demo'ing the title – by offering the full game for gamers to try out for a limited period of time.
If you have yet to play the console version, then you really have no excuse for at least giving it a whirl in February, after all, what else will you be doing early next year? Crying over credit card bills? Putting off that personal tax return (again)?
EA shows how to demo
EA and developer Criterion will let you play the full game for a limited time, including all of the game's events and multi-player options, choosing from three cars to destroy and mangle till your heart's content (well, for a limited time…)
The real advantage here is that you can check that the game runs alright on your PC before you decide to buy.
EA will be letting us know more details on how long the trial will be made available for shortly. | http://m.techradar.com/news/gaming/ea-offers-full-pc-games-as-demos-492625 | CC-MAIN-2014-10 | en | refinedweb |
17 June 2009 18:17 [Source: ICIS news]
WASHINGTON (ICIS news)--US oil and gas producers said on Wednesday they have formed lobbying alliance with 15 labour unions to press Congress and the Obama administration for more access to domestic oil and gas resources.
The American Petroleum Institute (API) said it has joined with unions representing workers in the energy industry to form the oil and natural gas industry labour-management committee.
The committee’s goal is “to preserve and create jobs by promoting innovative and affordable access to energy that is vital to the American economy”, according to the group’s announcement.
The group will launch a communications campaign “to educate the public and other stakeholders about the effects of legislation that would restrict exploration or hinder processing, refining and marketing of ?xml:namespace>
The API and other energy industry groups have complained that policies being advanced by the administration of President Barack Obama and legislation being pursued in Congress discourage and even penalise conventional oil and gas exploration and development.
“Some proposals being advanced by various interests are not in the best interest of
“And that is where some our interests come together [with labour unions] to educate people,” he said. “Our role will be to go up there arm-in-arm to not only educate them on the need for energy but also for the need for job creation that comes with energy development.”
Gerard said that issues the committee will pursue with the administration and Congress include “access to our nation’s vast oil and gas reserves and tax policies that discourage energy investment in the
The US petrochemical industry and downstream chemical makers also are concerned about access to domestic US energy reserves because they are heavily dependent on natural gas as a feedstock and power fuel.
Mark Ayers, president of the AFL-CIO’s building and construction trades department, said the new lobby group “will support policies that protect and promote job security and growth in the oil and natural gas industry”.
The alliance of oil and gas producers with labour unions could add weight to the energy industry’s efforts to lobby Congress.
While the energy industry traditionally has been aligned with the more pro-business Republican Party, labour unions have close ties with the Democrat Party and could provide added influence with the White House and the Democrat majority in Congress.
In addition to the AFL-CIO, unions represented in the alliance include the International Brotherhood of Teamsters, the International Brotherhood of Electrical Workers, the United Brotherhood of Carpenters and Joiners of America, and others representing metalworkers, bricklayers, masons and operating engineers. | http://www.icis.com/Articles/2009/06/17/9225726/us-oil-and-gas-producers-join-with-unions-on-energy-policy.html | CC-MAIN-2014-10 | en | refinedweb |
I can’t see how ‘ blist[in_id].erase();’ could possibly compile. It should be ‘ blist.erase(in_id);’
Please log in or register to post a reply.
I can’t see how ‘ blist[in_id].erase();’ could possibly compile. It should be ‘ blist.erase(in_id);’
No. The operand to ‘delete’ must be a pointer to the object you are trying to destroy, so dereferencing it first makes no sense.
However, take a good look at what you’re doing. You first destroy the object, and after it’s destruction, you tell it to remove itself from the map. How can you tell an object something if it’s already destroyed?
So you have to reverse the order of things. Or you could simply use the erase() method on the map using the index of the bullet.
@Kenneth Gorking
I can’t see how ‘ blist[in_id].erase();’ could possibly compile. It should be ‘ blist.erase(in_id);’
Oh, I actually assumed it was blist[in_id]->erase().
A note to the topicstarter: copy/paste (the isolated parts of) your code as is, to avoid this kind of confusion.
Thanks for all your input!
So… store the pointer in another pointer, erase it from the map, THEN delete the memory. Got it! I’ll try it when I get home.
Sorry about not copying the code as-is. I figured it was more theorycraft than anything. I’m actually at work where I have no access to my code. So thanks for bearing with me :)
Tried copying to pointer first, still crashes with fatal error. I now have the code in front of me. Please take a look if you can.
void BulletCollection::update() { // ***************************** update() ****************************** // update the collection and everything in it std::map < int, Bullet *>::iterator iter; // temp iterator to go through the map blist for ( iter = blist.begin(); iter != blist.end(); iter++ ) { iter->second->update(); } } void Bullet::update() { // ********************** Bullet Update() ****************************** if ( ttl-- < 0 ) { BC->killBullet( id ); // tell the collection to delete, id is private member of Bullet } } void BulletCollection::killBullet( int bulletid ) { // ************** kill a bullet ************* Bullet *btemp = blist[bulletid]; // temporary pointer to hold item to be erased blist.erase( bulletid ); // remove it from the list delete btemp; // delete the memory }
I believe something wonky is happening when I do blist.erase( bulletid )… When the crash happens, some file called xtree is opened up in my Visual Studio. Please help, I’m pulling hairs out over here.
BTW, even when I comment out // delete btemp; it still crashes, so it’s probably blist.erase
Thanks,
Flamesilver
Ah, classic mistake :)
You’re iterating over the map, but while you’re iterating, you’re deleting items. The ‘iter’ variable in BulletCollection::update() is still referencing an element that is already removed from the map, and incrementing that invalid iterator and dereferencing it will result in undefined behavior.
To circumvent the problem, you could increment the iterator before you call Bullet::update(), so you know which iterator to use in the next iteration of the loop.
Be aware of the iterator invalidation rules of various containers. For a std::map it is defined that only iterators to deleted items become invalidated. But for a std::vector, however, any iterator that points to or past the deleted element is invalidated.
Thanks for the help oisyn. The iterator range problem is fixed and I’m no longer crashing with Fatal Error. But now I’m getting a heap corruption error.
#include "vect2.h" #include "GameForm.h" #include "DarkGDK.h" #include "FulcrumPhy.h" #include <map> #define BULLETSTARTNUM 100 #define BULLETENDNUM 1000 class Bullet { // **************************** Bullet Class ***************************** private: int id; int ownerid; // id of creator int ttl; // number of cycles of life remaining BulletCollection *BC; // Collection so I know where to kill public: Bullet( int in_id, int in_ownerid, BulletCollection *in_bc, int in_ttl = DEFAULTTTL ); // CTor ~Bullet(); // DTor int getid() { return id; } // accessor for id int getttl() { return ttl; } // accessor for ttl int getownerid() { return ownerid; } // accessor for ttl void update(); }; class BulletCollection { // ************************** Hack BulletCollection Class (Precursor to GameSpace) ***************************** // * // * private: TicketSystem *TS; // TicketSystem used to assigning object id's std::map< int, Bullet *> blist; // bullet list - all currently live bullets public: FulcrumPhy *FP; // Fulcrum Physics Pointer BulletCollection( FulcrumPhy *in_Physics ); // CTor - allocate TicketSystem TS ~BulletCollection(); // DTor - free memory for TS and all void createBullet( int creatorid ); // make a bullet void killBullet( int bulletid ); // kill a bullet void update(); // update the collection and everything in it }; BulletCollection::BulletCollection( FulcrumPhy *in_Physics ) { // ********************** BulletCollection::CTor ****************************** // * allocate TicketSystem TS FP = in_Physics; TS = new TicketSystem(BULLETSTARTNUM, BULLETENDNUM); } BulletCollection::~BulletCollection() { // ********************** BulletCollection::DTor ****************************** // * // DTor - free memory for TS and all // * // * // delete the collection and everything in it std::map < int, Bullet *>::iterator iter; // temp iterator to go through the map blist for ( iter = blist.begin(); iter != blist.end(); iter++ ) { killBullet ( iter->first ); } delete TS; } void BulletCollection::createBullet( int creatorid ) { // ********************** createBullet ****************************** // * // * make a Bullet and add it to blist // * int creatorid - the guy who made the bullet // * Bullet *b = new Bullet ( TS->getTicket(), creatorid, this ); // allocate a new Bullet object blist[b->getid()] = b; // ** add b to the map of all bullets so it can get updated ** // Create a vector that's pointing away from the ship vect2 vPadding; vPadding.setXYFromAM( dbObjectAngleZ( creatorid ), 20 ); // ** Set the Bullet position to the player's, Move the bullet according to the player but faster by scale ** FP->setPosition ( b->getid(), dbObjectPositionX( creatorid ) + vPadding.x, dbObjectPositionY( creatorid ) + vPadding.y, 0 ); FP->setLinearVelocity ( b->getid(), vPadding.x * 5 + FP->getLinearVelocityX ( creatorid ), vPadding.y * 5 + FP->getLinearVelocityY ( creatorid ), 0 ); /*FP->setLinearVelocity ( b->getid(), FP->getLinearVelocityX ( creatorid ) * 3, FP->getLinearVelocityY ( creatorid ) * 3, 0 );*/ } void BulletCollection::killBullet( int bulletid ) { // ************** kill a bullet ************* // remove it from the list Bullet *btemp = blist[bulletid]; // temporary pointer to hold item to be erased blist.erase( bulletid ); delete btemp; } void BulletCollection::update() { // ***************************** update() ****************************** // update the collection and everything in it std::map < int, Bullet *>::iterator iter = blist.begin(); // temp iterator to go through the map blist Bullet *tb; // temp bullet pointer while ( iter != blist.end() ) { tb = iter->second; iter++; // iterate BEFORE possibly calling killBullet() and invalidating the whole thing tb->update(); // now call update } /*for ( iter = blist.begin(); iter != blist.end(); iter++ ) { iter->second->update(); }*/ } Bullet::Bullet( int in_id, int in_ownerid, BulletCollection *in_bc, int in_ttl ) { id = in_id; ownerid = in_ownerid; BC = in_bc; ttl = in_ttl; dbMakeObjectSphere ( id, 3 ); // create physical object BC->FP->makeSphere ( id, true ); // add to physics program } Bullet::~Bullet () { // *********** DTOR *********** // * Release the object created BC->FP->releaseActor(id); // release Actor (delete Object) from Physics through BulletCollection dbDelete(id); // delete the object from DGDK } void Bullet::update() { // ********************** Bullet Update() ****************************** if ( ttl < 0 ) { BC->killBullet( id ); // tell the collection to delete, id is private member of Bullet } ttl--; }
I did look up Heap Corruption, and now have the idea that I must be trying to free the same resource twice… but void BulletCollection::killBullet( int id ) is the only place I have delete!
Please advise.
Thanks,
Flamesilver
PS: Yes, I’m aware that \~BulletCollection() DTor still has that iterator problem. That’s an easy fix. But alas, it’s still crashing when a ttl runs to 0 on a bullet, I think.
Heap corruption can be due to a number of issues
.edit: are you sure GetTicket() never returns the same int twice?
The only reason why I don’t think the TicketSystem class is at fault is because as soon as the first bullet dies (ttl < 0) I get the heap corruption error.
I’m really going to have to think long and hard and test a few things to see what’s really bugging the system…
FOUND IT!
void Bullet::update() { // ********************** Bullet Update() ****************************** ttl--; // decrement BEFORE so we're not writing to already deleted memory if ( ttl <= 0 ) { BC->killBullet( id ); // tell the collection to delete, id is private member of Bullet } }
Previously –ttl; was after the killbullet call, so it would try and write to a variable that was deleted.
Thanks for telling me about the rules of Heap. Devmaster.net is so awesome!
PS: Without you guys, I wouldn’t’ve gotten very far. So far I’ve got a 3D space game with overhead fixed camera, overhead chase, and 3rd person camera view, full physics implemented via fulcrum, and I can fire bullets that interact with other ships (and give knockback). Soon I’ll have a working game! Thanks guys!
Need some help on dynamic memory allocation (actually, de-allocation) as I’m re-navigating the learning waters for C++.
Say I have 2 classes -
class BulletCollection;
class Bullet;
BulletCollection is responsible for instantiating / destroying Bullet objects by allocating new Bullet instances and storing the pointer in its std::map<int, Bullet*> so it can be iterated through, etc. Looks something like::
My problem is my BulletCollection::killBullet() is giving me weird issues (crashes).
And in my BulletCollection::killBullet( in_id ) I have something like:
…? | http://devmaster.net/posts/19332/dynamic-memory-destruction-in-objects | CC-MAIN-2014-10 | en | refinedweb |
The C++ header requires several properties and methods that must be overridden from the base class:
Use only ASCII characters for file include path, C++ class name, and variables.
If you have third-party Arduino® libraries for your Arduino hardware that you will use with your add-on, install it at the following locations:
Windows® and Linux® -
"
arduinoio.IDERoot/portable/sketchbook/libraries/"
Mac- "~/Documents/Arduino/libraries/"
The LibraryBase class provides all the necessary
functionality for executing the code from the #bu7z4iu. At the beginning of the file C++ header file, you
must include the
LibraryBase.h library:
#include "LibraryBase.h"
You can include additional libraries following
LibraryBase.h.
Typically, these libraries are third-party Arduino libraries for your Arduino hardware that provide direct access to specific functionality.
Your base add-on class C++ header must extend the LibraryBase class:
class MyAddon : public LibraryBase { ... };
If you have included additional third-party libraries, make sure the name of
your add-on class (e.g.
MyAddon) is not the same as the name
of any of the classes defined in the third-party libraries.
Extending the
LibraryBase.h class provides access to the
appropriate methods and properties. The following diagram shows the typical method
inheritance for an add-on:
The add-on constructor defines the name of your add-on library and registers the
library with the main Arduino program. Your add-on class must override the default constructor
method of the LibraryBase. The constructor uses the same
name as your add-on class and takes a reference to a
MWArduinoClass object.
public: MyAddon(MWArduinoClass& a) { libName = "MyAddonPackageFolder/MyAddon"; a.registerLibrary(this); }
The library name property,
libName, must be the same string
defined in the Library Specification of the MATLAB Add-On Class:
<AddonFolderName>/<AddonName>
The add-on library is registered with the general
MWArduinoClass object using the
registerLibrary method. For example, the constructor from the
Create HelloWorld Add-On example uses the following constructor:
public: HelloWorld(MWArduinoClass& a) { libName = "ExampleAddon/HelloWorld"; a.registerLibrary(this); }
The
commandHandler method is the entry point for the commands
executed in your MATLAB Add-On Class that were executed by the
sendCommand. Your add-on class
must override the default
commandHandler method of the LibraryBase class.
public: void commandHandler(byte cmdID, byte* dataIn, unsigned int payloadSize) { switch (cmdID){ case 0x01:{ … sendResponseMsg(cmdID, val, 13); break; } … // Other cases with appropriate cmdIDs default:{ // Do nothing } } }
The switch statement uses the command identifiers,
cmdID, to
determine the segment of code to execute. The
cmdIDs must match
those defined in the MATLAB Add-On Class. At the end of each switch
statement, the
commandHandler must call the
sendResponseMsg function:
sendResponseMsg(byte commandID, byte* dataOut, unsigned int payloadSize)
The data assigned to the input arguments
dataOut, and
payloadSize returned to the output arguments of the
sendCommand function.
Execution of the
sendCommand called within the
MATLAB Add-On Class held until either a
sendResponseMsg executes or the
timeout condition is reached.
The
commandHandler method from the Create HelloWorld Add-On example shows how a string,
'Hello
World!', can be created in the C++ code and returned to the MATLAB Add-On Class through the
commandHandler:
public: void commandHandler(byte cmdID, byte* dataIn, unsigned int payloadSize) { switch (cmdID){ case 0x01:{ byte val [13] = "Hello World!"; sendResponseMsg(cmdID, val, 13); break; } default:{ // Do nothing } } }
The
setup method can be used to initialize and set the initial
values. Your add-on class can override the default
setup method
of the LibraryBase class to initialize variables. The Create LCD Add-on example overrides the default
setup method to reset the cursor to the first row upon
initialization as shown:
public: void setup() { cursorRow=0; }
The
loop method can be used to perform certain repetitive
tasks. Your add-on class can override the default
loop method of
the LibraryBase class. In the example below, if
mcused is true, the controller remains on.
void loop() { if(mcused) { controllerMW.ping(); } }
Do not use any blocking operation in the
loop
method.
The LibraryBase also provides a convenient function,
debugPrint, to display messages to the MATLAB® command line to help in development of
your add-on.
The
debugPrint function uses the same syntax as the C++
printf function:
debugPrint(MSG_EXAMPLE_DEBUG);
The debug message must be declared in the C++ header file using the following syntax:
const char MSG_EXAMPLE_DEBUG[] PROGMEM = "This is a debug message.\n";
where the string
PROGMEM is the message displayed. Additional
information can be included in the debug message using format specifiers. To enable
debugPrint messages to be displayed to the MATLAB command line during run-time, you must set
the additional Name-Value property ‘trace’ in the
arduino function:
The Create HelloWorld Add-On example prints to the MATLAB command line a sample debug message with
the last
commandID that was included using a format
specifier:
const char MSG_EXAMPLE_DEBUG[] PROGMEM = "Example debug message: cmdID %d\n"; ... debugPrint(MSG_EXAMPLE_DEBUG, cmdID);
Add-On Package Folder | MATLAB Add-On Class | https://la.mathworks.com/help/supportpkg/arduinoio/ug/c-header-file.html | CC-MAIN-2020-10 | en | refinedweb |
/* $NetBSD: extern.c,v 1.7 2003/08/07 09:37:10 agc Exp $ */ /*- *[] = "@(#)extern.c 8.1 (Berkeley) 5/31/93"; #else __RCSID("$NetBSD: extern.c,v 1.7 2003/08/07 09:37:10 agc Exp $"); #endif #endif /* not lint */ #include <curses.h> #include "deck.h" #include "cribbage.h" BOOLEAN explain = FALSE; /* player mistakes explained */ BOOLEAN iwon = FALSE; /* if comp won last game */ BOOLEAN quiet = FALSE; /* if suppress random mess */ BOOLEAN rflag = FALSE; /* if all cuts random */ char explan[128]; /* explanation */ int cgames = 0; /* number games comp won */ int cscore = 0; /* comp score in this game */ int gamecount = 0; /* number games played */ int glimit = LGAME; /* game playe to glimit */ int knownum = 0; /* number of cards we know */ int pgames = 0; /* number games player won */ int pscore = 0; /* player score in this game */ CARD chand[FULLHAND]; /* computer's hand */ CARD crib[CINHAND]; /* the crib */ CARD deck[CARDS]; /* a deck */ CARD known[CARDS]; /* cards we have seen */ CARD phand[FULLHAND]; /* player's hand */ CARD turnover; /* the starter */ WINDOW *Compwin; /* computer's hand window */ WINDOW *Msgwin; /* messages for the player */ WINDOW *Playwin; /* player's hand window */ WINDOW *Tablewin; /* table window */ | http://cvsweb.netbsd.org/bsdweb.cgi/src/games/cribbage/extern.c?rev=1.7&content-type=text/x-cvsweb-markup&sortby=author&only_with_tag=mjf-devfs2-base | CC-MAIN-2020-10 | en | refinedweb |
With Cognos® Analytics on Cloud you can purchase any number of Standard, Plus and Premium seats
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More about the Enterprise Edition
The enterprise edition can be hosted by IBM or hosted on your own infrastructure. If you host it, you can access all of the traditional Cognos tools, including Compatible Query Mode and Legacy Studios.
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Shorten payback period up to 20 percent, compared to up-front payment. | https://www.ibm.com/eg-en/products/cognos-analytics/pricing | CC-MAIN-2020-10 | en | refinedweb |
Lesson 18 - Java - Writing/reading data types to/from Windows registry
Quite often there's an issue on ICT.social and other forums with certain
settings we made in a program earlier and now we started the program again and
we want it to remember these. There are, of course, several ways to do it. We
can save these settings to a file via character or byte streams (e.g.
*.txt,
*.bin, and other file types) or via parsers to
configuration
*.xml files, or Java allows us to keep the data in
Windows registry. And since Java is cross-platform, it should also support this
feature on other OSs. No framework is needed to use Windows registry, the
technique is part of the Java SE 4 and higher APIs.
In Windows, it's the registry we access with the
regedit.exe
command. The Java API allows us to write to two registry keys. A key is the Preferences
object, which is in the Java API. The technology also has its own
documentation and usage description found in Oracle
Documents
- HKEY_CURRENT_USER - The key is located in
HKEY_CURRENT_USER\SOFTWARE JavaSoft\Prefs\
- HKEY_LOCAL_MACHINE - The key is located in
HKEY_LOCAL_MACHINE\SOFTWARE\JavaSoft\Prefs\
We won't discuss how the registry works here and neither its rules (e.g. different users, access rights, etc.). And not to be "racist", this programming technique can also be successfully used on alternative operating systems, according to stackoverflow. However, I haven't tried saving to the registry on Linux, Unix, Solaris, and MacOS.
On Unix / Linux, the storing path for SystemRoot is
/etc/.java
and for UserRoot
${user.home}/.java/.userPrefs. For MacOS,
the saved data should be located in
/Users/"User"/Library/Preferences/.
We can access SystemRoot (HKEY_LOCAL_MACHINE) like this:
Preferences.systemRoot()
And we access UserRoot (HKEY_CURRENT_USER) like this:
Preferences.userRoot()
Example - creating a node
We'll demonstrate how to work with the
Preferences object. In
this first example, we'll create a new node in the registry in the
HKEY_CURRENT_USER region. If the node already exists, it won't
be created and initializing the
Preferences object will connect us
to the registry level defined in our program.
import java.util.prefs.Preferences; public class CreateNode { @SuppressWarnings("unused") private static Preferences prefs; public static void main(String[] args) { System.out.println("Program started"); // create node prefs = Preferences.userRoot().node("IctSocialNode"); System.out.println("Program ended"); } }
Open the registry and see that a new node named
IctSocialNode
has been created in the registry path
HKEY_CURRENT_USER\SOFTWARE\JavaSoft\Prefs\/Ict/Social/Node.
Saving data to keys
The
Preferences object only allows to store several data types
(e.g.
String,
boolean,
byte array, ..).
In this example, we'll show how to store these values to the registry easily.
Each data type has its own method in the API, the first parameter is the key
identifier and the second parameter is the value.
import java.util.prefs.Preferences; public class StoringData { private static Preferences prefs; public static void main(String[] args) { System.out.println("Program started"); // create/connect to the node prefs = Preferences.userRoot().node("Example2"); // store data String string = "Stores String to the registry"; prefs.put("stringKey", string); prefs.putBoolean("booleanKey", true); prefs.putDouble("doubleKey", 3.5646d); prefs.putFloat("floatKey", 45646.234654f); prefs.putInt("intKey", 215646); prefs.putLong("longKey", 1846546465); System.out.println("Program ended"); } }
The example is saved to the
HKEY_CURRENT_USER\SOFTWARE\JavaSoft\Prefs\/Example2 node. A total
of 6 keys are created.
Reading from keys
We have shown how to store data to the registry, so as you probably expect,
we're now going to get the data from the registry back to our program again. The
Preferences object has methods that retrieve various data types.
The return type of these methods is the data type (information retrieved) from
the registers. The first parameter is the name of the key and the second
parameter is the value of the data type if the key doesn't exist (see retrieving
the
"ssKey", which doesn't exist in the registry). Therefore, if
the key doesn't exist in the given node, the second parameter is what the method
will return.
import java.util.prefs.Preferences; public class RetrievingData { private static Preferences prefs; public static void main(String[] args) { System.out.println("Program started"); // create node prefs = Preferences.userRoot().node("Example2"); // retrieve data from the registry String string = null; string = prefs.get("stringKey", string); System.out.println("The String value: " + string); System.out.println("The Double value: " + prefs.getDouble("doubleKey", 0d)); System.out.println("The Float value: " + prefs.getFloat("floatKey", 0f)); System.out.println("The Int value: " + prefs.getInt("intKey", 0)); System.out.println("The Long value: " + prefs.getLong("longKey", 0L)); System.out.println("The Boolean value: " + prefs.getBoolean("booleanKey", false)); System.out.println("A String key which doesn't exist : " + prefs.get("ssKey", "No value")); System.out.println("Program ended"); } }
Working with nested nodes
In the last chapter, we're going to show how to create a nested node, list keys in the node, and then a few methods that list the path information of the node, the node's parent, and the node information.
import java.util.prefs.*; public class NodeHierarchy { private static Preferences prefs; @SuppressWarnings("static-access") public static void main(String[] args) throws BackingStoreException { System.out.println("Program started"); prefs = Preferences.userRoot().node("Program2"); System.out.println("Node name : " + prefs.absolutePath()); System.out.println("Parent node : " + prefs.parent()); System.out.println("Node info : " + prefs.systemRoot()); prefs = null; prefs = Preferences.userRoot().node("Node1").node("Node2").node("Node3"); System.out.println("Node name : " + prefs.absolutePath()); System.out.println("Parent node : " + prefs.parent()); System.out.println("Node info: " + prefs.systemRoot()); // write keys and values prefs.put("Key1", "Value1"); prefs.put("Key2", "Value2"); // print keys String[] klice = prefs.keys(); for (String s : klice) { System.out.println("Key : " + s); } System.out.println("Program end"); } }
As you can see, the Java API allows us to store and retrieve registry data. At the same time it allows to work with nested nodes as well.
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A simple and small ORM supports postgresql, mysql and sqlite
peewee
Peewee is a simple and small ORM. It has few (but expressive) concepts, making it easy to learn and intuitive to use.
- a small, expressive ORM
- python 2.7+ and 3.4+ (developed with 3.6)
- supports sqlite, mysql, postgresql and cockroachdb
- tons of extensions
Examples
Defining models is similar to Django or SQLAlchemy:
from peewee import * import datetime db = SqliteDatabase('my_database.db') class BaseModel(Model): class Meta: database = db class User(BaseModel): username = CharField(unique=True) class Tweet(BaseModel): user = ForeignKeyField(User, backref=lie') # Get tweets created by one of several users. usernames = ['charlie', 'huey', 'mickey'] users = User.select().where(User.username.in_(usernames)) tweets = Tweet.select().where(Tweet.user.in_(users)) # We could accomplish the same using a JOIN: tweets = (Tweet .select() .join(User) .where(User.username.in_ twitter app <>_. | https://pythonawesome.com/a-simple-and-small-orm-supports-postgresql-mysql-and-sqlite/ | CC-MAIN-2020-10 | en | refinedweb |
I am with Orcon myself so made the call with some intentions in mind. After being on hold for a while I got the message that the retention team wasn't contactable at the moment and they will call me back. Stay tuned for those results.
What I had in mind was, seeing as they removed a service that I signed up for I feel I should be either
a) paying less (a similar service cost around $5/month) or
b) getting something in return (a bump up to a faster plan)
I'm also going to push for the my contract break out to be waived as per their email.
If an agreement cant be reached then it will have to be another providers turn.
Has anyone else made the call and what were the results?
PS. not sure if this is the right sub. | https://www.geekzone.co.nz/forums.asp?forumid=151&topicid=177525 | CC-MAIN-2020-10 | en | refinedweb |
Transforms Tip: Transforms based on Time
In some cases, you may want to have certain actions kick off based on the time that the event comes in. Here are some quick examples of how you could do this...
Example 01
In the following example, we want to drop an event for the device named "ottawa" between 3am and 4am:
import time if evt.device == 'ottawa': if time.localtime()[3] >= 3 and time.localtime()[3] < 4: evt._action = 'drop'
Example 02
If we wanted to do the same thing, but for 3pm to 4pm we would do:
import time if evt.device == 'ottawa': if time.localtime()[3] >= 15 and time.localtime()[3] < 16: evt._action = 'drop'
The following are the values which can be accessed:
Current Year: time.localtime()[0]
Current Month: time.localtime()[1]
Current Day: time.localtime()[2]
Current Hour: time.localtime()[3]
Current Minute: time.localtime()[4]
Current Second: time.localtime()[5]
Current Day of Week: time.localtime()[6]
Day of the week index:
0: Monday
1: Tuesday
2: Wednesday
3: Thursday
4: Friday
5: Saturday
6: Sunday
Author: Ryan Matte
Version: 10
Source: | http://wiki.zenoss.org/index.php?title=Transforms_Tip:_Transforms_based_on_Time&oldid=4853 | CC-MAIN-2020-10 | en | refinedweb |
In C, I did not notice any effect of the
extern
extern int f();
extern int f();
int f() {return 0;}
extern int f() {return 0;}
gcc -Wall -ansi
//
extern
extern
extern
We have two files, foo.c and bar.c.
Here is foo.c
#include <stdio.h> volatile unsigned int stop_now = 0; extern void bar_function(void); int main(void) { while (1) { bar_function(); stop_now = 1; } return 0; }
Now, here is bar.c
#include <stdio.h> extern volatile unsigned int stop_now; void bar_function(void) { while (! stop_now) { printf("Hello, world!\n"); sleep(30); } }
As you can see, we have no shared header between foo.c and bar.c , however bar.c needs something declared in foo.c when it's linked, and foo.c needs a function from bar.c when it's linked.
By using 'extern', you are telling the compiler that whatever follows it will be found (non-static) at link time, don't reserve anything for it since it will be encountered later.
It's very useful if you need to share some global between modules and don't want to put / initialize it in a header.
Technically, every function in a library public header is 'extern', however labeling them as such has very little to no benefit, depending on the compiler. Most compilers can figure that out on their own. As you see, those functions are actually defined somewhere else.
In the above example, main() would print hello world only once, but continue to enter bar_function(). Also note, bar_function() is not going to return in this example (since it's just a simple example). Just imagine stop_now being modified when a signal is serviced (hence, volatile) if this doesn't seem practical enough.
Externs are very useful for things like signal handlers, a mutex that you don't want to put in a header or structure, etc. Most compilers will optimize to ensure that they don't reserve any memory for external objects, since they know they'll be reserving it in the module where the object is defined. However, again, there's little point in specifying it with modern compilers when prototyping public functions.
Hope that helps :) | https://codedump.io/share/JmtdltL1bzv6/1/effects-of-the-extern-keyword-on-c-functions | CC-MAIN-2017-39 | en | refinedweb |
I had wanted some opinions about a portion of code that I have written. My UI consists of a QTableWidget in which it has 2 columns, where one of the 2 columns are populated with QComboBox.
For the first column, it will fill in the cells with the list of character rigs (full path) it finds in the scene, while the second column will creates a combobox per cell and it populates in the color options as the option comes from a json file.
Right now I am trying to create some radio buttons that gives user the option to show all the results, or it will hides those rows if there are no color options within the combobox for that particular row.
As you can see in my code, I am populating the data per column, and so, when I tried to put in
if not len(new_sub_name) == 0:
def populate_table_data(self):
self.sub_names, self.fullpaths = get_chars_info()
# Output Results
# self.sub_names : ['/character/nicholas/generic', '/character/mary/default']
# self.fullpaths : ['|Group|character|nicholas_generic_001', '|Group|character|mary_default_001']
# Insert fullpath into column 1
for fullpath_index, fullpath_item in enumerate(self.fullpaths):
new_path = QtGui.QTableWidgetItem(fullpath_item)
self.character_table.setItem(fullpath_index, 0, new_path)
self.character_table.resizeColumnsToContents()
# Insert colors using itempath into column 2
for sub_index, sub_name in enumerate(self.sub_names):
new_sub_name = read_json(sub_name)
if not len(new_sub_name) == 0:
self.costume_color = QtGui.QComboBox()
self.costume_color.addItems(list(sorted(new_sub_name)))
self.character_table.setCellWidget(sub_index, 1, self.costume_color)
You can hide rows using setRowHidden. As for the rest of the code, I don't see much wrong with what you currently have, but FWIW I would write it something like this (completely untested, of course):
def populate_table_data(self): self.sub_names, self.fullpaths = get_chars_info() items = zip(self.sub_names, self.fullpaths) for index, (sub_name, fullpath) in enumerate(items): new_path = QtGui.QTableWidgetItem(fullpath) self.character_table.setItem(index, 0, new_path) new_sub_name = read_json(sub_name) if len(new_sub_name): combo = QtGui.QComboBox() combo.addItems(sorted(new_sub_name)) self.character_table.setCellWidget(index, 1, combo) else: self.character_table.setRowHidden(index, True) self.character_table.resizeColumnsToContents() | https://codedump.io/share/Ld5O74enWqXl/1/hiding-rows-in-qtablewidget-if-1-of-the-column-does-not-have-any-values | CC-MAIN-2017-39 | en | refinedweb |
class OEDirectoryScan
This class represents OEDirectoryScan.
The OEDirectoryScan class provides a portable way of retrieving the names of all the files and subdirectories in a given directory.
OEDirectoryScan(const char *dname)
The constructor for OEDirectoryScan specifies the name of the directory to scan. A NULL pointer, (char*)0, is taken to mean the current directory and is equivalent to ".".
operator bool() const
Checks whether the OEDirectoryScan has been successfully opened and is still valid. A return value of true does not guarantee that the next call to the Next method will not return (const char*)0.
void Close()
Closes the OEDirectoryScan and frees any system resources. This method is invoked automatically by the classes’ destructor. Following a call to Close, operator bool will always return false.
const char *Next()
Returns the next file name sequentially in the directory scan. This function automatically advances the directory pointer. The returned value is a pointer to the local filename, i.e. without its directory prefix. Upon reaching the end of the directory, this function returns (const char*)0, and the OEDirectoryScan is closed. | https://docs.eyesopen.com/toolkits/python/oechemtk/OEPlatformClasses/OEDirectoryScan.html | CC-MAIN-2017-39 | en | refinedweb |
Qt Creator, linked boost library and debug
Hello.
I have found a strange problem with Qt Creator and boost library.
I have a simple "Hello World!" program in the Qt Creator. So far so good. But I need to use the boost::filesystem library.
So I add:
@
#include <boost/filesystem.hpp>
@
to the source code and
@
INCLUDEPATH += C:/boost
LIBS += C:/boost/stage/lib/libboost_filesystem-mgw45-mt-d-1_46_1.a
LIBS += C:/boost/stage/lib/libboost_system-mgw45-mt-d-1_46_1.a
@
to the .pro file
Building the application for the "release" target is OK, no errors. Result executable executes and works well.
But for the "debug" target it doesn't. I got the error:
The process could not be started: %1 is not a valid Win32 application.
Debugging can be started but it ignores all breakpoints and terminates immediately.
Don't you know what could case this problem?
If I don't have #include <boost/filesystem.hpp> in the source code, the "debug" executable can be executed, but when I include boost/filesystem, it immediately becomes invalid win32 application. However "release" executable works well in both cases.
Thank you.
P.S.
I tried to create the same simple application in Code::Blocks, just to test whether included boost libraries are compiled correctly and yes, there's no problem with both release and debug build targets, all works fine. So it doesn't seem to be a problem with boost libraries.
I'm using Qt SDK 1.1, Qt Creator 2.2 installed later, Windows 7 Ultimate x64
[EDIT: code formatting, please wrap in @-tags, Volker]
That looks a lot like some stale files being left behind from one build being used in the new one.
Did you clean out the build directory after switching to debug or did you use different shadow build directories for debug and release?
Doing a clean rebuild should fix this.
Thanks for the answer.
Unfortunately this is not the problem. I have cleaned the project, then I have deleted the entire directory boosttest-build-desktop and then "debug" built again - and the same problem occured.
What more, just commenting out the line "#include <boost/filesystem.hpp>" and "rebuild project" makes the .exe file executable in "debug" target again. So there IS something wrong with linking but I have no idea what it can be.
Thanks.
On windows you're using .dll, not .a.
So what's you compiler ? (mingw 4.5 ?)
Don't use QTCreator 2.2 wich is not delivered with Qt SDK 1.1
try :
-L : this is a path
-l : is a file without extension (.a or .lib is added)
\ : continue on following line
$$quote(..) : useful for path like 'c:/program files'
@DEFINES += BOOST_ALL_DYN_LINK # for using dynamic libraries
LIBS += -L$$quote(C:/boost/stage/lib) \
-llibboost_filesystem-mgw45-mt-d-1_46_1
-llibboost_system-mgw45-mt-d-1_46_1@
eventually make separate config for debug and release
@
CONFIG(debug, debug|release) {
LIBS += -L$$quote(C:/boost/stage/lib) \
-llibboost_filesystem-mgw45-mt-d-1_46_1
-llibboost_system-mgw45-mt-d-1_46_1
} else {
LIBS += -L$$quote(C:/boost/stage/lib) \
-llibboost_filesystem-mgw45-mt-1_46_1
-llibboost_system-mgw45-mt-1_46_1
}
@
Hi.
Thank you for your reply.
You know what? You have solved my problem with one sentence:
Don’t use QTCreator 2.2 wich is not delivered with Qt SDK 1.1
That is, it works with Qt Creator 2.1 supplied with Qt SDK, but not with QTC 2.2. (Maybe different version of MinGW coming with this new version...?)
I didn't even had to change LIBS += settings in the .pro file.
And about .dll - they are used for dynamic linking, but I want statick link, I want to produce single .exe file.
Thank you very much for your help.
Well, great that this helps for now, but the SDK will eventually upgrade to Qt Creator 2.2 and then you will have the same issue. I would really appreciate getting this nailed down:-)
Can you make your example available to us? How did you build it in codeblocks? Did you use a different build system or did you reuse the qmake .pro-file you had? Did codeblocks and creator use the same mingw?
Hi.
Well, it seems there's really problem with MinGW versions I have installed, you're right.
My default MinGW installation (C:\MinGW) is version 4.5.0
Code::Blocks uses this default installation, so it's running on 4.5.0
Compilation of boost libraries (bootstrap, bjam) used this default MinGW too, it's compiled with 4.5.0
But QtSDK comes with its own MinGW - 4.4.0
And Qt Creator 2.2 also comes with its own MinGW - also 4.4.0
In "Build Settings" of both Qt Creators (2.1 from QtSDK and standalone 2.2) I can see the same settings in Qt version - "Qt 4.7.3 for Desktop - MinGW 4.4 (Qt SDK)," referencing "c:\qtsdk\desktop\qt\4.7.3\mingw\bin\qmake.exe" directory.
So I have boost libraries compiled with MinGW 4.5.0, but Qt Creator uses its own 4.4.0 for my program. It can be the problem, I see.
But why release works fine and only debug fails in Qt Creator 2.2?
And why Qt Creator 2.1 releases and debugs with no problem - especially if both 2.1 and 2.2 use the same Qt from QtSDK?
For Code::Blocks I created a new project from scratch - in fact it creates a "Hello World" main.cpp automatically when new project is created, so all I had to do was to add libraries to linker, includes to compiler and one line of code: #include <boost/filesystem.hpp>
Thank you.
Could you please try setting up mingw 4.5 in Qt Creator? Go to Tools->Options->Tool chain and add a new mingw tool chain. Point it to the g++ of the mingw 4.5, rename the whole thing (click on the name in the table) and apply the whole thing.
You should not be able to select that version to build your project. Does it work when building with the newer mingw?
Just few comments
Qt Creator 2.2 work fine on windows xp/seven with Qt SDK 1.1
install Visual C++ 2008 Express Edition (free, uncheck SQL serveur express if you don't have to use)
install QtSDK 1.1 VS2008 (uncheck all about MinGW, check delete QtCreator previous settings)
install QtCreator 2.2 (uncheck MinGW)
Both Qt Creator 2.1/2.2 work fine (release and debug)
@Tobias Hunger:
Oh yes, that's it. It works now.
Qt Creator 2.1 probably choose the right MinGW by itself (I cannot check it, Tool Chain combobox is disabled in build settings there and no "Tool Chain" option in Tools/Options is present) but 2.2 set up its toolchain to QtSDK's MinGW 4.4.0.
When I changed ToolChain to "MinGW (x86 32bit) - 4.5.0" in QTC 2.2, both release and debug builds started to work fine.
Thank you very much, Tobias.
- formiaczek
If you happen to change boost versions, this is perhaps more generic way of doing this:
(define your environment variable pointing at boost-root, e.g. C:\boost_1_54_0)
than, for gcc4.7.2 (e.g. from qt 5.0.2)
in .pro file:
@ INCLUDEPATH += $(BOOST_ROOT)
BOOST = $(BOOST_ROOT)
GCC_VER = system(gcc -dumpversion)
COMPILER = gcc-mingw-$${GCC_VER}
#dunno how to make mgw47 from gcc-mingw and 4.7.2 from here..
COMPILER_SHORT = mgw47
BOOST_SUFFIX = $${COMPILER_SHORT}-mt-${BOOST_VER} LIBS += -L$${BOOST}/stage/lib // now you can add your libraries, e.g. LIBS += -lboost_system-$${BOOST_SUFFIX} LIBS += -lboost_WHATEVER-$${BOOST_SUFFIX} // just change 'WHATEVER' to a valid lib name..@
(obviously above is assuming you've compiled your boost with the same compiler, e.g.:
@cd %BOOST_ROOT%;
set PATH=C:\Qt\Qt5.0.2\Tools\MinGW\bin;%PATH%;
boostrap gcc
b2 --build-dir=/temp/build-boost toolset=gcc stage@
if you're using boost_1_54, you'd better off defining following in your project-config.jam before the build:
@using gcc : : :
<cxxflags>-std=c++0x
<cxxflags>"-include cmath"
;@
etc.. | https://forum.qt.io/topic/5866/qt-creator-linked-boost-library-and-debug | CC-MAIN-2017-39 | en | refinedweb |
public class BufferedInputStream extends FilterInputStream.
protected volatile byte[] buf
The internal buffer array where the data is stored. When necessary, it may be replaced by another array of a different size.
protected int count
The index one greater than the index of the last valid byte in the buffer. This value is always in the range
0 through
buf.length; elements
buf[0] through
buf[count-1]
contain buffered input data obtained from the underlying input stream.
protected int.
buf
protected int markpos] through
buf[pos-1] must remain in the buffer array (though they may be moved to another place in the buffer array, with suitable adjustments to the values of
count,
pos, and
markpos); they may not be discarded unless and until the difference between
pos and
markpos exceeds
marklimit.
mark(int),
pos
protected int marklimit
The maximum read ahead allowed after a call to the
mark method before subsequent calls to the
reset method fail. Whenever the difference between
pos and
markpos exceeds
marklimit, then the mark may be dropped by setting
markpos to
-1.
mark(int),
reset()
public BufferedInputStream(InputStream in)
Creates a
BufferedInputStream and saves its argument, the input stream
in, for later use. An internal buffer array is created and stored in
buf.
in- the underlying input stream.
public BufferedInputStream(InputStream in, int size)
Creates a
BufferedInputStream with the specified buffer size, and saves its argument, the input stream
in, for later use. An internal buffer array of length
size is created and stored in
buf.
in- the underlying input stream.
size- the buffer size.
IllegalArgumentException- if
size <= 0.
public int read() throws IOException
See the general contract of the
read method of
InputStream.
readin class
FilterInputStream
-1if the end of the stream is reached.
IOException- if this input stream has been closed by invoking its
close()method, or an I/O error occurs.
FilterInputStream.in
public int read(byte[] b, int off, int len) throws IOException
Reads bytes from this byte-input stream into the specified byte array, starting at the given offset., or
availablemethod of the underlying stream returns zero, indicating that further input requests would block.
readon the underlying stream returns
-1to indicate end-of-file then this method returns
-1. Otherwise this method returns the number of bytes actually read.
Subclasses of this class are encouraged, but not required, to attempt to read as many bytes as possible in the same fashion.
readin class
FilterInputStream
b- destination buffer.
off- offset at which to start storing bytes.
len- maximum number of bytes to read.
-1if the end of the stream has been reached.
IOException- if this input stream has been closed by invoking its
close()method, or an I/O error occurs.
FilterInputStream.in
public long skip(long n) throws IOException
See the general contract of the
skip method of
InputStream.
skipin class
FilterInputStream
n- the number of bytes to be skipped.
IOException- if the stream does not support seek, or if this input stream has been closed by invoking its
close()method, or an I/O error occurs.
public int available() throws IOException.
This method returns the sum of the number of bytes remaining to be read in the buffer (
count - pos) and the result of calling the
in.available().
availablein class
FilterInputStream
IOException- if this input stream has been closed by invoking its
close()method, or an I/O error occurs.
public void mark(int readlimit)
See the general contract of the
mark method of
InputStream.
markin class
FilterInputStream
readlimit- the maximum limit of bytes that can be read before the mark position becomes invalid.
reset()
public void reset() throws IOException
See the general contract of the
reset method of
InputStream.
If
markpos is
-1 (no mark has been set or the mark has been invalidated), an
IOException is thrown. Otherwise,
pos is set equal to
markpos.
resetin class
FilterInputStream
IOException- if this stream has not been marked or, if the mark has been invalidated, or the stream has been closed by invoking its
close()method, or an I/O error occurs.
mark(int)
public boolean markSupported()
Tests if this input stream supports the
mark and
reset methods. The
markSupported method of
BufferedInputStream returns
true.
markSupportedin class
FilterInputStream
booleanindicating if this stream type supports the
markand
resetmethods.
InputStream.mark(int),
InputStream.reset()
public void close() throws IOException
Closes this input stream and releases any system resources associated with the stream. Once the stream has been closed, further read(), available(), reset(), or skip() invocations will throw an IOException. Closing a previously closed stream has no effect.
closein interface
Closeable
closein interface
AutoCloseable
closein class
FilterInputStream
IOException- if an I/O error occurs.
FilterInputStream.in. | http://docs.w3cub.com/openjdk~8/java/io/bufferedinputstream/ | CC-MAIN-2017-39 | en | refinedweb |
If you looked at the variables, repetition and commands chapters, you already know a great deal about how to keep your code tidy and organized. Variables can be used to store data, commands to manipulate data, and for-loops to do things repeatedly. As you move on to bigger projects you’ll probably want to learn about classes as well. A class is a programming convention that defines a thing (or object) together with all of the thing’s properties (e.g. variables) and behavior methods (e.g. commands). If you take a look at the source code of PlotDevice libraries you’ll notice that they are full of classes.
For example, a Creature class would consist of all the traits shared by different creatures, such as size, position, speed and direction (properties), and avoid_obstacle(), eat_food() (methods).
We can then use the Creature class to generate many different instances of a creature. For example, an ant is a small and speedy creature that wanders around randomly looking for food, avoiding obstacles by going around them. A dinosaur is also a creature, but bigger and slower. It eats anything crossing its path and avoids obstacles by crashing through them.
As we saw in the Commands chapter, there’s a difference between defining something and using it. This same distinction also applies to classes: you first need to teach PlotDevice about your new object type, then later in the script you can create as many ‘instance’ of the type as you want.
Class definitions have a syntax that looks quite similar to what we’ve seen before. There’s a line starting with the class statement where we set the name for our new class, then an indented block of one or more method definitions. As always, don’t forget the colon that begins the indented block:
class ClassName: ... # method defintions
Every class has a method named __init__() which is executed once when an instance of the class is created. This method sets all the starting values for an object’s properties and defines the parameters accepted when creating new objects.
For example, here’s what a simple definition of a Creature class would look like:
class Creature: def __init__(self, x, y, speed=1.0, size=4): self.x = x self.y = y self.speed = speed self.size = size
As you can see, a creature has x and y properties (its location in space) as well as speed and size properties (which we’ll use to move the creature around). Since speed and size are defined with default values, they are optional when instantiating a new creature.
You create instances of a class by calling the class name as if it were a command, but including the parameters defined in its __init__() method. The one tricky bit is that you should ignore the
self argument, since it will be filled in automatically (see below).
ant = Creature(100, 100, speed=2.0) dinosaur = Creature(200, 250, speed=0.25, size=45)
To change a property value for a creature later on we can simply re-assign it:
ant.speed = 2.5
As with command names, Python has some conventions for naming classes that you should try to follow:
CamelCasenotation.
_
Let’s add a roam() method to the Creature class to move creatures around randomly. A class method looks exactly like a command definition but it always takes self as the first parameter. The self parameter is the current instance of the class. It allows you to access all of an object’s current property values and methods from inside the method.
class Creature: def __init__(self, x, y, speed=1.0, size=4): self.x = x self.y = y self.speed = speed self.size = size self._vx = 0 self._vy = 0 def roam(self): """ Creature changes heading aimlessly. """ v = self.speed self._vx += random(-v, v) self._vy += random(-v, v) self._vx = max(-v, min(self._vx, v)) self._vy = max(-v, min(self._vy, v)) self.x += self._vx self.y += self._vy
So now we have added two new properties to the class, _vx and _vy, which store a creature’s current heading. Both property names start with an underscore because they are for private use inside the class methods (i.e., no one should directly manipulate ant._dx from the outside).
Each time the roam() method is called we add or subtract a random proportion of the creature’s speed from its heading, like a pinwheel twirling around randomly. We also make sure the horizontal and vertical ‘velocities’ don’t exceed the creature’s maximum speed. Otherwise the creature would start going faster and faster which isn’t very realistic. Finally, we update the creature’s position by stepping it toward the new heading.
Now we can create two ants (a small fast one and a big slow one). Since their size and speed differ they will roam in different ways.
ant1 = Creature(300, 300, speed=2.0) ant2 = Creature(300, 300, speed=0.5, size=8) speed(30) def draw(): ant1.roam() ant2.roam() arc(ant1.x, ant1.y, radius=ant1.size) arc(ant2.x, ant2.y, radius=ant2.size)
Now that we know the basics about classes, properties and methods, we can take things a lot further. We can define different classes for different things and have them interact with each other.
If we want to have our little critters avoid obstacles while wandering around, they will need to have some sense of the world around them. Our code will need to keep track of where the obstacles are located, and the creature will need to have some sort of ‘feeler’ so it can detect looming collisions.
A feeler could be the creature’s sight, hearing, or antennae – it’s really just a metaphor for the sensory feedback we’ll be providing it from ‘the world’. For our simple class it can represented as an
x/
y ‘test’ point just in front of the creature’s current heading. If this point falls inside an obstacle, it’s time for the creature to change its direction.
The creature is heading into an obstacle – it can ‘sense’ the obstacle with its feeler and will need to adjust its bearing clockwise to avoid colliding with it.
We’ll start out by creating a World class which we can use to store a list of obstacles. Later on we can add all sorts of other stuff to the world (e.g. weather methods, colony location properties, etc.). Note that we’re defining it as a class even though we’ll only ever create one
World object in any of our simulations.
class World: def __init__(self): self.obstacles = []
Next we’ll define an Obstacle class. In our simulation we’ll be creating a number of
Obstacle objects and storing them in a shared
World object. The
Obstacle itself doesn’t need to know about the world-at-large (since all it ‘does’ is occupy space), so it only keeps track of its personal location and size:
class Obstacle: def __init__(self, x, y, radius): self.x = x self.y = y self.radius = radius
To know if a creature is going to run into an obstacle we need to know if the tip of its feeler intersects with an obstacle. Obviously we’re going to need some math to calculate the coordinates of the tip of the feeler. Luckily everything we need is already described in the tutorial on geometry. We could use the methods provided by Point objects, but instead let’s define some equivalent geometry commands that work with plain-old numbers:
from math import degrees, atan2 from math import sqrt, pow from math import radians, sin, cos def angle(x0, y0, x1, y1): """Returns the angle between two points.""" return degrees( atan2(y1-y0, x1-x0) ) def distance(x0, y0, x1, y1): """Returns the distance between two points.""" return sqrt(pow(x1-x0, 2) + pow(y1-y0, 2)) def coordinates(x0, y0, distance, angle): """Returns the coordinates of given distance and angle from a point.""" return (x0 + cos(radians(angle)) * distance, y0 + sin(radians(angle)) * distance) def reflect(x0, y0, x1, y1, d=1.0, a=180): """Returns the coordinates of x1/y1 reflected through x0/y0""" d *= distance(x0, y0, x1, y1) a += angle(x0, y0, x1, y1) x, y = coordinates(x0, y0, d, a) return x, y
With the above coordinates() command we can:
So first of all we’ll need to add a new feeler_length property to the Creature class, and a new heading() method that calculates the angle between a creature’s current position and its next position. We also add a new world property to the Creature class. That way each creature has access to all the obstacles in the world. We loop through the list of the world’s obstacles in the avoid_obstacles() method.
The avoid_obstacles() method will do the following:
class Creature: def __init__(self, world, x, y, speed=1.0, size=4): self.x = x self.y = y self.speed = speed self.size = size self.world = world self.feeler_length = 25 self._vx = 0 self._vy = 0 def heading(self): """ Returns the creature's heading as angle in degrees. """ return angle(self.x, self.y, self.x+self._vx, self.y+self._vy) def avoid_obstacles(self, m=0.4, perimeter=4): # Find out where the creature is going. a = self.heading() for obstacle in self.world.obstacles: # Calculate the distance between the creature and the obstacle. d = distance(self.x, self.y, obstacle.x, obstacle.y) # Respond faster if the creature is very close to an obstacle. if d - obstacle.radius < perimeter: m *= 10 # Check if the tip of the feeler falls inside the obstacle. # This is never true if the feeler length # is smaller than the distance to the obstable. if d - obstacle.radius <= self.feeler_length: tip_x, tip_y = coordinates(self.x, self.y, d, a) if distance(obstacle.x, obstacle.y, tip_x, tip_y) < obstacle.radius: # Nudge the creature away from the obstacle. m *= self.speed if tip_x < obstacle.x: self._vx -= random(m) if tip_y < obstacle.y: self._vy -= random(m) if tip_x > obstacle.x: self._vx += random(m) if tip_y > obstacle.y: self._vy += random(m) if d - obstacle.radius < perimeter: return def roam(self): """ Creature changes heading aimlessly. With its feeler it will scan for obstacles and steer away. """ self.avoid_obstacles() v = self.speed self._vx += random(-v, v) self._vy += random(-v, v) self._vx = max(-v, min(self._vx, v)) self._vy = max(-v, min(self._vy, v)) self.x += self._vx self.y += self._vy
Play movie | view source code
Another easy example of classes is the Tendrils item in the gallery. | https://plotdevice.io/tut/Classes | CC-MAIN-2017-39 | en | refinedweb |
If i want to customize an activation function, and can be easily called in torch.nn.functional. What should I do? Thanks
what do you mean by "customize an activation function"?and why do you need it to be called in torch.nn.functional?
torch.nn.functional
I guess, "customize an activation function" means "how to implement some custom activation functions of his own".
If you can write your activation function using Torch math operations, you don't need to do anything else to "implement" it.
Let's implement a truncated gaussian for example.
def trucated_gaussian(x, mean=0, std=1, min=0.1, max=0.9):
gauss = torch.exp((-(x - mean) ** 2)/(2* std ** 2))
return torch.clamp(gauss, min=min, max=max) # truncate
I'm sorry I did not express what I meant, and I mean is how I could use my own function in a net instead of using the activation function provided in the pytorch framework. So,which document can reference? thanks.
One way to do it is to derive from nn.Module and implement the forward method. Don't bother about backpropagation if you use autograd compatible operations. For example, @fmassa's truncated gaussian from above:
nn.Module
forward
import torch
import torch.nn as nn
from torch.autograd import Variable
class MyActivationFunction(nn.Module):
def __init__(self, mean=0, std=1, min=0.1, max=0.9):
super(MyActivationFunction, self).__init__()
self.mean = mean
self.std = std
self.min = min
self.max = max
def forward(self, x):
gauss = torch.exp((-(x - self.mean) ** 2)/(2* self.std ** 2))
return torch.clamp(gauss, min=self.min, max=self.max)
my_net = nn.Sequential(
nn.Linear(7, 5),
MyActivationFunction()
)
y = my_net(Variable(torch.rand(10, 7)))
y.backward(torch.rand(10, 5))
Note that it's not necessary to derive from nn.Module to write your functions, and everything can be handled with normal python functions, and backpropagation will just work fine (if you pass in a Variable).
Variable
@fmassa Can you please give an example on that?I tried to implement a simple exponential activation for my rnn
class my_rnn(nn.Module):
def __init__(self, input_size=2, hidden_size=20, num_layers=3, output_size=1,
batch_size=10):
super(my_rnn, self).__init__()
self.input_size = input_size
self.hidden_size = hidden_size
self.num_layers = num_layers
self.output_size = output_size
self.batch_size = batch_size
self.rnn = nn.RNN(input_size=self.input_size, hidden_size=self.hidden_size,
num_layers=self.num_layers, batch_first=True, nonlinearity=self.exp_activation)
# The last layer is applied on the last output only of the RNN (not like
# TimeDistributedDense in Keras)
self.linear_layer = nn.Linear(self.hidden_size, self.output_size)
self.hidden = Variable(torch.zeros((self.num_layers, self.batch_size, self.hidden_size))).cuda()
def forward(self, input_sequence):
out_rnn, self.hidden = self.rnn(input_sequence, self.hidden)
in_linear = out_rnn[:, -1, :]
final_output = self.linear_layer(in_linear)
return final_output
def init_hidden(self):
self.hidden = Variable(torch.zeros((self.num_layers, self.batch_size, self.hidden_size))).cuda()
def exp_activation(self, data):
return torch.exp(data)
but it gives this error ValueError: Unknown nonlinearity '<bound method my_rnn.exp_activation of my_rnn ()>'
ValueError: Unknown nonlinearity '<bound method my_rnn.exp_activation of my_rnn ()>'
nn.RNN supports only tanh or relu for nonlinearity [code]. One easy way to solve your problem is to write your own loop over the sequence just like in this example.
nn.RNN
tanh
relu
nonlinearity
maybe you are trying to call a non @staticmethod?Anyway, if your exp_activation is outside of the class definition, you can use it normally.
@staticmethod
exp_activation
def exp_activation_square(x):
return torch.exp(x) ** 2
x = Variable(torch.rand(3), requires_grad=True)
y = Variable(torch.rand(3), requires_grad=True)
z = exp_activation_square(x * y).sum()
z.backward()
Ah, @Tudor_Berariu is right, I didn't see all your code so I didn't get where the problem was.Yes, if you want to try another non-linearity which is not currently supported in nn.RNN, you need to write your own for loop.Although it wouldn't be hard to add support for it in nn, but I'm not sure it's a very common use-case
nn
Ah okay, I see your point now. Thank you @fmassa and @Tudor_Berariu
thank you ！everyone,I will try it, | https://discuss.pytorch.org/t/customize-an-activation-function/1652 | CC-MAIN-2017-39 | en | refinedweb |
Content-type: text/html
#include <sys/cred.h>
int priv_policy(const cred_t *cr, int priv, int err, const char *msg);
int priv_policy_only(const cred_t *cr, int priv);
int priv_policy_choice(const cred_t *cr, int priv);
Solaris DDI specific (Solaris DDI).
cr
The credential to be checked.
priv
The integer value of the privilege to test.
err
The error code to return.
msg.
EINVAL
This might be caused by any of the following:
• The flags parameter is invalid.
• The specified privilege does not exist.
• The priv parameter contains invalid characters.
ENOMEM
There is no room to allocate another privilege.
ENAMETOOLONG
An attempt was made to allocate a privilege that was longer than {PRIVNAME_MAX} characters.
This functions can be called from user, interrupt, or kernel context.
See attributes(5) for a description of the following attributes:
acct(3HEAD), attributes(5), privileges(5)
Writing Device Drivers | https://backdrift.org/man/SunOS-5.10/man9f/priv_policy.9f.html | CC-MAIN-2017-39 | en | refinedweb |
Destructor randomly throw EXC_BAD_ACCESS
Hello everybody !
I'm making an app for a company, and I'm already stuck on the first window T_T
Here is what I want to do: I have a "MainWindow" class which inherits "QMainWindow". It has a method called "buildWelcomeWidget" which init an internal "WelcomeWidget" widget (inherits QWidget) and assign it as the centralWidget.
Talking about it, the WelcomeWidget has internal "signinWidget" and "signupWidget" which are built and called on a QPushButton click.
My main.cpp init the MainWindow, call buildWelcomeWidget and show the MainWindow, which works perfectly fine. The problem is when I close the widget (with the red cross button), it calls the destructor or the MainWindow, which deletes the welcomeWidget, and there is a EXC_BAD_ACCESS in the destructor of my welcomeWidget, which deletes every pointers I'm using but in the right order (I delete the buttons, then the layouts, then the widgets, no matter if they've been init or not).
I think it's fine to delete a pointer 2 times, but not if it's NULL, right ?
Here is some extracts:
main.cpp
@int main(int argc, char *argv[])
{
QApplication a(argc, argv);
MainWindow mw;
mw.buildWelcomeWidget();
mw.show();
return (a.exec());
}@
MainWindow.cpp
@
MainWindow::~MainWindow()
{
delete this->_welcomeWidget;
}
void MainWindow::buildWelcomeWidget(void)
{
this->_welcomeWidget = new WelcomeWidget(this);
this->setCentralWidget(this->_welcomeWidget);
}@
WelcomeWidget.cpp
@WelcomeWidget::WelcomeWidget(MainWindow *parent) : QWidget(parent)
{
this->_vboxLayout = new QVBoxLayout(this);
this->_signinButton = new QPushButton(tr("Sign-In"), this);
this->_signupButton = new QPushButton(tr("Sign-Up"), this);
this->_vboxLayout->addWidget(this->_signinButton);
this->_vboxLayout->addWidget(this->_signupButton);
this->setLayout(this->_vboxLayout);
this->setAttribute(Qt::WA_MacBrushedMetal);
connect(this->_signinButton, SIGNAL(clicked()), SLOT(signinClicked()));
connect(this->_signupButton, SIGNAL(clicked()), SLOT(signupClicked()));
}
WelcomeWidget::~WelcomeWidget()
{
delete this->_cancelSigninButton; // Fails randomly here
delete this->_cancelSignupButton;
delete this->_okSigninButton;
delete this->_okSignupButton;
delete this->_signinButton;
delete this->_signupButton;
delete this->_usernameSigninField; // Fails randomly here
delete this->_usernameSignupField;
delete this->_passwordSigninField;
delete this->_passwordSignupField;
delete this->_password2Field;
delete this->_emailField;
delete this->_firstnameField;
delete this->_lastnameField;
delete this->_emailValidator;
delete this->_hboxSigninLayout;
delete this->_hboxSignupLayout;
delete this->_vboxLayout;
delete this->_formSigninLayout;
delete this->_formSignupLayout;
delete this->_signinWidget;
delete this->_signupWidget;
}@
Is there an explanation somewhere :) ?
Thank you for your help.
Why do you delete the widgets in the first place? They are deleted by Qt automatically.
You can delete a null pointer, but you are not allowed to delete an object twice, never.
[quote author="Lukas Geyer" date="1342024242"]Why do you delete the widgets in the first place? They are deleted by Qt automatically.
[/quote]
I'm deleting the widget to respect the rule "1 new, 1 delete", even if it's deleted automatically, is it wrong ?
[quote author="Lukas Geyer" date="1342024242"]
You can delete a null pointer, but you are not allowed to delete an object twice, never.[/quote]
Okay okay, I was wrong. In my destructor, I'm deleting QWidgets that have been initialized, and non initialized. Are you saying I shouldn't ?
What should I do then ?
- mlong Moderators
If you create a QWidget (or, rather, a QObject) which has a non-null parent, then you shouldn't need to delete it yourself. The parent-child hierarchy of QObjects take care of deleting these objects for you. (Giving an object a parent hands ownership of that object to its parent, who will clean it up.)
With that said, if you do delete any of these objects manually, then you need to set their pointers to 0 (NULL) after you've deleted them. Clearing a pointer to null after a delete is a always good practice, regardless.
[quote author="Max13" date="1342024765"]I'm deleting the widget to respect the rule "1 new, 1 delete", even if it's deleted automatically, is it wrong?[/quote]It isn't wrong, but it's quite unfamiliar in Qt, especially when it comes to QObject, where you usually either rely on ownership (as explained by mlong) or smart pointers to delete objects.
[quote author="Max13" date="1342024765"]Okay okay, I was wrong. In my destructor, I'm deleting QWidgets that have been initialized, and non initialized. Are you saying I shouldn't?[/quote]
I'm not quite sure what you mean exactly with 'initialized', but you are only allowed to <code>delete</code> an object (exactly once) which has been created using <code>new</code>, or a null object (be aware that this is only true for C++, not C). Everything else will result in undefined behaviour.
@
QObject objectA;
QObject *objectB;
QObject *objectC = 0;
QObject *objectD = new QObject;
QObject *objectE = new QObject(objectD);
delete &objectA; // WRONG, not created using new (stack object)
delete objectB; // WRONG, object neither initialized nor null
delete objectC; // RIGHT, null object
delete objectC; // RIGHT, null object
delete objectD; // RIGHT, initialized object created using new
delete objectD; // WRONG, object already deleted
delete objectE; // WRONG, object already deleted due to beeing child of objectD
@
Keep always in mind that not a pointer is deleted, but rather the object it points to!
[quote author="mlong" date="1342033053"]If you create a QWidget (or, rather, a QObject) which has a non-null parent, then you shouldn't need to delete it yourself. [...] With that said, if you do delete any of these objects manually, then you need to set their pointers to 0 (NULL) after you've deleted them.[/quote]
Ok. Thank you for your explanation, I'm not as advanced in C++ (low level) that I am in C.
[quote author="Lukas Geyer" date="1342037269"]I'm not quite sure what you mean exactly with 'initialized', but you are only allowed to <code>delete</code> an object (exactly once) which has been created using <code>new</code>, or a null object (be aware that this is only true for C++, not C). [...] Keep always in mind that not a pointer is deleted, but rather the object it points to![/quote]
By "initialized", I meant "newed". I thought (I should have verified) that Qt doesn't set a pointer to 0/NULL on a <code>delete</code>.
Something strange, is that I've tried something that cause an EXC_BAD_ACCESS too:
@this->_welcomeWidget = new WelcomeWidget;
delete this->_welcomeWidget;@
This should work isn't it ?
When entering the <code>delete</code> (<code>~WelcomeWidget()</code>) it fails at the first child <code>delete</code> (the destructor is the same as on my first post).
Is it for the same reason explained by mlong? ?
Thank again for your lights.
[quote author="Max13" date="1342044793"]I thought (I should have verified) that Qt doesn't set a pointer to 0/NULL on a <code>delete</code>.[/quote]
It (C++, not Qt) doesn't, because it can't. The pointer and the object it points two are two different things, with two different addresses in address space, occupying two different areas of memory.
If you pass a pointer to a function (or <code>delete</code>) you will always pass the address of the object it points to (the 'value' of the pointer), not the address of the pointer itself (which would be required to modify it).
@
void deleteObject(QObject *objectToDelete)
-----------------------
0x28fe30
{
delete objectToDelete;
--------------
0xfd7e738
}
QObject *object = new QObject;
0x28fe94 0xfd7e738
deleteObject(object);
@
As you can see, <code>deleteObject</code> cannot modify the pointer called <code>object</code>, because it has no access to it. You could theoretically do something like <code>delete 0xfd7e738;</code>, then there is no named pointer involved at all.
[quote author="Max13" date="1342044793"]Something strange, is that I've tried something that cause an EXC_BAD_ACCESS too:
@
this->_welcomeWidget = new WelcomeWidget;
delete this->_welcomeWidget;
@
[/quote]
Yes, because you <code>delete</code> a load of objects you haven't created using <code>new</code> nor are the pointers which point to them are <code>0</code>, for example <code>cancelSigninButton</code>.
Pointers (as other variables) are never initialized automatically (with a few exceptions, see 4.9.5). The contain a random value unless explicitly set (to for example <code>0</code>).
On a sidenote: identifiers (ie. variable names) should not start with an underscore, as they are (in most situations) reserved to the implementation (ie. compiler or standard library). See 7.1.3 and 17.4.3.2.1 of the C++ standard for further reference.
[quote author="Max13" date="1342044793" ?[/quote]
If you delete a child it is automatically removed from the parents child list. If you delete a parent, all children are automatically deleted as well. This means, that all pointers to child objects now point to objects in memory which have been already deleted, and you are not allowed to delete them twice.
I havn't thought about all of this...
I know these things about C++, about pointers specificities (address of the pointer, and address it points to).
Thank you for all your information. I think I will overload delete or add a "deleteObject" on QObject, using pointer reference and which will <code>delete</code> a pointer then = NULL. This is the default behavious I personnaly need on every project I'm developing, since I don't need the old address where the pointer was equal to.
Thanks again for your help.
I do not recommend doing so, because it is just an alleged saftey net, which will stab you in the back once you rely on it.
Keep in mind that there can be an arbitrary number of pointers referencing the same object, not just the one used to delete or create the object.
@
QObject *object = new QObject;
QObject *sameObject = object;
QObject *anotherObject = new QObject(object);
deleteAndNullifyPointer(&object);
deleteAndNullifyPointer(&sameObject); // BANG, already deleted
deleteAndNullifyPointer(&anotherObject); // BANG, already deleted
@
There is just a single solution to memory management in C/C++: having a well-defined model when objects are created and deleted and who is responsible for that.
There are two automatisms in Qt that will help you here. The ownership mechansim already explained and "smart pointers":, which are kind-of what you are trying to implement. | https://forum.qt.io/topic/18212/destructor-randomly-throw-exc_bad_access | CC-MAIN-2017-39 | en | refinedweb |
).
Aliases are no longer available in Brian 2. scalar parameter and update it using a user-defined function (e.g. a CodeRunner).
Flags¶
A new syntax is the possibility of flags. A flag is a keyword in brackets,.
- scalar
- this means that a parameter or subexpression isn’t neuron-/synapse-specific but rather a single value for the whole NeuronGroup or Synapses. A scalar subexpression can only refer to other scalar variables.
Different. An open question is whether we should also allow it to depend on a parameter not defined as constant (I would say no).
Currently, automatic event-driven updates are only possible for one-dimensional linear equations, but it could be extended.')
In contrast to Brian 1, Equations objects do not save the surrounding namespace (which led to a lot of complications when combining equations), they are mostly convenience wrappers around strings. They do')
In contrast to Brian 1, specifying the value of a variable using a keyword argument does not mean you have to specify the values for all external variables by keywords. [Question: Useful to have the same kind of classes for Thresholds and Resets (Expression and Statements) just for convenience?] | http://brian2.readthedocs.io/en/2.0a8/user/equations.html | CC-MAIN-2017-39 | en | refinedweb |
I engaged a problem with inherited Controls in Windows Forms and need some advice on it.
I do use a base class for items in a List (selfmade GUI list made of a panel) and some inherited controls that are for each type of data that could be added to the list.
There was no problem with it, but I now found out, that it would be right, to make the base-control an abstract class, since it has methods, that need to be implemented in all inherited controls, called from the code inside the base-control, but must not and can not be implemented in the base class.
When I mark the base-control as abstract, the Visual Studio 2008 Designer refuses to load the window.
Is there a way to get the Designer work with the base-control made abstract?
I KNEW there had to be a way to do this (and I found a way to do this cleanly). Sheng's solution is exactly what I came up with as a temporary workaround but after a friend pointed out that the
Form class eventually inherited from an
abstract class, we SHOULD be able to get this done. If they can do it, we can do it.
We went from this code to the problem
Form1 : Form
public class Form1 : BaseForm ... public abstract class BaseForm : Form
This is where the initial question came into play. As said before, a friend pointed out that
System.Windows.Forms.Form implements a base class that is abstract. We were able to find...
Inheritance Hierarchy:
public **abstract** class MarshalByRefObject)
public class Form1 : MiddleClass ... public class MiddleClass : BaseForm ... public abstract class BaseForm : Form ...
This actually works and the designer renders it fine, problem solved.... except you have an extra level of inheritance in your production application that was only necessary because of an inadequacy in the winforms designer!
This isn't a 100% surefire solution but its pretty good. Basically you use
#if DEBUG to come up with the refined solution.
Form1.cs
#if DEBUG public class Form1 : MiddleClass #else public class Form1 : BaseForm #endif ...
MiddleClass.cs
public class MiddleClass : BaseForm ...
BaseForm.cs
public abstract class BaseForm : Form ...
What this does is only use the solution outlined in "initial solution", if it is in debug mode. The idea is that you will never release production mode via a debug build and that you will always design in debug mode.
The designer will always run against the code built in the current mode, so you cannot use the designer in release mode. However, as long as you design in debug mode and release the code built in release mode, you are good to go.
The only surefire solution would be if you can test for design mode via a preprocessor directive. | https://codedump.io/share/RXvfPjFVtKlo/1/how-can-i-get-visual-studio-2008-windows-forms-designer-to-render-a-form-that-implements-an-abstract-base-class | CC-MAIN-2017-39 | en | refinedweb |
Netcipher:
1. Stronger Sockets: Through support for the right cipher suites, pinning and more, we ensure your encrypted connections are as strong as possible.
2. Proxied Connection Support: HTTP and SOCKS proxy connection support for HTTP and HTTP/S traffic through specific configuration of the Apache HTTPClient library
You need to implement your own
Client that will execute Retrofit request on Netcipher http client.
Requestto appropriate Netcipher request (copy http method, headers, body)
Response(copy http status code, response, headers)
Pass your
Client to
RestAdapter.Builder.
Done.
public class NetcipherClient implements Client{ private Context mContext; public NetcipherClient(Context context){ mContext = context; //As far as I could see from the sample, Netcipher seems to be dependant on application `Context`. } @Override public retrofit.client.Response execute(retrofit.client.Request request) throws IOException { //Set up configuration for Netcipher (proxy, timeout etc) // Translate Request to Netcipher request // Execute and obtain the response // Build Response from response return response; } } | https://codedump.io/share/TnWnpJS08AXk/1/how-to-use-netcipher-with-retrofit-in-android | CC-MAIN-2017-39 | en | refinedweb |
I am trying to migrate from Unity to Simple Injector in my new project. It is so much faster than Unity that I have to give it a shot. I have had a few bumps, but nothing I could not work around. But I have hit another one with "Look-up by Key"
I have read this where the creater of simple injector states his belief that you should not need to resolve more than one class per interface.
I must be a poor programmer, because I have done that with Unity (which supports it very well) and want to do it in my current project.
My scenario is that I have an IRepository interface. I have two separate repositories I want to abstract using the IRepository interface. Like this:
container.Register<FirstData>(() => new FirstData());
container.Register<IRepository>(
() => new GenericRepository(container.GetInstance<FirstData>()));
container.Register<SecondEntities>(() => new SecondEntities());
container.Register<IRepository>(
() => new GenericRepository(container.GetInstance<SecondData>()));
Resolve
DefaultRequestHandler
OrdersRequestHandler
CustomersRequestHandler
GenericRepostory
GenericRepostory
We ended up changing our Generic Repository to look like this:
/// The Type parameter has no funcionality within the repository, /// it is only there to help us differentiate when registering /// and resolving different repositories with Simple Injector. public class GenericRepository<TDummyTypeForSimpleInjector> : IRepository
(We added a type parameter to it).
We then created two dummy classes like this (I changed the names of the classes to match my example):
// These are just dummy classes that are used to help // register and resolve GenericRepositories with Simple Injector. public class FirstDataSelector { } public class SecondDataSelector { }
Then I can register them like this:
container.Register<FirstData>(() => new FirstData()); container.Register(() => new GenericRepository<FirstDataSelector> (container.GetInstance<FirstData>())); container.Register<SecondEntities>(() => new SecondEntities()); container.Register(() => new GenericRepository<SecondDataSelector> (container.GetInstance<SecondData>()));
(Note the generic type param on the GenericRepository and that I do not register it as an IRepository. Those two changes are essential to making this work.)
This works fine. And I am then able to use that registration in the constructor injection of my business logic.
container.Register<IFirstBusiness>(() => new FirstBusiness (container.GetInstance<GenericRepository<FirstDataSelector>>())); container.Register<ISecondBusiness>(() => new SecondBusiness (container.GetInstance<GenericRepository<SecondDataSelector>>()));
Since my Business classes take an
IRepository it works fine and does not expose the IOC container or the implementation of my repository to the business classes.
I am basically using the Type parameter as Key for lookup. (A hack I know, but I have limited choices.)
It is kind of disappointing to have to add dummy classes to my design, but our team decided that the drawback was worth it rather than abandoning Simple Injector and going back to Unity. | https://codedump.io/share/WXuw3j62i8kG/1/resolve-more-than-one-object-with-the-same-class-and-interface-with-simple-injector | CC-MAIN-2017-39 | en | refinedweb |
hi,
a part of my senior project is about sparse matrix multiplication.
am getting very bad results in the timing, sometimes it's doubling.
in a previous thread, i was told that my loop has to have a big number of iterations...
so am asking some1 to help me solving my problem, GIVING ME THE RIGHT CODE, so that i can undertand better parallelism and implement it on my bigger task, sparse matrix myltiplication.
after parallelizing the code below, the time has increased instead of decreasing to half.
i have a core 2 duo centrino, am using microsoft visual C++ 2008.
these are the results from my parallel amplifier:
-before parallelism:
Elapsed Time: 0.355s
CPU Time: 0.275s
Unused CPU Time: 0.435s
Core Count: 2
Threads Created: 1
-after parallelism:
Elapsed Time: 0.400s
CPU Time: 0.312s
Unused CPU Time: 0.487s
Core Count: 2
Threads Created: 2
this is my code:
#include
#include
using namespace std;
int main()
{
int A[10000],B[10000];
for(int i=0;i<10000;i++)
{
A[i]=B[i]=2;
}
int count=0;
#pragma omp parallel for
for(int i=0;i<10000;i++)
{
count=count+A[i]*B[i];
}
cout< return 0;
}
plz gimme the correct code, i'm running out of time, i must undertanfd this little matter in order to be able to multiply my sparse matrix correctly.
if some1 is interested in helping me even more, plz add me to my e-mail: [email protected]
10X in advance :) | https://software.intel.com/en-us/forums/intel-parallel-studio/topic/266002 | CC-MAIN-2017-39 | en | refinedweb |
cpg_finalize man page
cpg_finalize — Terminate a connection to the CPG service
Synopsis
#include <corosync/cpg.h>
int cpg_finalize(cpg_handle_t handle);
Description
The cpg_finalize function is used to close a connection to the closed process group API. Once the connection is finalized, the handle may not be used again by applications. No more callbacks will be dispatched from the cpg_dispatch function.
Return Value
This call returns the CS_context_get(3), cpg_context_set(3), cpg_dispatch(3), cpg_fd_get(3), cpg_initialize(3), cpg_join(3), cpg_leave(3), cpg_local_get(3), cpg_mcast_joined(3), cpg_membership_get(3), cpg_model_initialize(3), cpg_overview(8), cpg_zcb_alloc(3), cpg_zcb_free(3), cpg_zcb_mcast_joined(3). | https://www.mankier.com/3/cpg_finalize | CC-MAIN-2017-39 | en | refinedweb |
getgrnam man page
Prolog
This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.
getgrnam, getgrnam_r — search group database for a name
Synopsis
#include <grp.h> struct group *getgrnam(const char *name); int getgrnam_r(const char *name, struct group *grp, char *buffer, size_t bufsize, struct group **result);
Description.
Return Value.
Errors.
The following sections are informative.
Examples);
Application Usage.
Rationale
None.
Future Directions
None.
See Also
endgrent(), getgrgid(), sysconf()
The Base Definitions volume of POSIX.1-2008, <grpgrent(3p), getgrgid(3p), grp.h(0p), newgrp(1p). | https://www.mankier.com/3p/getgrnam | CC-MAIN-2017-39 | en | refinedweb |
Next: Coding guidelines, Previous: Core algorithm, Up: Hacker's guide [Contents][Index]
In addition to all the common
Autoconf switches
such as
--prefix, Liquid War 6 has some custom switches:
--disable-console: allows you to turn on/off console support. Normally this is detected automatically but in case you really want to disable it on platforms which support it, you can. This will cause the program no to link against
libreadline, among other things.
--disable-gtk: allows you to turn on/off gtk support. Normally this is detected automatically but in case you really want to disable it on platforms which support it, you can. This will cause the program not to link against GTK libs.
--disable-cunit: allows you to turn on/off CUnit support. Normally this is detected automatically but in case you really want to disable it on platforms which support it, you can. This will cause the program not to link against CUnit libs.
--enable-optimize: will turn on optimizations. This will turn on compiler options such as
-fomit-frame-pointerbut also disable some code in the program. Indeed, most of the advanced memory checking in the game - which ensures it does not leak - will be turned of. This will certainly speed up things, however, it’s not recommended to turn this on until program is not stable enough so that memory leaks and other problems can be declared ’impossible’. Turn this on if you really have some speed problem, otherwise it’s safer to use the full-featured ’slow’ version of the game.
--enable-paranoid: will turn on very picky and pedantic checks in the code, try this when you suspect a serious memory bug, a race condition whatsoever, and want to track it down. Useless for players.
--enable-headless: will allow compilation without any graphics backend. The game is unplayable in that state but one can still wish to compile what is compilable, for testing purposes.
--enable-silent: will allow compilation without any sound backend. The game won’t play any music in that state but one can still wish to compile what is compilable, for testing purposes.
--enable-allinone: will stuff all the internal libraries into one big executable. Very convenient for profiling. The major drawback is that you need to have all the optional libraries installed to compile all the optional modules. Another side effect is that with this option there’s no more dynamic loading of binary modules, so if your platform has a strange or buggy support for
.sofiles, this option can help.
--enable-fullstatic: will build a totally static binary, that is using the
--staticoption for
gccand the
-all-staticoption for
libtool. Currently broken, this option could in the future allow for building binaries that run pretty much everywhere, without requiring any dependency but a Kernel.
--enable-gprof: will enable profiling informations. This will activate
--enable-allinone, else you would only track the time spent in functions in the main
liquidwar6executable, and exclude lots of interesting code contained in dynamic libraries.
--enable-instrument: will instrument functions for profiling. This will turn on the
-finstrument-functionsswitch when compiling, so that the hooks
__cyg_profile_func_enterand
__cyg_profile_func_exitare called automatically. Then you can link against tools like cprof or FunctionCheck.
--enable-profiler: will enable Google Performance Tools support. Basically, this means linking against
libtcmallocand
libprofiler. You could activate those by using
LD_PRELOADor by using your own
LDFLAGSbut using this option will also make the game tell you if
CPUPROFILEor
HEAPPROFILEare set when it starts. The
pprof -gvoutput is very handy. Note that on some systems
pprofis renamed
google-pprof.
--enable-gcov: will enable coverage informations, to use with gcov and lcov. This is for developpers only. It will activate
--enable-allinone, else there would be some link errors when opening dynamic libraries. The obtained information is available online: coverage. and GNU global.
--enable-valgrind: will enable some
CFLAGSoptions which are suitable for the use of Valgrind, to track down memory leaks and other common programming errors. Use for debugging only, usually together with
--enable-allinone.
Liquid War 6 does have a
./debian in both main and extra maps packages,
so it’s “debianized”.
To build the main
.deb package, untar the main source tarball, then:
make dist cd pkg cp ../liquidwar6-X.Y.Z.tar.gz . # X.Y.Z is the version make deb
Note that you have to copy the source tarball to
./pkg and move
to this directory before typing
make deb. This is, among other things,
to simplify the main
Makefile.
To build the extra maps
.deb package, untar the extra maps tarball, then:
make deb
Liquid War 6 does have a
.spec files in both main and extra maps packages.
To build the main
.rpm package, untar the main source tarball, then:
make dist cd pkg cp ../liquidwar6-X.Y.Z.tar.gz . # X.Y.Z is the version make rpm
Note that you have to copy the source tarball to
./pkg and move
to this directory before typing
make rpm. This is, among other things,
to simplify the main
Makefile.
To build the extra maps
.rpm package, untar the extra maps tarball, then:
make rpm
This section describes how to compile the game from source under Microsoft Windows. Note that players are encouraged to use a free system such as GNU/Linux, which is the platform Liquid War 6 is being hacked on by default. If you encounter problems with this port, you’ll probably save time by installing a double-boot with GNU/Linux coexisting with your previous Microsoft Windows install.
Basically, Liquid War 6 requires
MinGW.
More precisely, it requires MSYS.
A standard Cygwin installation won’t
work, because it is too UNIXish to allow third party libraries
like SDL to compile natively.
You might argue that SDL is available for Cygwin, but in reality,
the Cygwin port of SDL is a MinGW port. Indeed, Cygwin brings
all standard POSIX functions including the use of
main
instead of
WinMain and I suspect this is a problem for
graphical libraries like SDL which do require some sort of direct
access to the OS low-level functions. Therefore, MinGW is more
adapted for it does not define all these functions, and
allows any library to hook on Microsoft Windows internals directly.
Point is then, you also loose the cool effect of Cygwin which
is to have a complete glibc
available,
including network functions like
select defined the
POSIX way, and not the WinSock way. If you ever ported code from
POSIX sockets to WinSock 2, you know what I mean. Using MinGW
is also embarassing for some libraries won’t compile easily, and
for instance programs which heavily rely on a real
TTY
interface to work are usually hard to port. This includes
ncurses
and
GNU readline.
Liquid War 6 tries to have workarrounds for all this, and in
some cases the workarround is simply that embarassing code
is not compiled on Microsoft Windows. For this reason, some
features are not available on this platform. Period.
Now the reason you need MSYS and not only MinGW is that MSYS
will allow
./configure scripts to run, and this eases
up the porting process a lot. MinGW and MSYS packages are
downloadable on the
SourceForge MinGW download page. Alternatively, there is a
mirror on ufoot.org,
but files might be outdated.
To compile Liquid War 6, first download and unzip all the
following files in
the same directory, for instance
C:\MSYS.
If you do not have any tool to handle
.tar.gz and
.tar.bz2
files under Microsoft Windows, which is likely to be the case
when MSYS is not installed yet, you can untar these on any GNU/Linux box,
then upload the whole directory to the target Windows host.
This file list might contain file which are not absolutely mandatory for Liquid War 6, for instance the Fortran 77 compiler is absolutely useless, but installing it won’t harm either. Some packages might unzip things the right way, but some do it in a subfolder. You might need to run commands like:
cp -r coreutils*/* . rm -rf coreutils*
Get rid of useless files:
rm ._.DS_Store .DS_Store
It’s also mandatory to move everything that has been installed in
/usr or
/usr/local to
/ since MSYS has some
builtin wizardry which maps
/usr on
/.
You need to do this if you don’t unzip files from a MinGW shell,
which is obviously the case when you first install it. Usefull command
can be:
mv usr/* . rmdir usr
libintl is not correctly handled/detected by LW6,
and can raise an error like
"gcc.exe: C:/msys/local/lib/.libs/libintl.dll.a: No such file or directory"
so one needs to copy some libraries in
/usr/local/lib/.libs/:
mkdir local/lib/.libs cp local/lib/libintl.* local/lib/.libs/
Another step is to edit
/etc/profile and add lines like:
export CFLAGS="-g -I/usr/local/include" export LDFLAGS="-L/usr/local/lib" export GUILE_LOAD_PATH="C:\\MSYS\\local\\share\\guile\\1.8\\"
Close and re-launch your msys shell (rxvt) so that these changes take effect. Check that those values are correctly set:
env | grep FLAGS env | grep GUILE
Finally, your MSYS environment is (hopefully...) working.
Now you need to compile the following programs, from source.
Files are mirrored on ufoot.org for your convenience, however these might be outdated.
Still, there are known to work.
Proceed like if you were under a POSIX system.
Some packages use the
--disable-rpath swith, there are various
reasons for which rpath is an issue.
In the same manner,
--disable-nls when linking against
libintl
or
libiconv was painful.
make clean GC; cp pthread.h sched.h /usr/local/include/; cp pthreadGC2.dll /usr/local/bin/; cp libpthreadGC2.a /usr/local/lib/
gmp-4.2.2.tar.gzthen
./configure && make && make install
guile-1.8.5.tar.gz. Edit
libguile/guile.cand insert
#undef SCM_IMPORTjust before
#include <libguile.h>. Edit
./libguile/threads.cand place
struct timespec { long tv_sec; long tv_nsec; };just before
#include "libguile/_scm.h". Then
./configure --disable-nls --disable-rpath --disable-error-on-warning --without-threads && make && make install. The
GUILE_LOAD_PATHvalue must be correctly set for
guile-configto work. For unknown reasons, running
guilecan throw a stack overflow error. Don’t panic. See bug 2007506 on SourceForge.net for an explanation on why the Guile binary shipped with MSYS is not suitable for Liquid War 6.
expat-2.0.1.tar.gzthen
./configure && make && make install
sqlite-amalgamation-3.5.9.tar.gzthen
./configure && make && make install
libpng-1.2.29.tar.gzthen
./configure && make && make install
jpegsrc.v6b.tar.gzthen
./configure && make && make install && make install-lib
curl-7.18.1.tar.gzthen
./configure --without-ssl && make && make install
freetype-2.3.5.tar.gzthen
./configure && make && make install
libogg-1.1.3.tar.gzthen
./configure && make && make install
libvorbis-1.2.0.tar.gzthen
LDFLAGS="$LDFLAGS -logg" && ./configure && make && make install
SDL-1.2.13.tar.gzthen
./configure && make && make install
SDL_image-1.2.6.tar.gzthen
./configure && make && make install
SDL_mixer-1.2.8.tar.gzthen
./configure && make && make install
SDL_ttf-2.0.9.tar.gzthen
./configure && make && make install
For your convenience, a zip file containing a complete MSYS "Liquid War 6 ready"
environment is available. It is simply the result of all the operations
described above.
Simply unzip msys-for-liquidwar6-20080819.zip
(about 240 megs) in
C:\MSYS\.
All dependencies compiled in
/local have been generated
using the command:
cd /usr/local/src ./msys-for-liquidwar6-build.sh > ./msys-for-liquidwar6-build.log 2>&1
Note that this script does’t do everything, you’ll still need to edit Guile source code and patch it manually.
It might even be possible to use this MSYS environment
under Wine.
Simply unzip it under
$HOME/.wine/drive_c, and run
wine "$HOME/.wine/drive_c/windows/system32/cmd.exe" /c "c:\\msys\\msys.bat" and with
luck, you’ll get a working shell. Note that this might allow you to compile
the game, but running it is another story. Consider this MSYS over Wine trick
as a hack enabling the use of free software only when compiling for
Microsoft proprietary platform. It is not a reasonnable way to run the game.
If running under a UNIXish platform, or better, GNU, simply run native code.
Use the Windows 32-bit port only if you are jailed on a Microsoft system.
Now, let’s come to the real meat, untar the Liquid War 6 source tarball, launch your MSYS shell, and:
./configure make make install
Now the binary is in
src/.libs/liquidwar6.exe
(beware,
src/liquidwar6.exe is only a wrapper).
This binary is an MSYS/MinGW binary, so it read paths “Ã la”
Microsoft, that is, it has no knowledge of what
/usr is,
for instance. It requires paths starting by
C:\.
This is still experimental. Basically, install MacPorts, and most dependencies with,
except for SDL which you compile from source. The idea is to compile SDL using
the native OS X bindings (and not some other GL files you could have in
/opt/local
installed by MacPorts), then compile the game and other SDL dependencies
against this SDL.
The SDL_mixer library might need to be told to compile itself without dynamic ogg support.
By default it seems that it tries to load
libvorbisfile.dylib at runtime, and it can fail.
To disable this dynamic loading, use for instance :
/configure --prefix=/opt/extra --enable-music-ogg --disable-music-ogg-shared
Also, it might seem obvious for Mac OS X users, but there are some important issues related to compiling options and handling dynamic libraries at runtime.
ldddoes not exist, run
otool -Linstead.
LD_LIBRARY_PATHis
DYLD_LIBRARY_PATH.
.dyliband not
.so.
OBJCFLAGSenvironment variable along with
CFLAGSbecause the Mac OS X port uses some Objective-C code.
It is very important to have the right SDL flags when linking the Liquid War 6 binaries. For instance it could be:
-I/opt/extra/include -I/opt/local/include -Wl,-framework -Wl,CoreFoundation -I/opt/local/include -D_THREAD_SAFE -Wl,-framework -Wl,Cocoa -Wl,-framework -Wl,OpenGL -Wl,-framework -Wl,Cocoa
The point is to have Cocoa and OpenGL support. Depending on the way you installed SDL,
you might also need to include an SDL framework support, this is mostly if you installed SDL from
.dmg binary images, and not from source with the command line. A typical output of
sdl-config --libs is:
-L/opt/extra/lib -lSDLmain -lSDL -Wl,-framework,Cocoa
Another important issue is to include
SDL.h, which in turn includes
SDLmain.h, in
all the .c source files defining the standard
main function. This is done in liquidwar6 but
should you try to link yourself on liquidwar6 libraries and/or hack code, you must do this or
you’ll get errors when running the game. Such errors look like:
*** _NSAutoreleaseNoPool(): Object 0x420c90 of class NSCFNumber autoreleased with no pool in place - just leaking
The reason is that SDL replaces your
main with its own version of it. One strong implication
is that all the dynamic loading of SDL, which works on sandard GNU/Linux boxes, won’t work under
Mac OS X, since SDL hard codes itself by patching
main with
#define C-preprocessor commands.
A
.dmg file (disk image) containing a
Liquid War 6.app folder (OS X application)
is available for your convenience. It might work or not. In doubt, compile from source. The complicated part about this package (a “bundle” is OS X language) is that
it needs to embed various libraries which are typically installed in
/opt
by MacPorts on a developper’s machine. So to build this package a heavy use
of the utilility
install_name_tool is required, normally all libraries
needed ship with the binary, remaining depedencies concern frameworks which
should be present on any working Mac OS X install. Still, this is only theory.
Needs to be widely tested.
The layout of the bundle follows:
./Contents/Info.plist: metadata, bundle description file
./Contents/MacOS: contains the main binary
liquidwar6as well as all specific low-level libraries
./Contents/Resources/data: general game data, does not contain maps.
./Contents/Resources/music: music for the game.
./Contents/Resources/map: system maps, you can put your own maps (or “extra” maps) here if you want all users to share them.
./Contents/Resources/script: Liquid War 6 specific scripts, the scheme scripted part of the program.
./Contents/Resources/guile: common shared Guile scripts, part of Guile distribution.
./Contents/Resources/doc: documentation in HTML and PDF formats.
Additionnally, the Mac OS X port uses
/Users/<username>/Library/Application Support/Liquid War 6/ to store
configuration file, logs, etc. It does not use
$HOME/.liquidwar6 like the default UNIX port.
The Mac OS X port also has a special behavior, in order to load some libraries with dlopen
(SDL_image does this with libpng and libjpeg) it needs to set
DYLD_FALLBACK_LIBARY_PATH to a
value that contains these libraries. This is typically in the bundle distributed on the disk image.
On a developper’s computer this problem does not appear for those libs are often in places like:
/usr/local/lib
/usr/X11/lib
/opt/local/lib
So the program sets
DYLD_FALLBACK_LIBARY_PATH (but not
DYLD_LIBRARY_PATH else
it breaks internal OS X stuff which relies, for instance, on libjpeg library that has the
same name but different contents) but it needs to do it before it is even run, else
the various
dyld functions do not acknowledge the change. That is, calling the C
function
setenv(), even before
dlopen(), has no effect. So the program
calls
exec() to re-run itself with the right environment variable. This is why,
on Mac OS X, there are two lines (exactly the same ones) displaying the program description
when it is started in a terminal.
This is not working yet, but there are good hopes that some day, Liquid War 6 can run on a GP2X console. This handled gaming device uses a Linux kernel on an ARM processor, does support most GNU packages through cross-compilation, and has basic SDL support.
To compile Liquid War 6 for GP2X, you first need to set up a working “toolchain”. It’s suggested you do this on a working GNU/Linux box. There are several solutions, the recommended one being Open2x. Read the online documentation on how to install Open2x.
Basically, the following should work:
mkdir /opt/open2x # check that you can write here svn co open2x-toolchain ./open2x-gp2x-apps.sh cd open2x-toolchain
Then, for your environment to be complete, you need to set up some environment variables. For instance:
export OPEN2X_SYSTEM_PREFIX=/opt/open2x/gcc-4.1.1-glibc-2.3.6/arm-open2x-linux export GP2X_USER_PREFIX=$HOME/gp2x export CC=${OPEN2X_SYSTEM_PREFIX}/bin/arm-open2x-linux-gcc export CPP=${OPEN2X_SYSTEM_PREFIX}/bin/arm-open2x-linux-cpp export CXX=${OPEN2X_SYSTEM_PREFIX}/bin/arm-open2x-linux-g++ export AS=${OPEN2X_SYSTEM_PREFIX}/bin/arm-open2x-linux-as export CFLAGS=''-I${OPEN2X_PREFIX}/include -I${GP2X_USER_PREFIX}/include'' export CPPFLAGS=''-I${OPEN2X_PREFIX}/include -I${GP2X_USER_PREFIX}/include'' export CXXFLAGS=''-I${OPEN2X_PREFIX}/include -I${GP2X_USER_PREFIX}/include'' export LDFLAGS=''-L${OPEN2X_PREFIX}/lib -L${GP2X_USER_PREFIX}/lib'' export PATH=''${GP2X_USER_PREFIX}/bin:${OPEN2X_SYSTEM_PREFIX}/bin:$PATH''
In this setting, there’s a user
$HOME/gp2x directory which will
contain all the Liquid War 6 related libraries while the
/opt/open2x
remains untouched.
Then you need to install the requirements. All these packages need to
be cross-compiled. To make things clear and non-ambiguous, even if you
have
CC set up in your environment variables, pass
--build
and
--host arguments to the
./configure script of all these
packages. A typical command is:
./configure --build=i686-pc-linux-gnu --host=arm-open2x-linux --prefix=${GP2X_USER_PREFIX}
Here’s the list of the requirements:
./configure --prefix=$GP2X_USER_PREFIX --build=x86_64-pc-linux-gnu --host=arm-open2x-linux --disable-pulseaudio --disable-video-directfb
--witout-threadsswitch to the
./configurescript else it will try (and fail!) to run a test program. Liquid War 6 does not use Guile threads, it does use threads but uses them “directly” outside the Guile layer.
--buildand
--hostfor this one, they are unsupported. Package compiles fine anyway.
Next, one needs to install a special version of SDL, which targets the GP2X specifically. This is not a generic SDL, and it does have limitations, which are related to the GP2X peculiar hardware. There are installation instructions about how to do this. The following should work:
cvs -d :pserver:[email protected]:/cvsroot/open2x login # blank password cvs -d :pserver:[email protected]:/cvsroot/open2x co libs-gp2x
Next: Coding guidelines, Previous: Core algorithm, Up: Hacker's guide [Contents][Index] | http://www.gnu.org/software/liquidwar6/manual/html_node/Compilation-tips.html | CC-MAIN-2015-14 | en | refinedweb |
I’m dissecting a Max patch and still learning much of the basics. I’m confused by the Sends and Receives in this patch.
There’s an object [s ---rec]. To my understanding that should be sending to another object that has the same argument name [r ---rec]. However in the screenshot attached has a live.text object set up as a toggle called "Mute". This toggle is sending to [s ---rec] but there are no corresponding receive objects with the same argument name. Any explanations?
There is a patcher with the name "rec" though. The "Mute" button is sending information to that patch but why and how? Thanks in advance.
There is probably a [r ---rec] inside the [p rec] patcher, otherwise the [s ---rec] would make no sense.
Oh yes. Thank you. So you can send and receive to sub-patches. I guess I didn’t realize that. So the "—" is not some special kind of syntax in Max?
Named objects (like send, receive, buffer etc.) share a global namespace. That means, if you have a [s foo] object in one device, any [r foo] object in any m4l device will receive the messages you send to [s foo]. Even if it’s a completely different m4l device (let’s say the [send] is inside a max-midi-effect and the [receive] inside a max-audio-effect.
To prevent that, you can put "—" at the beginning of the name. The "—" gets replaced by a different number for each m4l device, for example the [s ---foo] will become [s 001foo] in the first device [s 002foo] in the second and so on.
There’s a very short explanation here :
Thanks a lot for that clarification.
When Thé patch is locked, click (or cmd-click maybe)on any send / receive and you will get a list of all objects in that namespace in your patch or sub patches. Choosing one in the list will select it.
oh, didn’t know Live had its own unique identifiers
that --- comes from the old pluggo times, and they were just leaving it like it was.
---
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Hi,
I've queried an EventLog using ManagementObjectSearcher (System.Management namespace for WMI access). So far I was able to retrieve log entries by querying the Win32_NTLogEvent instances.
But when I tried mapping the ManagementObject instances, the TimeGenerated and TimeWritten properties are in String form and not in DateTime type as documented (see MSDN:). I can't convert the String directly to DateTime. A sample value I'm getting is:
20060907105310.000000+480
It's the first time I've tried using the System.Management namespace, especially to access Event Logs. Please let me know if I'm doing something wrong here. Thanks.
use the management dateTime converter:
Microsoft is conducting an online survey to understand your opinion of the Msdn Web site. If you choose to participate, the online survey will be presented to you when you leave the Msdn Web site.
Would you like to participate? | https://social.msdn.microsoft.com/Forums/vstudio/en-US/0d94b9a3-4f94-4ea7-bd03-6994f9384473/wmi-win32ntlogevent-class-time-properties-not-datetime?forum=netfxbcl | CC-MAIN-2015-14 | en | refinedweb |
Egg cooking
Since Trac 0.9 it has been possible to write plugins for Trac to extend Trac functionality. Even better, you can deploy plugins as Python eggs that really makes plugin development fun.
This tutorial shows how to make an egg, successfully load an egg in Trac and in advanced topics how to serve templates and static content from an egg.
You should be familiar with component architecture and plugin development. This plugin is based on example in that plugin development article we just extend it a bit further.
Required items
First you need setuptools. For instructions and files see EasyInstall page.
Then you need of course Trac 0.9. Currently, it means source checkout from Subversion repository. Instructions for getting it done are located at TracDownload page.
Directories
To develop a plugin you need to create few directories to keep things together.
So let's create following directories:
./helloworld-plugin/ ./helloworld-plugin/helloworld/ ./helloworld-plugin/TracHelloworld.egg-info/
Main plugin
First step is to generate main module for this plugin. We will construct simple plugin that will display "Hello world!" on screen when accessed through /helloworld URL. Plugin also provides "Hello" button that is by default rendered on far right as a module
Since this is not enough, we need to make our simple plugin as a module. To do so, you simply create that magic __init__.py into ./helloworld-plugin/helloworld/:
# Helloworld module from helloworld import *
Make it as an egg
Now it's time to make it as an egg. For that we need a chicken called setup.py that is created into ./helloworld-plugin/:
from setuptools import setup PACKAGE = 'TracHelloworld' VERSION = '0.1' setup(name=PACKAGE, version=VERSION, packages=['helloworld'])
To make egg loadable in Trac we need to create one file more. in ./helloworld-plugin/TracHelloworld.egg-info/ create file trac_plugin.txt:
helloworld
First deployment
Now you could try to build your first plugin. Run command python setup.py bdist_egg in directory where you created it. If everthing went OK you should have small now reading EggCookingTutorial/AdvancedEggCooking to really integrate plugin into Trac layout.
Attachments (2)
- helloworld-plugin-1.tar.gz (775 bytes) - added by rede 10 years ago.
First version of tutorial plugin
- helloworld-plugin-1-trac-0.9.5.tar.gz (774 bytes) - added by maxb 9 years ago.
Tutorial files, updated for Trac 0.9.5
Download all attachments as: .zip | http://trac-hacks.org/wiki/EggCookingTutorial/BasicEggCooking?version=3 | CC-MAIN-2015-14 | en | refinedweb |
...one of the most highly
regarded and expertly designed C++ library projects in the
world. — Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
Returns the result type of
replace, given the types of
the input sequence and element to replace.
template< typename Sequence, typename T > struct replace { typedef unspecified type; };
result_of::replace<Sequence,T>::type
Return type: A model of Forward Sequence.
Semantics: Returns the return type of
replace.
Constant.
#include <boost/fusion/algorithm/transformation/replace.hpp> #include <boost/fusion/include/replace.hpp> | http://www.boost.org/doc/libs/1_57_0/libs/fusion/doc/html/fusion/algorithm/transformation/metafunctions/replace.html | CC-MAIN-2015-14 | en | refinedweb |
On 08/17/2010 03:47 PM, Paul Eggert wrote: > On 08/17/10 23:17, Eric Blake wrote: > >> libvirt is currently LGPLv2+ > > Can this be changed to LPGLv3+? That'd solve the problem. True, but it would have knock-on effects on all sorts of other clients of libvirt. I'm re-adding the libvirt list for thoughts from anyone else. > >> Is it worth relaxing the license on the *printf-posix family of modules >> to LGPLv2+ from their current LGPLv3+, or is this too big of a request? > > I dunno, at some point we should be encouraging people to switch > to LGPLv3+. It makes sense for the FSF to request that GNU projects use better licenses. Unfortunately, libvirt is not a GNU project; so it is more a question as to how Red Hat wants to license it, rather than what the FSF prefers. At any rate, I think the ultimate decision on how libvirt is licensed is rather political in nature, and will involve quite a bit of discussion among more than just the software developers contributing to libvirt. But at least libvirt is LGPLv2+; unlike some projects (like git) that are explicitly v2-only and can't do the upgrade. Meanwhile, I tend to agree that relaxing printf-posix to LGPLv2+ is a rather hefty sledge-hammer, and probably not appropriate for gnulib. > >> since using umaxtostr penalizes 32-bit machines for converting to the >> 64-bit intermediary, maybe it's worth adding a size_t variant? > > That would be fine. The *tostr routines were mainly written > for two reasons. First, for platforms that can't/couldn't portably > and reliably output wide integers. Second, speed. > >> What a shame that POSIX omitted an <inttypes.h> PRIu* for size_t. > > We could add one in gnulib, no? In a quick google search, I found this use of PRIdS (which is geared more for ssize_t, but the analog PRIuS would apply to size_t): However, S is awfully short; I'd prefer something a bit longer like PRIuSIZE. Is there any other project already using gnulib that has invented a PRIuXXX name for size_t? It would also be nice if we had some prior art from glibc or even one of the BSD systems to copy a commonly-used name. Meanwhile, the idea is slightly more appealing than relicensing lots of gnulib or using the inttostr code; but it still requires auditing code and forbidding "%zu" in favor of "%"PRIuSIZE (or whatever other name we settle on). Also, it seems like we might want to create a new intttypes-plus (or inttypes-gnu) module, and leave the existing inttypes module as providing just the namespace guaranteed by glibc, while requiring the use of the new module to pollute the namespace with these new (but useful) macros. -- Eric Blake eblake redhat com +1-801-349-2682 Libvirt virtualization library
Attachment:
signature.asc
Description: OpenPGP digital signature | https://www.redhat.com/archives/libvir-list/2010-August/msg00412.html | CC-MAIN-2015-14 | en | refinedweb |
iSequenceCondition Struct Reference
A sequence condition. More...
#include <ivaria/sequence.h>
Inheritance diagram for iSequenceCondition:
Detailed Description
A sequence condition.
This is also a callback to the application. This condition returns true on success.
Main creators of instances implementing this interface:
- Application using the sequence manager.
Main users of this interface:
Definition at line 71 of file sequence.h.
Member Function Documentation
Do the condition.
The dt parameter is the difference between the time the sequence manager is at now and the time this condition was supposed to be called. If this is 0 then the condition is called at the right time. If this is 1000 (for example) then the condition was called one second late. This latency can happen because the sequence manager only kicks in every frame and frame rate can be low.
The documentation for this struct was generated from the following file:
- ivaria/sequence.h
Generated for Crystal Space 2.1 by doxygen 1.6.1 | http://www.crystalspace3d.org/docs/online/api/structiSequenceCondition.html | CC-MAIN-2015-14 | en | refinedweb |
12 May 2011 13:38 [Source: ICIS news]
LONDON (ICIS)--?xml:namespace>
MMTC closed a tender for an unspecified quantity of urea on 4 May. It subsequently issued the following awards to traders at $399/tonne (€279/tonne) CFR (cost and freight):
• 55,000 tonnes to Toepfer for Mundra port
• 40,000-50,000 tonnes to Swiss Singapore for Mundra port
• 25,000 tonnes to Transglobal for Kandla port
The urea is for shipment before the end of June.
Toepfer is expected to supply from
The quantity awarded was less than expected and could result in a different Indian state agency issuing a tender again soon for additional quantities.
($1 = €0.70) | http://www.icis.com/Articles/2011/05/12/9459459/indias-mmtc-awards-120000-130000-tonnes-under-urea-tender.html | CC-MAIN-2015-14 | en | refinedweb |
Note: This framework is a framework that has 100% compatibility with standard MVC FOR SPRING in J2EE and MVC.NET 3.00 and is running on top of them and adds many capabilities which did not exist in this arena before.
I always disliked webforms because of its low quality of code and also the non web nature it had. Moreover, I liked C#, but because of leaking of MVC architecture in this platform, I went to JAVA whose library we are talking about also has a JAVA (MVC FOR SPRING) component Library but I would like to introduce C# and MVC.NET version as my favorite product.
The goals of this design were:
IFrame
Popup
DIV
IFRAME
This system is:
Compare after we have done the job.
We wrote the same code for the same reason and we tested them in three different platforms. Here, you can see the results:
As you see, MVC PLUS needs one third of MVC.NET and less than half of WebForms to spend it in development which means, less cost, more high quality code and exactly a cheaper and better product in code quality and overall.
Here, we compared these frameworks in line of Rendering size which also means less Render Time in server side which is effective if you use SSL (less cost for application server and much faster data transfer):
As you see, Average Forms rendered with MVC Plus have a size between 5 to 10 Kilobytes which is much less than other competitors, even less than half of their size in MVC.NET (Using Telerik Components).
Note: All tests passed in my friends' office, later I will publish the sample codes (these were a real product for business, so my friend might cut some parts of code).
Note that all tests were done for the similar form design in view and reason and scenario.
In standard MVC, you have to write your models as below:
public class Person{
public string name {get ; set ; }
public string FamilyName {get ; set ; }
}
public class ADDRESS{
public string name {get ; set ; }
public string FamilyName {get ; set ; }
}
Each view can support only up to one Model, for example, you can have only Person Model or address Model accessible.
In MVC Plus, you have to declare your Models separated from Meta Models and Meta Models will be used in Controllers and Views:
First, write your Models (which work as repository or DAL):
public class Person:WLBaseModel {
[PrimaryKey]
public int PersonID;
[stringLength (max:50)]
[REQUIRED]
public string name {get ; set ; }
[REQUIRED]
[stringLength (max:50)]
public string FamilyName {get ; set ; }
}
public class ADDRESS:WLBaseModel {
[PrimaryKey]
public int addrssID {get ; set ;}
[ForeignKey(Person)]
public int PersonID {get ; set ;}
[REQUIRED]
[stringLength (max:50)]
public string City {get ; set ; }
[REQUIRED]
[stringLength (max:65535)]
public string Address {get ; set ; }
}
And then you have to declare your META MODELS as below:
public class MetaModel :WLBaseMetaModel
{
[ApplicationServerCache { timeOut:10}]
public Person Person{get ; set ;}
[ApplicationServerCache { timeOut:10}]
public Address Address {get ; set ;}
}
In Standard MVC 3.00, you cannot have access to both models. In MVC PLUS And Meta Models, you can have many models in one Meta Model.
We only support RAZOR in MVC.NET 3.00, so, other view engines are not supported by now and we don’t think we will support them later.
You can use META MODELS you declared in your View as below:
@Html.WLControlFor(m=>m.Person.Name)
@Html.WLControlFor(m=>m.Person.FamilyName)
@Html.WLControlFor(m=>m.Address.City)
@Html.WLControlFor(m=>m.Address.Addrsss)
All Model members will be connected to each other: Grids, Trees, Editors, checkboxes, Combos, etc., I repeat this phrase that you have to separate concept of Models and Meta Models from each other.
Here, you can see what I mean in the upper lines:
As you see, Tree and Editors are connected to each other.
But how does it work? In brief, we have an architecture like this. It was a complex architecture but we did it once to have a safe way of development:
Later, I will introduce how hard it is to implement such a code in a heavy JavaScript and C# Library (mostly in architecture which was a hard to do).
Note that this is a huge and great architecture for WEB, maybe for the first time??? (I don’t know! Just maybe.) We did several new things to supply these abilities.
In standard MVC, data transfer can transfer a single record and you need to do much custom code for multiple records.
Hard for development in most cases you want to transfer several records to/from Server.
In MVC, you can send / receive multiple records at once and we can name it Batch Transfer. It is useful for most cases of development.
As an extra advantage in architecture, MVC Plus has a two side (server/client) cache in both client and server which will guarantee:
You can set Model Behavior as Live.
Since data is changed in client and you change cursor position in client or modify client data, Client will send Update or Inserted or Deleted item to Server.
Address.LiveData = true;
You can set Model Behavior as Offline.
You can send batch records, for example 10 modified records to server at once.
Person.LiveData = false;
To handle batch or single records, you have triggers such as:
Beforeinsert
BeforeUpdate
BeforeSelect
Before
BeforeChange
BeforeOtherCommands
And also you have:
Afterinsert
AfterUpdate
AfterSelect
After
AfterChange
AfterOtherCommands
In MVC Plus, you can make Models available in Meta Models as Master detail, but don’t worry, no need to do much code - you just have to do it with few lines of code. You can connect two models as Master details as below:
Address.Master = Person;
or:
[AutoConnectModels(“*”)]
public class MetaModel {
… {Models …
}
No need for extra code.
Required data for automatic actions will be provided through attributes over model properties:
[PrimaryKey]
public int addrssID {get ; set ;}
[ForeignKey(Person)]
public int PersonID {get ; set ;}
Validations will show beside controls and client will show a message before sending them to the Application Server.
Validation is very similar to standard MVC, but you can have:
RowValidation
FieldValidation
This is not required to do RowValidation most of the time, but you can also add it to client and server.
RowValidation
By default, most of the validations will be done automatically.
A sample code would be:
[Required]
[RangeOf(OnlyAlphabet)]
[MaxMinLength(5,50)]
public string Name {get ; set ;}
Or even:
[Required]
[Password(StrongPassord)]
[MaxMinLength(5,32)]
[EqualTo(“confirmPassword”]
Public string Password {get ; set ; }
Also, the system will automatically validate type of model members in both client and server.
Validations will show beside controls and client will show a message before sending them to the Application Server. You can set a special shape for them easily but by default, we have four different ways of showing them:
Each single control should have a FieldName, which is similar to Model’s Property name in application server, these will be generated automatically by C# or J2EE components.
FieldName
Model
Property
Just leave your control simply in view:
@Html.WLControlFor(m=>m.Address.Addrsss)
We have many components ready for this Framework:
Html.WLTextEditFor
Html.WLWebEditorFor
Html.WLDivEditFor
Html.WLDisplayfor
Html.WLTreefor
Html.WLCheckBoxFor
Html.WLComboBoxFor
Html.WLSpinEditFor
Html.WLAutoCompleteFor
Html.WLLookUpFor
Html.WLGridFor
And more than 109 other READY TO USE components.
In the pictures, you can see some pages are designed with this system. Note that these tabs are not IFRAMES but they come from different sources and they are used from JAVASCRIPT SandBox Model, always you can run any JS Command from server side without refresh.
IFRAMES
MVC PLUS 2.00 now support TREE MODELS which did not exist before:
Model.IsTree=True;
And then in view:
@Html.WLTreeFor(m=>m.Person)
Ryan Samiee
BCs and 16 years Professional Experience (since I had 14 years old I started working with companies as a professional developer) and 14 years experience in Component Development in Delphi and then WEB Components.. | http://www.codeproject.com/Articles/189276/MVC-PLUS-for-MVC-NET-3-00?fid=1623936&df=90&mpp=10&noise=1&prof=False&sort=Position&view=None&spc=None | CC-MAIN-2015-14 | en | refinedweb |
Details
- Type:
New Feature
- Status: In Progress
- Priority:
Major
- Resolution: Unresolved
- Affects Version/s: 3.5
- Fix Version/s: None
-
- Labels:
- Environment:
All
Description.
Activity
One API issue is how to give error codes... looking at the HTTP list () there seem to be 2 that fit the bill:
409 Conflict
Indicates that the request could not be processed because of conflict in the request, such as an edit conflict.[2]
412 Precondition Failed
The server does not meet one of the preconditions that the requester put on the request.[2]
Looks like 409 is closer though.
FYI, I've got a patch that seems to work fine... I'm just still finishing up some of the tests.
We have been working on it ourselves (SOLR-3173 and SOLR-3178), and will really prefer that we get to contribute our changes. Please have a look at - review comments are very very welcome. We will be ready to contribute the entire solution within the next couple of weeks. It is already running pilot-production inhouse and nicely handling 100+ mio inserts/updates per day.
We just decided to always use response code 400 (as you can see on the Wiki), but you suggestion about using other codes is good. I will hav a look at that.
Regards, Per Steffensen
Changed the response codes to not always be 400. Comments and suggestions of changes are very welcome.
Regards, Per Steffensen
Here's a patch that seems to work fine.
There's really no extra input-API - all you do is supply a version in the document (or as a parameter on the URL for a delete) and you get back a 409 if it's incorrect.
I'll probably commit this soon and we can incrementally improve by adding better support to SolrJ (I'm not sure there's an easy way to specify the version for a delete from solrJ).
I will have a look at the patch provided by you and merge any ideas in there that is not already in our solution into our solution, but please do not commit your patch. I really hope you will wait until we provide our patch which implements everything described on and more - e.g. SolrServers that return Future<NamedList<Object>> instead of just NamedList<Object>, which is needed to make the error propagation also described on work for ConcurrentSolrServer. Everything in our contribution (the patch I deliver soon) will be fully covered by tests.
Regards, Per Steffensen
I think the best way to do this is really incrementally.
What's done so far should really be a strict sub-set of everything you were thinking of (since changed to use 409 as the error code), and is useful on it's own.
Don't worry... you'll get credit!
I dont care about credit
It is just that I put myself on as Assigned to indicate that I was working on it. And I have been - with a pause of a few weeks because my product owner prioritized me to look at something different (money talkes - you know
). I am soon ready to provide a full solution so why not wait for that. My solution is a little bit different than yours (just had a very short peek at your patch) but basically it is doing the same thing, but there is no need for both your and my solution. I really hope you will wait until you see my contribution - it is much more complete than what you have done until now, and we are already using it successfully in a highly concurrent pilot-production environment.
My contribution solves at least a few problems that yours doesnt seem to solve (yet):
- It (also) works for multi-document update request, providing fully detailed feedback to the client about which document-updates failed (and why) and which succeeded. I believe your solution will just result in a 409 HTTP response if just one of many documents in the same request failed, leaving no information to the user about which of the other documents in the request where successfully handled (and stored), and if more of the documents (comming after the on that did fail) would also have failed.
- It works (have been tested by heavily concurrent tests) in highly concurrent environments. Looking shortly at you patch, I belive, that if two threads in the server JVM overlaps in a way that is unfortunate enough, then it is possible that data will not be stored or will be overwritten without an error being sent back to the client indicating that.
- Feedback to client is even possible if using ConcurrentSolrServer, because it has been changed to provide a Future from "request" - a Future that will eventually provide the calling client with the result from the request.
I understand your point about doing this incrementally, and I have done that internally. But since I am not a Solr committer it is hard to push too many small partly-done features. If I had been a committer you would have been able to follow the progress of my work more closely. But fact is, that I have a full and well tested solution that I would like to provide as a contribution very soon. I really hope you will wait for that, before committing a different partly done solution to the same problems. Thanks a lot!
I would much rather want you to carefully read and provide feedback and comments. I will deliver everything described there (and more) very soon. And then tell me how to ajust remaining time on this issue
Regards, Per Steffensen
it is hard to push too many small partly-done features.
As committers it's the opposite - it's sometimes hard to consume patches that do a lot of different things..
Some other additions that can be handled later that I see:
- SolrJ support for easier passing of version on a delete, constants for version, etc
- Use of "1" as a generic "exists" version (i.e. update document only if it already exists)
- If one document in a batch fails, don't automatically abort, and provide info back about which docs succeeded and which failed (your first point).
That last one in particular needs some good discussion and design work and really deserves it's own issue.
Down to the specifics of this patch... it's very non-invasive to core, consisting of the following code block (once for add, once for delete):
if (versionOnUpdate != 0) { Long lastVersion = vinfo.lookupVersion(cmd.getIndexedId()); long foundVersion = lastVersion == null ? -1 : lastVersion; if ( versionOnUpdate == foundVersion || (versionOnUpdate < 0 && foundVersion < 0) ) { // we're ok if versions match, or if both are negative (all missing docs are equal) } else { throw new SolrException(ErrorCode.CONFLICT, "version conflict for " + cmd.getPrintableId() + " expected=" + versionOnUpdate + " actual=" + foundVersion); } }!
Are there any technical objections to this patch?
It really piggybacks on all of the SolrCloud work done to pass around and check versions, so it's really small.
The API is as follows:
- If you provide a version > 0 with an add or a delete, the update will fail with a 409 unless the provided version matches exactly the latest in the index for the ID.
- If you provide a version < 0 with an add or delete, the update will fail with a 409 if the ID exists in the index.
That's the whole scope of this patch, and I believe is compatible with the larger scope of what Per will provide in the future.
Per Steffensen, can you attach whatever you have, even if it's in rough form, so that the two approaches can be compared?
Mark Miller, we are working on a internal SVN branch where we started by talking in HEAD of apache solr trunk. From time to time we have merged new developments on apache solr trunk into our SVN branch. Right now we are in the process of doing that again, so that the patch we deliver will be a patch on top of a recent apache solr revision. Until that merge has finished I cannot attach our modifications unless you want them to fit on top of a pretty old (a month or so) revision of apache solr.
My intention was to deliver nicely finished (completely tested, documented etc) features to you, but based on what I have heard from you and Yonik the last couple of days, I will change my strategy and deliver a rough patch as soon as the merge has finished, and then leave the final polishing for a more complete patch a little bit later. I hope to be able to deliver my rough patch in the middle of next week.
Thanks a lot for you cooperation!
Regards, Per Steffensen
Yonik Seeley, I agree that some of the stuff that I have added deserves own issues, but it doesnt change the fact that we hope to contribute them all in one go. I understand that it would have been nicer if we had sent you many smaller contributions instead one big contribution. We will learn from that and do that for future contributions. I hope this time that you (the committers) will accept a big contribution.
I have created a separate issue for one of the things that is also going to be in our contribution - SOLR-3382
I will change my strategy and deliver a rough patch as soon as the merge has finished
+1 - the Apache model likes dev to happen in the open as much as possible in piecemeal - it's more digestible, and helps ensure a lot of work is not done in a direction that others may not end up agreeing with. You don't want to dump a ton of finely polished work that has been fully documented and then find the community has other intentions.
Even a patch that does not compile has a lot of value! Just specify it's early state and limitations - but it lets us know the general direction you are taking, allows early feedback, and helps any committers digest the work.
Mark Miller, its noted and I will certainly try to ajust behaviour for future work on Solr. Thanks for helping me understand the Apache process better.
Regards, Per Steffensen
I will change my strategy and deliver a rough patch as soon as the merge has finished
That's great, I'm sure you'll find more success with breaking it up into many smaller issues - different committers will be able to help on different things as their interest & time allow.
I'd really like to try and get the bare essentials of optimistic locking in soon, so the sooner you can show us a draft patch for just that piece so we can decide what approach to go with, the better! There's no need to wait to merge up to trunk to show us how your approach differs.
Will supply patch early next week.
Guess I have broken (or will break it) the following "rule" on "How to contribute":
"Combine multiple issues into a single patch, especially if they are unrelated or only loosely related."
I have added the following to "How to contribute | Contributing your work" in order to state the philosophy described by Mark a little more clearly to future newbie contributers. Feel free to modify:
."
Regards and have a nice weekend
it is hard to push too many small partly-done features.
As committers it's the opposite - it's sometimes hard to consume patches that do a lot of different things.
I could imagine. Im sorry that it is possibly going to be a little bit like that this time. But I believe I will provide great stuff.).
Yes I agree. See SOLR-3382. The solution I will provide is generic in the way that is supports giving feedback to the client about "parts" of a request that failed. The client will know that the "parts" which are not reported to have failed did succeed. Usefull for any kind of request where parts of it can fail and other parts can succeed. The client provide a "partRef" for all parts, and partial errors from the server each contain a "partRef" in order to let the client know which part(s) failed. I only use it for multi-document (or batch-updates as I see you call it in come places) updates (here each document is a "part"), but I guess it could also be used for other things like
- Reporting which operations of a multi-operation (e.g. one containing both adds, deletes, commits, etc) update that failed.
- Reporting if a single update partly failed (e.g. if using replication and the update was successfull on leader but not on one of more of the replicas)
- Etc.).
Looking closer at your code I would like to withdraw my concern about your solution. I didnt see that you are doing both "get existing version and check against provided version" and "store updated version" inside the same block governed by two sync-locks
- A readlock on a ReadWriteLock which is writelocked during deleteByQueries (your "vinfo.lockForUpdate"), protecting against concurent deletes (by query)
- A lock on the uniqueKey field (or a hash of it in order to be efficient) of the document (your "synchronized (bucket)"), protecting against concurrent updates and deletes (by id)
So basically I have repeated that locking-pattern in DirectUpdateHandler2 where I chose to place the "unique key constaint"- and "versioning"- check. Guess my locking can be removed if it is really necessary to have this kind of locking "this far up in the callstack" (in DistributedUpdateProcessor.versionAdd). For the purpose of "unique key constraint"- and "versioning"-check I believe it is only necessary to have this kind of locking around the actual updates in DirectUpdateHandler2 (when leader and not peer_sync) - and the smaller you can make synchronized blocks the better. But maybe you have reasons (related to SolrCloud) where you need the locking "this far up in the callstack".
But besides that fact that the locking I did in DirectUpdateHandler2 can be removed I really believe that the actual checking of "unique key constraint"- and "version"-violation logically belong in DirectUpdateHandler2, so I guess I will still try to convince you to take that part of my patch in.
Besides that, I believe your solution just implements what I call semantics-mode "classic-consistency-hybrid" on. I believe the "classic" mode and "consistency" mode are very nice to have in order to provide complete backward compabitility (classic mode) and a very strict consistency mode where it is not possible to "break the checks" by providing _version_ = 0 (consistency mode).
Finally I believe my solution is a little better with respect to "design" and "separation of concerns", by isolatating the rules and rule-checks in a separate class instead of just coding it directly inside DistributedUpdateProcessor which already deals with a lot of other concerns, but that is another discussion, and should not count as the deciding argument..
Created the isolated issue - see SOLR-3383
Some other additions that can be handled later that I see:
SolrJ support for easier passing of version on a delete, constants for version, etc
Well basically I have moved VERSION_FIELD = "_version_" from VersionInfo to SolrInputDocument.
Use of "1" as a generic "exists" version (i.e. update document only if it already exists)
Well I started out by wanting that feature (update only if exists, but no exact version check), but you couldnt see the good reason for that. Since then I realized that you are probably right and have removed that exact possibility - of course in classic and classic-consistency-hybrid modes you can still do updates without providing the exact version, but there is error if the document does not exist.
If one document in a batch fails, don't automatically abort, and provide info back about which docs succeeded and which failed (your first point).
That is part of my solution - basically the thing making it necessary to add the ability to send many errors back to the client - SOLR-3382
That last one in particular needs some good discussion and design work and really deserves it's own issue.
Agree. Go discuss and comment on SOLR-3382!
Agree, so I guess you could go commit, but that would just make my merge-task a little bigger, so I hope you will hold your horses a few days more.
Are there any technical objections to this patch?
Except for the things I mention here and there in this response, no. And those are all things that could be fixed later, going nicely hand in hand with your great philosophy of "progress, not perfection".
It really piggybacks on all of the SolrCloud work done to pass around and check versions, so it's really small.
Yes it is small and beautiful
The API is as follows:
a) If you provide a version > 0 with an add or a delete, the update will fail with a 409 unless the provided version matches exactly the latest in the index for the ID.
b) If you provide a version < 0 with an add or delete, the update will fail with a 409 if the ID exists in the index.
You always provide the same error (except the versions in the message). You do not distinguish between DocumentAlreadyExist, DocumentDoesNotExist and VersionConflict errors as I do. Of course the client would know that it is a DocumentAlreadyExists if he sent a negative version number and got 409 (at least as long as 409 is not used for other kind of conflicts that can also happen when version < 0) and that it is DocumentDoesNotExist or VersionConflict if he sent a positive version number and got 409 (at least ...). But he really doesnt know if it is DocumentDoesNotExist or VersionConflict unless he parses the error message, and that might be important to know because he might want to react differently - e.g.
- On DocumentDoesNotExist: Either do nothing or go do a create (version < 0) of the document
- On VersionConflict: Go refetch the document from Solr, merge in his changes (automatically or by the help from a user) and try update again.
Of course you also need to parse error-type in my solution to know exactly what the problem is, but you need no "rules" on client side (e.g. knowing that if you sent version > 0 and you got version-already-in-store < 0 back, it is DocumentDoesNotExist), and in SolrJ my solution automatically parses error-type and throw corresponding exceptions.
Ad b) Maybe you dont want an error if you try to delete a document which has already been deleted, but probably ok
That's the whole scope of this patch, and I believe is compatible with the larger scope of what Per will provide in the future.
Agree!
Find attached SOLR_3173_3178_3382_plus.patch which should fit on top of revision 1327417.
Patch includes:
- All our code-changes done during the work with SOLR-3173, SOLR-3178 and SOLR-3382. How it is supposed to work in more detail, is described on and is of course also expressed in included tests.
- Also includes
- Misc clean-up
- E.g. removing constants redundant OVERWRITE = "overwrite" so that only UpdateParams.OVERWRITE is left. You need very good arguments to ever use different "names" for the same thing (overwrite) among XML, JSON, HTTP request params etc, so it is kind of wrong to have the constant defined for each of those.
- "Unimportant changes" - e.g.
- Corrected spelling errors
- Removed unnecessary imports
Not implemented yet
- Error propagation for redistributed updates. That is, the responses from the redistributed updates in DistributedUpdateProcessor using SolrCmdDistributor, have to be collected an merged into a combined response from "this" DistributedUpdateProcessor.
- Both implementation and tests are missing.
- Tests verifying that updates using JSON and CSV requests as described on also works as described. Especially transfer of partRefs in JSON and CSV requests.
- Tests verifying that semanticsMode "consistency" works as it is supposed to - just like ClassicConsistencyHybridXXXTests tests this for "classic-consistency-hybrid" semanticsMode and like ClassicUpdateSemanticsTest shortly tests it when semanticsMode is explicitly set to "classic" ("classic" is the default so this mode is already tested a lot using all the others tests in the project)
Other stuff not done yet
- Add Apache 2.0 Licence to all new files
- Check correct indenting
- JavaDoc for public methods
Thanks for the patch Per!).
Regardless - we are where we are right now... and doing the version check in the update handler presents some problems. For cloud, we want to start sending to replicas at the same time as indexing locally.).
So I think the best way forward is to commit the patch that does the version check in the distributed update processor, and then build off of that (for instance your more nuanced error messages and the set/get requestVersion on the update command).
First of all. Thanks a lot for getting back to me, and taking the time to try to understand such a big patch covering several jira issues - Im still sorry about that.)..
Regardless - we are where we are right now... and doing the version check in the update handler presents some problems. For cloud, we want to start sending to replicas at the same time as indexing locally.
boolean getAndCheckAgainstExisting = semanticsMode.needToGetAndCheckAgainstExistingDocument(cmd) && cmd.isLeaderLogic();.
So I think the best way forward is to commit the patch that does the version check in the distributed update processor, and then build off of that (for instance your more nuanced error messages and the set/get requestVersion on the update command).)
> For cloud, we want to start sending to replicas at the same time as indexing locally.
As I read the code, we are not doing that as it is today.
Right - I just realized the ambiguity of the phrasing. By "we want to start", I meant that we want to investigate/implement that option (to send to replicas concurrently with indexing locally).
Yeah, it would be nice to offer a wide range of indexing options - I'd really like to see us offer down to "fire and forget" - the add waits for no response and adds are done locally and remotely in parallel. AFAIK MongoDB actually does this by default - I don't think we should do that, but I'm interested in offering a range from that up to full guarantees.
Agree, people have different preferences on how to use Solr, and therefore a.o. how the exact semantics of update should be. My solution is also better prepared for that, since I offer the "semanticsMode" property in updatehandler (DirectUpdateHandler2) where you can state if you want strict versioning ("consistency" mode) or the good old semantics ("classic" mode) or a mix ("classic-consistency-mode" mode). Guess we will always need to do leader-first-then-replica I cases where we want to do strict versioning control, but in "classic" mode (or a new future mode) we could certainly consider doing leader-and-replica-in-parallel. Will provide new patch today or tomorrow.
since I offer the "semanticsMode" property in updatehandler
Seems like this should be up to the client... why wouldn't update semantics be handled on a per-request basis?
since I offer the "semanticsMode" property in updatehandler
Seems like this should be up to the client... why wouldn't update semantics be handled on a per-request basis?
Maybe we misunderstand each other a little bit. I just agree that people want Solr to provide different kinds of semantics - some want strict version-check, some dont, some will have an fire-and-forget approach, some will not. I just ment to say that for some of those types of semantics you want server-side Solr to behave in a certain way. For that you probably need a configuration telling the server how to behave. I have introduced that for updates with the "semanticsMode" config on updatehandler.
I believe, when it comes to whether you want strict unique-key-constraint- and version-checks or not, it is probably something you want to configure server-side, so that you can control the possibilities of your clients. Not all Solr-based systems will have complete control over all its clients, and then it is nice on server-side to be able to say (using semanticsMode):
- consistency: I dont want you as a client to make updates to documents, without even having read the existing document first (and merged your updates into that), and I dont want you to be able to overwrite changes to that document that happend to be made between the time you read it and the time you provided your updated version. And I dont want you to incidentally overwrite an existing document, if your intent was to create a new one.
- classic: All updates just go right into Solr, but you risk overwriting exsisting stuff
- classic-concistency-hybrid: You can do both consistency and classic updates, be casefull when doing classic updates
I believe this kind of control belongs in a server-side config, because it is a way of "protecting" your data against badly written clients.
With respect to whether you want to do fire-and-forget or not, that should be up to the client, but it kinda is by definition - basically just ignore results. But fire-and-forget strategy on clients is really not worth much, if you have to wait for the server to reply when you do updates (like you have to do today). SOLR-3383 will provide a all-async client SolrJ API (Future-based all the way) so that you can really just "fire", and if you intent is to "forget" anyway, then you can move on immediately after your "fire" without waiting for the server to reply.
That is not the reason we made SOLR-3383 though. It is because we want to be able to get results back when using ConcurrentSolrServer, and that requires a Future-based request API.
Regards, Per Steffensen
Find attached SOLR-3173_3178_3382_3428_plus.patch
The patch fits on top of trunk revision 1332666 and is ready for commit.
Since last patch (SOLR_3173_3178_3382_plus.patch) I have made the following:
- Implemented test ClassicConsistencyHybridUpdateSemanticsSolrCloudTest verifying that partial errors are propagated correctly in a cloud (ZK) setup, when an update document is not sent directly to the Solr instance running the leader of the slice where the document is to be stored, and the Solr instance therefore has to forward the document to the leader, and when the leader forwards to replica. This made me discover the problems discribed in SOLR-3428, which I had to fix in order to make the test green.
- Implemented tests (in JsonLoaderTest and CSVRequestHandlerTest) verifying that you can send part references as claimed on when you are sending JSON or CSV requests
- Documents for which a partial error occur on leader will not be forwarded to replica.
- Partial errors are now catched and collected for the entire request in DistributedUpdateProcessor, but the actual version-check etc is still performed in DirectUpdateHandler2 (because that is an per-document-level task)
- Added Apache License 2.0 text to all new files
- Added class-level-JavaDoc to all new classes
- Removed a few unimportant changes
I will be leaving for an extended weekend now, and will not be available again before wedensday next week. I will probably read and answer comments from time to time until saturday night, though.
I really really really hope to return to the great news about the patch having been committed. I believe it is now really ready - well worked through features, well covered by tests and all existing plus new tests are green. Great progress, maybe not perfection, but we can shape the last edges later if we find any. Hope you will take the opportunity to commit before too long, now that you have a patch based on a fairly new revision, to avoid having to many conflicts to solve.
Just to avoid any mistakes - the patch covers SOLR-3173, SOLR-3178, SOLR-3382 and SOLR-3428.
Regards, Per Steffensen
Sad to see that you chose to commit a different patch for this one, making me believe that you are not going to take my patch in. I really dont understand why, because I think my solution is at least as good or better in any aspect, and besides that it is more complete, backward compatible and solves a lot of other issues (SOLR-3173, SOLR-3382 and SOLR-3428) already - can I ask you to tell me why you made that choice? Maybe what is wrong with our patch since it is not taken in, what we need to change etc?
Please also elaborate on your plans wrt the other issues
- Using unique key constraints to protect against overwriting existing data, when intent is to just insert a new document (kinda what SOLR-3173 was thought to be about) - DocumentAlreadyExists error
- Even though an document update fails, still try updating the rest of the documents in the same update request, and therefore the feature of being able to report several errors back to the client linking each error to a specific document in the request (basically SOLR-3382)
- Nicely "typed" errors so that you as a client can detect which kind of error occurred in an easier way than guessing from http status code and textual error messages (also SOLR-3382)
- The SOLR-3428 bug
I need to know what to tell my product owners wrt how long we need to run on our own version of Solr (containing our patches etc.) in our high-throughput and high-concurrency pilot-prod system and therefore also for how long we need to keep merging changes from Solr trunk in? And when we can get to contribute additional code - mostly stability/endurance-related bug fixes. We already gave you the fix for
SOLR-3437 but some of our additional fixes are kinda dependent on some of the stuff in SOLR-3173_3178_3382_3428_plus.patch. Do you have any plans revealing if we have to wait
- Forever? (= our patch is not going to be committed)
- Weeks/Days? (= you are working on understanding our patch and expect to commit later)
- Or?
Regards, Per Steffensen
I had missed this last update during the crazy week of the lucene revolution conference..
Just speaking for myself, when I get time to look at optimistic locking stuff again, I'll probably browse your latest patch to see what improvements I can cherrypick (assuming no one else gets around to making some smaller patches first)..
I understand, but things are very related, so its hard for me to go back and divide into smaller patches and feed them one by one to you. Things are related because "optimistic locking"-errors and "unique key constraints"-errors are not worth much if exact information about what went wrong does not go back to the client (therefore adding the feature of sending typed errors back to the client is needed). And the two kinds on new errros are the first "single document"-related errors in Solr, and therefore it, for the first time in history of Solr, is very nice to have the ability to keep processing documents in a multi-document-update-request even though one document-update fails with one of those errors (therefore multi-error responses with references on each error to the document it relates to is needed). And backward compability is just always nice, and it this case required, IMHO
Just speaking for myself, when I get time to look at optimistic locking stuff again, I'll probably browse your latest patch to see what improvements I can cherrypick (assuming no one else gets around to making some smaller patches first).
I would really like that, and I will be available for any help you need. Or just make me a committer, and you will live happily ever after
I am very experienced doing this kind of stuff.
BTW, I saw that you committed some "inc" stuff on this JIRA. As I understand it, it is a new feature where you are able to tell server-side Solr to add to a field, instead of doing it yourself on client side. Server-side Solr can then do it while having the lock on the document, and therefore no optimistic locking is needed in principle - but only if your updates use "inc"s only. I think it deserves its own JIRA, because it doesnt have anything to do with optimistic locking, except that you do not need optimistic locking if your updates use "inc"s only. It is probably not realistic that any real world application would ever be able to do its updates based on "inc"s alone, so in isolation I think the feature is kinda useless. But if you generalize on the feature it could be great. Generalize in a way where you can have any update-semantic performed on your document server-side (while having the document lock), then utilizing this feature heavily would enable you to avoid using optimistic locking and that might be prefered in some situations - just even another reason while backward compability on optimistic locking is nice, so that you can have it disabled (even though you would like to have a full-featured Cloud-setup with updateLog, version field etc.) if you are not going to use it.
I imagine that you can install document(-field)-manipulating primitives on server-side Solr and associate them with a names (e.g. associate the name "inc" with a piece of code adding to a field, "multiply" with a piece of code multiplying to a field, "string-concat" with a piece of code that concats to fields into a third field, etc) and then have pairs of document-field and document(-field)-manipulating-ref in your updates (e.g. send updates saying "update document A manipulate fields inc(field1,13), multiply(field2,4), string-concat(field3,field4,field5)"). But as long as "inc"s is the only such manipulate-on-server-side-while-having-the-lock-primitive it is kinda useless. The code you associate with primitives ("inc", "multiply", "string-concat" etc) could just be a small piece of Java code, and the association needs to go on in solrconfig.xml. Or if you are really cool (and you trust your clients are not doing SQL-injection-ish hacks on you) you can allow clients to install primitives on-demand, either as part of update-requests that use those primitives or as separate primitive-registration-request that you do before you start using a primitive. Such request-carried primitives could be in the form of Groovy code, Ruby code, JavaScript code, or whatever the JVM is able to compile and use on-demand.
Regards, Per Steffensen
Regarding error handling, I tracked down the original issue: SOLR-445
Yes, SOLR-445 is solved by my patch - the nice way. On certain kinds of errors (PartialError subclasses) during the handling of a particular document in a nultidocument/batch-update the processing of subsequent documents will continue. The client will receive a response describing all errors (wrapped in PartialErrors) that happend during the processing of the entire update-request (multidocument/batch). Please have a look at
It's just a guess, but I think it unlikely any committers would feel comfortable tackling this big patch, or even have time to understand all of the different aspects. They may agree with some parts but disagree with other parts
Of course that is up to you, but I believe Solr has a problem being a real Open Source project receiving contributions from many semi-related organistions around the world, if you do not "trust your test suite". Basically when taking in a patch a committer do not need to understand everything down to every detail. It should be enough (if you "trust your test suite") to
- Verify that all existing tests are still green - and havnt been hacked
- Verify that all new tests seem to be meaningfull and covering the features described in the corresponding Jira (and in my case the associated Wiki page), indicating that the new features are usefull and well tested (in order to be able to "trust the test suite" will reveal if future commits will ruin this new feature)
- Scan through the new code to see if it is breaking any design principals etc., and in general if it seems to be doing the right thing the right way
As long as a patch does not break any existing functionality, and seems to bring nice new functionality (you should be able to see that from the added tests) a patch cannot be that harmfull - you can always refactor if you realize that you "disagree with some parts". It all depends on "trusting your test suite". Dont you agree, in principle at least?
Regards, Per Steffensen
bulk fixing the version info for 4.0-ALPHA and 4.0 all affected issues have "hoss20120711-bulk-40-change" in comment
SOLR-3173_3178_3382_3428_plus.patch updated to fit on top of revision 1355667 on 4.x branch.
I have tried to describe for (almost) all files in the patch, which problem the changes in them solve. Please see below. A lot of files has changed, but it is very small changes in most of the files basically just making sure SolrRequestInfo-threadlocal is set in tests and other stuff like that. The solutions to SOLR-3173 and SOLR-3178 are not very big. Actually much more code has been done to solve SOLR-3382. With those descriptions I hope to convince you to do the commit. Trust you test-suite - it has not been changed, except that additional asserts has been added.
I am really not religious about whether the version-control code is in DistributedUpdateProcessor or DirectUpdateHandler2, but I am religious about being backward compatible wrt such fundamental changes in semantics, and I am religious about getting typed errors/exceptions back in responses, so that I can react properly. I do believe version-control belong in DirectUpdateHandler2, but if you want it in DistributedUpdateProcessor, basically just refactor (after commit) and move the changes in DirectUpdateHandler2 to DistributedUpdateHandler.
- Solved SOLR-3173 and SOLR-3178 (implementation of fail-on-unique-key-violation and version-check), by introducing 3 "modes" Solr server can run in (controlled by "semanticsMode" in solrconfig.xml | updateHandler) - one for backward compatibility, one for a very strict version control, and a hybrid (default).
- solr/core/src/java/org/apache/solr/update/DirectUpdateHandler2.java (the new features are controlled from here, but basically using the rules in UpdateSemanticsMode. Got rid of duplicate code in constructors - grrrr)
- solr/core/src/java/org/apache/solr/update/UpdateSemanticsMode.java (enum that encapsulates the essence in the 3 possible "semanticsModes". Used by DirectUpdateHandler2. Nice "separation of concern")
- solr/core/src/java/org/apache/solr/update/UpdateCommand.java (added leaderLogic calculated (as isLeader) in DistributedUpdateProcesser to UpdateCommand so that it is available in DirectUpdateHandler2, where it is used to know if the new checks must be performed or not. UpdateCommand also carrying requestVersion, the version sent in the request)
- solr/core/src/java/org/apache/solr/core/SolrConfig.java (control via configuration which semantics-mode to use)
- solr/core/src/java/org/apache/solr/update/processor/DistributedUpdateProcessor.java (maintains leaderLogic on UpdateCommand)
- solr/core/src/java/org/apache/solr/update/SolrCmdDistributor.java (maintains requestVersion on UpdateCommand)
- solr/core/src/java/org/apache/solr/update/UpdateLog.java (maintains requestVersion on UpdateCommand)
- solr/core/src/java/org/apache/solr/update/PeerSync.java (maintains leaderLogic and requestVersion on UpdateCommand)
- solr/core/src/test-files/solr/collection1/conf/solrconfig-classic-semantics.xml (default test solrconfig.xml but with "classic" semantics-mode, used to test that the new features fail-on-unique-key-violation and version-check are not activated when running "classic" semantics - the backward compatible "mode")
- solr/core/src/test-files/solr/collection1/conf/solrconfig-classic-consistency-hybrid-semantics.xml (default test solrconfig.xml but with "classic-consistency-hybrid" semantics-mode. Actually default solrconfig.xml could have been used since "classic-consistency-hybrid" semantics is default, but used to test that it (also) works when this mode is selected explicitly)
- (basically just a lot of changes making testing easier)
- Removed the (temporary and poor IMHO) implementation of fail-on-unique-key-violation and version-check, but kept the introduced tests, so you can see that the same functionality is still provided (on default semantics "classic-consistency-hybrid")
- solr/core/src/java/org/apache/solr/update/processor/DistributedUpdateProcessor.java
- solr/core/src/test/org/apache/solr/search/TestRealTimeGet.java (now we do not only get exceptions in "bad" situations, we get typed exceptions telling us what is wrong)
- Solved SOLR-3382 - partRef and PartialError(s) introduced in multi-document-update-requests so that "request parts" (essentially documents sent for update) can be paired up with errors in responses, so that the client will know that document-updates failed with what errors and therefore also which documents where updated successfully
- solr/solrj/src/java/org/apache/solr/common/RequestPart.java (new generic interface to be implemented by all parts of a request that is "just a part", and where an error that occures during the handling of this particular part does not mean that handling other parts will also result in error. Just to make it a little generic from the start, but by now only SolrInputDocuments in update-requests are such "request-parts")
- solr/solrj/src/java/org/apache/solr/common/RequestPartImpl.java (new default impl of RequestPart, to be used by classes that really want to be a "request-part")
- solr/solrj/src/java/org/apache/solr/common/SolrInputDocument.java (a "request part" implemented using RequestPartImpl)
- solr/solrj/src/java/org/apache/solr/client/solrj/impl/HttpSolrServer.java (dealing with errors returned in responses. removed a poor initial but never finished attempt to transport errors in responses, and replaced with my way of doing it (complete and finished solution). this indicates a problem with the approach of only accepting small patches - you very easily end up having partly implemented features that no-one ever finishes)
- solr/solrj/src/java/org/apache/solr/client/solrj/impl/ConcurrentUpdateSolrServer.java (dealing with errors returned in responses)
- solr/solrj/src/java/org/apache/solr/common/partialerrors/WrongUsage.java (new error type indicating that the client is using the system in a wrong way - basically that a request is inconsistent with server rules about how the request must be)
- solr/solrj/src/java/org/apache/solr/common/partialerrors/PartialError.java (super-class of all partial-error-types)
- solr/solrj/src/java/org/apache/solr/common/partialerrors/update/DocumentUpdatePartialError.java (super-class of all partial-error-types that has to do with updates)
- solr/solrj/src/java/org/apache/solr/common/partialerrors/update/DocumentAlreadyExists.java (new error type indicating that the document you tried to create (not update) already exists)
- solr/solrj/src/java/org/apache/solr/common/partialerrors/update/DocumentDoesNotExist.java (new error type indicating that the document you tried to update (not create) does not already exist (maybe it has been deleted))
- solr/solrj/src/java/org/apache/solr/common/partialerrors/update/VersionConflict.java (new error type indicating that there is a version-mismatch in the document that the client tries to update. Basically the client loaded a version of the document, made some updates to it and sent it to the server for storage of the changes, but the document on the server has changed since the document was loaded by the client, and the client has therefore created his updated document based on a obsolete version of the document. Nothing to do but reload, change and attempt update again)
- solr/solrj/src/java/org/apache/solr/common/partialerrors/PartialErrors.java (new error type able to carry a map between "request parts" and the errors that occurred when they where handled)
- solr/core/src/java/org/apache/solr/update/processor/DistributedUpdateProcessor.java (catching PartialErrors (defined as errors only related to the document currently being handled) and continues with next document after adding it to response linked to document that triggered the error)
- solr/core/src/java/org/apache/solr/servlet/SolrDispatchFilter.java (encodes errors. If multiple partial-errors occurred (e.g. multi-document-updates) a body is still needed in the response, telling about the map between errors and the documents they occurred for. If only single error occurred still just report that back using HTTP-error-code and reason-phrase. Also set HTTP header including the error-type (namespace + name = java-package + java-class-name). The actual encoding/decoding of errors in responses is isolated in SolrException)
- solr/solrj/src/java/org/apache/solr/common/SolrException.java (encapsulating the logic to encode/decode errors in responses - also visible for SolrJ clients so we can decode there in a nice way)
- solr/core/src/java/org/apache/solr/response/SolrQueryResponse.java (able to carry information about partial-errors and handled "parts" of a request)
- solr/core/src/java/org/apache/solr/handler/ContentStreamLoader.java and solr/core/src/java/org/apache/solr/handler/loader/ContentStreamLoader.java (a few constants - strings used to identify partRefs in requests - why two classes!?!)
- solr/core/src/java/org/apache/solr/handler/loader/JsonLoader.java (partRef can be sent in JSON requests)
- solr/core/src/java/org/apache/solr/handler/loader/CSVLoaderBase.java (partRefs can be sent in CSV requests)
- solr/core/src/java/org/apache/solr/handler/loader/XMLLoader.java (partRefs can be sent in XML requests)
- solr/solrj/src/java/org/apache/solr/client/solrj/util/ClientUtils.java (partRefs can be sent in XML requests)
- solr/solrj/src/java/org/apache/solr/common/util/JavaBinCodec.java (partRefs can be sent in binary requests)
- solr/solrj/src/java/org/apache/solr/client/solrj/SolrResponse.java (gives access to partial-errors, map between "request parts" (essentially documents) and corresponding partial-errors, number of partial-errors etc.)
- solr/solrj/src/java/org/apache/solr/client/solrj/response/UpdateResponse.java (see SolrResponse.java)
- (return errors in helper-assertFailed-methods, so that those errors can be inspected in further more specific assertions - basically just a lot of changes making testing easier)
- solr/solrj/src/test/org/apache/solr/client/solrj/SolrExampleTests.java (nicer asserts including asserting on correct type (class) of exception)
- solr/core/src/test/org/apache/solr/handler/JsonLoaderTest.java (test of it when using JSON requests and responses)
- solr/core/src/test/org/apache/solr/handler/CSVRequestHandlerTest.java
- In DirectUpdateHandler2 (solving SOLR-3173 and SOLR-3178) and other places Im working with the SolrQueryRequest and SolrQueryResponse found in the threadlocal of SolrRequestInfo, so therefore this threadlocal needs to be set (and cleared) in many tests
- solr/core/src/test/org/apache/solr/update/processor/FieldMutatingUpdateProcessorTest.java
- solr/core/src/test/org/apache/solr/update/processor/SignatureUpdateProcessorFactoryTest.java
- solr/core/src/test/org/apache/solr/update/processor/UniqFieldsUpdateProcessorFactoryTest.java
- solr/core/src/test/org/apache/solr/update/TestIndexingPerformance.java
- solr/core/src/test/org/apache/solr/request/TestBinaryResponseWriter.java
- solr/core/src/test/org/apache/solr/request/TestFaceting.java
- solr/core/src/test/org/apache/solr/core/TestArbitraryIndexDir.java
- solr/core/src/test/org/apache/solr/TestGroupingSearch.java
- solr/core/src/test/org/apache/solr/SampleTest.java
- solr/core/src/test/org/apache/solr/EchoParamsTest.java
- solr/core/src/test/org/apache/solr/search/function/TestFunctionQuery.java
- solr/core/src/test/org/apache/solr/search/TestValueSourceCache.java
- solr/core/src/test/org/apache/solr/search/TestSearchPerf.java
- solr/core/src/test/org/apache/solr/search/QueryEqualityTest.java
- solr/core/src/test/org/apache/solr/search/TestSort.java
- solr/core/src/test/org/apache/solr/cloud/BasicZkTest.java
- solr/core/src/test/org/apache/solr/highlight/FastVectorHighlighterTest.java
- solr/core/src/test/org/apache/solr/highlight/HighlighterConfigTest.java
- solr/core/src/test/org/apache/solr/highlight/HighlighterTest.java
- solr/core/src/test/org/apache/solr/BasicFunctionalityTest.java
- solr/core/src/test/org/apache/solr/DisMaxRequestHandlerTest.java
- solr/core/src/test/org/apache/solr/handler/XsltUpdateRequestHandlerTest.java
- solr/core/src/test/org/apache/solr/handler/StandardRequestHandlerTest.java
- solr/core/src/test/org/apache/solr/handler/component/StatsComponentTest.java
- solr/core/src/test/org/apache/solr/handler/MoreLikeThisHandlerTest.java
- solr/core/src/java/org/apache/solr/servlet/DirectSolrConnection.java
- solr/contrib/dataimporthandler/src/test/org/apache/solr/handler/dataimport/AbstractDataImportHandlerTestCase.java
- solr/contrib/dataimporthandler/src/test/org/apache/solr/handler/dataimport/TestDocBuilder2.java
- solr/contrib/uima/src/test/org/apache/solr/uima/processor/UIMAUpdateRequestProcessorTest.java
- solr/test-framework/src/java/org/apache/solr/SolrTestCaseJ4.java
- solr/test-framework/src/java/org/apache/solr/util/AbstractSolrTestCase.java
- solr/test-framework/src/java/org/apache/solr/util/TestHarness.java
- SolrRequest sub-classes has a lot of duplicated code (grrrr). Cleaned up and put shared code in one place - SolrRequest
- solr/solrj/src/java/org/apache/solr/client/solrj/SolrRequest.java
- solr/solrj/src/java/org/apache/solr/client/solrj/request/AbstractUpdateRequest.java
- solr/solrj/src/java/org/apache/solr/client/solrj/request/FieldAnalysisRequest.java
- solr/solrj/src/java/org/apache/solr/client/solrj/request/DirectXmlRequest.java
- solr/solrj/src/java/org/apache/solr/client/solrj/request/LukeRequest.java
- solr/solrj/src/java/org/apache/solr/client/solrj/request/CoreAdminRequest.java
- solr/solrj/src/java/org/apache/solr/client/solrj/request/DocumentAnalysisRequest.java
- solr/solrj/src/java/org/apache/solr/client/solrj/request/SolrPing.java
- solr/solrj/src/java/org/apache/solr/client/solrj/request/QueryRequest.java
- Think we should work with a common (for both server and client side) "version" String constant, but VersionInfo is not available for client side, so I removed VERSION_FIELD = "version" from VersionInfo to SolrInputDocument in order to make it available for both server and client (SolrJ) side.
- solr/core/src/java/org/apache/solr/update/VersionInfo.java
- solr/solrj/src/java/org/apache/solr/common/SolrInputDocument.java
- solr/core/src/java/org/apache/solr/update/DirectUpdateHandler2.java
- solr/core/src/java/org/apache/solr/update/processor/DistributedUpdateProcessor.java
- solr/core/src/test/org/apache/solr/update/DirectUpdateHandlerTest.java
- solr/core/src/test/org/apache/solr/cloud/FullSolrCloudDistribCmdsTest.java
- Added some new tests with focus on testing the new version- and unique-key-based features - ability to fail instead of overwriting on unique-key violation and ability to report errors on version conflict
- solr/core/src/test/org/apache/solr/update/ClassicConsistencyHybridUpdateSemanticsTest.java
- solr/core/src/test/org/apache/solr/update/ClassicConsistencyHybridUpdateSemanticsPartialErrorsTest.java
- solr/core/src/test/org/apache/solr/update/ClassicUpdateSemanticsTest.java
- solr/core/src/test/org/apache/solr/cloud/ClassicConsistencyHybridUpdateSemanticsSolrCloudTest.java
- solr/solrj/src/test/org/apache/solr/client/update/ClassicConsistencyHybridUpdateSemanticsTest.java
- solr/solrj/src/test/org/apache/solr/client/update/ClassicConsistencyHybridUpdateSemanticsConcurrencyTest.java
- Renamed AddUpdateCommand.overwrite to AddUpdateCommand.classicOverwrite, because this is a field that is now only used when running with "classic" semantics
- solr/core/src/java/org/apache/solr/update/DirectUpdateHandler2.java
- solr/core/src/java/org/apache/solr/update/SolrCmdDistributor.java
- solr/core/src/java/org/apache/solr/handler/loader/JsonLoader.java
- solr/core/src/java/org/apache/solr/handler/loader/JavabinLoader.java
- solr/core/src/java/org/apache/solr/handler/loader/CSVLoaderBase.java
- solr/core/src/java/org/apache/solr/handler/loader/XMLLoader.java
- solr/contrib/extraction/src/java/org/apache/solr/handler/extraction/ExtractingDocumentLoader.java
- solr/solrj/src/java/org/apache/solr/client/solrj/request/UpdateRequestExt.java
- solr/core/src/java/org/apache/solr/update/AddUpdateCommand.java
- solr/core/src/test/org/apache/solr/update/TestIndexingPerformance.java
- solr/core/src/test/org/apache/solr/handler/XmlUpdateRequestHandlerTest.java
- solr/core/src/test/org/apache/solr/handler/BinaryUpdateRequestHandlerTest.java
- etc
- When putting config-files into ZK you can have them named something different in there than their file-name on disk. E.g. ./my/folder/my-solrconfig.xml can be named solrconfig.xml in ZK
- solr/core/src/test/org/apache/solr/cloud/AbstractZkTestCase.java
- solr/core/src/test/org/apache/solr/cloud/AbstractDistributedZkTestCase.java
- Misc unimportant cleanup - removed unneeded imports, etc.
- solr/core/src/test/org/apache/solr/update/DirectUpdateHandlerOptimizeTest.java
- solr/core/src/test/org/apache/solr/request/TestWriterPerf.java (just a nicer way to look and afterwards use rsp.getException())
- solr/core/src/java/org/apache/solr/servlet/DirectSolrConnection.java (just a nicer way to look and afterwards use rsp.getException())
- solr/core/src/java/org/apache/solr/client/solrj/embedded/EmbeddedSolrServer.java (just a nicer way to look and afterwards use rsp.getException())
- solr/solrj/src/java/org/apache/solr/client/solrj/impl/LBHttpSolrServer.java
rmuir20120906-bulk-40-change
More detailed descriptions of the added features in SOLR-3173 and SOLR-3178 here: | https://issues.apache.org/jira/browse/SOLR-3178?focusedCommentId=13266385&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel | CC-MAIN-2015-14 | en | refinedweb |
typogrify 2.0.3
Filters to enhance web typography, including support for Django & Jinja templates
Typogrify provides a set of custom filters that automatically apply various transformations to plain text in order to yield typographically-improved HTML. While often used in conjunction with Jinja and Django template systems, the filters can be used in any environment.
Installation
The following command will install via pip. Pay particular attention to the package name:
pip install typogrify
Alternatively, you can run the following command inside the project’s root directory:
python setup.py install
Last but not least, you can simply move the enclosed typogrify folder into your Python path.
Requirements
Python 2.3 and above is supported, including Python 3. The only dependency is SmartyPants, a Python port of a project by John Gruber.
Installing Jinja or Django is only required if you intend to use the optional template filters that are included for those frameworks.
Usage
The filters can be used in any environment by importing them from typogrify.filters:
from typogrify.filters import typogrify content = typogrify(content)
For use with Django, you can add typogrify to the INSTALLED_APPS setting of any Django project in which you wish to use it, and then use {% load typogrify_tags %} in your templates to load the filters it provides.
Experimental support for Jinja is in typogrify.templatetags.jinja_filters.
Included filters
amp
Wraps ampersands in HTML with <span class="amp"> so they can be styled with CSS. Ampersands are also normalized to &. Requires ampersands to have whitespace or an on both sides. Will not change any ampersand which has already been wrapped in this fashion.
caps
Wraps multiple capital letters in <span class="caps"> so they can be styled with CSS.
initial_quotes
Wraps initial quotes in <span class="dquo"> for double quotes or <span class="quo"> for single quotes. Works inside these block elements:
- h1, h2, h3, h4, h5, h6
- p
- li
- dt
- dd
Also accounts for potential opening inline elements: a, em, strong, span, b, i.
smartypants
Applies SmartyPants.
typogrify
Applies all of the following filters, in order:
- amp
- widont
- smartypants
- caps
- initial_quotes
widont
Based on Shaun Inman’s PHP utility of the same name, replaces the space between the last two words in a string with to avoid a final line of text with only one word.
Works inside these block elements:
- h1, h2, h3, h4, h5, h6
- p
- li
- dt
- dd
Also accounts for potential closing inline elements: a, em, strong, span, b, i.
- Downloads (All Versions):
- 98 downloads in the last day
- 652 downloads in the last week
- 2280 downloads in the last month
- Author: Christian Metts, Justin Mayer, Chris Drackett
- License: BSD
- Categories
- Package Index Owner: xian, chrisdrackett, jmayer
- Package Index Maintainer: jmayer, richleland
- DOAP record: typogrify-2.0.3.xml | https://pypi.python.org/pypi/typogrify/2.0.3 | CC-MAIN-2015-14 | en | refinedweb |
Ticket #7001 (closed defect: duplicate)
Export and then Import fails to install. Error suggests that the ovf file has wrong information
Description
Exporting an appliance from Windows and Importing to Linux fails now. It looks like the encoding of the OVF file has static information stored in it that will not allow it to be imported. The D:\Shared folder was setup on the guest, but that should not stop the install. It should continue and dis-allow the shared folder information as it has in the past. Now that I know I guess I can always delete the share folders before exporting but that seems like a step that should not be needed plus it makes it a major problem if this were at different locations. At the very least it should be a setting that I can uncheck on the Import screen.
Attachments
Change History
Changed 5 years ago by Perryg
- attachment Import-error.png
added
Changed 5 years ago by Perryg
- attachment Windows-XPpro-Bridged.ovf
added
Changed 5 years ago by Perryg
- attachment WrongPrimaryDrive.png
added
Changed 5 years ago by Perryg
- attachment XPpro-Bridged.ovf
added
New OVF
comment:1 Changed 5 years ago by Perryg
Update:
I removed the shared folder and exported again and Import failed. Seems the SATA on the XP on Windows made Linux mad. No worries I switched it back to IDE on both drives and exported again. Import succeeded but I was presented with found no bootable media.
It seems that something in the export Import is broken. It Imported the drives backwards, Primary/Secondary were reversed, but one other thing. I looks like it exported the secondary drive and the Primary drive as one and the original (19GB) file is nowhere to be found.
Attaching the Windows screen shot and the Linux import screen shot as well as the Log file from the Linux host of the imported XP guest. Also the new OVF file
I did try to switch them around but neither will boot as I suspect the export/import has something bad wrong in it.
Changed 5 years ago by Perryg
- attachment export-error.jpg
added
WindowsXP-Original
comment:2 Changed 5 years ago by umoeller
- Owner set to umoeller
- Status changed from new to assigned
Thanks for the report. If I see this correctly, we fail because there are platform-specific settings in the OVF such as the shared folder path which doesn't exist on Linux. So the import code should probably issue a warning but not fail. We'll look into this.
comment:3 Changed 5 years ago by whiochon
I have the same problem. It occurs when there are multiple virtual disk images associated with the machine. Note in the .ovf files attached the UUID of all the images in the <StorageControllers> section at the bottom of the file is the same. They should match the UUIDs of the images listed in the <DiskSection> section at the top of the file, in the same order.
I have been able to import the ovf by editing it first to fix the error, and removing the .mf file (otherwise VirtualBox complains as it has also calculated the wrong SHA key on export)
comment:4 Changed 5 years ago by javaboyuk
I have an export import issue too:
export from a solaris host (but has a shared are "/datapool"
import onto a windows host, gives error "/datapool" not absolute
if you edit the .ovf file to add say c: to path you get a checksum eror on the file as you've edited it!
not work arround
comment:5 Changed 5 years ago by whiochon
Checksum error can be avoided by removing the checksum file (*.mf) But it sounds like the shared folder issue is another issue altogether.
comment:6 Changed 5 years ago by TheOtherPhilC
My experience is same as whiochon. I have two SATA disks attached to one controller. UUIDs are correct in the DiskSection of the .ovf, but one UUID is listed twice in the VirtualSystem/vbox:Machine/StorageControllers/StorageController/AttachedDevice sections for the relevant controller.
As with whiochon, I was able to get past it by renaming the .mf and editing the .ovf with the correct UUID.
In my case, there are no shared folders to confuse the issue. The only possible anomaly I can find other than the UUID problem is that while the original VM has one IDE (PIIX4) controller with a single port having a DVD identified as "IDE Secondary Master", the OVF PIIX4 controller has a count of two ports with the DVD attached to port 1.
Changed 4 years ago by wgregori
- attachment ubuntuMaster.ovf
added
comment:7 follow-up: ↓ 8 Changed 4 years ago by wgregori
I'm having the same problem with a linux export of a linux machine trying to import it to the same linux box. I have the same problem with a window's box. I've attached the ovf file.
comment:8 in reply to: ↑ 7 Changed 4 years ago by wgregori
comment:9 Changed 4 years ago by myersjj
I have this same problem using the latest version 4.0.6. This is quite disturbing :( I'm running Windows 7 x64 with a Linux guest.
comment:10 Changed #7941
comment:11 Changed 4 years ago by poetzsch
- Status changed from assigned to closed
- Resolution set to duplicate | https://www.virtualbox.org/ticket/7001 | CC-MAIN-2015-14 | en | refinedweb |
Details
Description
According to j2se 1.4.2 specification for Charset forName(String charsetName) the method must throw UnsupportedCharsetException "if no support for the named charset is available in this instance of the Java virtual machine". The method does not throw exception if a unsupported name started with "x-". For example, the method throws an exception for not supported name "xyz", but does not for "x-yz".
Code to reproduce:
import java.nio.charset.*;
public class test2 {
public static void main (String[] args) {
try
catch (UnsupportedCharsetException e){ System.out.println("***OK. Expected UnsupportedCharsetException " + e); }
}
}
Steps to Reproduce:
1. Build Harmony (check-out on 2006-01-30) j2se subset as described in README.txt.
2. Compile test2.java using BEA 1.4 javac
> javac -d . test2.java
3. Run java using compatible VM (J9)
> java -showversion test2
Output:
C:\tmp>C:\jrockit-j2sdk1.4.2_04\bin\java.exe -showversion test2
java version "1.4.2_04"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.2_04-b05)
BEA WebLogic JRockit(TM) 1.4.2_04 JVM (build ari-31788-20040616-1132-win-ia32, Native Threads, GC strategy: parallel)
***OK. Expected UnsupportedCharsetException java.nio.charset.UnsupportedCharsetException: x-yz
C:\tmp>C:\harmony\trunk\deploy\jre\bin\java -showversion test2
(c) Copyright 1991, 2005 The Apache Software Foundation or its licensors, as applicable.
***BAD. UnsupportedCharsetException must be thrown instead of creating Charset[x-yz]
Suggested junit test case:
------------------------ CharsetTest.java -------------------------------------------------
import java.nio.charset.*;
import junit.framework.*;
public class CharsetTest extends TestCase {
public static void main(String[] args)
public void test_forName() {
try
catch (UnsupportedCharsetException e) {
}
}
}
Activity
ICU team has fixed this bug. Here are the libraries I build from icu4jni's latest code.
Richard,
When you say "icu4jni's latest code" can you be more specific? Was this HEAD or a release ... ?
We need to know exactly what it contains before deciding whether to use it.
Thanks,
Tim
Svetlana,
We have decided to defer this fix until the next official release of ICU4JNI becomes available. Let us know if this is a problem.
Thanks
Tim
Tim, I have no objection. Let's wait.
I verified that it has been fixed in icu4jni3.6.
Would you please close it?
Was fixed in later version of ICU.
This behaviour originates from the ICU provider code, I'll see what they say about it first: | https://issues.apache.org/jira/browse/HARMONY-64 | CC-MAIN-2015-14 | en | refinedweb |
Attribute entity. More...
#include <RAttributeEntity.h>
Attribute entity.
Exports the entity to the given exporter.
The exporter might be a file exporter, a graphics scene or any other platform one can export entities to.
Reimplemented from RTextBasedEntity.
Implements RTextBasedEntity.
Implements RTextBasedEntity.
Reimplemented from RTextBasedEntity.
Stream operator for QDebug.
Reimplemented from RTextBasedEntity.
Sets the given property to the given value.
If this property owner does not know a property with that ID, it is up to the property owner what happens. The property might be added into a list of dynamic properties or dropped.
Reimplemented from RTextBasedTextBasedEntity. | http://www.qcad.org/doc/qcad/latest/developer/class_r_attribute_entity.html | CC-MAIN-2015-14 | en | refinedweb |
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java script and velidatores i made a job portal and in it many fields which required validate how i do throw java script.. can you help me please... Friend,
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Name:
|
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JOIN US...;
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return false;
}
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PLZZZ
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sends me email
sends me email How do I create a link that sends me email | http://www.roseindia.net/tutorialhelp/comment/88074 | CC-MAIN-2015-14 | en | refinedweb |
Agenda
See also: IRC log
<trackbot> Date: 30 March 2011
<danbri> yesterday's notes:
<danbri> draft minutes:
<matt> Scribe: danbri
discussing recap from yesterday
role/value of rdf
oh might be useful, 'Select the name, lowest and highest age ranges, capacity and pupil:teacher ratio for all schools in the Bath & North East Somerset district ' (uk open linked data example)
<martinL> test
<matt> trackbot, start meeting
<trackbot> Meeting: Points of Interest Working Group Teleconference
<trackbot> Date: 30 March 2011
<JonathanJ> see yesterday's minutes :
JonathanJ, yes I think that might be useful. Perhaps in terms of exploiting externally maintained data (e.g. school-related info)
<inserted> scribe: matt
<danbri> ahill mentioning eg. from yesterday, ... not a POI but potentially a movie showing in a local POI
<danbri> ronald, see also
[[introductions around the table again]]
<danbri> 15 Gigs of OSM data: -dontcrashyourbrowser- .de/pub/openstreetmap/planet-110323.osm.bz2
<scribe> Scribe: matt
Martin: I'm the CTO of Mobilizy/Wikitude.
Thomas: Bertine and I are working on an AR browser at a company called LostAgain.
cperey: Who has implemented a browser?
[[everyone but Matt and Dan]]
<scribe> scribe: cperey
Matt: new agenda
<matt> -> Day 2 Agenda
<danbri> 'lost again':
Matt: AR Landscape Drafts
... what Jonathan has put up and the AR vocabulary, to extend the core work, what is the shape of this, get an editor
Alex: do we have room for AR Notes? Yes, Landscape Note is part of what we will do
Matt: our charter
<matt> POI Charter
Matt: first is POI recommendation. Then, the charter says that we will produce two AR Notes. A note is slightly less rigorous thing
... could be published on our web site. Vocabulary to extend teh core recommendation Might include presentational characteristics... could include anything
... we have started the Vocabulary at all yet
... have NOT started yet
<danbri>
Matt: we have AR Landscape.
<danbri>
<matt> scribe: matt
cperey: It's not a gap analysis document
... This is more of a product feature landscape an inventory of what's in the products today.
... I'm looking to codify the standards that describe the different functional blocks that AR uses.
<scribe> scribe: cperey
<scribe> scribe: matt
cperey: I think that this is will focus on those parts that are about making AR on the Web. There may be scenarios where there is a client.
<scribe> scribe: cperey
matt: this is just a starting point. we will discuss it. I think this will evolve into a gap analysis of current standards wrt the Web and AR.
Ronald: is this group chartered to look at the full range of AR?
... or are we going to focus on POI
Matt: we are broader than just the POI in this area
bit from the charter... Dan... we should begin the conversations
Matt: there is distinct possibility that when we get core draft done, we can recharter
Alex: but I tihnk what Ronald is asking about is the AR note
<danbri> (so where are we collecting info about geo APIs: e.g. ...etc etc ...?)
Alex: my feeling that the AR notes was restricted to what this group is chartered to speak about
... what is the POI we are putting forward and how it applies to AR
<matt> danbri, I'd suggest adding them to:
Alex: if it includes talking about 3D, then great, it probably means that talking about Device APIs, we don't need to cover the whole gamut
... in some sense, a landscape of all existing browser is not a requirement of our discussion, to understand how we go forward
... it is not necessarily in our charter that we cover all of that depth
<danbri> 'The WG may also publish use case and requirements, primers and best practices for Points of Interest as Working Group Notes. ' --
Matt: should we look at list of mobile user agents on browser page
<danbri> (so if someone e.g. wanted to make a 'how real projects are putting geo-related info in QR Codes, imho that'd be in scope for a separate Note)
martin: supported platforms could be added to the tables
Matt: Jonathan how d you want to proceed?
Jonathan: I'd like to talk about the document
... as mentioned, the landscape is main document, browser document is the details of one area
... I have discussed with many Korean people and community
... gathered many criteria so far
... first, is the comparison targets. I think we need to make a narrow scope for AR apps
<danbri> (matt, ok I've added them to )
Jonathan: because too many applications in AR domain. We can make technical specification for our standard. We need to narrow the scope
... I have written the features. First the .. second, linking to web services, third is rendering, fourth is...
... Collected a list in the document, about 13 products
... Christine made some comments. this are on the page
Alex: where do we the line? our browser is not commercially supproted
... it is in teh iTunes store but anyone can make an application. it's penetration is negligible but the features are important because it demonstrates some of what we are talking about
... some applications/user agents don't codify AR, read it...
Thomas: the data standard must look at main commercial ones. because if the standard can't do what they say that they do
Martin: mixare is downloadable, available outside of the laboratory environment
Jonathan: need to consider extensibility
Alex: the list is probably right.
Martin: as soon as something is publically in use
Matt: we stop collecting when we have all the features covered
Alex: Google Goggles is AR
... Recognizes a POI
... information about the POI pops up
... it may have features
Thomas: API for visual recognition engine could be on their roadmap. The feature that they have is one which AR browsers will have
Ronald: Visual Search and AR will merge
Martin: we can't separately Geo and Visual
Alex/Thomas: Nokia Point and Find should be added
<matt> ACTION: Jonathan to add Nokia Point and Find: [recorded in]
<trackbot> Created ACTION-38 - Add Nokia Point and Find: [on Jonathan Jeon - due 2011-04-06].
<matt> ACTION: Jonathan to fix link for Wikitude [recorded in]
<trackbot> Created ACTION-39 - Fix link for Wikitude [on Jonathan Jeon - due 2011-04-06].
Alex: Nokia Point and Find at some point you could download it for a phone
... some features I've seen demoed, are not available to everyone, but worth looking at and considering again
<JonathanJ> I was referenced a good report from edinbergh univ. -
Alex: some of the things that Petros mentioned , aggregating POIs into footprint of buildings
... street view like browsing
... so does StreetView belong on this list
Thomas: and you can use the gyro in your phone to see things
Alex: it's not strictly AR
but what should we be focused on?
<matt> Petro/Nokia's position paper
Alex: I want to say that the definition is not tight or exclusive to keep StreetView and Goggles out
... these are close enough to be considered here
<matt> close ACTION-39
<trackbot> ACTION-39 Fix link for Wikitude closed
Alex: it's remote, browser based, worth considering
Thomas: AR is a potential output method, the same data can be viewed on many different applications, in an AR form if appropriate
... non-issue what you call AR or not
Alex: and at some point there will be a maturation of this definition
... like VR, lots of things expanded outside the original definition
<Zakim> danbri, you wanted to ask about qrcodes
Alex: It's a visualization method for POI
Dan: what about QR codes?
... I find AR unconstrained, it's fine, does lots of cool things
... useful for navigation in real time
... QR codes are quite well understood technoogy
... I'd like to make a pitch that they are in scope for this group
... I just want one standards thing taht is part of QR code
<matt> GIST QR codes
Thomas: AR should be small enough to act as a direct link to the data
<matt> [GIST]QR_Code_Data_Representation_for_AR.pdf QR Code Data Representation for AR
Thomas: QR code is very limited in what and how much it can store
Alex: I second what Dan is saying
<danbri> can we resolve unanimously that this group hopes to make some contribution around the use of QR codes for POIs? (whether documenting existing practice, or suggesting a design...)
Alex: for the notes, for us considering the implications of a POI standard, this use case of seeing a QR code and sanpping it is applicable
... it should be in scope
Martin: looking at the list, these are all mobile applications
... we should also include in scope non-mobile applications
... like Total Immersion things on desktop
Alex: but didn't you (Jonathan) want to restrict it to mobile browsers
<danbri> re QR code capacity, see my thread last year on lengths of URIs 'in the wild'
Alex: at the same time, you could imagine street view
... if you have been excluding it from the discussion is the wrong thing to do
Thomas: it would be ludicrous if you had to pull down data from one source for desktop and a different place for mobile
<danbri> oops wrong link. 'URI length statistics "in the wild"?'
Thomas: for content providers that would be a show breaker
... we want to avoid all the systems that labs have done but at the same time, it is appropriate to include StreetView
Alex: I recommend that it be included in the list
Thomas: if you are dealing with image relative position, there is a great advantage to including them
... at the end of the day it is a marker and a model (3D model) on the marker
... a standard way of associating a marker and a 3D model regardless of where it is would be useful
Jonathan: we need more time
Luca: my feeling for AR is that it is something that you put on the real world
... for example, StreetView it is not exactly AR. Desktop can be included as long as you use a webcam to put things in teh real world
<JonathanJ> It is not problem, what product is included or excluded
Luca: for me, for what I include when I think AR, it is display of information on top of the real world. Google Maps is not AR. You do not see the real world
<danbri> Luca, not everyone can see...
Alex: if you are walking down the street and you take away the background
Jacques: you are switching from AR to mixed reaity
Dan: is AR only for people with good vision
Thomas: geo-located sound is in scope
Alex: he's talking about it is synthesized background. but if you take away the backgrond ad you see the same content, the same rendering engine is doing
... that is Ar
<JonathanJ> I don't think AR only for people with good vision.
Luca: because we don't have to be on the street for us to have AR experience
... I don't want to say that only geo located can be AR. It can be visual recognition, sensors, printers, etc all of this is included and in scope
<JonathanJ> ISSUE: what AR is our scope
<trackbot> Created ISSUE-6 - What AR is our scope ; please complete additional details at .
Alex: overall features.... is there anything on this list that doesn't make sense. I see the idea. Does it have an SDK
... is it using Points of Interest?
Jonathan: I can see that filling out this table is going to get messy. Everyone is going to be full of caveats
Thomas: what user interaction standards should be defined
... define a click action
Alex: for me the biggest differentiation is Web 1.0 and Web 2.0
... whether you can put your finger on it and stretch the world, manipulate the model
... data representation is an important feature to add
... I think is of value. We use KML and HTML for Argon
... I don't know what Acrossair does
Martin: Acrossair is closed and proprietary system
Alex: edits into the document
Thomas: should the data representation be separate from the POI? Is that important? Is that relevant to discuss
Alex: for first pass, we list what we know about these things.
... filling in the table
... does anyone at this table know anything about Google Goggles data representation
Thomas: it is probably going to be like MapAPI
<martinL>
Alex: how they do it. this is where the rubber meets the road
<fons> s/probsbly/probably
Ronald: you get XML back and you get a URL to which you can go
Alex: is that a POI? Did it return a POI?
Martin: is a POI tied to a location?
Alex: if I'm standing in front of building, and I shoot an image, and I get the name of the building, have I got a POI?
... yes
Thomas: whatever links the real world to the virtual content is POI
Alex: I pick up my phone and I look at the courtyard and I see a Polar bear. it is AR.
... nothing is there but a lot of people who argue it is a POI
... sometims these lines are difficult to draw
... we agree that kooaba is returning data and POI
Ronald: It's JSON. No ties to any other standards at this time
Alex: but the JSON is returning POI and data
... maybe because what we need is a column that describs how we are triggering in some sense
... Have it in the table
... why don't we change user interaction
Dan: finish the column
... ovijet
... put proprietary
Jonathan: they are visual search
<fons> s/tey/they
Alex: what is sekaicamera
... it is social AR in geospace
... this doesn't answer the question of data representation
Sekai camera is also JSON
<matt> Mixare JSON docs
Alex: wikitude
Martin: ARML, based on KML
Alex: when we say KML we mean XML
Thomas: the format is same but KML has things already sorted , already specifies location
Alex: what is the difference between name space and ...
... markup language
Dan: XML was born as a simplification of SGML
... it XML was created, they wanted to interleaved
<matt> xmlns is the default, prefix is the non-default ones
<danbri> re XML namespaces see
<JonathanJ> There are a missing point. I want to compare from 1st cloumn (Data Representation) what they support 2D, 3D format.
Coffee break.
Alex: it's become obvious that we need to focus on our objective. We don't have time to flesh out the document here
... we need to focus on what's available and how our POI standard effect people who want to deliver AR
... how do we answer that
Matt:
Matt: technologies listed here. some with work going on in W3C
<JonathanJ> see
Matt: gyroscope work in progress
... microphone work in progress
Thomas: these are all very big things,
martin: there are other people doing work on these
... as a reference, we should point to others who are working on this
Dan: I don't see video feed here
Jonathan: add camera input
Matt: add the applicable standards
Alex: where are we going to put this
<matt> scribe: ahill
thomas: should we separate device access standards from POI standards?
<cperey>
<matt> ACTION: matt to add links to existing standards [recorded in]
<trackbot> Created ACTION-40 - Add links to existing standards [on Matt Womer - due 2011-04-06].
<danbri> (finished editing now)
<cperey>
agreed
thomas: what about user rotation in the POI spec?
ronald: we've discussed the orientation of content, but not the orientation of the user
martin: we need to separate meta data of POI, geo-location and data representation (visualization)
<matt> scribe: cperey
martin: we need a clear separation. We go to this point and not further
Alex: I never felt that our responsibility would be to render teh content
... the question is how do we facilitate teh data coming with the POI
Thomas: there is some overlap, may want inline data with teh POI you don't want to link to a remote text file if you want only a two line...
Bertine: maybe a CSS?
Alex: we all have in our minds, ideas of POIs that include lable and description
... you're saying that's so cannonical that we don't want an extra standards for describing that
... does this argue that there should be a place in teh standard to relate that?
Thomas: you wouldn't embed a JPEG in an HTML page
... same with a model. If you have a short bit of text it makes more sense for it to be in line
... it has to be related
... needs to be standard for a simple label annotation. It needs to be in a Standard
Ronald: we have name primitive in our browser
... style sheet is not directly part of POI Spec
... you can say that POI Spec has a couple of fields but up to the specific browser to show content of a particular type
Thomas: but does the creator of content want to specify how it is visualized?
Ronald: yes, but not in the POI spec
... the question is if it is part of POI. Or if you have a link to the visualization within the POI
ThomasL should POI include a class reference
Martin: KML does something like that
Essentially what you have is an XML represetnation of a POI
Martin: do we define a new POI standard. KML defines almost everything we have talked about
... our proposal is to eliminate all of the stuff we do not need in AR
... we pull the KML tags we need and we add AR tags we need
Alex: let's say that the way you describe coordinates, if you disagree with that then you would be leaving the standard
Thomas: simple differences like Lat vs. Latitude
Alex: funny to hear say that. Dan was showing how we could put RDFa into a web page. Lots of angle brackets. Seems a little verbose
... point of view, perspective changes the definition of "verbose"
probably not worth it for us to invent another way to represent
Alex: at some point we are going to need to peruse other standards and come up with ways to improve them
WGS84, etc
Alex: we need to get down to brass tacks and say who's description we are adopting and what we think it is going to look at
<matt> trackbot, close action-40
<trackbot> ACTION-40 Add links to existing standards closed
Alex: wouldn't necessarily throw out KML if verbose, if millions of people are using it
Thomas: you establish key value pairs and maybe in a few year's time, the changes may come
Matt: eXdInterchange
<danbri> re XML compression, see Efficient XML Interchange Evaluation
<matt> Efficient XML Interchange WG and specs
<danbri> . "
<JonathanJ> matt, I think we need cooperate with DAP -
Alex: back to KML, we were talking about representation.... I'm not... not to say it's not the right way to approach it but in our KARML version, we take desription tag
and it is HTML. YOu can have styles. Put some text in and browser would render as a default, but you can add HTML for presentaiton. You could imagine extending , add some SVG instead
Alex: so in that case, now the data is inline with the POI
... the isue is that in some circumstances we want a link to presentation data. so effectively, we get the POI data, it has a link to Web Page, and that's the data we want to present in AR
... yesterday we were looking at the entire web page. bottm line is the minimal set that we want to allow people to inline
Dan: there are part of the HTML ....
you can ask it to bring back a really simple version
Dan: can't remember the header names. At the HTTP level thre's a whole set of ...
<matt> alex: How common is content negotiation?
matt: very common, gzip
<matt> matt: Depends on the content types. For instance, most browsers support saying "I accept HTML, and gzipped HTML" -- this is widely deployed.
content negotiation, if we define a format with its own MIME type, one of its characteristics could be its compressed
Dan: wikipedia might implement it
<danbri> see
Ronald: web servers also try to figure out what type to send
Alex: but that's not reducing what gets sent, it is an efficiency
Thomas: yes it is
Martin: one question return to. What metadata
... do we really need a separate POI Standard separate from what already exists? can't we just pull out what we need form KML?
Marin: what tags would we really need?
Alex: we agree with you in general
Matt: we would take a profile of GML and augment with our specific vocabulary
Thomas: we need metadata. If there's an existing standard we should use it
<danbri> (re existing standards, also )
Alex: we only chose KML because it was the broadest adopted markup
Not because we said it was the most/best
Alex: so yes, if you say GML, I agree
... I imagine in the future what we are adding to the dialog is quite small
matt: Yes, it could be a profile of GML.
Martin and Alex are in agreement
<JonathanJ> s/profiel/profile/
<Zakim> danbri, you wanted to assert that extensions shouldn't be an afterthought
Dan: yeah there's all these existing standards
... we've already begun picking up common elements
... story how they are the same is useful. Strongest we can do is extensibility
... figuring out the specific use cases, to specify how different datasets are represented
... connecting hop between what other's do and what AR does/needs is what we can do
Thomas: ...
... it needs to be automatically coming up when the conditinos are right
Dan: value adding services need to be able to bring out their data and the people to publish POI data to provide connections between their data and other data without W3C coming up with new vocabulary
Thomas doesn't need to define a movie database format
Dan: example of semantic markup,
<matt> scribe: Matt
ahill: When you say linked data is the way to go, can you describe it? I'm walking down the street looking for particular data, and you're talking about returning links?
Thomas: machine readable links.
ahill: My browser could follow these links and add information from these databases. We don't need to reinvent how to do that by any means.
... What do we need to do to facilitate this?
... Some people might argue that we would need a registry to facilitate these things.
Thomas: I don't think so.
danbri: Maybe at a high level to bring them all together, but the Web is it's own regsitry.
<JonathanJ> see Linked Data -
danbri: I'm walking along and my phone is relating my location to some service. I get a notification that there is a movie playing nearby with actors you like in it.
ahill: My project is relaying this to proxies who then go find this information out, rather than from the device directly.
... What is the difference between agent based semweb stuff and AR?
thomas: I don't think there is one.
ahill: Good, rather than reinvent the wheel we can piggy-back on other efforts.
cperey: I want to throw a monkey wrench in this: you haven't paid for this information. There should be a token to authorize that agent. It's not all just for free.
-> scratch pad
cperey: Then there are ethics, laws. Is this person looking for illegal stuff?
... I just looked at a building and it had one picture, but now it has another, who has the rights for changing that?
Thomas: I don't think that's up for us to implement it.
cperey: Don't you want it in a standardized fashion?
Thomas: There are already standards for these things, SSL, certificates, etc.
cperey: Then we need to write that there are other standards that we could use.
ahill: I don't see the AR uniqueness here. So we don't have to worry about it then.
Ronald: There are security standards.
ahill: People are solving those problems already.
cperey: People aren't solving the problem of predatory real-estate.
Thomas: There's not going to be a one-to-one relationship, the user choses to accept whatever datapublisher they wish.
... If I use a mail service, I'm going to have their ads, that's known. Whatever source we use is going to be responsible for the adverts, etc.
ahill: Another thing we're doing in Argon is offloading to the proxy server under the acknowledgement that search becomes a bigger issue when you walk over to a place and it has 1000 POIs, that's a mess. Your trust network, who your friends or whatever, is really going to affect it.
... We have to acknowledge that at one location there will be a large number of things people have vied to get there.
<Zakim> danbri, you wanted to say 3 things before brain fills up: i) thinking about incentives is good; in my simple scenario, tushinki haveincentive to get customers ii) those are real
danbri: You're right to think about incentives. In the movie case, they want customers. If we do something as simple as Facebook, they'll get customers.
... The social issues exist. We'll have to look at them.
... And last, oauth is a big piece of this. They want their app to work and be deployable to lots of devices. OAuth seems to be the solution of choice at the moment for that.
Thomas: I think there is a lot of power to come from it. I don't think it's up to us to decide on that.
... The spec shouldn't require a third part auth.
Ronald: Responding to Christine's suggestion to standardize the too much content problem: I'm not sure that's really feasible. Are search engine results standardized in how they order things?
... No. That area of discovery of information, I'm not sure it's standardizable.
... It's a real problem for AR, but not necessarily one that gets solved by standardization.
Thomas: It's a big issue and so much room for innovation that I think that is where clients will differentiate.
cperey: How do you formulate the query could be standardized, but not how the response is formulated.
... When I heard query POI I was thinking: "Oh, that's talking about a directory of POIs", which isn't the same thing as querying.
... "These are my circumstances, here's a query for that" vs a directory of layers/channels.
<danbri> (ahill, if someone queries for Amsterdam Red Light District, their AR service(s) should route them to )
<danbri> (but that's a marketplace thing)
Ronald: In the end from our findings, it was quite difficult to get to something that the user really valued.
ahill: With them being the authority.
... No one on the web has defined how to index content in a standardized way.
cperey: There's SEO. In libraries we used the Dewey decimal system and found that to be useful.
bertine: I think the difference with the library example is that books are static.
Thomas: It could start off fantastic and then get swamped with ads.
... The order shouldn't be defined, but the request could be, is that right?
Martin: Web pages care about being ordered, but that's all search engine based.
Ronald: There is part of the HTML specification with keyword metadata.
... That gives content providers a way to find the right information.
ahill: Sounds like when possible we could leverage such things.
Thomas: metadata on the Web isn't useful anymore, hard to trust.
... search engines basically ignore metadata these days.
ahill: That's a shifting tide thing though. Might have been useful years ago though.
<danbri> google do use
ahill: So how do we standardize around it?
Thomas: There will likely be AR search engines that look into the AR data and figure out if it's being abused.
<danbri> (you need another signal for trust and quality, eg. google rank, or facebook LIKE, ... then metadata can be exploited)
cperey: Is this matching our agenda?
matt: Is it what the group wants to talk about?
ahill: I think we should talk about these things now.
... I think the tone is that AR is going to be visually based. I think people see that as something very different than the kind of AR we have today.
... I think the points where these things come together is maybe location and description.
... Take the visual sensor example. I'm agnostic about the sensor.
cperey: That whole thing is heavily what the interface that the sensor web folks worked on.
Thomas: That's why I like to call them triggers.
... I'd argue that the POI has to contain the trigger.
matt: I don't understand why trigger has to be a unique part of the structure?
Ronald: I think we said that the trigger is part of the location primitive, maybe not using that word.
<JonathanJ> I'd like to suggest to make another document, something like "Requirements and Use Case for Linked POIs" by danbri
ahill: I could do a search around me and get 100 POIs around me, one of them is this cup. Some people want to call this a trigger, some people like me want to just say "I have the means to know I am in front of this cup".
Thomas: The difference I see is the metadata what you use to search with, while the trigger is an automatic thing.
... For instance the only ones that are in the field of view are triggered.
danbri: It's not up to the objects to determine that.
<cperey> trigger position paper
ahill: Looking at a web page there's a ton of links. You scroll down and click on any of these things with the mouse. The triggers thing seems to be a way to simplify that, but it's more complicated than that, I could have preferences, etc.
Thomas: I'm thinking it's just more of a passive thing. Something that appears merely by association. A browser may or may not display them. I think there's a clear differentiation between active and passive things.
<cperey> trigger by Thomas
martinL: I think location then is a trigger as well.
matt: Why isn't any data in the POI a trigger?
Ronald: It sounds like search criteria.
Thomas: While you could search to have something appear automatically, it's not automatic. I search and don't get all of those results popping out all at one time.
<JonathanJ> POIs could be crawlable by search engine ?
Thomas: With AR there's a lot more automatic than the Web. We can't just have users activating everything manually.
<cperey> in the public mailing list
Thomas: I think it's the association of where the content creation believes the data should be put, whether it's image/location/sound based. That's slightly different than what the user wants to see at any given time.
ahill: Imagine there's a landscape with one item. The author specifies where it is, what it looks like,etc. That's AR, I don't need the word trigger yet to filter that.
... I need an argument for the word trigger now.
Thomas: I think you need a way to represent the association.
... A way to associate the data you want and an intended location.
martinL: Alex said filter, I like that, that's essentially what it is.
cperey: no!
ahill: We're talking about filter at one place, and then this trigger that describes the POI that is there.
bertine: It's trigger like a landmine, not a trigger like a gun.
Thomas: We can call it something else if trigger is confusing.
danbri: I found it confusing on the mailing list.
ahill: It's a linkage between place and content.
Thomas: I'd say it's part of the linkage.
... There's two parts: what causes it and what goes to it.
... The trigger is what causes you to go to it.
danbri: So is it up to the client to recognize the class of thing?
Thomas: Yes.
ahill: Is this linkage a POI that the spec is to connect data (SVG, HTML, COLLADA models) to a context of the user. That is our charge.
... Then when you talk about seeing a pen and using a trigger, it makes it confusing.
... A lot of people think "I see this and something is going to happen" -- that's a somewhat different subject.
<danbri> 'trigger' for me has a strong imperative reading, ... that the 'triggering' is inevitable
Thomas: The POI is a link between real and virtual.
... I was using trigger or whatever the word is to indicate the category of the sensor that you're correlating to.
ahill: So, there is a unique item, if I got a description of how to recognize it visually, I could dereference that eventually to the exact location on this table and then it's just like a movie theater, or whatever.
... So it's the same, but a different matter of how we get there.
... Then there's the example of "every pen that looks like this" -- which is a reasonable use case, but to me it's more of a pattern than a trigger to me.
<JonathanJ> POI trigger is like this ? -
ahill: Now, say every building from a company sets aside an area for AR, and that's a pattern. Buses could have a sign on the side --
Thomas: How do you find it if the data isn't there in the POI?
ahill: I know I'm in a store, I look at my coordinates, dereference and I'm done.
Thomas: But that store is static. This is ludicrous, then the bus must relay it's coordinates to a server then the client has to fetch it.
... I have nothing against publishing moving coordinates.
... I also think that POIs should be able to specify relative coordinates. I just don't think you can limit it to just the coordinate space.
ahill: This just isn't unique to the domain of visual recognition. I think we will use visual recognition, I'm just saying that visual triggering can happen the same way by other means
... I'm more inclined to push it towards a special case in some sense.
Thomas: To me we need both. The most basic visual recognition is QR codes. That's literally just an image that is then decoded to a URL.
ahill: But that's not a trigger, that's just a linkage.
Thomas: We're associating an image with data, that's just as useful as associating coordinates, whether static or moving.
... The POI needs the capacity for both.
ahill: We need both, but they're not different enough in my mind that they can't be handled.
Thomas: I'm just saying a field in the POI that has coordinates or an image.
ahill: This is what Ronald was alluding to, that a location could have a visual description of pen.
Ronald: And it can be a combination of geo and visual too.
cperey: How it's stored is part of the POI, but not what is in there.
Ronald: Sure, the algorithms will change, etc.
cperey: The device which detects those conditions on behalf of a user, whether mobile or stationary, is using sensors.
ahill: Something like identifying a particular pen could have a number of criteria, so how do you author it. My sensor is going to be picking up that pen all over, but it's not necessarily going to be triggered.
Thomas: The system would have the image criteria already in it's memory.
cperey: You're never looking at the real object, you're just encoding those unique features that identify that class of object. Only those features, so you have an extremely fine sample, you're not walking around sending entire photographs of the pen around to be detected.
Ronald: Most of the time you're sending an image from the mobile to a server.
Thomas: There can be client side recognition.
cperey: But the point is the server side would probably just maintain the extracted features for recognition.
ahill: if I want to recognize this computer, I take multiple image that then get distilled down to something recognizable.
<Carsten> Morning, just wanted to have a quick look at what you guys are doing
martinL: I don't think there's a chance of standardization there as under different conditions have different better algorithims.
<danbri> (lunch-7.5 mins and counting....)
<Zakim> danbri, you wanted to discuss pre-lunch recap. Any actions arising?
danbri: Where are we? We've been chatting, but what action items are coming out of this?
cperey: We've been here before, and we've had people with agendas from geo-physical data that they want to solve.
ahill: And they didn't want this in scope.
matt: That's not what I saw at the last f2f.
cperey: In the next few minutes, the composition of the people in the group has shifted a bit. And it can shift back.
ahill: This is the part of the meeting where we are addressing AR stuff. We are talking about what are the implications? How does the POI stuff relate to AR?
cperey: This is entirely in scope as the subject of long/lat.
... And the traditional problems of those who own large POI databases?
ahill: Our existing spec solves that. It allows the POI database folks to add WGS 84 coord and a name/description/ec.
... Our existing spec also allows for a pen POI with a visual description and an unknown location.
<danbri> (this is a good time to have people make commitments to do things, and to record those in the issue tracker. I'd be happy to take an action to summarise what I could find out about encoding of URIs in QR Codes, for example)
ahill: In my mind I've got a search that includes "pen's that belong to Layar" -- I have those POIs, but I may not be displaying them. To me that's not any different than a POI that's on a building over there that's occluded by a building over there.
... I don't see it as any different than things popping in there.
Thomas: 99% of the time they'll be preloaded, there is a lot of precaching and displaying later.
ahill: You're interests, your context at the moment, those things all determine context that determine which POIs are in my browser currently.
danbri: If this room has a POI, there's a URI to it.
Thomas: QR code could be the link.
<scribe> ACTION: danbri to summarize URIs in QR codes to POIWG group [recorded in]
<trackbot> Created ACTION-41 - Summarize URIs in QR codes to POIWG group [on Dan Brickley - due 2011-04-06].
ahill: In my mind our spec at the moment could work for a QR code with linkage to some data.
... I could imagine a QR code being the equivalent of a pen being recognized.
Thomas: There's also the case where the QR code could contain the POI itself, QR codes don't have to be links.
ahill: Practically what is happening? I see a QR code, it's got a URL, I get back a POI. It needs to be linked to something physical, maybe it's a marker to track, or the QR code itself, or four inches from the phone. That's the POI, the QR code is a specific means to encode the URL and there's a separation there.
Thomas: I am seeing a scenario where the QR code decodes to a link which has a POI which then may link to the 3D model.
... But the QR code could be just the POI itself and go directly to the 3D model.
<JonathanJ> QR code can encode in other many information bytes.
ahill: I see that you want to be pragmatic about the links followed etc, but I'm not sure that's what we need to accomodate in our charge.
Thomas: Perhaps not specifically, but it would be nice.
... We're talking a minimal spec and lots of optionals. Maybe the small thing could be in a QR code.
ahill: In our lab we worked with markers for ever, and now they're totally out. We recognize full-on images, which doesn't have any data encoded in those images. I could imagine that some day if we did push for QR codes that people would laugh at us in the future.
Thomas: I see advantages to not having the data require a separate lookup.
ahill: I think no one here wants to create a byzantine set of links.
... We've had a lot of discussion but no consensus.
<JonathanJ> we need raise issues
ahill: I think we can resolve that our POI standard that we've put forward accommodates many different scenarios.
... Whether it handles triggers, image recognition, etc. I've resolved in my mind that we haven't excluded any of those things. We haven't excluded any representations too, like COLLADA models, or HTML.
... I think that's valuable, as someone always pipes up on something like this and then we have the discussion again. I don't think we should have to do this conversation again.
<danbri> do we agree? "..."
<JonathanJ> +1
<Ronald> +1
PROPOSED.
<Luca> +1
<cperey> +1
<JonathanJ> s/%1D//
Thomas: future issue: are the different criterias and-ed or or-ed?
<danbri> ... not hearing any objections; are we resolved?
ahill: True. I think people handle lots of this sort of thing in code. I think if people want conditions... they write code..
Thomas: It's a fair point that we don't want to go into the logic too much.
... If you make a web page you don't have to code the functionality of a link. Metaphorically we're working on the equivalent of that, right?
ahill: I won't disagree with that. We're trying to provide some structure that keeps people from writing code to present data.
cperey: Is this called a "data format"?
... Because the OMA folks said specifically say they're considering doing an AR data format.
... I think these two words have universal meaning.
ahill: I'm concerned about making such a statement that is someone will say "POI is not an AR data format". I'd be inclined to say that our POI data format can be used for AR and we have specifically taken note of it. We haven't created a specific AR data format, but we believe it could be applied to that.
<JonathanJ> "AR data format" can include anything
ahill: I'd be hesitant to say it's an "AR data format".
Ronald: There's a reason there's a Core data format.
matt: And part of that is because there are other things that will use the POI format without being AR.
ahill: AR is the linkage format.
<danbri>
<danbri> another use case where the publisher has incentive to be found: Best Buy stores:
<danbri> ACTION: danbri identify relevant specs for rotation/orientation included at point of photo/video creation - what is current practice? [recorded in]
<trackbot> Created ACTION-42 - Identify relevant specs for rotation/orientation included at point of photo/video creation - what is current practice? [on Dan Brickley - due 2011-04-06].
<danbri> eg scenario: I'm stood in middle of Dam Square, looking (west?) towards the palace, running e.g Layar + a flickr layer. Would it be useful to show only photos that are taken facing that same direction, ie. showing the palace and stuff behind it, ... or also the things behind me (Krasnapolsky hotel...)?
<JonathanJ> geolocation WG have been making the orientation spec. -
matt: I see this:
... but it appears to be just about the image orientation.
... iPhone appears to capture in EXIF the data: "Exif.GPSInfo.GPSImgDirectionRef", from:
-> EXIF 2.2 spec includes GPSImgDirectionRef and GPSImgDirection
<danbri> matt, thanks I'll read
<danbri> i made a test image but maybe i have geo turned off
<scribe> Scribe: cperey
<danbri> matt, re ... how do we go about getting a filetree for a testcases repo?
I'll scribe for an hour
when are we going to finish March 31? at 6 PM
Matt: we are moving the AR vocabulary to the end, in order to begin working on POI core spec page
... is there anything in the Landscape since last time we reviewed the AR landscape?
Alex: what are we going to do? don't want to go through item by item
<matt> Landscape Document
Alex: we should move on
Matt: get into core drafting, do more of this tomorrow when we have a better understanding of what's in/out of the core.
Alex: Or dedicate a future teleconference to it.
<matt> Agenda again
Matt: questions about the core draft
... we should deal with these up front, some we dealt wth yesterday
Ronald: are we trying to split up the work?
... can different people take more focus on specific sections?
Alex: maybe we should take the easier items and get them out of the way
... get the ball rolling with Time and Categorization. It also gives us a process.
Matt: we look at requirements of each primitive
Alex: if we do that as a group, then it's a shorter list
... we have (after Time and Cat) Relationship Primitive-- not something to be done in a smaller group
... then we have location, which is core
Thomas: agree that we need to work together
... Location is low hanging fruit already
Alex: Time establishes the format of what we are going to write
<matt> Core Draft
<danbri> matt can/should I bug sysreq for a poiwg repo? for testcases etc (and specs eventually...)
Alex: we might start with something circumspect
... location can get messy
Ronald: agree that location is pretty complex
Alex: begin with time
<matt> Time primitive
Alex: POI must--> can have a time primitive
... could be time when business is opened and closed
... that is relegated to metadata, not the primary function of POI
... time when this POI was created. This falls in provenance
... time that this thing came into existence.
... it's not obvious that every POI needs to come into existence and left
Thomas: if you say that something exists in this range of time, you are saying that we will move the user forward and backward in time
Alex: Google earth (KML) has a time stamp and time Span
<matt> KML Time primitive
Alex: Time Stamp says when and a date
... Time Span has a beginning and an end
... this is used in Google earth, to slide back in time to see content in past
... that's about the extent that we need to define
Thomas: suggestion that we have one more, ideally, time stamp of the last time the data was updated.
... it is useful for the client to know if they need to download it again or not
Expiration date
Thomas: it is a form of time which is useful
... Modification time
Ronald: might be better to put this in the metadata primitive
<matt> [[what about recurring time sets? (e.g. open hours) or relative times? (a store has open hours relative to the hours of the mall it is in)]]
Alex: this is where the conversation has gotten baroque
... lots of attributes you might want to stamp
... let's say some linked data has a date stamp
Thomas: technical level it is only necessity to have this type of time stamp in the linked data
Alex: how many links are we limiting a POI to?
Thomas: thinking it was One
... if it is more than one, it could be a time stamp per linked data
Alex: we ask for header, pull out o fheader, say no I don't want the data. Ct short the request, inspect the header
Thomas: COLLADA, X3D don't have those types of headers, may be wrong on that
Alex: is that our scope? to provide mechanism for lInk data to provide an expiration data
Ronald: don't think so. I'm not sure it is valuable. Adds too much complexity. In Layar we have.... to all the links (do they all need modification time stamp)
... in our concept they are all linked to the same POI
Thomas: i don't want clients to constantly update/download big files to see if it has been updated recently or not
Matt: HTML has this distinction
... it gets messy
We need a data modification
Ronald: in Layar definition, we have a single modificaation time and that it applies to all the data
Alex: concerned that utility might be limited. People might over-ride it. Head did not really capture what we wanted
Thomas: adamant that either it is possible to do this without time stamp, if it can't be done, it has to be there
... if not possible to do in header, it HAS to be in POI
... this could cause huge problems down the road.
Alex: that's a good argument for time modification time stamp, time span, time of applicability, could have a beginning and end
Matt: when this is being served over HTTP, these headers.... and any other transport mechanism must similarly
<danbri> (ok i've requested a poiwg repo for testcases etc to be added at ... time to read the Mercurial manual...)
Alex: if other POI query other links, they want to be able to send a time stamp to you to relect how recently the underlying digital object has been updated
<matt> matt: Basically, I think we should say "if you are transporting POIs over HTTP, you should be setting these X,Y, Z headers with the appropriate values. Other transport mechanisms should likewise provide such information."
matt: If I got a POI and it indicated that something has been changed, then it is my responsibility to go through and check each and to identify which elements have been updated
Alex: save the consumers of this data having to go through the subsegments and check this "manually"
Jacques: this is a basic feature of collaborative AR
Alex: can you please expand or give an example?
Jacques: for example, for guidance application, someone is outside, blind person, and you are looking in VR on a map, and you want to change some audio POI
... so you need to know when the audio POI can be changed
Alex: there's just me
Jacques: the expert is remote
the person in teh field
Jacques: you can change the content of a POI
Alex: there's a POI, and we want a way to indicate that the user (remote person changed the POI) that the content has changed
the browser needs to know that the content has changed
Alex: the POI has changed, how does the browser find out about it?
Thomas: this is a pull or push thing. This is web page expiration.
... if you are using a different protocol, it is not for us to decide which protocol i sused.
<JonathanJ> I think it seems like POI trigger, or POI pushing
Thomas: any additional downloads are the result, not the ....
Matt: the information about the delivery of the POI goes OUTSIDE of the POI itself
... It's in the envelope
Thomas: if can is virtual. and the person decides to move it. Change the POI location. It would not change the mesh of the can.
... So therefore the client would not be redownloading it, it would download the POI data but not the attached model
Ronald: we are talking aout the modificaiton time
Alex: we have the POI. The model has changed teh same. Location has been updated. Does the POI modification time change?
... the POI is in the local agent. Either I need to poll it or it needs to be pushed to me
Which?
Thomas: you don't need to transmit the update time
... just needs to communicate that the .... has been updated
Alex: look at a POI and knowing when it was updated sounds fine, but...
Thomas: The header may be a way to do this.
... the client may need to check to make sure if it has been updated
Alex: isn't that what happens already?
... in the web browser?
Thomas: the server gives recommendations about when to refresh
Martin: there are metatags
Alex: there's a big image, already local (cache) is it not pretty much the case that you have to tell the browser, hey that changed
... the image doesn't have meta, no header, we don't have a mechanism for that
... that's a problem, but it is not clear that it is our problem (yet)
<martinL> +1 for alex
Thomas: if it can't be done in the header, there's not another solution than to have it in the POI recommendation
Alex: reluctant to shoe horn this into the POI spec
Ronald: do we really want to have changeable mesh models
Thomas: most of these things will be fairly static. Meshes will probably be the same
... update time stamp is a simple solution
Alex: the problem is that it is a Macro, it is global to th POI, but not specific to what part of it changed, so it doesn't really solve the problem
Thomas; you need one orientation per link
Alex: no, I argue that you don't need that
... if there are multiple link, and oriented differently, but the base the frame of reference from which they are, that's what a single orientation accomplishes
... it sets down a frame of reference. It's not the billboarding
... it is that a single point in space... arbirtarily given is not adequate
<Luca> etag or any metatagit's better to understand i something has changed instead of timestamp that can't be unique for all the client
Alex: a discussion about time for POI, needs to be very specific. What is it about POI that need time?
... what is inherent to POI?
<Luca>
Alex: a time that this POI applies, whatever that means, that time period is really the need for the POI
... In agreement that we should at least have that one
... this is where have to decide what we do now. Do we hunt around for time specs?
Thomas: time span.... what time zone is it specified in?
<matt> XML Schema 2 time section
Thomas: do we need to explicitly tell the client the explicity time frame
<matt> KML time primitive
Alex: KML uses time stamp, they use datatypes Second edition
<ahill>
Alex: ISO 8601 convention
... this time stamp assumes UTC. If it is not, you can add + or - something
... that's a reasonable place to go
... does this spec have a beginning and end
... KML has that, is that a wrapper.
Matt: looking at XML schema spec
... they have lower level primitive
... no recurrence
Thomas: suggestion would be that if year is not included it repeats annually
... what about something that repeats weekly? where do you draw the line
Alex: Other people who have sat around tables, have addressed frequency.
<danbri> matt, could you do a quick followup to my sysreq mail saying "agreed - with staff contact hat on" or similar? in case it bounces due to need for officialrequestness
Thomas: what do you mean the time span to mean in terms of repetition
... we are illeminating the possibility of any recurrence?
Alex: no, I don't have a problem with idea of recurrence, but we don't need a time stamp
Thomas: do not specify a year or a day.
Alex: but I don't know it includes something like Friday
Ronald if you goes to GDAY. It is a Gregorian day that recurs
Dan: really wished that we have the use cases
... the use cases is approach that if a user wants
... can we get 5 POI in english
<matt> scribe: matt
danbri: Let's get some use cases
Thomas: 1. A hot dog stand that is occasionally there, but also has open/closed hours.
danbri: What else might you want to know? Health inspections? Kosher?
ahill: Yes, sure, let's throw it into our examples.
Thomas: 2. A historical church that used to exist and is now destroyed.
ahill: 3. A congregation that was at a church for a period of time. The physical building may have it's own POI, but the type of church might only be there for a period of time.
danbri: Maybe people are exploring their roots.
cperey: Maybe a timestamp around when a member of the congregation can be trusted or not.
Thomas: This might be linked data from the POI to the person, rather than inline.
ahill: Agree on that.
... Is a person a POI? It's really hard for me to make a good argument that people are not points of interest.
Ronald: If that cup of coffee is a POI and I'm not, I'll be offended!
[[general agreement]]
cperey: The congregant, the congregation and the space in which they all may be are all distinct.
ahill: In the last f2f the major concern about these things were that if we do this we'll have to describes everything and anything.
martinL: 4. Football stadium that is open on Mondays and sometimes Wednesdays.
Thomas: I think at some level of complexity it becomes a manual process.
<danbri> for recurring events, see
martinL: I wouldn't say we want to get too complex, but we then need to have multiple time elements.
Ronald: If we can multiple POI times then we're there.
cperey: What about a church that adds wings?
Thomas: I'd argue that's a different POI.
martinL: I think it should be one of the examples, you might have one POI with a time slider.
ahill: If I am driving down the street, I see the church, not the sub POIs, the altar, toilet, etc. I'm interested in the church, now and I'm sliding through time and these things become obvious and apparent.
<danbri> ronald, re calendar/rdf stuff also
<danbri> ...and microformat markup for events
Thomas: The specs for times seem pretty good.
ahill: We don't have the spec for it yet from us.
Ronald: If we're talking about existence then a single time span is sufficient. The other use cases where it's opening hours and things that change, then that's different.
cperey: Should it be in the spec?
ahill: In practical use for these things a time span is something you can include then if you don't include it it's right now and permanent.
... If you have one time span, then you could imagine that being a situation where you could see two of them.
... If two time spans get delivered with a POI, there's just two time spans, what would it break? There's not a parent/child relationship.
Thomas: So you'd treat them as an or relationship?
ahill: Talk of "will that hot dog stand be there?" is really about future things and not real time.
Thomas: Do we have a proposed format?
ahill: I think we can look at what's here and figure it out.
cperey: And then apply it to the use cases.
ahill: We're going to have a POI time, we've got a fundamental unit of time. It doesn't describe a duration.
... I think it just says a duration of two hours, rather than a start/end time.
... I think if the spec we looked at had a begin/end time then KML would have used it.
<danbri> re times, for content
[[caldav seems to have a time-range defined]]
cperey: We had a discussion about location changing over time. We talked about having locations good for specific durations.
... The side of the bus is only valid while it's moving through this geo location.
martinL: That would be a property animation?
Thomas: We talked about having an ad appear at this location.
-> W3C Schools (no relation) sample elements for a date range.
<JonathanJ> 1. present condition (periodical) 2. historical condition (duration), 3. acting condition (irregularity)
Ronald: I remember this discussion and don't remember the outcome. Do we store the entire history, or not?
ahill: I think we can say we don't store the history in the POI.
... KML breaks some of these apart too. Not necessarily embedded.
Thomas: Merely having a date span then you have the possibility of history through multiple POIs. Assign them to different dates with same location.
ahill: You can use a POI to do that, or not. Or you could have metadata to do it in one POI. You don't have to use it either way.
Thomas: Then you have to be very precise in the metadata itself. It becomes not metadata but data.
... The metadata should be describing the content, not the content.
<danbri> "The distinction between "data" and "metadata" is not an absolute one; it is a distinction created primarily by a particular application, and many times the same resource will be interpreted in both ways simultaneously."
Thomas: A building that has different shapes at different dates and times.
ahill: This strikes me as different representations.
Thomas: Not really.
<danbri>
<danbri> :)
ahill: The London Bridge is now in Arizona.
... If I remodel my house, it's still my house. Some people are not going to like the idea that it's a different POI.
... If POIs have URIs, then people are going to want to have a stable URI to describe the building.
... Your proposed solution does not solve everything.
Thomas: Yours would have multiple time stamps that seems more complex than new POIs.
matt: I think there are use cases for both. If you want a historical slider, you include multiple time stamps, and if you want a canonical representation of the house now, then you don't put in multiple timestamps.
ahill: Thomas you're also assuming that the model has to be tied to the POI. There could be a separation, could be from a different database, different metadata.
Thomas: They'd be different POIs then.
ahill: I think this is semantics.
danbri: What are we talking about?
ahill: There are two constituencies, one that wants historical and one that wants permanence.
Thomas: If you don't want the history then you could have it be on POI, but if you want history then you want multiple POIs.
<danbri> matt, good question
ahill: There was some convention for mutation of points.
martinL: Essentially we're talking about the visualization changes over time.
... We have the data and the visualizations are different.
Thomas: No. I see this as the same as CSS and HTML. DIfferent things sent to different clients based on specs or whatever criteria.
... If you've got data associated with it, that too is a piece of data.
... My instinct is different POIs with different time spans.
ahill: The spec will let both work.
Thomas: Then you have to be prepared to spec out multiple timespans. Is that ok?
ahill: Yes.
Ronald: Didn't we agree that the history is outside of the spec?
ahill: Yes, but we're using different history means here.
matt: We've been talking about these primitives as a building block that can be used in different ways.
ahill: So we've been saying that the POI might have a time and the location may have a time.
... It's a bit of a can of worms.
-> GML begin/end
<ahill>
ahill: If in the end we get something that's very close to GML, I think that's OK.
... This could be very similar to what we did with KHARML and KML. We had things we needed to add.
PROPOSED RESOLUTION: The world is complicated.
<JonathanJ> +1
+1
<danbri> oh, 'Profiling GML for RSS/Atom, RDF and Web developers' finally relevant ;)
-> GML subset tools
<scribe> scribe: Ronald
<danbri> discussing ... GML subset tool
ahill: we need to move on, but we also need to capture our discussion
... are the notes ok, or do we need to write the document
martin: we might be able to make focus groups to write it out
matt: we might not have to do it today, but I like the fact of teaming up people
martin: I volunteer for the timespan
thomas: I can help
<matt> ACTION: martinL to work on time spans with Thomas [recorded in]
<trackbot> Sorry, couldn't find user - martinL
<matt> ACTION: martin to work on time spans with Thomas [recorded in]
<trackbot> Created ACTION-43 - Work on time spans with Thomas [on Martin Lechner - due 2011-04-06].
ahill: I remember that someone said openstreetmap has a time definition as well
jacques: for opening hours for shopping centers, not XML, but in text
... it is very easy and compact
luca: we should prepare some use case to define the timestamp to check whether each language is good or not
... for example, for movie show times, we need to decide what is in scope or out of scope
ahill: talking to dan and we were looking into creating some examples in mercurial
<matt> ACTION: Alex to place some examples in mercurial [recorded in]
<trackbot> Created ACTION-44 - Place some examples in mercurial [on Alex Hill - due 2011-04-06].
luca: my question was because the discussion was very wide regarding the POI we can describe, but we should start with something easy to get started
... and maybe in the second draft add other use cases
<danbri> we have to start simple for starters, maybe with a bias towards re-using nearby related specs (like icalendar)
luca: this can be applied to any primitive. Just to move forward and make decisions
matt: thinking of creating an issue for time and spans
<matt> POI tracker
ronald: but are all the primitives issues?
matt: yes, we should be closing them one by one
<Luca> icalendar
<matt> some notes on time primitive
matt: where do we want to gather requirements for the time primitive?
<danbri> (re terminology: icalendar is the ietf data format spec; caldev is a web-dav based protocol for managing a calendar, ... and 'ical' used to be a nickname for it, until Apple named their icalendar-compatible app 'ical' too)
<JonathanJ> icalendar spec -
thomas: we also need to pick a name for the field. 'time' or 'timerange'
ahill: if anyone else already has a spec for time, what do we do with it. Reuse it directly, or renaming things and embed it in our spec?
thomas: we can include it. I don't think it is copyrighted
ahill: but things are namespaces. Are we ok to combining different kinds of namespaces?
<matt> trackbot, close action-3232
<trackbot> Sorry... closing ACTION-3232 failed, please let sysreq know about it
<matt> trackbot, close action-32
<trackbot> ACTION-32 Invite Henning after Matt has put ID requirements in the wiki closed
bertine: we need to be careful there is not any slight difference in meaning
thomas: we should not make something different, just to make something different
ahill: GML, KML refer to ISO for timestamps, but it is a more fundamental concept
... in KML, there is a time primitive, which is an abstract class of which timestamp and timespan extend
thomas: does their timespan combine two time primitives?
ahill: in their context not really
martin: what would be the desired outcome of a focus group
matt: for editorial stuff, I am going to be a gatekeeper
... we will propose text on the mailing list, and I will put it in the wiki
... please include the text ISSUE-7 in the subject or body of the message for tracking
martin: ISSUE-7 or ACTION-43
matt: there are multiple actions to an issue, so discussion on the issue without closing an action
thomas: are we ready to move to the next item
alex: let's talk about categories
<matt> Category Primitive
christine: we talked about categories before, and the general thinking was
cperey: IETF and ? have done a lot of work on documenting not just places of interest
... they have their own structure for categories
... governments and international bodies have their own category systems, hierarchical systems, beautiful systems
<ahill>
cperey: it is unlikely that we as an organization pick one system
... we are insufficient domain experts
... there are experts out there, but not at our table. Henning has not replied and does not seem interested
thomas: is category going to be a required field
ahill: no
... it is not required, but in most cases it is valueable
<matt> PROPOSED RESOLUTION: Category primitive is NOT required
ahill: I can imagine a character string "category", but it is not going to solve the problem. For example we might need to support multiple categories
... we might need to make our own category, and people can choose to ignore
cperey: but it is better to reuse existing category systems
thomas: it could just be a link
cperey: exactly
thomas: a POI needs to be able to have multiple categories and these categories should be URIs
<matt> PROPOSED RESOLUTION: Category primitive is NOT required. Category can be identified by a URI. POIs can have more than one category.
cperey: if we just specify it this way, we don't need to invite an expert to come talk to us... it is an implementation detail
ahill: at some stage we need to work out the meaning
<matt> Good Relations categories
thomas: there are also simple formatting issues, e.g. comma seperated list or multiple entries
ahill: how about an action item of finding an example of a system using different category systems
<danbri>
thomas: we should just focus on allowing linking, and not go into the meaning. that is up to the systems
<danbri> hot dog stand:
matt: can you walk me through the bestbuy example
<matt> [[<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML+RDFa 1.0//EN" ""><html xmlns=""
danbri: it is a particular store, if you view source and search for "property="
<matt> xmlns:rdfs=""
<matt> xmlns:dc=""
<matt> xmlns:xsd=""
<matt> xmlns:foaf=""
<matt> xmlns:gr=""
<matt> xmlns:geo=""
<matt> xmlns:v=""
danbri: you find lat lon, twitter account
<matt> xmlns:<head profile=""><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /]]
danbri: they also have it on products they sell
ahill: should we go to a product page
danbri: would not bother now, but we can expect that data to be on the web and there should be links from the POI information
<matt> [[<div class="column right"><div class="hours" rel="gr:hasOpeningHoursSpecification"><h3>Store Hours</h3><ul><li class="day0" typeof="gr:OpeningHoursSpecification" about="#storehours_sun"> <span rel="gr:hasOpeningHoursDayOfWeek" resource="" class="day">Sun</span>]]
ahill: I want to look at an implementation that uses categories
matt: I see they are using opening hours from the good relations
thomas: but we are not looking at opening hours yet from the time primitive
<ahill>
ahill: when I went here, the website shows a category, but in the source I can't see any link to categories
... I need an example. I have the feeling we need a dictionary or a schema to define what the category is and where it is in the category hierarchy
<matt> [[I suggest we install the RDFa bookmarklet and use that instead of view source: ]]
danbri: library classification schemes don't work that well as category scheme
... it is not really a thing in a category. it is a bit fuzzy
... it is thesaurus type stuff
... scos
<danbri>
<matt> Best Buy example
danbri: if the POI is art related, the category will be using skos
<JonathanJ> +1
<danbri>
danbri: if it is representing things, rdf uses different mechanics
<danbri>
<danbri>
<bertine>
<matt> scribe: matt
danbri: The resource itself is:
... But the page is
<scribe> scribe: Ronald
danbri: yaga is a organization on top of wikipedia
... is explaining dbpedia
thomas: is a broader term a parent type?
danbri: it is not really hierarchical
cperey: librarians have their own standardisation systems
<danbri>
<danbri>
<danbri> a smooth-textured sausage of minced beef or pork usually smoked; often served on a bread roll ('en' language string)
<matt> Linked Data Cloud diagram
<danbri>
danbri: most of the data sets are sturctured similarly
<danbri>
danbri: we don't need to choose
<danbri> try sindice.com
<danbri>
<cperey> NFAIS Standards
<cperey>
thomas: can I ask yahoo for green fruit. the linked data is not really used fully yet
<danbri>
ahill: until I feel that google is doing something other than proprietary mapping, I did not think the web is linked
matt: we are talking about categorization, right?
<matt> categorization primitive
thomas: there is potentially infinite categories, so using URIs seems a reasonable solution
<matt> Thread on cat primitive
<danbri> (you can probly use to define a query for green fruit)
thomas: do we need to create an action point to decide what form to use.
ahill: if someone else has figured out time, and someone else categories... do we add a wrapper around it or recommend to use these specs
... do we need a wrapper that says this is a POI
<matt> Karl's document on categories
ahill: is it some sort of key-value pair?
thomas: there needs to be an identifying string saying this is a POI
... it may be the nature of the transmission that assumes it is a POI, but it depends on how it is used
... if an AR browser gets information from a server, it can assume it is a POI, but if it is on the web, we need to know it is a POI
<matt> [[This category description does not replace existing industry classification models, rather it enables reference to such standards and local domain derivations from such standards as:...]] -- Karl's document
<danbri> proposal: "The WG agrees that integra
<danbri> tes existing deployed practice, as well as describing how to use Linked Data (skos, dbpedia etc.) for such tasks.
ahill: if all we end up with is a bunch of existing standards, do we need to invent something around it
thomas: do we need a version of it, or is it implicit?
<JonathanJ> +1
thomas: do we include the fact that a POI can have more than one category?
danbri: I see that as something implicit
cperey: does this mean that we do not need a core primitive?
<matt> PROPOSED practic
<matt> well as describing how to use Linked Data (skos, dbpedia etc.) for such tasks.
ahill: we may not need to have a structure
cperey: how do we decide it is expressed like that?
ahill: by convention
cperey: is there an action to decide what the convention is?
<danbri> I could write <dbpedia:HotDogStand ...
<matt> practice, as wel
<matt> describing how to use Linked Data (skos, dbpedia etc.) for such tasks.
matt: let's go back to an earlier resolution that I wrote a while ago
<matt> RESOLUTION: Category primitive is not required.
danbri: if a POI is a category, it is a boring category. so category is optional
<jacques> amenitie=stand cuisine=hotdog in OSM
<matt> Karl's doc
matt: let's look at the examples
... using URIs makes it easy to refer to categories from dbpedia
cperey: the proposal says one or more, but we just backed of and said none required
... we could have one... a useless one
danbri: that would be just "POI"
cperey: not sure what is the right way of treating it
martin: if you don't want to specify, you should be able to leave i | http://www.w3.org/2011/03/30-poiwg-minutes.html | CC-MAIN-2015-14 | en | refinedweb |
The purpose of an operating system is to multiplex shared resources between applications. Traditional operating systems have presented physical resources to applications by virtualisation, e.g. UNIX applications run in virtual time on a virtual processor - most are unaware of the passage of real time and that they often do not receive the CPU for prolonged periods. The operating system proffers the illusion that they are exclusive users of the machine.
Multimedia applications tend to be sensitive to the passage of real time. They need to know when they will have access to a shared resource and for how long. In the past, it has been considered sufficient to implement little more than access-control on physical resources. It is becoming increasingly important to account, schedule and police shared resources so as to provide some form of QoS guarantee.
Whilst it is necessary to provide the mechanisms for multiplexing resources, it is important that the amount of policy hard-wired into the operating system kernel is kept to an absolute minimum. That is, applications should be free to make use of system-provided resources in the manner which is most appropriate. At the highest level, a user may wish to impose a globally consistent policy, but in the Nemesis model this is the job of a QoS-Manager agent acting on the user's behalf and under the user's direction. This is analogous to the use of a window manager to allow the user to control the decoration, size and layout of windows on the screen, but which does not otherwise constrain the behaviour of each application.
Figure 1.1: The Structure of a Nemesis System
Nemesis was designed to provide QoS guarantees to applications. In
a microkernel environment, an application is typically implemented by
a number of processes, most of which are servers performing work on
behalf of more than one client. This leads to enormous difficulty in
accounting resource usage to the application. The guiding principle
in the design of Nemesis was to structure the system in such a way
that the vast majority of functionality comprising an application
could execute in a single process, or domain. As mentioned
previously, this leads to a vertically-structured operating
system (figure 1.1).
The Nemesis kernel consists of a scheduler (one version was less than 250 instructions) and a small amount of code known as the NTSC, used for Inter-Domain Communication (IDC) and to interact with the scheduler. The kernel also includes the minimum code necessary to initialise the processor immediately after booting and handle processor exceptions, memory faults, unaligned accesses, TLB misses and all other low-level processor features. The Nemesis kernel bears a striking resemblance to the original concept of an operating system kernel or nucleus expressed in [Brinch-Hansen 70].
The kernel demultiplexes hardware interrupts to the stage where a device specific first-level interrupt handler may be invoked. First-level interrupt handlers consist of small stubs which may be registered by device-drivers. These stubs are entered with all interrupts disabled and with the minimal number of registers saved and usually do little more than send notification to the appropriate device driver.
The term domain is used within Nemesis to refer to an executing program and can be thought of as analogous to a UNIX process - i.e. a domain encapsulates the execution state of a Nemesis application. Each domain has an associated scheduling domain (determining CPU time allocation) and protection domain (determining access rights to regions of the virtual address space).
Nemesis is a SAS operating system i.e. any accessible region of physical memory appears at the same virtual address in each protection domain. Access rights to a region of memory, however, need not be the same. The use of a single address space allows the use of pointers in shared data-structures and facilitates rich sharing of both program text and data leading to significant reduction in overall system size.
All operating system interfaces are written using an IDL known as
MIDDL which provides a platform and language independent
specification. Modules, with interfaces written in
MIDDL,
are used to support the single address space and allow operating
system code to be migrated into the application. These techniques are
discussed in detail in [Roscoe 95b].
Table 1.1: Alpha NTSC Call Interface.
The NTSC interface may be divided into two sections - those calls which may be invoked by any domain and those which may only be invoked by a privileged domain. Unprivileged calls are used for interaction with the kernel scheduler and to send events to other domains. Privileged calls are used to affect the processor mode and interrupt priority level and to register first-level interrupt stubs. As an example, table 1.1 lists the major NTSC calls for the Alpha architecture.
The NTSC interacts with domains and the kernel scheduler via a per-domain area of shared memory known as the DCB. Portions of the DCB are mapped read-write into the domain's address-space, whilst others are mapped read-only to prevent modification of privileged state. The read-only DCB contains scheduling and accounting information used by the kernel, the domain's privilege level, read-only data structures used for implementing IDC channels and miscellaneous other information. The read-write section of the DCB contains an array of processor-context save slots and user-writable portions of the IDC channel data structures.
Nemesis presents the processor to domains via the Virtual Processor Interface (VP.if). This interface specifies a platform independent abstraction for managing the saving and restoring of CPU context, losing and regaining the real processor and communicating with other domains. It does not however attempt to hide the multiplexing of the underlying processor(s). The virtual processor interface is implemented over the NTSC calls described in section 1.2.2.
When a domain is handed the processor, it is informed whether it is currently running on guaranteed time, or merely being offered use of some of the slack-time in the system. QoS-aware applications must take account of this before deciding to adapt to apparent changes in system load. This may be used to prevent QoS feedback mechanisms from reacting to transient improvements in resource availability.
When a virtual processor loses the CPU, its context must be saved. The DCB contains an array of context-save slots for this purpose. Two indices into this array specify the slots to use when in activation mode and when in normal mode, based on the current state of the activation flag.
When a domain is preempted it will usually be executing a user-level thread. The context of this thread is stored in the save slot of the DCB and may be reloaded by the activation handler of the domain when it is next upcalled. If a domain is preempted whilst in activation mode, the processor context is saved in the resume slot and restored transparently when the domain regains the CPU rather than the usual upcall.
The only means of communication directly provided by the Nemesis kernel is the event. Each domain has a number of channel-endpoints which may be used either to transmit or to receive events. A pair of endpoints may be connected by a third party known as the Binder, to provide an asynchronous simplex communications channel.
This channel may be used to transmit a single 64-bit value between two domains. The event mechanism was designed purely as a synchronisation mechanism for shared memory communication, although several simple protocols have been implemented which require nothing more than the event channel itself, e.g. the TAP protocol, described in [Black 94], used for start-of-day communication with the binder. Unlike message-passing systems such as Mach [Accetta 86] or Chorus [Rozier 90], the kernel is not involved in the transfer of bulk data between two domains.
Nemesis also separates the act of sending an event and that of losing the processor. Domains may exploit this feature to send a number of events before being preempted or voluntarily relinquishing the CPU. For bulk data transports such as the Rbufs mechanism, described in section 1.4.3, pipelined execution is usually desirable and the overheads of repeatedly blocking and unblocking a domain may be avoided. For more latency-sensitive client-server style communication a domain may choose to cause a reschedule immediately in order to give the server domain a chance to execute.
Various forms of IDC have been implemented on top of the Nemesis event mechanism. Some of the most commonly used are described below.
Since Nemesis domains share a single address space, the use of shared memory for communication is relatively straightforward. Data structures containing pointers are globally valid and the only further requirement is to provide some synchronisation mechanism to allow the data structure to be updated atomically and to prevent readers from seeing an inconsistent state. Very lightweight locking primitives may easily be built on top of the kernel-provided event mechanism.
Same-machine RPC [Birrell 84] is widely used within Nemesis. Although the majority of operating system functionality is implemented within the application, there are many out-of-band operations which require interaction with a server in order to update some shared state.
When a server wishes to offer a service to other domains, it locates an IDC transport module and requests a new offer (step 1 in figure 1.2) from it. It then places it into the Object Table of the server domain (2). The object table maintains a mapping between offers and interfaces.
Figure 1.2: Offering an RPC service
Before RPC can take place, the offer must be given to the client by the server. Typically, the server will place an offer into a traded namespace shared between all domains on the system and the client will retrieve it from there but it could just be passed directly.
When the client obtains the offer, it invokes a bind operation on the offer (step 3 in figure 1.2, step 1 in figure 1.3). This causes the offered IDC service to be added to the client domain's object table. A third party domain, the binder, then establishes the event channels necessary for invocations between the client and the server. The binder domain also causes the connection detailed to be looked up in to the object table of the server and thus the server side connection state to be established.
Figure 1.3: Binding to an RPC service
The default RPC transport is based on an area of shared memory and a pair of event channels between the client and server domains. To make an invocation (step 1 in figure 1.4), the client marshalls an identifier for the call and the invocation arguments into the shared memory (step 2) and sends an event to the server domain (step 3). The server domain receives the event, unmarshalls the arguments (step 4) and performs the required operation (step 5). The results of the call, or any exception raised are then marshalled into the shared memory (step 6) and an event sent back to the client (step 7). The client unmarshalls the result (step 8) and returns from the client stub. Marshalling code and the client and server stubs are generated automatically from the MIDDL interface definition and loaded as shared libraries.
Figure 1.4: Invoking an RPC service
The average cost of a user-thread to user-thread null-RPC between two
Nemesis domains, using the default machine-generated stubs and the
standard user-level threads package, was measured at just over
on the Sandpiper platform [Roscoe 95b].
It is worth noting that the above complexity is largely hidden by the use of standard macros. Typical code on the server side looks like:
ServerType server; IDC_EXPORT("svc>myservice", ServerType, server);
And, on the client side:
ServerType server; server = IDC_OPEN("svc>myservice", ServerType); result = Server$Method(server, args);
Figure 1.5: High Volume I/O Using Rbufs
The transport mechanism is once again implemented using Nemesis event-channels and shared memory. Three areas of shared memory are required as shown in figure 1.5. One contains the data to be transferred and the other two are used as FIFOs to transmit packet descriptors between the source and sink. The head and tail pointers of these FIFOs are communicated by Nemesis event-channels.
Packets comprised of one or more fragments in a large pool of shared memory are described by a sequence of (base, length) pairs known as iorecs. Figure 1.5a shows iorecs describing two packets, one with two fragments and the other with only a single fragment. Rbufs are highly suited to protocol processing operations since they allow simple addition or removal of both headers and trailers and facilitate segmentation and reassembly operations.
In receive mode, the sink sends iorecs describing empty buffer space to the source, which fills the buffers and updates the iorecs accordingly before returning them to the sink. In transmit mode, the situation is the converse. The closed loop nature of communication provides back-pressure and feedback to both ends of the connection when there is a disparity between the rates of progress of the source and sink.
The intended mode of operation relies on the ability to pipeline the processing of data in order to amortise the context-switch overheads across a large number of packets. Sending a packet on an Rbufs connection does not usually cause a domain to lose the CPU. Figure 1.6 shows the MIDDL interface type for the Rbufs transport.
Figure 1.6: MIDDL interface for Rbufs (IO.if)
Scheduling can be viewed as the process of multiplexing the CPU resource between computational tasks. The schedulable entity of an operating system often places constraints both on the scheduling algorithms which may be employed and the functionality provided to the application.
The recent gain in popularity of multi-threaded programming due to languages such as Modula-3 [Nelson 91] has led many operating system designers to provide kernel-level thread support mechanisms [Accetta 86, Rozier 90]. The kernel therefore schedules threads rather than processes. Whilst this reduces the functionality required in applications and usually results in more efficient processor context-switches, the necessary thread scheduling policy decisions must also be migrated into the kernel. As pointed out in [Barham 96], this is highly undesirable.
Attempts to allow applications to communicate thread scheduling policy to the kernel scheduler [Coulson 93, Coulson 95] lead to increased complexity of the kernel and the possibility for uncooperative applications to misrepresent their needs to the operating system and thereby gain an unfair share of system resources. For example, in the above systems user processes are required to communicate the earliest deadline of any of their threads to the kernel thread scheduler.
Nemesis allows domains to employ a split-level scheduling regime with the multiplexing mechanisms being implemented at a low level by the kernel and the application-specific policy decisions being taken at user-level within the application itself. Note that the operating system only multiplexes the CPU resource once. Most application domains make use of a threads package to control the internal distribution of CPU resource between a number of cooperating threads of execution.
Inter-process scheduling in Nemesis is performed by the kernel scheduler. This scheduler is responsible for controlling the exact proportions of bulk processor bandwidth allocated to each domain according to a set of QoS parameters in the DCB. Processor bandwidth requirements are specified using a tuple of the form (p, s, x, l) with the following meaning:
The p and s parameters may be used both to control the amount of processor bandwidth and the smoothness with which it is provided. The latency hint parameter is used to provide the scheduler with an idea as to how soon the domain should be rescheduled after unblocking.
The kernel scheduler interacts with the event mechanism allowing domains to block until they next receive an event, possibly with a timeout. When a domain blocks it loses any remaining CPU allocation for its current period - it is therefore in the best interest of a domain to complete as much work as possible before giving up the processor.
The current kernel scheduler employs a variant of the EDF algorithm
[Liu 73] where the deadlines are derived from the QoS
parameters of the domain and are purely internal to the scheduler.
The scheduler is capable of ensuring that all guarantees are respected
provided that
and is described in detail in [Roscoe 95b]. Despite the
internal use of deadlines, this scheduler avoids the inherent problems
of priority or deadline based scheduling mechanisms which focus on
determining who should be allocated the entire processor resource
and provide no means to control the quantity of resource handed out.
In order to provide fine-grained timeliness guarantees to applications which are latency sensitive, higher rates of context-switching are unavoidable. The effects of context-switches on cache and memory-system performance are analysed in [Mogul 91]. Mogul showed that a high rate of context switching leads to excessive numbers of cache and TLB misses reducing the performance of the entire system. The use of a single address space in Nemesis removes the need to flush a virtually addressed cache on a context switch and the process-ID fields present in most TLBs can be used to reduce the number of TLB entries which need to be invalidated. The increased sharing of both code and data in a SAS environment also helps to reduce the cache-related penalties of context-switches.
Intra-process scheduling in a multimedia environment is an entirely application-specific area. Nemesis does not have a concept of kernel threads for this reason. A domain may use a user-level scheduler to internally distribute the CPU time provided by the kernel scheduler using its own policies. The application specific code for determining which context to reload is implemented in the domain itself.
The activation mechanism described in section 1.3.1 provides a convenient method for implementing a preemptive user-level threads package. The current Nemesis distribution provides both preemptive and non-preemptive threads packages as shared library code.
The default thread schedulers provide lightweight user-level synchronisation primitives such as event counts and sequencers [Reed 79] and the mutexes and condition variables of SRC threads [Birrell 87]. The implementation of various sets of synchronisation primitives over the top of event counts and sequencers is discussed in [Black 94].
It is perfectly possible for a domain to use an application specific
threads package, or even to run without a user-level scheduler. A
user-level threads package based on the ANSAware/RT
[ANSA 95] concepts of Tasks and Entries
has been developed as part of the DCAN project at the Computer
Laboratory.
The ANSAware/RT model maps naturally onto
the Nemesis Virtual Processor interface.
Nemesis is a SAS operating system; i.e., translations from virtual to physical addresses are shared between all executing domains. This is in contrast to existing commercial operating systems such as Unix, VMS and Windows NT, where each executing process (or task) its own `personal' virtual address space.
The use of an SAS by an operating system gives a number of advantages:
Global translations do not in any way imply any lack of inter-domain protection: all domains execute in some protection domain which contains a set of access rights for any given page. Thus there is a clear seperation between the concepts of protection and of translation.
On a single machine in Nemesis, any process will `see' the same virtual address space, the only difference being the access rights that the process has on each part of the address space. The virtual address space is divided into pages, which are the smallest protectable component of the space.
The machine itself presents a Physical Address Space, which includes any physically addressable location in a machine's memory, not just RAM. The physical address space is divided into frames, which are the physical equivalents of pages. A frame typically contains the same number of bytes as a page.
Protection is in terms of sets of mappings of the virtual address space to the set of access rights. These mappings, known as protection domains, represent the protection environments in which domains execute.
The basic unit of allocation of virtual memory is the stretch, which is a contiguous region of the virtual address space, all of which has the same accessibility in any protection domain. This is similar to a region in Mach or Chorus, or even to a MS-DOS arena. It is not, however, to be confused with a Unix-style segment, which can shrink and grow at will -- a stretch corresponds to the same set of contiguous pages throughout its lifetime. Stretches are disjoint, i.e., they cannot overlap. One consequence is that stretches cannot be refined: if you have a stretch it doesn't make sense to talk to the VM system about a subset of the stretch.
A stretch must be associated with a stretch driver before it can be useful. A stretch by itself is merely an abstract object created by the stretch allocator; it has no meaning to the rest of the system. The stretch driver provides physical resources, page fault handling, or whatever, to the stretch, and sets up virtual to physical mappings by invoking the mapping systems. The stretch driver is a close analogue of what in System VR4 is called a segment driver, or what in Mach is called a memory object.
The translation system is a machine-specific component which enters, removes and updates both mapping and protection information for virtual addresses.
An outline of the components of the virtual memory system is shown in figure 1.7.
Figure 1.7: Virtual memory system components
Of key importance within Nemesis is the idea of accountability: every domain should perform whatever tasks are necessary for its own execution. In terms of the VM system, this means that a domain is responsible for satisfying any faults which occur on stretches which it owns. There is no concept of a ``system pager'', or of an ``application level pager'': instead, every domain is its own pager. The domain will typically invoke a stretch driver provided in an existing library, though it may use a private implementation if it desires.
In order to support such a mechanism, Nemesis extends guarantees to the allocation of physical memory. Every domain has a guaranteed number of physical frames which it is allowed. This is initially negotiated at domain creation time though may be renogiated at a later stage. A frame stack structure is shared between the frames allocator and the owning domain. The former keeps track of the number of frames which have been allocated, while the domain maintains their attributes (i.e. free, mapped, etc.).
On a page fault, the NTSC sends an event to the faulting domain. The next time the domain is activated, its driver for the stretch in question should resolve the fault. This may involve simply mapping one of its unmapped frames, or may involve paging out a resident page. The decision on which page to replace is totally under the control of the domain which hence may use whatever policy it prefers. In the case that resolution of the page fault may take significant time, the domain's user-level thread scheduler may decide to simply run another thread.
Temporal bounds on the actual paging operation are facilitated by the use of a user-safe disk (USD) [Barham 97]. Each domain owning a pageable stretch generally has a pre-established binding to the USD, owns certain extents (which it may use for paging) and holds a particular rate guarantee. Hence it is possible for the domain to predictably determine an upper bound to the amount of time required to load a given page from disk. This allows individual domains to make both disk layout and page replacement decisions which maximise either throughput or capacity as it sees fit.
A domain may also be allocated physical frames beyond the scope of its guarantee. These are known as optimistic frames and may, if necessary, be revoked by the frames allocator. Clearly revocation of a physical frame could have catastophic consequences for a domain, and hence a domain need be careful with what it maps into such frames.
Only low level I/O primitives are supported with the majority of
high-level data-path processing performed by the client using shared
libraries. The structure of a generic Nemesis device driver is shown
in figure 1.8. As can be seen from the diagram,
the functionality is implemented by two main
modules:
Figure 1.8: Nemesis Device Driver Architecture
The DDM is intended to contain the minimal functionality to provide secure user-level access to the hardware and support QoS guarantees to clients. The DDM serves three main purposes:
Application domains communicate with block- and packet-based device
drivers using an asynchronous shared-memory communications mechanism
known as RBufs [Black 94]. Each connection to the
driver has an independent queue and so the
QoS-crosstalk,
prevalent in FCFS queueing systems, is avoided.
Rbufs also provide effective low-latency feedback to
applications since clients are able to observe both the length of the
queue and the rate at which requests are being serviced and may use
this information to adapt their behaviour.
Out-of-band control of the translation, protection and multiplexing functions of the DDM is performed by a separate management entity known as the Device Control-Path Module (DCM). The DCM communicates with the multiplexing layer of the DDM in order to set up new connections and adjust the QoS-parameters associated with existing connections. The DCM is never involved with the in-band operations of the device driver.
The DCM uses high-level descriptions of access-permissions (e.g. meta-data for a file-system, or window placement in a window system), together with access-control policies to generate the low-level protection and translation information required by the DDM. These low-level permissions are often cached within the DDM's per-connection state records to reduce the number of interactions with the device manager. This cache provides conceptually similar functionality to the TLB of modern processors.
Device drivers typically require access to hardware registers which can not safely be made accessible directly to user-level code. This can be achieved by only mapping the registers into the address space of the device driver domain.
Some hardware registers are inherently shared between multiple device drivers, e.g. interrupt masks and bus control registers. The operating system must provide a mechanism for atomic updates to these registers. In kernel-based operating systems this has traditionally been performed by use of a system of interrupt-priority levels within the kernel. On most platforms, Nemesis provides similar functionality via privileged NTSC calls.
The majority of I/O devices have been designed with the implicit assumption that they can asynchronously send an interrupt to the operating system which will cause appropriate device-driver code to be scheduled immediately with absolute priority over all other tasks. Indeed, failure to promptly service interrupt requests from many devices can result in serious data loss. It is ironic that serial lines, the lowest bit-rate I/O devices on most workstations, often require the most timely processing of interrupts due to the minimal amounts of buffering and lack of flow-control mechanisms in the hardware. [Barham 96] describes how this phenomenon influences DMA arbitration logic on the Sandpiper.
More recently designed devices, particularly those intended for multimedia activities, are more tolerant to late servicing of interrupts since they usually have more internal buffering and are expected to cope with transient overload situations.
In order to effectively deal with both types of device, Nemesis allows drivers to register small sections of code known as interrupt-stubs to be executed immediately when a hardware interrupt is raised. These sections of code are entered with a minimal amount of saved context and with all interrupts disabled. They thus execute atomically. In the common case, an interrupt-stub will do little more than send an event to the associated driver causing it to be scheduled at a later date, but for devices which are highly latency sensitive it is possible to include enough code to prevent error conditions arising. The unblocking latency hint to the kernel scheduler is also useful for this purpose.
This technique of decoupling interrupt notification from interrupt servicing is similar to the scheme used in Multics which is described in [Reed 76], but the motivation in Nemesis is to allow effective control of the quantity of resources consumed by interrupt processing code, rather than for reasons of system structure. [Dixon 92] describes a situation where careful adjustment of the relative priorities of interrupt processing threads led to increased throughput under high loads when drivers were effectively polling the hardware and avoiding unnecessary interrupt overhead. The Nemesis mechanisms are more generic and have been shown to provide better throughput on the same hardware platform [Black 94].
The majority of device-driver code requires no privilege, but small
regions of device driver code often need to execute in kernel mode.
For example, performing I/O on a number of processors requires the use
of instructions only accessible within a privileged processor mode.
Nemesis provides a lightweight mechanism for duly authorised domains
to switch between kernel and user mode. | http://www.cl.cam.ac.uk/research/srg/netos/old-projects/pegasus/publications/overview/node3.html | CC-MAIN-2015-14 | en | refinedweb |
IETF Drops RFC For Cosmetic Carbon Copy 63
paulproteus writes "Say you have an email where you want to send an extra copy to someone without telling everyone. There's always been a field for that: BCC, or Blind Carbon Copy. But how often have you wanted to do the opposite: make everyone else think you sent a copy to somebody without actually having done so? Enter the new IETF-NG RFC: Cosmetic Carbon Copy, or CCC. Now you can conveniently email all of your friends (with a convenient exception or two...) with ease!"
This would actually be useful. (Score:2, Insightful)
Although it is an April Fool's...this would actually be useful. I can see a couple times where CCCing a Boss or someone else would get things done quicker.
I hate being a "tatle" but this would work to scare some people into action.
Re: (Score:2)
I'm curious as to how an actual implementation would be supposed to handle a Reply-All.
This is discussed in the "Security considerations" (Score:2)
If you're willing to break the CCC standard, you could mangle the "." in an email address. There are plenty of Unicode characters that look like a dot that aren't the real dot. That way, the reply-all to the CCC'd recipient would bounce.
Otherwise, well, um, see the Security considerations section.
Re: (Score:1, Redundant)
actually, the 'CCC standard' allows obfuscation of Ccc addresses when they get merged with CC. Option is left up to the implementation as obviously both have drawbacks. No obfuscation means reply all would show the CCCed person they were left out, obfuscation would allow the CCed person to know who was CCCed if they looked closely or hit reply all.
Re: (Score:2)
An easier way to fix this problem is to simply use the existing system, but with misspellings:
to: [email protected]
cc: [email protected], [email protected], [email protected], [email protected], [email protected]
Observant people will notice the mis-spelling, but most people won't and they'll think the Boss is watching, so they'd better get off their twinkie-fat ass and do some work.
Re: (Score:1)
Re: (Score:1, Funny)
Since when does a boss read e-mails anyway? In this case, CC and CCC would function the same.
Re: (Score:3, Insightful)
If you just want to trick people, I've found adding a:
CCd To: (addresses here)
in the message body accomplishes it well enough, it only fails if they actually think about it, which generally only happens if they already suspect you of being full of shit
:) Most people however (at least outside the geek world) are too oblivious to realize its just text in the message.
Re: (Score:3, Insightful)
I've been amazed lately by the number of regular e-mail users who take no notice of any headers at all. Anything in the Subject: line might as well not be there, and I keep getting replies from people to whom I've Cc:ed something saying, "Who did you send this to originally?"
There are are quite a few people out there to whom nothing but the message body exists.
Re: (Score:2, Funny)
Actually, it's the "CC" field. (Score:3, Funny)
Re:This would actually be useful. (Score:4, Insightful)
I have actually wanted this feature at times and wondered why there was no way in the MUA UI to do it. Not for keeping people out of the loop, but for resending emails that get bounced (say, misspelled email or delivery failure) or to recipients I forgot the first time.
Lets say that you are sending out a move invite to a number of friends. Just after you send it you notice that you forgot Alice. Now you need to send the invite just to her, but you prefer the email to look as the original so that she can see who else is invited. This is a common occurrence! And it would be very convenient if you could just bring up the email again, move everyone from To/Cc into Ccc, and then put her as the only CC.
Please explain to me again why this is presented as an Aprils fool, rather than a genuine feature?
Re: (Score:2)
Please explain to me again why this is presented as an Aprils fool, rather than a genuine feature?
Because functionally supporting this header has the exact same result as not functionally supporting the header. An RFC just puts it in the official header namespace, otherwise you could have always used X-Ccc:
Personally, I'd like support for multiple Dcc: headers: Disjoint Carbon Copies. I want to send the same message to multiple groups of addresses where I want those in one set to know they were all copied but want to hide that it was sent to the other group, and vice versa. Those in the To: header would)
Sounds more like you'd want to recall the original, and re-send the revision. With a CCC, the original group still doesn't know Alice is invited. With a recalled E-Mail, nobody is the wiser- except those who are quick to read the E-Mail, or don't have a "recall this E-Mail" aware client.
Re: (Score:2)
I am absolutely opposed to a feature that would allow people to alter email I have already received. I often use my email as an historic record of events, and would hate if I could not be sure that it is immutable.
Also, I'm pretty sure there is no standard for doing this across mail systems. To roll it out would require a major revamp of email as we know it today, since it requires some careful form of cross-realm authentication.
Re: (Score:2)
You could always use "Forward", which includes the original message along with the list of original recipients.
Re: (Score:2)
Which usually requires you to add an awkward "Hi, I forgot to send this to you" to not make the inline headers too confusing. Sure, this is what I do today, but it is less convenient than Ccc: would be, and exposes my mistake, which I'd rather avoid if I could.
Re: (Score:2)
when I was allowed to use thunderbird for email, it allowed me to open my sent messages, choose forward, then paste all the original recipients into the "Reply To:" box. Thus Alice can see the original email, and contacts, and dates, and no one got a second set of emails. If she chooses to "reply" then she will email the whole list back by default.
more honest...
Although I don't know the difference in "Reply to" and Follow up" to. Also doesn't matter I am stuck with Lotus notes now at work anyway.
(Or is "
Re: (Score:2)
Select forward, when asked for type of forward choose 'Redirect'. This works
Re: (Score:2)
Thanks for the tip. I didn't know about this (needs a plugin for thunderbird)
But I couldn't find a standard for redirected email, is there a rfc for this? Essentially it is like Ccc: + setting a custom from address. To me this really proves how this Aprils fools joke really isn't a joke. Rather, it would be nice with a standard for headers that covers this functionality.)
It'll be interesting to see if management abandons the policy of plunking Flash cookies [wikipedia.org] on our computers when a new day comes. Every click on a discussion sets another one. Let's hope today was not just a convenient way to sneak them in from now on.
Please, Slashdot, drop the Flash cookies when the joke is over.
Useful (Score:2)
Enough April Fool's Already. (Score:5, Interesting)
Re: (Score:2)
With most sites cought in self-imposed circlejerk of 1 IV stories, I can imagine that...no, there's actually not that much to report
:/
(though that wouldn't excuse Slashdot, it being usually late with anything...except for the fraking April Fool's, apparently...sigh))
Do you seriously mean to tell me that there are no important tech stories taking place today?
Do you seriously mean to tell me that there could be any actually important stories taking place today?
Perhaps you aren't familiar with the concept of April Fool's and more importantly, how people AVOID making announcements on this day to avoid confusion.
Re: (Score:2)
iirc, gmail was initially announced around this time of year and people weren't exactly sure if it was a joke or not... but that only helped with the initial publicity.
but personally, i can't wait until the big joke on april 1st is to do no joke at all.
Re: (Score:2)
I laughed. But I am not entirely full of hate.
There's fortunately a religious holiday of some sort these days, so outside gang-rapes and train derails, there aren't any serious news worth reporting on. Look back a little, and you'll agree this is better than the year of OMGPONIES
;)
Re:Enough April Fool's Already. (Score:4, Funny)
Just wait
...
You're going to see a post from an unexpected new slashdot mod
... his/her post will be something like:
I couldn't take it anymore. I've killed them all. Slashdot will now be closed because I had to save the world from them. I'm going to turn myself in now, you're all welcome.
To which I suggest we all respond with donations to their legal fund.
Re: (Score:1)
Jokes are funny. This is just painfully stupid. One day out of the year for funny stories would be awesome. One day out of the year for boring lies... eh. I could do without.
Re: (Score:2)
Do you seriously mean to tell me that there are no important tech stories taking place today?
No, I think they mean to tell you that none of the tech articles were ever all that important, and thus could wait a day.
Seriously, if you're life hangs on Slashdot, well, that's just sad.
10CC (Score:2)
Re: (Score:2)
Re: (Score:2)
Do you understand what it does? It DOESN'T CC the person but makes it look like you did.
This could actually be more useful than a BCC. Instead of BCCing my boss on an email I'm sending to a Co-worker telling him to get his work done, possibly upsetting my boss with bothering him with trivial stuff to have him review the other person, I could CCC my boss, and so my boss is left ouf of it entirely but the co-worker believes I've told him to get to work and the boss knows.
Anti-CC )
Greetings and Salutations....
I fully support this concept, and, would go on to require that it be the DEFAULT for all mail messages that are addressed to more than one or two people at a time.
Since a vast majority of the multiple-receiver emails I get are mindless twaddle, this would go a long way towards cutting the excess loads on the InterTubes.
Regards
Dave Mundt
Thank God for Chrome (Score:1)
Re: (Score:1)
Furthermore you can keep touching yourself without anyone else looking at you. Definitely not bad.
not required already possible with RFC822 (Score:1, Interesting)
Re: (Score:1)
You can already do this.. (Score:3, Interesting)
Envelope headers are different than actual recipients. Mail clients don't implement it, but there's nothing in the SMTP protocol preventing you from putting a Cc: header in your message with a list of names/email addresses, but not actually delivering the messages. It's just a matter of a mail client offering this functionality. For now, you'll have to telnet into port 25
;) | http://tech.slashdot.org/story/10/04/01/156206/IETF-Drops-RFC-For-Cosmetic-Carbon-Copy | CC-MAIN-2015-14 | en | refinedweb |
This article demonstrates what LINQ to SQL is and how to use its basic functionality. I found this new feature amazing because it really simplifies a developer's debugging work and offers many new ways of coding applications.
For this article, I have used the Northwind database sample from Microsoft. The database is included in the ZIP file or can be found on the Microsoft website.
The LINQ Project is a codename for a set of extensions to the .NET Framework that encompasses language-integrated query, set and transform operations. It extends C# and Visual Basic with native language syntax for queries. It also provides class libraries to take advantage of these capabilities. For more general details, refer to the Microsoft LINQ Project page.
LINQ to SQL is a new system which allows you to easily map tables, views and stored procedures from your SQL server. Moreover, LINQ to SQL helps developers in mapping and requesting a database with its simple and SQL-like language. It is not the ADO.NET replacement, but more an extension that provides new features.
In this section I'll show you how to use LINQ to SQL from the start, at project creation.
The Object Relational Designer is a design surface that maps a database table into a C# class. To do that, just drag and drop tables from the database explorer into the designer. The designer automatically displays the tables in a UML way and represents the relationship between them. For example, I have dragged and dropped the four tables Customers, Order, Order_Detail and Product, as shown below:
In NorthwindDataClasses.designer.cs (under NorthwindDataClasses.dbml from the project explorer), you will find definitions for all classes corresponding to tables like this:
;
private EntitySet<Order> _Orders;
//..............
}
dataContext is a class that gives direct access to C# classes, database connections, etc. This class is generated when the designer is saved. For a file named NorthwindDataClasses.dbml, the class NorthwindDataClassesDataContext is automatically generated. It contains the definition of tables and stored procedures.
dataContext
NorthwindDataClassesDataContext
This keyword is used when you do not know the type of the variable. Visual Studio 2008 automatically chooses the appropriate type of data and so does IntelliSense!
var anInteger = 5;
var aString = "a string";
var unknown_type = new MyClass();
Once the database is modeled through the designer, it can easily be used to make queries.
//creating the datacontext instance
NorthwindDataClassesDataContext dc = new NorthwindDataClassesDataContext();
//Sample 1 : query all customers
var customers =
from c in dc.Customers
select c;
//display query result in a dataGridView
dataGridResult.DataSource = customers.ToList();
//Sample 2 : query customers which country is UK
//constructing the query
var customers_from_uk =
from c in dc.Customers
where c.Country == "UK"
select c;
Use a very simple class definition.
public class CMyClassTwoStrings
{
public CMyClassTwoStrings(string name, string country)
{
m_name = name;
m_country = country;
}
public string m_name;
public string m_country;
}
For example:
//Sample 4a : query customers(name and country) which contact name starts with a 'A'
//using specific class
var customers_name_starts_a_2col_in_specific_class =
from c in dc.Customers
where c.ContactName.StartsWith("A")
select new CMyClassTwoStrings (c.ContactName, c.Country );
//using the returned collection (using foreach in
//console output to really see the differences with the dataGridView way.)
foreach (CMyClassTwoStrings a in customers_name_starts_a_2col_in_specific_class)
Console.WriteLine(a.m_name + " " + a.m_country);
//Sample 4b : query customers(name and country) which contact name starts with a 'A'
//using anonymous class
var customers_name_starts_a_2col_in_anonymous_class =
from c in dc.Customers
where c.ContactName.StartsWith("A")
select new {
Name = c.ContactName, //naming the column Name
Country = c.Country //naming the column Country
};
foreach (var a in customers_name_starts_a_2col_in_anonymous_class)
Console.WriteLine(a.Name + " " + a.Country);
This example demonstrates how to use an anonymous class that is (in this example) composed of two strings. The aim of this feature is to create a new class for temporary storage that the developer does not want (or need) to declare. It may be useful in some cases where the declaration of class is used only for storage.
For example, in the sample 4a, the class CMyClassTwoStrings is used only to create the interface between the query engine and the output in the console. It is not used anywhere else and is a loss of time. This new way of writing enables the developer to create temporary classes with an unlimited number of attributes of any type. Every attribute is named, either by specifying the name with Name = c.ContactName or by leaving the attribute without, i.e. Name =. IntelliSense also works with anonymous classes!
CMyClassTwoStrings
Name = c.ContactName
Name =
//Sample 5 : query customers and products
//(it makes a cross product it do not represent anything else than a query
var customers_and_product =
from c in dc.Customers
from p in dc.Products
where c.ContactName.StartsWith("A") && p.ProductName.StartsWith("P")
select new { Name = c.ContactName, Product = p.ProductName };
The resulting collection is the cross product between all contact names starting with "A" and all products starting with "P."
//Sample 6 : query customers and orders
var customers_and_orders =
from c in dc.Customers
from p in dc.Orders
where c.CustomerID == p.CustomerID
select new { c.ContactName, p.OrderID};
This example demonstrates how to specify the relation between tables' joins on an attribute.
//Sample 7 : query customers and orders with entityref
var customers_and_orders_entityref =
from or in dc.Orders
select new {
Name = or.Customer.ContactName,
OrderId = or.OrderID,
OrderDate = or.OrderDate
};
In this example, the entityref property is used. The class orders have an attribute named Customer that refers to the customer who realizes the order. It is just a pointer to one instance of the class Customer. This attribute gives us direct access to customer properties. The advantage of this feature is that the developer does not need to know exactly how tables are joined and access to attached data is immediate.
entityref
Customer
As you may want to execute SQL that is not yet supported by LINQ to SQL, a way to execute SQL queries in the old way is available.
//Sample 8 : execute SQL queries
dc.ExecuteCommand("UPDATE Customers SET PostalCode='05024' where CustomerId='ALFKI' ");
LINQ to SQL provides a new way of managing data into database. The three SQL statements INSERT, DELETE and UPDATE are implemented, but using them is not visible.
INSERT
DELETE
UPDATE
//Sample 9 : updating data
var customers_in_paris =
from c in dc.Customers
where c.City.StartsWith("Paris")
select c;
foreach (var cust in customers_in_paris)
cust.City = "PARIS";
//modification to database are applied when SubmitChanges is called.
dc.SubmitChanges();
To make modifications to a database, just modify any relevant object properties and call the method SubmitChanges().
SubmitChanges()
To insert a new entry into the database, you just have to create an instance of a C# class and Attach it to the associated table.
Attach
//Sample 10 : inserting data
Product newProduct = new Product();
newProduct.ProductName = "RC helicopter";
dc.Products.InsertOnSubmit(newProduct);
dc.SubmitChanges();
Deleting data is quite easy. When requesting your database, give a collection of data. Then just call DeleteOnSubmit (or DeleteAllOnSubmit) to delete the specified items.
DeleteOnSubmit
DeleteAllOnSubmit
//Sample 11 : deleting data
var products_to_delete =
from p in dc.Products
where p.ProductName.Contains("helicopter")
select p;
dc.Products.DeleteAllOnSubmit(products_to_delete);
dc.SubmitChanges();
IntelliSense works into the query definition and can increase developer productivity. It's very interesting because it pops up on DataContext, tables and attributes. In this first example, IntelliSense shows the list of tables mapped from the database, the connection instance and a lot of other properties.
DataContext
For a table, the list contains all of its columns:
For an attribute, it will display methods and properties depending on the type (string, integer, etc).
To use LINQ to SQL, a developer must know exactly when a query is executed. Indeed, LINQ to SQL is very powerful because the query is executed when it's required, but not at definition! In the first sample, we have this code:
///constructing the query
var customers =
from c in dc.Customers
select c;
The query is not yet executed; it is just compiled and analysed. In fact, the query is run when the code makes an access to the customer variable, like here:
//display query result in a dataGridView
dataGridResult.DataSource = customers.ToList();
LINQ to SQL supports deferred loading options. This functionality allows a user to modify query engine behaviour when retrieving data. One of them is the deferred loading that will load all the data of a query. As an example, a query on the Order table gives you entry to the customer properties by entityref. If Datacontext.DeferredLoadingEnabled is set at true (default) then the Customer attribute will be loaded when an access to the Order entry is made. Otherwise (when at false), it is not loaded. This option helps a developer when optimizing requests, data size and time for querying. There is a good example about that here.
Datacontext.DeferredLoadingEnabled
true
false
When the function SubmitChanges() is executed, it starts by verifying if there is no conflict that occurs by an external modification. For a server/client application, the application must take conflicts into account in case multiple clients access the database at the same time. To implement conflict resolution, SubmitChanges() generates a System.Data.LINQ.ChangeConflictException exception. The DataContext instance gives details about conflicts to know why exactly they throw. I wrote a basic conflict resolution, but I will not give the full details of all other possibilities because I think it should be an entire article.
System.Data.LINQ.ChangeConflictException
try{
//query the database
var customers_in_paris_conflict =
from c in dc.Customers
where c.City.StartsWith("Paris")
select c;
foreach (var cust in customers_in_paris_conflict)
cust.City = "PARIS";
//Make a breakpoint here and modify one customer entry
//(where City is Paris) manually (with VS for example)
//When external update is done, go on and SubmitChanges should throw.
dc.SubmitChanges();
}
catch (System.Data.LINQ.ChangeConflictException)
{
//dc.ChangeConflicts contains the list of all conflicts
foreach (ObjectChangeConflict prob in dc.ChangeConflicts)
{
//there are many ways in resolving conflicts,
//see the RefreshMode enumeration for details
prob.Resolve(RefreshMode.KeepChanges);
}
}
If you want more details about conflict resolution, I suggest you to refer to this page (in VB).
As a conclusion to this article, I summarize the important points of LINQ to. | http://www.codeproject.com/Articles/22000/LINQ-to-SQL?fid=928498&df=90&mpp=10&sort=Position&spc=None&tid=2901284 | CC-MAIN-2015-14 | en | refinedweb |
class print_command:public cCmdScript("print_command")
std::vector<cCmdScript> m_scripttable;
cCmdLoader::m_scripttable.emplace_back(this);
bool haschildand
int numchildneed to be static.
cCmdLoader::m_scripttable.push_back(this)
#include <string>not
#include "string.h"
static std::vector<scriptptr> m_scripttable;
<>and
""in an include statement. The convention is that you use
<>for including standard/third-party header files, and
""for your own header files.
.h(or sometimes
.hpp) extension. Basically, standard library headers don't, and all others (including ones you've written) do.
static std::vector<scriptptr> m_scripttable;
std::vector<cCmdLoader::scriptptr> cCmdLoader::m_scripttable;
class {};block, you'll need to explicitly qualify both the name of the variable, and the scriptptr type, with the name of the class they belong to. | http://www.cplusplus.com/forum/beginner/125423/ | CC-MAIN-2015-14 | en | refinedweb |
doublerather than
inthere. Not only will that allow the input and output of decimal values, it also reduces rounding errors.
intI now use
double, along with writing the code so that if the user inputs 0 for the degrees in Celsius, the program will quit, and I believe making the buffer clear in every iteration of the loop. Updated code is below.
system("ls");
#include <iostream>, and then had to spend 20 minutes trying to figure out why cout and cin didn't work. This is merely the first program i've made that did something remotely useful. Also, I don't have a Unix system, just Windows 7. Don't know how much that actually changes anything in relation to programming. | http://www.cplusplus.com/forum/beginner/93858/ | CC-MAIN-2015-14 | en | refinedweb |
How to allow multi-line in TextBox or TextBlock in Silverlight 5
I recently needed a multi-line TextBox box in a Silverlight 5 application. I looked at the RichTextEdit Control but it was too much for what I needed. It turns out that the TextBox control supports multi-line display and entry of text but there are a few things you need to know.
The basic TextBlock & TextBox controls with TextWrapping=”Wrap” supporting multi-line but it doesn’t support entry of “Return”.
<TextBox TextWrapping="Wrap" Text="{Binding Note}" />
<TextBlock TextWrapping="Wrap" Text="{Binding Note}" />
Tip: Silverlight TextBox Uses \r For New Lines, not Environment.NewLine
Silverlight has a really unusual way of handling text, and “Returns” in general. You have to specify AcceptsReturn=True to allow the user to enter return but instead of using System.Newline which consists of a return and newline special character (aka \r\n ) it uses only \r . This can cause problems if your data needs to be normalized for other systems.
How can you solve the quirky behavior? One solution is to write a normalization method like below to replace \r with \r\n. I adapted this code from an example here.
using System;
using System.Text.RegularExpressions;
namespace PHPAdmin {
public static class StringExtensions {
public static string NormalizeNewLines (this string value)
{
if( value == null ) return value;
return Regex.Replace( value, @"\r(?!\n)|(?<!\r)\n", Environment.NewLine );
}
}
After writing the normalize routine you can callNormalizeNewLines
like below:
private void Button_Click_1( object sender, RoutedEventArgs e ) {
txtInput.Text = txtInput.Text.NormalizeNewLines();
}
How to allow multi-line in TextBox or TextBlock in Silverlight 5
So if you need to accept multi-line input from a TextBox in Silverlight be sure to normalize the input as the data may not be in the format you expect. There is a bug listed on Microsoft Connect indicating this behavior is by design. | http://www.displacedguy.com/tech/how-to-wrap-text-in-silverlight-textbox-control/ | CC-MAIN-2015-14 | en | refinedweb |
fn:resolve-QName( qname as xs:string?, element as element() ) as xs:QName?
Returns.
Sometimes the requirement is to construct an
xs:QName
without using the default namespace. This can be achieved by writing:
if ( fn:contains($qname, ":") ) then ( fn:resolve-QName($qname, $element) ) else ( fn:QName("", $qname) )
If the requirement is to construct an
xs:QName using the
namespaces in the static context, then the
xs:QName
constructor should be used.
If $qname does not have the correct lexical form for
xs:QName
an error is raised [err:FOCA0002].
If $qname is the empty sequence, returns the empty sequence.
More specifically, the function searches the namespace bindings of $element for a binding whose name matches the prefix of $qname, or the zero-length string if it has no prefix, and constructs an expanded QName whose local name is taken from the supplied $qname, and whose namespace URI is taken from the string value of the namespace binding.
If the $qname has a prefix and if there is no namespace binding for $element that matches this prefix, then an error is raised [err:FONS0004]. discussed in Section 2.1 Terminology[DM].
Assume that the element bound to $element has a single namespace binding bound to the prefix "eg". fn:resolve-QName("hello", $element) => a QName with local name "hello" that is in no namespace. fn:resolve-QName("eg:myFunc", $element) => an xs:QName whose namespace URI is specified by the namespace binding corresponding to the prefix "eg" and whose local name is "myFunc".
Stack Overflow: Get the most useful answers to questions from the MarkLogic community, or ask your own question. | https://docs.marklogic.com/fn:resolve-QName | CC-MAIN-2022-27 | en | refinedweb |
Introduction to Space Complexity
Introduction
You may have at various points heard about Space Complexity in discussions related to the analysis of multiple algorithms. This is an essential topic for interview preparations and for building a better understanding of various algorithms. This article will help you understand the importance of considering Space Complexity when designing or learning a new algorithm.
What is Space Complexity?
Space Complexity is the measure of memory consumed by a program to operate on the input of a given size. Hence, Space complexity is essentially the sum of Auxillary Memory used and the memory used by input. However, this definition isn’t popularly used for comparing algorithms; otherwise, the space complexity of bubble sort and merge sort would be the same as O(n).
This is why it’s best to say that certain algorithms like bubble sort requires O(1) extra memory, and merge sort require O(n) extra memory when the discussion is about the complexity analysis of algorithms.
Discussion and examples
1. Consider the code given below -
#include <bits/stdc++.h> using namespace std; int32_t main(){ int a = 1, b = 2; int prod = a * b; cout << prod << endl; return 0; }
Space Complexity: O(1)
Explanation:
We create 3 variables in the above program and print them. The exact memory consumed by this program will be (assuming int = 4 bytes, it can be 2 bytes in some old 16-bit computers) will be equal to 3 * 4 = 12 bytes.
2. Consider the code given below -
#include <bits/stdc++.h> using namespace std; int32_t main(){ int n = 10; int a[n]; for(int i = 0; i < n; i++){ // the loop will run 5 times a[i] = i; } return 0; }
Space Complexity: O(n)
Explanation:
We create an array of integers “a” of size n. In addition to this, we create two variables, “i” and “n”, contributing 4 bytes each, and there’s also “a” that’s a pointer to the initial element of the array, consuming 4 bytes. In total, we get 4 * n + 12 bytes. The 12 byte part, however, is just a constant, and thus, the memory being consumed by the above program can be said to be O(n) in terms of big-O notation.
3. Consider the code given below -
#include <bits/stdc++.h> using namespace std; int stack_memory(int n){ if(n == 1) return 1; return n + stack_memory(n / 2); } int32_t main(){ int n = 10; cout << stack_memory(n) << endl; return 0; }
Space Complexity: O(log2(n))
Explanation:
This is a slightly different case. In this case, because of recursion, the previous states have to be stored onto the stack memory at every call of the function stack_memory(). The function has to be called floor(log2(n))+1 times in total. Hence, we are storing the floor(log2(n))+1 states onto the stack, rest of the other memory being consumed due to other temporary variables is a constant and therefore, the space complexity is O(log2(n)). As shown below, the same code can be implemented with a while loop with O(1) space complexity.
#include <bits/stdc++.h> using namespace std; int32_t main(){ int n = 10; int ans = 1; while(n != 1){ ans += n; n /= 2; } cout << ans << endl; }
Recursion also does the same task with the same result. However, the iterative approach doesn’t consume extra space of O(log2(n)). There is also a catch here in the case of tail recursion; when recursive functions don’t store previous calls on to the stack memory, refer here for more about tail recursion.
FAQs
- List an example where increasing the Space complexity led to improvements in time complexity.
A famous example for this case is merge sort that consumes O(n) memory and O(n * log(n)) time, while bubble sort takes O(1) memory, but you have to instead pay in the form O(n2) time. This tradeoff allows a significant boost from an O(n2) time algorithm to an O(n * log(n)) time algorithm. There are an almost infinite number of such cases, for example, all dynamic programming algorithms.
- What is Auxillary Memory?
Auxiliary memory refers to the cheap, slow and large memory units such as HDDs in our computer. Most of the information related to a program is stored for long term storage when not being used.
- If a recursive approach is always slower and consumes memory, should one ever use it?
The recursive method is often slower and consumes stack memory on each consecutive function call compared to an iterative approach. It shines when you need to code faster and write smaller functions that are less prone to bugs, such as the case with a tower of Hanoi problem that would otherwise be difficult to solve without recursion. This may be your need in a contest with limited time. For example, sometimes, it’s straightforward to code a dynamic programming problem using recursion with fewer missed edge cases.
- What is stack memory?
It’s a memory usage method that allows accessing and storing memory chunks temporarily in a last-in-first-out manner, i.e., one can access the last inserted chunk of data first.
- What is Tail Recursion?
Tail recursion occurs when the last line to be executed in a function is the same function call itself. In such a case, there is no need to store the previous states of the functions, and as such, no extra stack memory is consumed (all this is taken care of by the compiler). Euclidean’s GCD algorithm’s recursive function code is an excellent example of tail recursion.
Key Takeaways
This article covers the basics of space complexity and discusses its importance and necessary tradeoffs between space and time complexity to achieve an algorithm for our needs. To understand the blog better, refer to the content here about time complexity analysis, and refer here for a quick revision on asymptotic notations.
Learn more about the C++ STL library from here if you have trouble understanding some part of the code. Visit the link here for carefully crafted courses on campus placement and interview preparation on coding ninjas.
Happy learning! | https://www.codingninjas.com/codestudio/library/introduction-to-space-complexity | CC-MAIN-2022-27 | en | refinedweb |
CI Status:
Welcome to Exiv2Welcome to Exiv2
Exiv2 is a C++ library and a command-line utility to read, write, delete and modify Exif, IPTC, XMP and ICC image metadata.
The file ReadMe.txt in a build bundle describes how to install the library on the platform. ReadMe.txt also documents how to compile and link code on the platform.
TABLE OF CONTENTSTABLE
- Thread Safety
- Library Initialisation and Cleanup
- Cross Platform Build and Test on Linux for MinGW
- Building with C++11 and other compilers
- Static and Shared Libraries
- Support for bmff files (CR3, HEIF, HEIC, and AVIF)
- License and Support
- Test Suite
- Platform Notes
2 Building, Installing, Using and Uninstalling Exiv22 Building, Installing, Using and Uninstalling Exiv2
You need CMake to configure the Exiv2 project and the GCC or Clang compiler and associated tool chain.
2.1 Build, Install, Use Exiv2 on a UNIX-like system2.1 Build, Install, Use Exiv2 on a UNIX-like system
$ cd ~/gnu/github/exiv2 # location of the project code $ mkdir build && cd build $ cmake .. -DCMAKE_BUILD_TYPE=Release $ cmake --build . $ make tests $ sudo make install
This will install the library into the "standard locations". The library will be installed in
/usr/local/lib, executables (including the exiv2 command-line program) in
/usr/local/bin/ and header files in
/usr/local/include/exiv2
cmake generates files in the build directory. cmake generates the project/solution/makefiles required to build the exiv2 library and sample applications. cmake also creates the files exv_conf.h and exiv2lib_export which contain compiler directives about the build options you have chosen and the availability of libraries on your machine.
Using the exiv2 command-line programUsing the exiv2 command-line program
To execute the exiv2 command line program, you should update your path to search /usr/local/bin/
$ export PATH="/usr/local/bin:$PATH"
You will also need to locate libexiv2 at run time:
$ export LD_LIBRARY_PATH="/usr/local/lib:$LD_LIBRARY_PATH" # Linux, Cygwin, MinGW/msys2 $ export DYLD_LIBRARY_PATH="/usr/local/lib:$DYLD_LIBRARY_PATH" # macOS
UninstallUninstall
I don't know why anybody would uninstall Exiv2.
$ cd ~/gnu/github/exiv2 # location of the project code $ cd build $ sudo make uninstall
These commands will remove the exiv2 executables, library, header files and man page from the standard locations.
2.2 Build and Install Exiv2 with Visual Studio2.2 Build and Install Exiv2 with Visual Studio
We recommend that you use conan to download the Exiv2 external dependencies on Windows. On other platforms (maxOS, Ubuntu and others), you should use the platform package manger. These are discussed: Platform Notes The options to configure and compile the project using Visual Studio are similar to UNIX like systems. See README-CONAN for more information about Conan.
When you build, you may install with the following command.
> cmake --build . --target install
This will create and copy the exiv2 build artefacts to C:\Program Files (x86)\exiv2. You should modify your path to include C:\Program Files (x86)\exiv2\bin.
2.3 Build options2.3 Build options
There are two groups of CMake options. There are many options defined by CMake. Here are some particularly useful options:
Options defined by /CMakeLists.txt include:
576 rmills@rmillsmm:~/gnu/github/exiv2/exiv2 $ grep ^option CMakeLists.txt option( BUILD_SHARED_LIBS "Build exiv2lib as a shared library" ON ) option( EXIV2_ENABLE_XMP "Build with XMP metadata support" ON ) option( EXIV2_ENABLE_EXTERNAL_XMP "Use external version of XMP" OFF ) option( EXIV2_ENABLE_PNG "Build with png support (requires libz)" ON ) ... option( EXIV2_ENABLE_BMFF "Build with BMFF support" ON ) 577 rmills@rmillsmm:~/gnu/github/exiv2/exiv2 $
Options are defined on the CMake command-line:
$ cmake -DBUILD_SHARED_LIBS=On -DEXIV2_ENABLE_NLS=Off
2.4 Dependencies2.4 Dependencies
The following Exiv2 features require external libraries:
On UNIX systems, you may install the dependencies using the distribution's package management system. Install the
development package of a dependency to install the header files and libraries required to build Exiv2. The script
ci/install_dependencies.sh is used to setup CI images on which we build and test Exiv2 on many platforms when we modify code. You may find that helpful in setting up your platform dependencies.
Natural language system is discussed in more detail here: Localisation
Notes about different platforms are included here: Platform Notes
You may choose to install dependences with conan. This is supported on all platforms and is especially useful for users of Visual Studio. See README-CONAN for more information.
LibiconvLibiconv
The library libiconv is used to perform character set encoding in the tags Exif.Photo.UserComment, Exif.GPSInfo.GPSProcessingMethod and Exif.GPSInfo.GPSAreaInformation. This is documented in the exiv2 man page.
CMake will detect libiconv of all UNIX like systems including Linux, macOS, UNIX, Cygwin64 and MinGW/msys2. If you have installed libiconv on your machine, Exiv2 will link and use it.
The library libiconv is a GNU library and we do not recommend using libiconv with Exiv2 when building with Visual Studio.
Exiv2 includes the file cmake/FindIconv.cmake which contains a guard to prevent CMake from finding libiconv when you build with Visual Studio. This was added because of issues reported when Visual Studio attempted to link libconv libraries installed by Cygwin, or MinGW or gnuwin32. Exiv2#1250
There are build instructions about Visual Studio in libiconv-1.16/INSTALL.window require you to install Cygwin. There is an article here about building libiconv with Visual Studio..
If you wish to use libiconv with Visual Studio you will have to build libiconv and remove the "guard" in cmake/FindIconv.cmake. Team Exiv2 will not provide support concerning libiconv and Visual Studio.
2.5 Building and linking your code with Exiv22.5 Building and linking your code with Exiv2
There are detailed platform notes about compiling and linking in
releasenotes/{platform}/ReadMe.txt
where
platform: { CYGWIN | Darwin | Linux | MinGW | msvc | Unix }
In general you need to do the following:
- Application code should be written in C++98 and include exiv2 headers:
#include <exiv2/exiv2.hpp>
Compile your C++ code with the directive:
-I/usr/local/include
Link your code with libexiv2 using the linker options:
-lexiv2and
-L/usr/local/lib
The following is a typical command to build and link with libexiv2:
$ g++ -std=c++98 myprog.cpp -o myprog -I/usr/local/include -L/usr/local/lib -lexiv2
2.6 Consuming Exiv2 with CMake2.6 Consuming Exiv2 with CMake
When exiv2 is installed, the files required to consume Exiv2 are installed in
${CMAKE_INSTALL_PREFIX}/lib/cmake/exiv2
You can build samples/exifprint.cpp as follows:
$ cd <exiv2dir> $ mkdir exifprint $ cd exifprint $ cat - > CMakeLists.txt <<EOF cmake_minimum_required(VERSION 3.8) project(exifprint VERSION 0.0.1 LANGUAGES CXX) set(CMAKE_CXX_STANDARD 98) set(CMAKE_CXX_EXTENSIONS OFF) find_package(exiv2 REQUIRED CONFIG NAMES exiv2) # search ${CMAKE_INSTALL_PREFIX}/lib/cmake/exiv2/ add_executable(exifprint ../samples/exifprint.cpp) # compile this target_link_libraries(exifprint exiv2lib) # link exiv2lib EOF $ cmake . # generate the makefile $ make # build the code $ ./exifprint # test your executable Usage: bin/exifprint [ path | --version | --version-test ] $
2.7 Using pkg-config to compile and link your code with Exiv22:
$ export PKG_CONFIG_PATH="/usr/local/lib/pkgconfig:$PKG_CONFIG_PATH"
To compile and link using exiv2.pc, you usually add the following to your Makefile.
PKGCONFIG=pkg-config CPPFLAGS := `pkg-config exiv2 --cflags` LDFLAGS := `pkg-config exiv2 --libs`
If you are not using make, you can use pkg-config as follows:
g++ -std=c++98 myprogram.cpp -o myprogram $(pkg-config exiv2 --libs --cflags)
2.8 Localisation2.8 Localisation
Localisation is supported on a UNIX-like platform: Linux, macOS, Cygwin and MinGW/msys2. Localisation is not supported for Visual Studio builds.
Crowdin have provided Exiv2 with a free open-source license to use their services. The Exiv2 localisation project is located at. You will also need to register to have a free user account on Crowdin. The Crowdin setup is discussed here: Exiv2#1510. It is recommended that you coordinate with Leonardo before contributing localisation changes on Crowdin. You can contact Leonardo by via GitHub..
- Running exiv2 in another language
$ env LANG=fr_FR exiv2 # env LANGUAGE=fr_FR exiv2 on Linux! exiv2: Une action doit être spécifié exiv2: Au moins un fichier est nécessaire Utilisation : exiv2 [ option [ arg ] ]+ [ action ] fichier ... Image metadata manipulation tool. $
- Adding additional languages to exiv2
To support a new language which we'll designate 'xy' for this discussion:
2.1) Generate a po file from the po template:
$ cd <exiv2dir> $ mkdir -p po/xy $ msginit --input=po/exiv2.pot --locale=xy --output=po/xy.po
2.2) Edit/Translate the strings in po/xy.po
I edited the following:
#: src/exiv2.cpp:237 msgid "Image metadata manipulation tool.\n" msgstr ""
to:
#: src/exiv2.cpp:237 msgid "Image metadata manipulation tool.\n" msgstr "Manipulate image metadata.\n"
2.3) Generate the messages file:
$ mkdir -p po/xy/LC_MESSAGES $ msgfmt --output-file=po/xy/LC_MESSAGES/exiv2.mo po/xy.po
2.4) Install and test your messages:
You have to install your messages to test them. It's not possible to test a messages file by executing build/bin/exiv2.
$ sudo mkdir -p /usr/local/share/locale/xy/LC_MESSAGES $ sudo cp -R po/xy/LC_MESSAGES/exiv2.mo /usr/local/share/locale/xy/LC_MESSAGES $ env LANG=xy exiv2 # env LANGUAGE=xy on Linux! exiv2: An action must be specified exiv2: At least one file is required Usage: exiv2 [ option [ arg ] ]+ [ action ] file ... Manipulate image metadata. <--------- Edited message! $:
$ zip xy.po.zip po/xy.po adding: po/xy.po (deflated 78%) ls -l xy.po.zip -rw-r--r--+ 1 rmills staff 130417 25 Jun 10:15 xy.po.zip $
2.9 Building Exiv2 Documentation2.
$ cmake ..options.. -DEXIV2_BUILD_DOC=On $ make doc
To build the documentation, you must install the following products:
2.10 Building Exiv2 Packages2.
- Platform Package (header files, binary library and samples. Some documentation and release notes)
Create and build exiv2 for your platform.
$ git clone $ mkdir -p exiv2/build $ cd exiv2/build $ cmake .. -G "Unix Makefiles" -DEXIV2_TEAM_PACKAGING=On ... -- Build files have been written to: .../build $ cmake --build . --config Release ... [100%] Built target addmoddel $ make package ... CPack: - package: /path/to/exiv2/build/exiv2-0.27.1-Linux.tar.gz generated.
- Source Package
$ make package_source Run CPack packaging tool for source... ... CPack: - package: /path/to/exiv2/build/exiv2-0.27.1-Source.tar.gz generated.
You may prefer to run
$ cmake --build . --config Release --target package_source
2.11 Debugging Exiv22.11 Debugging Exiv2
- Generating and installing a debug library
In general to generate a debug library, you should use the option cmake option
-DCMAKE_RELEASE_TYPE=Debug and build in the usual way.
$ cd <exiv2dir> $ mkdir build $ cd build $ cmake .. -G "Unix Makefiles" "-DCMAKE_BUILD_TYPE=Debug" $ make
You must install the library to ensure that your code is linked to the debug library.
You can check that you have generated a debug build with the command:
$ exiv2 -vVg debug exiv2 0.27.1 debug=1 $
- About preprocessor symbols
NDEBUGand
EXIV2_DEBUG_MESSAGES
Exiv2 respects the symbol
NDEBUG which is set only for Release builds. There are sequences of code which are defined within:
#ifdef EXIV2_DEBUG_MESSAGES .... #endif
Those blocks of code are not compiled unless you define
EXIV2_DEBUG_MESSAGES. They are provided for additional debugging information. For example, if you are interested in additional output from webpimage.cpp, you can update your build as follows:
$ cd <exiv2dir> $ touch src/webpimage.cpp $ make CXX_FLAGS=-DEXIV2_DEBUG_MESSAGES $ bin/exiv2 ... -- or -- $ sudo make install $ exiv2 ...
If you are debugging library code, it is recommended that you use the exiv2 command-line program as your test harness as Team Exiv2 is very familiar with this tool and able to give support.
- Starting the debugger
This is platform specific. On Linux:
$ gdb exiv2
- work on macOS and use Xcode to develop Exiv2. For a couple of years, Team Exiv2 had free
open-source licences from JetBrains for CLion. I really liked CLion as it is cross platform
and runs on Windows, Mac and Linux. It has excellent integration with CMake and will automatically
add
-DCMAKE_BUILD_TYPE=Debug to the cmake command. It keeps build types in separate directories
such as
<exiv2dir>/cmake-build-debug.
- cmake --build . options
--config Release|Debugand
--target install
Visual Studio and Xcode can build debug or release builds without using the option
-DCMAKE_BUILD_TYPE because the generated project files can build multiple types. The option
--config Debug can be specified on the cmake command-line to specify the build type. Alternatively, if you prefer to build in the IDE, the UI provides options to select the configuration and target.
With the Unix Makefile generator, the targets can be listed:
$ make help The following are some of the valid targets for this Makefile: ... all (the default if no target is provided) ... clean ... depend ... install/local .........
2.12 Building Exiv2 with clang and other build chains2.12 Building Exiv2 with clang and other build chains
- On Linux
$ cd <exiv2dir> $ rm -rf build ; mkdir build ; cd build $ cmake .. -DCMAKE_C_COMPILER=$(which clang) -DCMAKE_CXX_COMPILER=$(which clang++) $ cmake --build .
OR
$ export CC=$(which clang) $ export CXX=$(which clang++) $ cd <exiv2dir> $ rm -rf build ; mkdir build ; cd build $ cmake .. $ cmake --build .
- On macOS
Apple provide clang with Xcode. GCC has not been supported by Apple since 2013. The "normal unix build" uses Clang.
- On Cygwin, MinGW/msys2, Windows (using clang-cl) and Visual Studio.
I have been unable to get clang to work on any of those platforms.
2.13 Building Exiv2 with ccache2:
$ sudo apt install --yes ccache
To build with ccache, use the cmake option -DBUILD_WITH_CCACHE=On
$ cd <exiv2dir> $ mkdir build ; cd build ; cd build $ cmake .. -G "Unix Makefiles" -DBUILD_WITH_CCACHE=On $ make # Build again to appreciate the performance gain $ make clean $ make. Exiv2#361
2.14 Thread Safety2.14 Thread Safety
Exiv2 heavily relies on standard C++ containers. Static or global variables are used read-only, with the exception of the XMP namespace registration function (see below). Thus Exiv2 is thread safe in the same sense as C++ containers: Different instances of the same class can safely be used concurrently in multiple threads.
In order to use the same instance of a class concurrently in multiple threads the application must serialize all write access to the object.
The level of thread safety within Exiv2 varies depending on the type of metadata: The Exif and IPTC code is reentrant. The XMP code uses the Adobe XMP toolkit (XMP SDK), which according to its documentation is thread-safe. It actually uses mutexes to serialize critical sections. However, the XMP SDK initialisation function is not mutex protected, thus Exiv2::XmpParser::initialize is not thread-safe. In addition, Exiv2::XmpProperties::registerNs writes to a static class variable, and is also not thread-safe.
Therefore, multi-threaded applications need to ensure that these two XMP functions are serialized, e.g., by calling them from an initialization section which is run before any threads are started. All exiv2 sample applications begin with:
#include <exiv2/exiv2.hpp> int main(int argc, const char* argv[]) { Exiv2::XmpParser::initialize(); ::atexit(Exiv2::XmpParser::terminate); #ifdef EXV_ENABLE_BMFF Exiv2::enableBMFF(true); #endif ... }
The use of the thread unsafe function Exiv2::enableBMFF(true) is discussed in 2.19 Support for bmff files
2.15 Library Initialisation and Cleanup2.15 Library Initialisation and Cleanup
As discussed in the section on Thread Safety, Exiv2 classes for Exif and IPTC metadata are fully reentrant and require no initialisation or cleanup.
Adobe's XMPsdk is generally thread-safe, however it has to be initialized and terminated before and after starting any threads to access XMP metadata. The Exiv2 library will initialize this if necessary, however it does not terminate the XMPsdk.
The exiv2 command-line program and sample applications call the following at the outset:
Exiv2::XmpParser::initialize(); ::atexit(Exiv2::XmpParser::terminate); #ifdef EXV_ENABLE_BMFF Exiv2::enableBMFF(true); #endif
2.16 Cross Platform Build and Test on Linux for MinGW2.16 Cross Platform Build and Test on Linux for MinGW
You can cross compile Exiv2 on Linux for MinGW. We have used the following method on Fedora and believe this is also possible on Ubuntu and other distros. Detailed instructions are provided here for Fedora.
Cross Build and Test On FedoraCross Build and Test On Fedora
1 Install the cross platform build tools1 Install the cross platform build tools
$ sudo dnf install mingw64-gcc-c++ mingw64-filesystem mingw64-expat mingw64-zlib cmake make
2 Install Dependancies2 Install Dependancies
You will need to install x86_64 libraries to support the options you wish to use. By default, you will need libz and expat. Your
dnf command above has installed them for you. If you wish to use features such as
webready you should install openssl and libcurl as follows:
[rmills@rmillsmm-fedora 0.27-maintenance]$ sudo yum install libcurl.x86_64 openssl.x86_64 Last metadata expiration check: 0:00:18 ago on Fri 10 Apr 2020 10:50:30 AM BST. Dependencies resolved. ========================= Package Architecture Version Repository Size ========================= Installing: ...
3 Get the code and build3 Get the code and build
$ git clone://github.com/exiv2/exiv2 --branch 0.27-maintenance exiv2 $ cd exiv2 $ mkdir build_mingw_fedora $ mingw64-cmake .. $ make
Note, you may wish to choose to build with optional features and/or build static libraries. To do this, request appropriately on the mingw64-cmake command:
$ mingw64-cmake .. -DEXIV2_TEAM_EXTRA_WARNINGS=On \ -DEXIV2_ENABLE_WEBREADY=On \ -DEXIV2_ENABLE_WIN_UNICODE=On \ -DBUILD_SHARED_LIBS=Off
The options available for cross-compiling are the same as provided for all builds. See: Build Options
4 Copy "system dlls" in the bin directory4 Copy "system dlls" in the bin directory
These DLLs are required to execute the cross-platform build in the bin from Windows
for i in libexpat-1.dll libgcc_s_seh-1.dll libstdc++-6.dll libwinpthread-1.dll zlib1.dll ; do cp -v /usr/x86_64-w64-mingw32/sys-root/mingw/bin/$i bin done
5 Executing exiv2 in wine5 Executing exiv2 in wine
You may wish to use wine to execute exiv2 from the command prompt. To do this:
[rmills@rmillsmm-fedora build_mingw_fedora]$ wine cmd Microsoft Windows 6.1.7601 Z:\Home\gnu\github\exiv2\main\build_mingw_fedora>bin\exiv2 exiv2: An action must be specified exiv2: At least one file is required Usage: exiv2 [ option [ arg ] ]+ [ action ] file ... Image metadata manipulation tool.
If you have not installed wine, Fedora will offer to install it for you.
6 Running the test suite6 Running the test suite
On a default wine installation, you are in the MSDOS/cmd.exe prompt. You cannot execute the exiv2 test suite in this environment as you require python3 and MSYS/bash to run the suite.
You should mount the your Fedora exiv2/ directory on a Windows machine on which you have installed MinGW/msys2. You will need python3 and make.
My build machines is a MacMini with VMs for Windows, Fedora and other platforms. On Fedora, I build in a Mac directory which is shared to all VMs.
[rmills@rmillsmm-fedora 0.27-maintenance]$ pwd /media/psf/Home/gnu/github/exiv2/0.27-maintenance [rmills@rmillsmm-fedora 0.27-maintenance]$ ls -l build_mingw_fedora/bin/exiv2.exe -rwxrwxr-x. 1 rmills rmills 754944 Apr 10 07:44 build_mingw_fedora/bin/exiv2.exe [rmills@rmillsmm-fedora 0.27-maintenance]$
On MinGW/msys2, I can directly access the share:
$ cd //Mac/Home/gnu/github/exiv2/0.27/maintenance/build_mingw_fedora $ export EXIV2_BINDIR=$pwd/bin $ cd ../test $ make tests
You will find that 3 tests fail at the end of the test suite. It is safe to ignore those minor exceptions.
2.17 Building with C++11 and other compilers2.17 Building with C++11 and other compilers
Exiv2 uses the default compiler for your system. Exiv2 v0.27 was written to the C++ 1998 standard and uses
auto_ptr. The C++11 and C++14 compilers will issue deprecation warnings about
auto_ptr. As
auto_ptr support has been removed from C++17, you cannot build Exiv2 v0.27 with C++17 or later compilers._ Exiv2 v1.0 and later do not use
auto_ptr and will require a compiler compliant with the C++11 Standard.
To build Exiv2 v0.27.X with C++11:
cd <exiv2dir> mkdir build ; cd build cmake .. -DCMAKE_CXX_STANDARD=11 -DCMAKE_CXX_FLAGS=-Wno-deprecated make
The option -DCMAKE_CXX_STANDARD=11 specifies the C++ Language Standard. Possible values are 98, 11, 14, 17 or 20.
The option -DCMAKE_CXX_FLAGS=-Wno-deprecated suppresses warnings from C++11 concerning
auto_ptr. The compiler will issue deprecation warnings about video, eps and ssh code in Exiv2 v0.27. This is intentional. These features of Exiv2 will not be available in Exiv2 v1.0.
Caution: Visual Studio users should not use -DCMAKE_CXX_FLAGS=-Wno-deprecated.
2.18 Static and Shared Libraries2.18 Static and Shared Libraries
You can build either static or shared libraries. Both can be linked with either static or shared run-time libraries. You specify the shared/static with the option
-BUILD_SHARED_LIBS=On|Off You specify the run-time with the option
-DEXIV2_ENABLE_DYNAMIC_RUNTIME=On|Off. The default for both options default is On. So you build shared and use the shared libraries which are
.dll on Windows (msvc, Cygwin and MinGW/msys),
.dylib on macOS and
.so on Linux and UNIX.
CMake creates your build artefacts in the directories
bin and
lib. The
bin directory contains your executables and .dlls. The
lib directory contains your static libraries. When you install exiv2, the build artefacts are copied to your system's prefix directory which by default is
/usr/local/. If you wish to test and use your build without installing, you will have to set you PATH appropriately. Linux/Unix users should also set
LD_LIBRARY_PATH and macOS users should set
DYLD_LIBRARY_PATH.
The default build is SHARED/DYNAMIC and this arrangement treats all executables and shared libraries in a uniform manner.
Caution: The following discussion only applies if you are linking to a static version of the exiv2 library. You may get the following error from CMake:
CMake Error at src/CMakeLists.txt:30 (add_library): Target "my-app-or-library" links to target "Iconv::Iconv" but the target was not found. Perhaps a find_package() call is missing for an IMPORTED target, or an ALIAS target is missing?
Be aware that the warning concerning
src/CMakeLists.txt:30 (add_library) refers to your file src/CMakeLists.txt. Although exiv2 has statically linked
Iconv(), your code also needs to link. You achieve that in your src/CMakeLists.txt with the code:
find_package(Iconv) if( ICONV_FOUND ) target_link_libraries( my-app-or-library PRIVATE Iconv::Iconv ) endif()
This is discussed: Exiv2#1230
2.19 Support for bmff files (CR3, HEIF, HEIC, and AVIF)2.19 Support for bmff files (CR3, HEIF, HEIC, and AVIF)
Attention is drawn to the possibility that bmff support may be the subject of patent rights. Exiv2 shall not be held responsible for identifying any or all such patent rights. Exiv2 shall not be held responsible for the legal consequences of the use of this code.
Access to the bmff code is guarded in two ways. Firstly, you have to build the library with the cmake option:
-DEXIV2_ENABLE_BMFF=On. Secondly, the application must enable bmff support at run-time by calling the following function.
EXIV2API bool enableBMFF(bool enable);
The return value from
enableBMFF() is true if the library has been build with bmff support (cmake option -DEXIV2_ANABLE_BMFF=On).
Applications may wish to provide a preference setting to enable bmff support and thereby place the responsibility for the use of this code with the user of the application.
3 License and Support3 License and Support
All project resources are accessible from the project website.
3.1 License3.1 License
Copyright (C) 2004-2021 Exiv2 authors. You should have received a copy of the file.
3.2 Support3.2 Support
For new bug reports, feature requests and support: Please open an issue in Github.
4 Running the test suite4 Running the test suite
Different kinds of tests:Different kinds of tests:
The term bash scripts is historical. The implementation of the tests in this collection originally required bash. These scripts have been rewritten in python. Visual Studio Users will appreciate the python implementation as it avoids the installation of mingw/cygwin and special PATH settings.
Environment Variables used by the test suite:Environment Variables used by the test suite:
If you build the code in the directory <exiv2dir>build, tests will run using the default values of Environment Variables.
The Variable EXIV2_PORT or EXIV2_HTTP can be set to None to skip http tests. The http server is started with the command
python3 -m http.server $port. On Windows, you will need to run this manually once to authorise the firewall to permit python to use the port.
4.1 Running tests on a UNIX-like system4.1 Running tests on a UNIX-like system
You can run tests directly from the build:
$ cmake .. -G "Unix Makefiles" -DEXIV2_BUILD_UNIT_TESTS=On $ make ... lots of output ... $ make tests ... lots of output ... $
You can run individual tests in the
test directory. Caution: If you build in a directory other than <exiv2dir>/build, you must set EXIV2_BINDIR to run tests from the
test directory.
$ cd <exiv2dir>/build $ make bash_tests addmoddel_test (testcases.TestCases) ... ok .... Ran 176 tests in 9.526s OK (skipped=6) $ make python_tests ... lots of output ... test_run (tiff_test.test_tiff_test_program.TestTiffTestProg) ... ok ---------------------------------------------------------------------- Ran 176 tests in 9.526s OK (skipped=6) $
4.2 Running tests on Visual Studio builds from cmd.exe4.2 Running tests on Visual Studio builds from cmd.exe
Caution: _The python3 interpreter must be on the PATH, build for DOS, and called python3.exe. I copied the python.exe program:
> copy c:\Python37\python.exe c:\Python37\python3.exe > set "PATH=c:\Python37;%PATH%
You can execute the test suite as described for UNIX-like systems. The main difference is that you must use cmake to initiate the test as make is not a system utility on Windows.
> cd <exiv2dir>/build > cmake --build . --target tests > cmake --build . --target python_tests
Running tests from cmd.exeRunning tests from cmd.exe
You can build with Visual Studio using Conan. The is described in detail in README-CONAN.md
As a summary, the procedure is:
c:\...\exiv2>mkdir build c:\...\exiv2>cd build c:\...\exiv2\build>conan install .. --build missing --profile msvc2019Release c:\...\exiv2\build>cmake .. -DEXIV2_BUILD_UNIT_TESTS=On -G "Visual Studio 16 2019" c:\...\exiv2\build>cmake --build . --config Release ... lots of output from compiler and linker ... c:\...\exiv2\build>
If you wish to use an environment variables, use set:
set VERBOSE=1 cmake --build . --config Release --target tests set VERBOSE=
4.3 Unit tests4.3 Unit tests
The code for the unit tests is in
<exiv2dir>/unitTests. To include unit tests in the build, use the cmake option
-DEXIV2_BUILD_UNIT_TESTS=On.
There is a discussion on the web about installing GTest: Exiv2#575
$ pushd /tmp $ curl -LO $ tar xzf release-1.8.0.tar.gz $ mkdir -p googletest-release-1.8.0/build $ pushd googletest-release-1.8.0/build $ cmake .. ; make ; make install $ popd $ popd
4.4 Python tests4.4 Python tests
You can run the python tests from the build directory:
$ cd <exiv2dir>/build $ make python_tests
If you wish to run in verbose mode:
$ cd <exiv2dir>/build $ make python_tests VERBOSE=1
The python tests are stored in the directory tests and you can run them all with the command:
$ cd <exiv2dir>/tests $ export LD_LIBRARY_PATH="$PWD/../build/lib:$LD_LIBRARY_PATH" $ python3 runner.py
You can run them individually with the commands such as:
$ cd <exiv2dir>/tests $ python3 runner.py --verbose bugfixes/redmine/test_issue_841.py # or $(find . -name "*841*.py")
You may wish to get a brief summary of failures with commands such as:
$ cd <exiv2dir>/build $ make python_tests 2>&1 | grep FAIL
4.5 Test Summary4.5 Test Summary
The name bash_tests is historical. They are implemented in python.
4.6 Fuzzing4.6 Fuzzing
The code for the fuzzers is in
exiv2dir/fuzz
To build the fuzzers, use the cmake option
-DEXIV2_BUILD_FUZZ_TESTS=ON and
-DEXIV2_TEAM_USE_SANITIZERS=ON.
Note that it only works with clang compiler as libFuzzer is integrated with clang > 6.0
To build the fuzzers:
$ cd <exiv2dir> $ rm -rf build-fuzz ; mkdir build-fuzz ; cd build-fuzz $ cmake .. -DCMAKE_CXX_COMPILER=$(which clang++) -DEXIV2_BUILD_FUZZ_TESTS=ON -DEXIV2_TEAM_USE_SANITIZERS=ON $ cmake --build .
To execute a fuzzer:
cd <exiv2dir>/build-fuzz mkdir corpus ./bin/fuzz-read-print-write corpus ../test/data/ -jobs=$(nproc) -workers=$(nproc) -max_len=4096
For more information about fuzzing see
fuzz/README.md.
4.6.1 OSS-Fuzz4.6.1 OSS-Fuzz
Exiv2 is enrolled in OSS-Fuzz, which is a fuzzing service for open-source projects, run by Google.
The build script used by OSS-Fuzz to build Exiv2 can be found here. It uses the same fuzz target (
fuzz-read-print-write) as mentioned above, but with a slightly different build configuration to integrate with OSS-Fuzz. In particular, it uses the CMake option
-DEXIV2_TEAM_OSS_FUZZ=ON, which builds the fuzz target without adding the
-fsanitize=fuzzer flag, so that OSS-Fuzz can control the sanitizer flags itself.
5 Platform Notes5 Platform Notes
There are many ways to set up and configure your platform. The following notes are provided as a guide.
5.1 Linux5.1 Linux
Update your system and install the build tools and dependencies (zlib, expat, gtest and others)
$ sudo apt --yes update $ sudo apt install --yes build-essential git clang ccache python3 libxml2-utils cmake python3 libexpat1-dev libz-dev zlib1g-dev libssh-dev libcurl4-openssl-dev libgtest-dev google-mock
For users of other platforms, the script /ci/install_dependencies.sh has code used to configure many platforms. The code in that file is a useful guide to configuring your platform.
Get the code from GitHub and build
$ mkdir -p ~/gnu/github/exiv2 $ cd ~/gnu/github/exiv2 $ git clone $ cd exiv2 $ mkdir build ; cd build ; $ cmake .. -G "Unix Makefiles" $ make
5.2 macOS5.2 macOS
You will need to install Xcode and the Xcode command-line tools to build on macOS.
You should build and install libexpat and zlib. You may use brew, macports, build from source, or use conan.
I recommend that you build and install CMake from source.
5.3 MinGW/msys25.3 MinGW/msys2
Please note that the platform MinGW/msys2 32 is obsolete and superceded by MinGW/msys2 64.
MinGW/msys2 64 bitMinGW/msys2 64 bit
Install:
The file
appveyor_mingw_cygwin.yml has instructions to configure the AppVeyor CI to configures itself to build Exiv2 on MinGW/msys2 and Cygwin/64.
I use the following batch file to start the MinGW/msys2 64 bit bash shell from the Dos Command Prompt (cmd.exe)
@echo off setlocal set "PATH=c:\msys64\mingw64\bin;c:\msys64\usr\bin;c:\msys64\usr\local\bin;" set "PS1=\! MSYS \u@\h:\w \$ " set "HOME=c:\msys64\home\rmills" if NOT EXIST %HOME% mkdir %HOME% cd %HOME% color 1f c:\msys64\usr\bin\bash.exe -norc endlocal
Install MinGW DependenciesInstall MinGW Dependencies
Install tools and dependencies:
for i in base-devel git coreutils dos2unix tar diffutils make \ mingw-w64-x86_64-toolchain mingw-w64-x86_64-gcc mingw-w64-x86_64-gdb \ mingw-w64-x86_64-cmake mingw-w64-x86_64-gettext mingw-w64-x86_64-python3 \ mingw-w64-x86_64-libexpat mingw-w64-x86_64-libiconv mingw-w64-x86_64-zlib \ mingw-w64-x86_64-gtest do (echo y | pacman -S $i) ; done
Download exiv2 from github and buildDownload exiv2 from github and build
$ mkdir -p ~/gnu/github/exiv2 $ cd ~/gnu/github/exiv2 $ git clone $ cd exiv2 $ mkdir build ; cd build ; $ cmake .. -G "Unix Makefiles" # or "MSYS Makefiles" $ make
5.4 Cygwin/645.4 Cygwin/64
Please note that the platform Cygwin/32 is obsolete and superceded by Cygwin/64.
Download: and run setup-x86_64.exe. I install into c:\cygwin64
You need: make, cmake, curl, gcc, gettext-devel pkg-config, dos2unix, tar, zlib-devel, libexpat1-devel, git, libxml2-devel python3-interpreter, libiconv, libxml2-utils, libncurses, libxml2-devel libxslt-devel python38 python38-pip python38-libxml2
The file
appveyor_mingw_cygwin.yml has instructions to configure the AppVeyor CI to configures itself to build Exiv2 on MinGW/msys2 and Cygwin/64.
To build unit tests, you should install googletest-release-1.8.0 as discussed 4.3 Unit tests
I use the following batch file "cygwin64.bat" to start the Cygwin/64 bash shell from the Dos Command Prompt (cmd.exe).
@echo off setlocal set "PATH=c:\cygwin64\usr\local\bin;c:\cygwin64\bin;c:\cygwin64\usr\bin;c:\cygwin64\usr\sbin;" if NOT EXIST %HOME% mkdir %HOME% set "HOME=c:\cygwin64\home\rmills" cd %HOME% set "PS1=\! CYGWIN64:\u@\h:\w \$ " bash.exe -norc endlocal
5.5 Visual Studio5.5 Visual Studio
We recommend that you use Conan to build Exiv2 using Visual Studio. Exiv2 v0.27 can be built with Visual Studio versions 2008 and later. We actively support and build with Visual Studio 2015, 2017 and 2019.
As well as Visual Studio, you will need to install CMake, Python3, and Conan.
- Binary installers for CMake on Windows are availably from.
- Binary installers for Python3 are available from python.org
- Conan can be installed using python/pip. Details in README-CONAN.md
..>copy c:\Python37\python.exe c:\Python37\python3.exe
The python3 interpreter must be on your PATH.
5.6 Unix5.6 Unix
Exiv2 can be built on many Unix and Linux distros. With v0.27.2, we are starting to actively support the Unix Distributions NetBSD and FreeBSD. For v0.27.3, I have added support for Solaris 11.4
We do not have CI support for these platforms on GitHub. However, I regularly build and test them on my MacMini Buildserver. The device is private and not on the internet.
I have provided notes here based on my experience with these platforms. Feedback is welcome. I am willing to support Exiv2 on other commercial Unix distributions such as AIX, HP-UX and OSF/1 if you provide with an ssh account for your platform. I will require super-user privileges to install software.
For all platforms you will need the following components to build:
- gcc or clang
- cmake
- bash
- sudo
- gettext
To run the test suite, you need:
- python3
- chksum
- dos2unix
- xmllint
NetBSDNetBSD
You can build exiv2 from source using the methods described for linux. I built and installed exiv2 using "Pure CMake" and didn't require conan.
You will want to use the package manager
pkgsrc to build/install the build and test components listed above.
I entered links into the file system
# ln -s /usr/pkg/bin/python37 /usr/local/bin/python3 #FreeBSD
Clang is pre-installed as ``/usr/bin/{cc|c++}` as well as libz and expat. FreeBSD uses pkg as the package manager which I used to install cmake and git.
$ su root Password: # pkg install cmake # pkg install git # pkg install bash # pkg install python
Caution: The package manager pkg is no longer working on FreeBSD 12.0. I will move to 12.1 for future work. Others have reported this issue on 12.1. Broken package manager is very bad news. There are other package managers (such as ports), however installing and getting it to work is formidable.
634 rmills@rmillsmm-freebsd:~/gnu/github/exiv2/0.27-maintenance/build $ sudo pkg install libxml2 340.2kB/s 00:19 pkg: repository meta /var/db/pkg/FreeBSD.meta has wrong version 2 pkg: Repository FreeBSD load error: meta cannot be loaded No error: 0 Unable to open created repository FreeBSD Unable to update repository FreeBSD Error updating repositories! 635 rmills@rmillsmm-freebsd:~/gnu/github/exiv2/0.27-maintenance/build $
SolarisSolaris
Solaris uses the package manager pkg. To get a list of packages:
$ pkg list
To install a package:
$ sudo pkg install developer/gcc-7
Written by Robin Mills
[email protected]
Updated: 2021-09-21 | https://giters.com/exiftool/exiv2 | CC-MAIN-2022-27 | en | refinedweb |
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Hello,
We would like to import RSproxy inside C4D using Python script but we don't find any documentation about how we can set the import path and the animation type.
these fields seams unaccesible with python in C4D.
This one:
and this one:
Is it right?
Thanks
Hello @umd,
welcome to the Plugin Café and thank you for reaching out to us.
Is it right?
Is it right?
Well, the answer is yes and no at the same time. The type of the file parameter is indeed not exposed (not only in Python but also in C++), but it is a composed type and its subchannels are exposed. The topic was discussed in Attribute Error when accessing Redshift parameters before where I gave a brief overview of the technical background.
You can explore the subchannels of a parameter with the option "Show Sub-channels" in the Attribute Manger. To then get the full set of DescLevel for that subchannel, you can then use the console approach of discovering parameter symbols.
DescLevel
In your case the specific DescID for (File, Path) would for example be c4d.REDSHIFT_PROXY_FILE,c4d.REDSHIFT_FILE_PATH.
DescID
c4d.REDSHIFT_PROXY_FILE,c4d.REDSHIFT_FILE_PATH
Cheers,
Ferdinand
Hello @ferdinand ,
thank you for your answer !
But we have another issue with that!
We want to edit the REDSHIFT_PROXY_SELECTION_OBJECTS parameter after import
but this parameter does not seem to be initialized on creation and it returns an empty string.
I tried to refresh c4d ui, switch frame, etc.. to force reload but nothing happens
To get the param value I have to run another script by hand after the import command.
Here is the simplified code:
proxy = proxy_utils.import_proxy(doc, "tutu", "hello")
c4d.EventAdd()
print(proxy[c4d.REDSHIFT_PROXY_SELECTION_OBJECTS])
>>
Thanks
Hey @umd,
Your question and code example are a bit ambiguous for me. You say:
We want to edit the REDSHIFT_PROXY_SELECTION_OBJECTS parameter after import, but this parameter does not seem to be initialized on creation and it returns an empty string.
We want to edit the REDSHIFT_PROXY_SELECTION_OBJECTS parameter after import, but this parameter does not seem to be initialized on creation and it returns an empty string.
and then show this line which I assume uses a private module proxy_utils of yours:
proxy_utils
proxy = proxy_utils.import_proxy(doc, "tutu", "hello")
proxy = proxy_utils.import_proxy(doc, "tutu", "hello")
From this I would conclude that when you say import or creation, you mean that you manually instantiate an RSProxy object and set its proxy file, likely in the function import_proxy. So, the interesting thing to show would have been what this function does, but I assume you are not building the caches there for the returned BaseObject. A scene state, among other things: its caches, can be evaluated with BaseDocument.ExecutePasses. See the example at the end of my posting for details.
RSProxy
import_proxy
BaseObject
BaseDocument.ExecutePasses
The result:
After parameter change: rsProxy[c4d.REDSHIFT_PROXY_SELECTION_OBJECTS] = ''
After passes: rsProxy[c4d.REDSHIFT_PROXY_SELECTION_OBJECTS] = '{"format":1,"objects":[{"name":"Cube","state":1,"type":0}]}\n'
>>>
The code:
"""Demonstrates executing the passes on a document to reflect parameter changes on an object within
the scope of a function.
"""
import c4d
import redshift
doc: c4d.documents.BaseDocument # The active document
def main() -> None:
"""
"""
# Setup the rsProxy object and set the proxy file.
rsProxy = c4d.BaseList2D(redshift.Orsproxy)
rsProxy[c4d.REDSHIFT_PROXY_FILE,c4d.REDSHIFT_FILE_PATH] = "/Users/f_hoppe/Desktop/Untitled 1.rs"
# Something like this wont work, as the cache for #rsProxy has not been built yet. This is
# basically the same as when we would have instantiated a cube object, its geometry would not
# have been build yet too.
print (f"After parameter change: {rsProxy[c4d.REDSHIFT_PROXY_SELECTION_OBJECTS] = }")
# The same applies to this ...
# doc.InsertObject(rsProxy)
# c4d.EventAdd()
# print (f"{rsProxy[c4d.REDSHIFT_PROXY_SELECTION_OBJECTS] = }")
# We must insert #rsProxy into some document and execute the passes on it. It is best to
# use a dummy document for that.
temp = c4d.documents.BaseDocument()
temp.InsertObject(rsProxy)
# Evaluate the scene state of #temp. It is likely enough to build the caches here (the fourth
# argument), but I do not know much about RSProxy, so I did evaluate everything. Feel free to
# optimize, but it should not make a big difference for "normal" scenes.
temp.ExecutePasses(
bt=None, animation= True, expressions=True, caches=True, flags=c4d.BUILDFLAGS_NONE)
# We can remove #rsProxy at this point from #temp, its cache will stay attached to the object.
# When we print the parameter you are interested in, it will now be populated.
rsProxy.Remove()
print (f"After passes: {rsProxy[c4d.REDSHIFT_PROXY_SELECTION_OBJECTS] = }")
# On the forum you said "We want to edit the REDSHIFT_PROXY_SELECTION_OBJECTS parameter after
# import". I am not sure if this is a good idea or possible. But again, I do not know much about
# RSProxy. The value returned here seems to be more a string representation of an internal
# state than an actual value, i.e., is meant to be read-only, but I might be wrong.
# Since we removed #rsProxy from #temp, we can also insert it into #doc if we wanted to.
doc.InsertObject(rsProxy)
c4d.EventAdd()
if __name__ == '__main__':
main()
Oh I see..
The ExecutePasses was the key !
ExecutePasses
Thank you for your answers ! | https://plugincafe.maxon.net/topic/14067/importing-rsproxies-using-python | CC-MAIN-2022-27 | en | refinedweb |
Businesses text analysis with Python that can help you transform your data into meaningful insights, quickly and at scale.
In this post, discover we’ll quickly go over what text analysis is, how to use text analysis with Python, and all the necessary steps to create your own custom sentiment analysis model.
Text analysis is the automated process of extracting and classifying text data using machine learning and natural language processing. . Analyzing these texts by hand is time-consuming, tedious, and ineffective – especially if you deal with large amounts of data every day.
Walmart, for example, receives 200 billion rows of transactional data in just a few weeks! Imagine if they wanted to process all this data manually: it would be impossible. Text analysis tools, on the other hand, and can analyze hundreds and thousands of pieces of data in just a few seconds.
There are different text analysis techniques you can run on your data, such as sentiment analysis, topic classification, urgency detection, and intent categorization.
In the tutorial that follows, we’ll show you how to perform sentiment analysis with Python.
Python is the most popular programming language today, especially in the field of scientific computing, as it is a highly intuitive language when compared to others such as Java. It is more concise, so it takes less time and effort to carry out certain tasks. Finally, the syntax and code readability make it efficient, easy to process, and easy to learn. All these perks make Python the perfect option to build a machine learning model for text analysis.
You might opt for open source libraries, such as Scikit-learn or NLTK, for example. Some other libraries include SpaCy (its API is simple and productive), Keras (a machine learning library with a focus on enabling fast experimentation)), TensorFlow (for using deep learning for analyzing text), or PyTorch (another library used for building deep neural networks for NLP).
However, building a text analysis model from scratch is not easy. You will need to spend time and resources building the necessary infrastructure to run the model, train it, text it, and start all over again until it can be put to use. .
SaaS tools can make your venture into text analysis a lot simpler . MonkeyLearn, for example, is a simple but powerful text analysis platform that provides ready-to-use text analysis tools, as well as an API that can be used in Python.
For example, this is how you make an API request to MonkeyLearn’s sentiment analysis model:
from monkeylearn import MonkeyLearn ml = MonkeyLearn(<<Insert your API Key here>>) data = ["This is a great tool!"] model_id = 'cl_pi3C7JiL' result = ml.classifiers.classify(model_id, data) print(result.body)
The API response for this request will look like this:
[ { "text": "This is a great tool!", "external_id": null, "error": false, "classifications": [ { "tag_name": "Positive", "tag_id": 33767179, "confidence": 0.998 } ] } ]
Now, pre-trained models are great to start with. They will give you an idea of how machine learning works and how you can get insights out from your texts. However, if you are looking for true accuracy then you should build your own model. As you will be the one defining the tags and training your model with relevant samples, you’ll get better results.
Let’s take a look at how to build a custom sentiment classifier. We’ll train a model that is able to automatically classify reviews from a SaaS into Positive and Negative. Don’t worry, it’s easy and you’ll be able to integrate your model’s API with Python in no time.
Access your dashboard and click 'create model' in the top right-hand corner of the page. Then, choose ‘classifier:
When you have reached a certain number of samples, your model will start making accurate predictions.
You just need to write something in the text box to see how well your model works:
If your model needs to improve its predictions, you just have to tag more samples.
Finally, you can use our API with Python to integrate the model with your apps. You can do this with a few lines of code:
from monkeylearn import MonkeyLearn ml = MonkeyLearn('<<Your API key here>>') data = ['Customer support team is great, super helpful!', 'The UI is super confusing'] model_id = <<Insert model ID here>> result = ml.classifiers.classify(model_id, data) print(result.body)
The API will return a response with the result:
[{ 'text': 'Customer support team is great', 'classifications': [{ 'tag_name': 'Positive', 'confidence': 0.944, 'tag_id': 33767179 }], 'error': False, 'external_id': None }, { 'text': 'The UI is super confusing', 'classifications': [{ 'tag_name': 'Negative', 'confidence': 0.951, 'tag_id': 33767178 }], 'error': False, 'external_id': None }]
Analyzing your texts manually is a drag. Not only is it time-consuming, but Analyzing your texts manually is time-consuming, ineffective and tedious. Human agents can only process a certain amount of information, no matter how hard they work. That is why text analysis with AI is essential for businesses – it allows teams to focus on more relevant and motivating tasks, and helps extract valuable and accurate insights in real time.
Using text analysis with Python will save you a lot of time and resources, especially if you use SaaS tools such as MonkeyLearn instead of building a solution from scratch.
Start using MonkeyLearn’s pre-trained models right away or request a demo if you’d like to know more. Our team is ready to answer any questions you have! | https://monkeylearn.com/blog/text-analysis-with-python/ | CC-MAIN-2022-27 | en | refinedweb |
Multiple" which is what is run when invoking
/usr/bin/python. On Fedora 21 RHEL:
Note that the use of
%{!? [...]} does allow this to work without the check for rhel versions but putting the conditional in documents when we can remove the entire stanza from the spec file.
In Fedora,/
Using installing python modules we include several different types of files.
- *.
Source files
Source files (*.py) must be included in the same packages as the byte-compiled versions of them.__/* %global with_python3 1 %else %{!?__python2: Arch: noarch BuildRequires: python2-devel %if 0%{?with_python3} BuildRequires: python3-devel %endif # if with_python3
When we build the python3 module in addition to the python.
%if 0%{?with_python3} cp -a python2 python3 find python3 -name '*.py' | xargs sed -i '1s|^#!python|#!%{__python3}|' %endif # with_python3 find python2 -name '*.py' | xargs sed -i '1s|^#!python|#!%{__python2}|'.
%build_sitelib} to
%{python3_sitelib}. Since we chose to install the python2 version of
%{_bindir}/easy_install earlier we need to include that file in the python2 package rather than the python3 subpackage.
The problem)
Guidelines rpms.1. 32_sitelib} or %{python2. | https://www.fedoraproject.org/w/index.php?title=Packaging:Python&direction=next&oldid=409010 | CC-MAIN-2022-27 | en | refinedweb |
c|oClon0/lat0/lonp/latp/scale[+v] or Oc|OClon0/lat0/lonp/latp/width[+v]
The projection is set with o or O. The central meridian is set by lon0/lat0. The projection pole is set by lonp/latp in option three. Align the y-axis with the optional +v. The figure size is set with scale or width.
Out:
<IPython.core.display.Image object>
import pygmt fig = pygmt.Figure() # Using the origin projection pole fig.coast( projection="Oc280/25.5/22/69/12c", # Set bottom left and top right coordinates of the figure with "+r" region="270/20/305/25+r", frame="afg", land="gray", shorelines="1/thin", water="lightblue", ) fig.show()
Total running time of the script: ( 0 minutes 1.050 seconds)
Gallery generated by Sphinx-Gallery | https://www.pygmt.org/v0.5.0/projections/cyl/cyl_oblique_mercator_3.html | CC-MAIN-2022-27 | en | refinedweb |
tornado.wsgi — Interoperability with other Python frameworks and servers¶
WSGI support for the Tornado web framework.
WSGI is the Python standard for web servers, and allows for interoperability between Tornado and other Python web frameworks and servers.
This module provides WSGI support via the
WSGIContainer class, which
makes it possible to run applications using other WSGI frameworks on
the Tornado HTTP server. The reverse is not supported; the Tornado
Application and
RequestHandler classes are designed for use with
the Tornado
HTTPServer and cannot be used in a generic WSGI
container.
- class tornado.wsgi.WSGIContainer(wsgi_application: WSGIAppType)[source]¶
Makes a WSGI-compatible function runnable on Tornado’s HTTP server.
Warning
WSGI is a synchronous interface, while Tornado’s concurrency model is based on single-threaded asynchronous execution. This means that running a WSGI app with Tornado’s
WSGIContaineris less scalable than running the same app in a multi-threaded WSGI server like
gunicornor
uwsgi. Use
WSGIContaineronly when there are benefits to combining Tornado and WSGI in the same process that outweigh the reduced scalability.
Wrap a WSGI function in a
WSGIContainerand pass it to
HTTPServerto run it. For example:
def simple_app(environ, start_response): status = "200 OK" response_headers = [("Content-type", "text/plain")] start_response(status, response_headers) return [b"Hello world!\n"] async def main(): container = tornado.wsgi.WSGIContainer(simple_app) http_server = tornado.httpserver.HTTPServer(container) http_server.listen(8888) await asyncio.Event().wait() asyncio.run(main())
This class is intended to let other frameworks (Django, web.py, etc) run on the Tornado HTTP server and I/O loop.
The
tornado.web.FallbackHandlerclass is often useful for mixing Tornado and WSGI apps in the same server. See for a complete example.
- static environ(request: HTTPServerRequest) Dict[str, Any] [source]¶
Converts a
tornado.httputil.HTTPServerRequestto a WSGI environment. | https://www.tornadoweb.org/en/latest/wsgi.html | CC-MAIN-2022-27 | en | refinedweb |
Miller cylindrical.
j[lon0/]/scale or J[lon0/]/width
The projection is set with j or J. The central meridian is set by the optional lon0, and the figure size is set with scale or width.
Out:
<IPython.core.display.Image object>
import pygmt fig = pygmt.Figure() fig.coast( region=[-180, 180, -80, 80], projection="J-65/12c", land="khaki", water="azure", shorelines="thinnest", frame="afg", ) fig.show()
Total running time of the script: ( 0 minutes 1.035 seconds)
Gallery generated by Sphinx-Gallery | https://www.pygmt.org/v0.5.0/projections/cyl/cyl_miller.html | CC-MAIN-2022-27 | en | refinedweb |
AWS Lambda offers some powerful resources for running serverless applications. It enables developers to create code without having to worry about the headaches of running and managing servers in the cloud.
However, with these remote processes, it can be a bit difficult to track errors. On a local or remote system, a developer can see verbose text associated with errors by logging into the system itself (via ssh or other methods), making it relatively easy to track down and solve problems. On Lambda, because there is no server running, errors can just occur, and the application may stop due to a timeout or another reason without providing a clear message. When a Lambda instance errs, it can be difficult to track. The function itself is gone, but errors and logs remain. So, how do you find errors within AWS Lambda?
This guide will go over a few methods for detecting, tracking, and (with some luck) solving some errors that occur when running in the Lambda environment.
3 Ways Lambda Fails
Most of the time when Lambda fails, it does so because of the following:
Unhandled Exceptions – these are cases where an invalid input is received, there is an error associated with an API, or there’s simply a coding error.
Timeouts – these can occur when your Lambda code runs longer than a specified timeout duration. One can set these timeouts to up to 5 minutes; however, the default case is 6 seconds.
Memory errors – If Lambda runs out of memory for a task, it will kill the function during the runtime and typically return an error which states, “Process exited before completing request.”
In each of these cases, Lambda may attempt to retry, but how it reties depends on the reason for the error.
The Various Ways Lambda Retries
Synchronous
For synchronous events, such as through the API gateway, retries are re-triggered by the service that called the function. In other words, the responsibility for restarting an application needs to be done outside of Lambda. In most cases, if the problem is simply due to a system hiccup (external temporal issue, like networking blips), it should automatically rerun successfully. If it does not, this means that there is an error in the originating application, which should be addressed.
Asynchronous
However, for most uses of Lambda, communication with applications is occurring asynchronously. In these cases, the application is no longer present to take care of the failure that occurs, so AWS will typically attempt to handle these on its own. It will retry this multiple times. If it fails after a couple of attempts, the error message will be sent to AWS’s dead letter queue, where the log file can be monitored.
Streaming
The third type of error in Lambda is associated with streaming events.
In these cases, Lambda will attempt to run the application repeatedly until the data has either processed successfully or the information expires. One thing that is common with each of these is that Lambda simply keeps trying until success or a specified failure limit has been met. Lambda will not accept any new input from an action until this condition has been satisfied.
Error Handling in AWS Lambda
Most Errors can be retrieved from the log files. These can typically be found in CloudWatch by opening the Lambda console functions. From here, you can choose your specific function that is erring, and then choose “monitoring.” Once you’re in monitoring, you can access individual log files by clicking on “View Logs in Cloudwatch.”
Below are some examples of types of errors one can retrieve from Lambda.
ServiceError enables you to retrieve all errors directly from Lambda
# rescue all errors from AWS Lambda begin # do stuff rescue Aws::Lambda::Errors::ServiceError # ... end
If you need to retrieve errors for specific error classes, use individual exceptions. For example:
begin # do stuff rescue Aws::Lambda::Errors::CodeStorageExceededException # ... end
Errors are returned in JSON format.
For instance, the following code:
def handler(event:, context:) puts "Processing event..." [1, 2, 3].thing("two") "Success" end
will generate the following error
{ "errorMessage": "no implicit conversion of String into Integer", "errorType": "Function
", "stackTrace": [ "/var/task/function.rb:3:in `thing'", "/var/task/function.rb:3:in `handler'" ] }
Common Issues
One common issue many users face when first deploying to Lambda is the dreaded “missing gem/library/package” error. This type of error is caused by various missing libraries or files.
Here’s an example of one of these types of errors:
"errorType": "Init\u003cLoadError\u003e", "errorMessage": "Error loading the 'postgresql' Active Record adapter. Missing a gem it depends on? libruby.so.2.5: cannot open shared object file: No such file or directory - /var/task/vendor/bundle/ruby/2.5.0/gems/pg-1.1.3/lib/pg_ext.so"
This particular error can be remedied by rebuilding the gems in the Ruby library to install the correct bundle.
Debugging Functions Locally
By using the Serverless framework and VS Code, one can mimic Lambda’s behavior on a local machine. All you need to do is use the “invoke local” command.
You may wish to install serverless as a dev dependency to both allow other developers to be able to make use of the functionality, but also to prevent incompatibility issues.
Conclusion
The use of AWS Lambda can help reduce the large amount of server overhead required to run complex applications. The biggest challenges occur when trying to monitor any errors during the process. Once you understand the types of errors that Lambda can produce, use tools like Airbrake Error Monitoring to ensure things run smoothly. | https://airbrake.io/blog/debugging/runtime-error-handling-in-aws-lambda | CC-MAIN-2022-27 | en | refinedweb |
The QDragMoveEvent class provides an event which is sent while a drag and drop action is in progress. More...
#include <QDragMoveEvent>
Inherits QDropEvent.
Inherited by QDragEnterEvent..
Destroys the event..
This is an overloaded member function, provided for convenience. member function, provided for convenience.
Calls QDropEvent::ignore(). | https://doc.qt.io/archives/qtopia4.3/qdragmoveevent.html | CC-MAIN-2019-26 | en | refinedweb |
WHO Library Cataloguing-in-Publication data World Health Organization, Regional Office for South-East Asia. Comprehensive guidelines for prevention and control of dengue and dengue haemorrhagic fever. Revised and expanded edition. (SEARO Technical Publication Series No. 60) 1. Dengue epidemiology - prevention and control - statistics and numerical data. 2. Dengue Hemorrhagic Fever epidemiology - prevention and control statistics and numerical data. 3. Laboratory Techniques and Procedures methods. 4. Blood Specimen Collection methods. 5. Insect Repellents. 6. Guidelines. ISBN 978-92-9022-387-0 (NLM classification: WC 528)
All rights reserved. Requests for publications, or for permission to reproduce or translate WHO publications whether for sale or for noncommercial distribution can be obtained from Publishing and Sales, World Health Organization, Regional Office for South-East Asia, Indraprastha Estate, Mahatma Gandhi Marg, New Delhi 110 002, India (fax: +91 11 23370197; e-mail: publications@searo does not necessarily represent the decisions or policies of the World Health Organization. Printed in India
Contents
Preface ......................................................................................................................... vii Acknowledgements ........................................................................................................ix Abbreviations and Acronyms ..........................................................................................xi 1. Introduction ............................................................................................................ 1 2. Disease Burden of Dengue Fever and Dengue Haemorrhagic Fever ......................... 3 2.1 2.2 Global .......................................................................................................... 3 The WHO South-East Asia Region ............................................................... 5
3. Epidemiology of Dengue Fever and Dengue Haemorrhagic Fever ............................ 9 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 The virus ...................................................................................................... 9 Vectors of dengue ......................................................................................... 9 Host ........................................................................................................... 12 Transmission of dengue virus ...................................................................... 12 Climate change and its impact on dengue disease burden .......................... 14 Other factors for increased risk of vector breeding ...................................... 14 Geographical spread of dengue vectors ...................................................... 15 Future projections of dengue estimated through empirical models .............. 15
4. Clinical Manifestations and Diagnosis .................................................................... 17 4.1 4.2 4.3 4.4 4.5 4.6 4.7 Clinical manifestations ................................................................................ 17 Clinical features .......................................................................................... 18 Pathogenesis and pathophysiology ............................................................. 22 Clinical laboratory findings of DHF ............................................................. 23 Criteria for clinical diagnosis of DHF/DSS.................................................... 24 Grading the severity of DHF ....................................................................... 25 Differential diagnosis of DHF ...................................................................... 25
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4.8 4.9
4.10 High-risk patients ....................................................................................... 27 4.11 Clinical manifestations of DF/DHF in adults ............................................... 28 5. Laboratory Diagnosis ............................................................................................. 31 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9 Diagnostic tests and phases of disease......................................................... 31 Specimens: Collection, storage and shipment ............................................ 32 Diagnostic methods for detection of dengue infection ............................... 34 Immunological response and serological tests ............................................. 37 Rapid diagnostic test (RDT) ........................................................................ 39 Haematological tests ................................................................................... 40 Biosafety practices and waste disposal ........................................................ 40 Quality assurance ....................................................................................... 40 Network of laboratories .............................................................................. 40
6. Clinical Management of Dengue/ Dengue Haemorrhagic Fever ............................. 41 6.1 6.2 Triage of suspected dengue patients at OPD ............................................... 42 Management of DF/DHF cases in hospital observation wards/on admission ................................................................................................... 45
7. Disease Surveillance: Epidemiological and Entomological ...................................... 57 7.1 7.2 7.3 7.4 7.5 7.6 Epidemiological surveillance ....................................................................... 57 International Health Regulations (2005) ...................................................... 59 Vector surveillance ..................................................................................... 60 Sampling approaches ................................................................................. 65 Monitoring insecticide resistance ............................................................... 66 Additional information for entomological surveillance ................................. 66
8. Dengue Vectors ..................................................................................................... 69 8.1 Biology of Aedes aegypti and Aedes albopictus ........................................... 69
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Biological control........................................................................................ 80 Chemical control ........................................................................................ 82 Geographical information system for planning, implementation and evaluation............................................................................................ 88
10. Integrated Vector Management (IVM) .................................................................... 93 10.1 Genesis and key elements .......................................................................... 93 10.2 Approach .................................................................................................. 95 10.3 IVM implementation ................................................................................ 103 10.4 IVM monitoring and evaluation ................................................................ 103 10.5 Budgeting ................................................................................................. 103 11. Communication for Behavioural Impact (COMBI) ............................................... 105 11.1 Planning social mobilization and communication: A step-by-step guide ........................................................................................................ 108 11.2 Ensuring health-care infrastructure/service/goods provision ....................... 123 11.3 Application of COMBI ............................................................................. 124 12. The Primary Health Care Approach to Dengue Prevention and Control ............... 127 12.1 Principle of primary health care ................................................................ 127 12.2 Primary health care and dengue prevention and control ........................... 128 13. Case Investigation, Emergency Preparedness and Outbreak Response.................. 139 13.1 Background and rationale ......................................................................... 139 13.2 Steps for case investigation and outbreak response ................................... 139 14. Monitoring and Evaluation of DF/D HF Prevention and Control Programmes ....... 145 14.1 Types of evaluation ................................................................................... 145 14.2 Evaluation plans ....................................................................................... 146 14.3 Cost-effective evaluation .......................................................................... 147 15. Strategic Plan for the Prevention and Control of Dengue in the Asia-Pacific Region: A Bi-regional Approach (20082015) ...................................................... 151 15.1 Need for a biregional approach and development of a Strategic Plan for the Prevention and Control of Dengue in the Asia-Pacific Region ................... 151 15.2 Guiding principles .................................................................................... 151
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15.3 Goal, vision and mission ........................................................................... 152 15.4 Objectives ................................................................................................ 152 15.5 Components of the Strategy...................................................................... 155 15.6 Supportive strategies ................................................................................. 155 15.7 Duration .................................................................................................. 157 15.8 Monitoring and evaluation ....................................................................... 157 15.9 Implementation of the Strategic Plan ....................................................... 158 15.10 Endorsement of the Asia-Pacific Srategic Plan (20082015)....................... 158 16. References .......................................................................................................... 159
Annexes
1. Arbovirus laboratory request form........................................................................ 169 2. International Health Regulations (IHR, 2005) ....................................................... 170 3. IHR Decision Instrument for assessment and notification of events....................... 172 4. Sample size in Aedes larval surveys...................................................................... 173 5. Pictorial key to Aedes (Stegomyia) mosquitoes in domestic containers in South-East Asia .................................................................................................... 175 6. Designs for overhead tank with cover masonry chamber and soak pit .................. 178 7. Procedure for treating mosquito nets and curtains ............................................... 179 8. Quantities of 1% temephos (abate) sand granules required to treat different-sized water containers to kill mosquito larvae ........................................ 184 9. Procedure, timing and frequency of thermal fogging and ULV space spray operations .................................................................................................. 185 10. Safety measures for insecticide use ...................................................................... 189 11. Functions of Emergency Action Committee (EAC) and Rapid Action Team (RAT) .......................................................................................................... 194 12. Case Investigation Form (prototype) ..................................................................... 195
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Preface
Dengue fever is the fastest emerging arboviral infection spread by Aedes mosquitoes with major public health consequences in over 100 tropical and sub-tropical countries in South-East Asia, the Western Pacific and South and Central America. Up to 2.5 billion people globally live under the threat of dengue fever and its severe formsdengue haemorrhagic fever (DHF) or dengue shock syndrome (DSS). More than 75% of these people, or approximately 1.8 billion, live in the Asia-Pacific Region. As the disease spreads to new geographical areas, the frequency of the outbreaks is increasing along with a changing disease epidemiology. It is estimated that 50 million cases of dengue fever occur worldwide annually and half a million people suffering from DHF require hospitalization each year, a very large proportion of whom (approximately 90%) are children less than five years old. About 2.5% of those affected with dengue die of the disease. Outbreaks of dengue fever in the 1950s and 1960s in many countries of the Asia-Pacific Region led to the organization of a biregional seminar in 1964 in Bangkok, Thailand, and a biregional meeting in 1974 in Manila, Philippines. Following these meetings, guidelines for the diagnosis, treatment and control of dengue fever were developed by the World Health Organization (WHO) in 1975. WHO has since then provided relentless support to its Member States by way of technical assistance, workshops and meetings, and issuing several publications. These include a set of revised guidelines in 1980, 1986 and 1995 following the research findings on pathophysiology and clinical and laboratory diagnosis. The salient features of the resolution of the Forty-sixth World Health Assembly (WHA) in 1993 urging the strengthening of national and local programmes for the prevention and control of dengue fever, DHF and DSS were also incorporated in these revised guidelines. A global strategy on dengue fever and DHF was developed in 1995 and its implementation was bolstered in 1999. Subsequently, the awareness of variable responses to the infection presenting a complex epidemiology and demanding specific solutions necessitated the publication of the Comprehensive Guidelines for the Prevention and Control of Dengue/DHF with specific focus on the WHO South-East Asia Region in 1999. This document has served as a roadmap for Member States of the Region and elsewhere by providing guidance on the various challenges posed by dengue fever, DHF and DSS. The 2002 World Health Assembly Resolution urged greater commitment to dengue from Member States and WHO. The International Health Regulations (2005) required Member States to detect and respond to any disease (including dengue) that demonstrates the ability to cause serious public health impact and spread rapidly globally. An Asia-Pacific Dengue Partnership was established
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in 2007 to increase public and political commitment, to more effectively mobilize resources, and implement measures of prevention and control in accordance with the Global Strategy. In 2008, a biregional (for the WHO South-East Asia and Western Pacific Regions) Asia-Pacific Dengue Strategic Plan (20082015) was developed to reverse the rising trend of dengue in the Member States of these regions. A voluminous quantity of research and studies conducted by WHO and other experts have additionally brought to light new developments and strategies in relation to case diagnosis and management of vector control, and emphasized regular sensitization and capacitybuilding. The publications underscored as well as reinforced the need for multisectoral partnerships in tandem with the revitalization of primary health care and transferring the responsibility, capability, and motivation for dengue control and prevention to the community, backed up by effective communication and social mobilization initiatives, for responsive behaviour en route to a sustainable solution of the dengue/DHF menace. This is important because dengue is primarily a man-made health problem attributed to globalization, rapid unplanned and unregulated development, deficient water supply and solid waste management with consequent water storage, and sanitary conditions that are frequently unsatisfactory leading to increasing breeding habitats of vector mosquitoes. All this, needless to say, necessitates a multidisciplinary approach. In this edition of the Comprehensive Guidelines for the Prevention and Control of Dengue and Dengue Haemorrhagic Fever, the contents have been extensively revised and expanded with the focus on new/additional topics of current relevance to Member States of the South-East Asia Region. Several case studies have been incorporated to illustrate best practices and innovations related to dengue prevention and control from various regions that should encourage replication subsequent to locale- and context-specific customization. In all, the Guidelines have 14 chapters that cover new insights into case diagnosis and management and details of surveillance (epidemiological and entomological), health regulations, vector bioecology, integrated vector management, the primary health care approach, communication for behavioural impact (COMBI), the Asia-Pacific Dengue Strategic Plan, case investigation, and emergency preparedness and outbreak response that has been previously published elsewhere by WHO and others. This revised and expanded edition of the Guidelines is intended to provide guidance to national and local-level programme managers and public health officials as well as other stakeholders including health practitioners, laboratory personnel and multisectoral partners on strategic planning, implementation, and monitoring and evaluation towards strengthening the response to dengue prevention and control in Member States. The scientists and researchers involved in vaccine and antiviral drug development will also find crucial baseline information in this document. It is envisioned that the wealth of information presented in this edition of the Guidelines will prove useful to effectively combat dengue fever, DHF and DSS in the WHO South-East Asia Region and elsewhere; and ultimately reduce the risk and burden of the disease.
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Acknowledgements
This revised and expanded edition of the Comprehensive Guidelines on Prevention and Control of Dengue and Dengue Haemorrhagic Fever was initially drafted by Mr Nand L. Kalra, independent expert on dengue prevention and control. An in-house appraisal of the draft document was done by Dr A.B. Joshi, Dr A.P Dash, Mr Alex Hilderbrand, Dr Busaba Sawguanprasitt, Dr Chusak Prasittisuk, . Dr Ferdinand Laihad, Dr Jai P Narain, Dr Madhu Ghimire, Dr Nalini Ramamurthy, Dr Nihal . Abeysinghe, Dr Ong-arj Viputsiri, Dr Oratai Rauyajin, Dr Sudhansh Malhotra, Dr Suvajee Good, Dr Suzanne Westman, and others. Subsequently, the draft document was critically reviewed at a peer review workshop held in Bangkok, Thailand, chaired by Dr Satish Apppoo, Director, Environmental Health, National Environment Agency, Singapore. The peer reviewers, including Dr Suchitra Nimmanitya, Dr Siripen Kalayanarooj, Dr Anon Srikiatkhachorn and Dr Suwit Thamapalo of Thailand; Dr Lucy Chai See Lum of Malaysia; Dr K.N. Tewari, Dr S.L. Hoti, Dr Kalpana Baruah, Mr N.L. Kalra and Dr Shampa Nag of India; Mr T. Chawalit from the WHO Country Office in Thailand; Dr Raman Velayudhan (WHO HQ/NTD), Dr Chang Moh Seng from the WHO Regional Office for the Western Pacific; Dr Chusak Prasittisuk, Dr Rajesh Bhatia, Dr Suvajee Good, Dr Shalini Pooransingh and Dr Busaba Sangwanprasitt from the WHO Regional Office for South-East Asia; and Dr D. J. Gubler (USA/Singapore) provided valuable inputs to and suggestions for the draft document. Revision and incorporation of comments of peer reviewers was performed by Mr Nand Lal Kalra and Dr Shampa Nag. Technical scrutiny of the final draft was undertaken by Dr Anon Srikiatkhachorn, Dr Busaba Sangwanprasitt, Dr Chusak Prasittisuk, Mr Nand Lal Kalra, Dr Shampa Nag, Prof. Siripen Kalayanarooj and Prof. Suchitra Nimmanitya. The chapters on Clinical Manifestations and Diagnosis and Clinical Management of Dengue/ Dengue Haemorrhagic Fever included in the Comprehensive Guidelines were reviewed yet again during a consultative meeting on dengue case classification and case management held in Bangkok, Thailand, in October 2010. The reviewers included Prof. Emran Bin Yunnus from Bangladesh; Dr Duch Moniboth from Cambodia; Dr Juzi Deliana and Dr Djatnika Setiabudi from Indonesia; Dr Khampe Phongsavarh from the Lao Peoples Democratic Republic; Prof. Lucy Lum Chai See from Malaysia; Dr Talitha Lea V. Lacuesta and Dr Edna A. Miranda from the Phillippines; Dr Lak Kumar Fernando from Sri Lanka; and Prof. Suchitra Nimmanitya, Dr Wichai Satimai, Prof. Siripen Kalyanarooj, Prof. Sayomporn Sirinavin, Prof. Kulkanya Chokpaibulkit, Prof. Saitorn Likitnukool, Prof. Mukda Vandveeravong, Dr Anon Sirikiatkhachorn, Dr Suchart Hongsiriwan, Dr Valaikanya Plasai, Dr. Pra-On Supradish, Queen Sirikit s National Institute of Child Health Bangkok. The final editing was done by Dr Chusak Prasittisuk, Dr N.L. Kalra and Dr A.P Dash. The . contributions of all reviewers are gratefully acknowledged.
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ABCS ADB Ae. AIDS ALT An. APDP APDSP APSED AST BCC BI BMA BP Bs BSL2 Bt.H-14 BUN CBC CDC CF CFR CI CNS CPG CPK CSF CT (or CAT) Cx
acidosis, bleeding, calcium, (blood) sugar Asian Development Bank Aedes acquired immunodeficiency syndrome alanine amino transferase Anopheles Asia-Pacific Dengue Partnership Asia-Pacific Dengue Strategic Plan Asia-Pacific Strategy for Emerging Diseases aspartate aminotransferase behaviour change communication Breateau Index Bangkok Municipal Administration blood pressure Bacillus sphaericus Biosafety Level-2 Bacillus thuringiensis serotype H-14 blood urea nitrogen complete blood count Center for Disease Control, Atlanta, USA complement fixation case-fatality rate Container Index central nervous system clinical practice guidelines creatine-phosphokinase cerebrospinal fluid computed axial tomography Culex
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COMBI CPG CSR CSF CVP DALY DDT DEET DENCO DeVIT DENV DF DHF DIC DNA D/NSS DLR DSS EAC ECG EIP ELISA ENVID ESR G-6PD GIS GPS HCT HE HFA HHT HI HI HIA HICDARM HIV ICP IEC IFN-g
communication for behavioural impact Clinical Practice Guidelines corporate social responsibility cerebrospinal fluid central venous pressure disability-adjusted lifeyear dichlorodiphenyltrichloroethane N, N-Diethyl-m-Toluamide Dengue and Control study (multicountry study) Dengue Volunteer Inspection Team dengue virus dengue fever dengue haemorrhagic fever disseminated intravascular coagulation deoxyribonucleic acid dextrose in isotonic normal saline solution dextrose in lactated Ringer's solution dengue shock syndrome Emergency Action Committee electrocardiography extrinsic incubation period enzyme-linked immunosorbent assay European Network for Diagnostics of Imported Viral Diseases erythrocyte sedimentation rate glucose-6-phosphatase dehydrogenase Geographical Information System Global Positioning System haematocrit health education Health For All hand-held terminal haemagglutination-inhibition House Index Health Impact Assessment hear, inform, convince, decision, action, reconfirmation, maintain human immunodeficiency virus intracranial pressure information, education and communication interferon gamma
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Comprehensive Guidelines for Prevention and Control of Dengue and Dengue Haemorrhagic Fever
IgG IgM IGR IHR (2005) IIFT IPM ITN IRS ISRE IV IVM KAP KABP LAMP LLIN MAC-ELISA MDGs M&E MoH mph MRI M-RIP MS.CREFS NASBA NGO NS NSAID NK NS1 NT OPD ORS PAHO PCR pH PHEIC PHC PI
immunoglobulin G immunoglobulin M insect growth regulator International Health Regulations (2005) insecticide impregnated fabric trap integrated pest management insecticide-treated mosquito net insecticide residual spraying intensive source reduction exercise intravenous integrated vector management knowledge, attitude, practice(s) knowledge, attitude, belief, practice(s) loop-mediated amplification long-lasting insecticidal net IgM antibody-capture enzyme-linked immunosorbent assay Millennium Development Goals monitoring and evaluation Ministry of Health miles per hour magnetic resonance imaging massive, repetitive, intense, persistent message, source, channel, receiver, effect, feedback, setting nucleic acid sequence-based amplification nongovernmental organization nonstructural protein non-steroidal anti-inflammatory drugs natural killer cells nonstructural protein 1 neutralization test outpatient department oral rehyadration solution Pan American Health Organization polymerase chain reaction potential hydrogen/presence of active hydrogen (hydrogen strength in a given substance to measure its acidity or alkalinity) public health emergency of international concern primary health care Pupal Index
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ppm PRNT PT PTT R&D RC RDT RNA RNAi RR RS RT-PCR SEA SEARO SMART TDR TNF-a TT ULV UN UNEP UNICEF USAID VHW VPC WBC WHA WHO WPRO
parts per million plaque reduction neutralization test prothrombin time partial thromboplastin time research and development Regional Committee (of WHO SEA Region) rapid diagnostic test ribonucleic acid RNA interference relative risk remote sensing reverse transcriptase polymerase chain reaction South-East Asia South-East Asia Regional Office (of WHO) specific, measurable, appropriate, realistic, time-bound tropical diseases research tumor necrosis factor-a thrombin time/tourniquet test ultra-low volume United Nations United Nations Environment Programme United Nations Childrens Fund United States Agency for International Development voluntary health worker ventricular premature contraction white blood cell World Health Assembly World Health Organization Regional Office for the Western Pacific (of WHO)
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1.
Introduction
Dengue fever (DF) and its severe formsdengue haemorrhagic fever (DHF) and dengue shock syndrome (DSS)have become major international public health concerns. Over the past three decades, there has been a dramatic global increase in the frequency of dengue fever (DF), DHF and DSS and their epidemics, with a concomitant increase in disease incidence (Box 1). Dengue is found in tropical and subtropical regions around the world, predominantly in urban and semi-urban areas. The disease is caused by a virus belonging to family Flaviviradae that is spread by Aedes (Stegomyia) mosquitoes. There is no specific treatment for dengue, but appropriate medical care frequently saves the lives of patients with the more serious dengue haemorrhagic fever. The most effective way to prevent dengue virus transmission is to combat the disease-carrying mosquitoes. According to the World Health Report 1996borne illnesses that affect large numbers of people in both the richer and poorer nations. Box 1: Dengue and dengue haemorrhagic fever: Key facts Some 2.5 billion people two fifths of the world's population in tropical and subtropical countries are at risk. An estimated 50 million dengue infections occur worldwide annually. An estimated 500 000 people with DHF require hospitalization each year. A very large proportion (approximately 90%) of them are children aged less than five years, and about 2.5% of those affected die. Dengue and DHF is endemic in more than 100 countries in the WHO regions of Africa, the Americas, the Eastern Mediterranean, South-East Asia and the Western Pacific. The South-East Asia and Western Pacific regions are the most seriously affected. Epidemics of dengue are increasing in frequency. During epidemics, infection rates among those who have not been previously exposed to the virus are often 40% to 50% but can also reach 80% to 90%. Seasonal variation is observed. Aedes (Stegomyia) aegypti is the primary epidemic vector. Primarily an urban disease, dengue and DHF are now spreading to rural areas worldwide. Imported cases are common. Co-circulation of multiple serotypes/genotypes is evident. The first confirmed epidemic of DHF was recorded in the Philippines in 19531954 and in Thailand in 1958. Since then, Member countries of the WHO South-East Asia (SEA) and Western Pacific (WP) regions have reported major dengue outbreaks at regular frequencies. In India, the
Comprehensive Guidelines for Prevention and Control of Dengue and Dengue Haemorrhagic Fever
first confirmed DHF outbreak occurred in 1963. Other countries of the Region, namely Indonesia, Maldives, Myanmar and Sri Lanka, have also reported major DHF outbreaks. These outbreaks prompted a biregional (SEA and WP regions) meeting on dengue in 1974 in Manila, the Philippines, where technical guidelines for the diagnosis, treatment, and prevention and control of dengue and DHF were developed. This document was later revised at a summit meeting in Bangkok in 1980. In May 1993, the Forty-sixth World Health Assembly (46th WHA, 1993) adopted a resolution on dengue prevention and control, which urged that the strengthening of national and local programmes for the prevention and control of dengue fever (DF), DHF and DSS should be among the foremost health priorities of those WHO Member States where the disease is endemic. The resolution also urged Member States to: (1) develop strategies to contain the spread and increasing incidence of dengue in a manner sustainable; (2) improve community health education; (3) encourage health promotion; (4) bolster research; (5) expand dengue surveillance; (6) provide guidance on vector control; and (7) prioritize the mobilization of external resources for disease prevention. In response to the World Health Assembly resolution, a global strategy for the operationalization of vector control was developed. It comprised five major components, as outlined in Box 2. Box 2: Salient Features of Global Strategy for Control of DF/DHF Vectors Selective integrated mosquito control with community and intersectoral participation. Active disease surveillance based on strong health information systems. Emergency preparedness. Capacity-building and training. Intensive research on vector control.
Accordingly, several publications were issued by three regional offices of the World Health OrganizationSouth-East Asia (SEARO) [Monograph on dengue/dengue haemorrhagic fever in 1993, a regional strategy for the control of DF/DHF in 1995, and Guidelines on Management of Dengue Epidemics in 1996]; Western Pacific (WPRO) [Guidelines for Dengue Surveillance and Mosquito Control in 1995]; and the Americas (AMRO PAHO) [Dengue and Dengue Haemorrhagic Fever in the Americas: Guidelines for Prevention and Control in 1994]. A 2002 World Health Assembly resolution (WHA 55.17) urged greater commitment to dengue from Member States and WHO. In 2005, the International Health Regulations (IHR) were formulated. These regulations stipulated that Member States detect and respond to any disease (for example, dengue) that has demonstrated the ability to cause serious public health impact and spread rapidly internationally.2 More recently, a biregional (SEA and WP regions) Asia-Pacific Dengue Strategic Plan (2008 2015) was developed to reverse the rising trend of dengue in the Member countries of these Regions. This has been endorsed by the Regional Committees of both the South-East Asia Region [resolution SEA/RC61/R5 (2008)] and the Western Pacific Region [resolution WPR/RC59/R6 (2008)]. Due to the high disease burden, dengue has become a priority area for several global organizations other than WHO, including the United Nations Childrens Fund (UNICEF), United Nations Environment Programme (UNEP), the World Bank, and the WHO Special Programme for Research and Training in Tropical Diseases (TDR), among others. In this backdrop, the 1999 Guidelines for Prevention and Control of Dengue/DHF (WHO Regional Publication, SEARO No. 29) have been revised, updated and rechristened as the Comprehensive Guidelines for Prevention and Control of Dengue and Dengue Haemmorhagic Fever: Revised and Expanded. These Guidelines incorporate new developments and strategies in dengue prevention and control.
Comprehensive Guidelines for Prevention and Control of Dengue and Dengue Haemorrhagic Fever
2.
2.1
Global
Dengue epidemics are known to have occurred regularly over the last three centuries in tropical, subtropical and temperate areas around the world. The first epidemic of dengue was recorded in 16353 in the French West Indies, although a disease outbreak compatible with dengue had been reported in China as early as 992 AD.4 During the 18th, 19th and early 20th centuries, epidemics of dengue-like diseases were reported and recorded globally, both in tropical as well as some temperate regions. Rush5 was probably describing dengue when he wrote of break-bone fever occurring in Philadelphia in 1780. Most of the cases during the epidemics of that time mimicked clinical DF, although some displayed characteristics of the haemorrhagic form of the disease. In most Central and South American countries, effective disease prevention was achieved by eliminating the principal epidemic mosquito vector, Aedes aegypti, during the 1950s and 1960s. In Asia, however, effective mosquito control was never achieved. A severe form of haemorrhagic fever, most likely akin to DHF, emerged in some Asian countries following World War II. From the 1950s through 1970s, this form of dengue was reported as epidemics periodically in a few Asian countries such as India, Philippines and Thailand. During the 1980s, incidence increased markedly and distribution of the virus expanded to the Pacific islands and tropical America.6 In the latter region, the species re-infested most tropical countries in the 1980s on account of disbanding of the Ae. aegypti eradication programme in the early 1970s. Increased disease transmission and frequency of epidemics were also the result of circulation of multiple serotypes in Asia. This brought about the emergence of DHF in the Pacific Islands, the Caribbean, and Central and South America. Thus, in less than 20 years by 1998, the American tropics and the Pacific Islands went from being free of dengue to having a serious dengue/ DHF problem.6 Every 10 years, the average annual number of cases of DF/DHF cases reported to WHO continues to grow exponentially. From 2000 to 2008, the average annual number of cases was 1 656 870, or nearly three-and-a-half times the figure for 19901999, which was 479 848 cases (Figure 1). In 2008, a record 69 countries from the WHO regions of South-East Asia, Western Pacific and the Americas reported dengue activity.
Comprehensive Guidelines for Prevention and Control of Dengue and Dengue Haemorrhagic Fever
Geographical extension of the areas with dengue transmission or resurgent dengue activity has been documented in Bhutan, Nepal, Timor-Leste, Hawaii (USA), the Galapagos Islands (Ecuador), Easter Island (Chile), and the Hong Kong Special Administrative Region and Macao Special Administrative Region of China between 2001 and 2004 (Figure 2). Nine outbreaks of dengue occurred in north Queensland, Australia, in four years from 2005 to 2008.7 Figure 1: Average annual number of cases of DF/DHF reported to WHO
1 800 000 1 600 000 1 400 000
Number of cases Number of countries
1 656 870
70 60 50 40 30
1 200 000 1 00 000 800 000 600 000 400 000 200 000 0 908 15 497 122 174 295 554 479 848
20 10
19551959
19601969
19701979
19801989
19901999
Source:.
Comprehensive Guidelines for Prevention and Control of Dengue and Dengue Haemorrhagic Fever
20002008
Number of countries
Number of cases
All four dengue viruses are circulating in Asia, Africa and the Americas. Due to early detection and better case management, reported case-fatality rates have been lower in recent years than in the decades before 2000.8 Countries/areas at risk of dengue transmission in 2008 are shown in Figure 2 and the major risk factors associated with DF/DHF are outlined in Box 3. Box 3: Risk factors associated with DF/DHF Demographic and societal changes: Demographic and societal changes leading to unplanned and uncontrolled urbanization has put severe constraints on civic amenities, particularly water supply and solid waste disposal, thereby increasing the breeding potential of the vector species. Water supply: Insufficient and inadequate water distribution. Solid waste management: Insufficient waste collection and management. Mosquito control infrastructure: Lack of mosquito control infrastructure. Consumerism: Consumerism and introduction of non-biodegradable plastic products, paper cups, used tyres, etc. that facilitate increased breeding and passive spread of the disease to new areas (such as via the movement of incubating eggs because of the trade in used tyres). Increased air travel and globalization of trade: Increased air travel and globalization of trade has significantly contributed to the introduction of all the DENV serotypes to most population centres of the world. Microevolution of viruses:9 The use of the most powerful molecular tools has revealed that each serotype has developed many genotypes as a result of microevolution. There is increasing evidence that virulent strains are replacing the existing non-virulent strains. Introduction of Asian DENV-2 into Cuba in 1981, which coincided with the appearance of DHF, is a classic example. The burden of illness caused by dengue is measured by a set of epidemiological indicators such as the number of clinical cases classified by severity (DF, DHF, DSS), duration of illness episode, quality of life during the illness episode, case-fatality rate and absolute number of deaths during a given period of time. All these epidemiological indicators are combined into a single health indicator, such as disability-adjusted life years (DALYs).a
2.2
Of the 2.5 billion people around the world living in dengue endemic countries and at risk of contracting DF/DHF, 1.3 billion live in 10 countries of the WHO South-East Asia (SEA) Region which are dengue endemic areas. Till 2003, only eight countries in the Region had reported dengue cases. By 2009, all Member countries except the Democratic Peoples Republic (DPR) of Korea reported dengue outbreaks. Timor-Leste reported an outbreak in 2004 for the first time. Bhutan also reported its first dengue outbreak in 2004.10 Similarly, Nepal too reported its first indigenous case of dengue in November 2004.11 The reported dengue cases and deaths between 1985 and 2009 in 10 countries of the WHO SEA Region (all Member States except DPR Korea) (Table 1 and Table 2) underscore the public health importance of this disease in the Region. The number of dengue cases has increased over the last three to five years, with recurring epidemics. Moreover, there has been an increase in the proportion of dengue cases with their severity, particularly in Thailand, Indonesia and Myanmar. The trends in reported cases and casefatality rates are shown in Figure 3.
a Details with example are presented in chapter 14. Comprehensive Guidelines for Prevention and Control of Dengue and Dengue Haemorrhagic Fever
Table 1: Dengue cases reported from countries of the SEA Region, 19852009
1990 0 0 6 291 22 807 0 5 242 0 1 350 92 002 43 511 41 125 67 017 51 688 60 330 37 929 101 689 129 954 24 826 18 617 139 327 114 800 62 767 1 048 656 750 582 440 1 298 980 1 275 1 688 3 343 4 304 8 931 4 749 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 463 38 367 434 121 401 78 742 63 769 98 589 90 194 106 196 102 248 139 079 218 821 54 811 63 672 211 039 188 212 140 635 6 772 1 685 2 279 11 647 2 477 1 854 4 500 13 002 5 828 1 884 15 695 16 047 7 907 7 369 0 0 0 0 0 0 3 1 750 118 180 73 27 38 742 1 126 17 454 0 5 994 45 893 1 128 152 503 179 918 21 120 17 620 17 418 18 783 35 102 44 650 30 730 72 133 21 134 33 443 45 904 40 377 51 934 79 462 95 279 2 683 11 125 7 494 7 847 16 517 1 177 707 944 650 3 306 1 926 12 754 4 153 11 985 12 317 106 425 2 768 11 383 25 11 980 42 456 162 189 830 0 0 0 0 0 0 0 0 0 0 0 0 0 2 579 11 116 120 5 023 157 442 1 680 15 285 3 7 314 62 949 227 250 509 0 0 0 0 0 0 0 0 273 5 555 2 430 6 104 486 3 934 1 048 2 198 466 1991 1992 1993 1994 1995 1996 1997 "1998 "1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 1 181 37 11 476 2009 474 351 15 535 155 607 156 052 1 476 14 480 6 6 555 89 626 108 774 24 287 30 35 010 25 194 175 280 552 232 530
Country
1985
1986
1987
1988
1989
Bangladesh
Bhutan
India
NA
NA
NA
Indonesia
13 588
16 529
23 864
44 573
10 362
Maldives
2 054
Myanmar
2 666
2 092
7 231
1 178
1 196
Nepal
Sri Lanka
10
203
Thailand
80 076
27 837
174 285
26 926
74 391
Timor-Leste
SEA Region
96 330
46 458
205 380
74 741
86 152
Table 2: Dengue deaths and case-fatality rates (CFR) reported from countries of the SEA Region, 19852009
1990 0 0 NA 821 0 179 0 54 414 137 136 222 140 183 31 15 7 7 11 0 0 0 0 0 0 54 116 282 37 67 461 53 18 0 0 0 0 0 0 0 82 0 17 253 578 509 418 471 885 1 192 681 3 12 36 4 10 545 36 18 1 414 0 211 0 8 424 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 4 0 17 422 1 88 0 14 56 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 93 0 7 472 1 14 0 37 32 2001 44 0 53 497 0 204 0 54 245 2002 58 0 33 533 1 170 0 64 176 2003 10 0 215 794 0 78 0 32 73 2004 13 0 45 957 3 79 0 88 48 2 1 468 1.21 1.31 1.11 0.76 1 031 709 750 1 083 1.20 142 1.08 1 925 1.88 1 069 0.77 2 075 0.95 602 1.10 656 1.03 1 097 0.52 1 035 0.55 1 202 0.85 1 235 0.81 2005 4 0 157 1 298 0 169 0 27 71 40 1 766 0.98 2006 11 0 184 1 096 10 128 0 44 59 0 1 532 0.81 2007 1 5 62 1 446 2 171 0 25 67 6 1 785 0.71 2008 0 3 79 940 3 100 0 19 102 1 1 247 0.44 2009 0 8 96 1 396 2 181 0 346 2 0 2 031 0.79
Country
1985
1986
1987
1988
1989
Bangladesh
Bhutan
India
NA
NA
NA
NA
NA
Comprehensive Guidelines for Prevention and Control of Dengue and Dengue Haemorrhagic Fever
Indonesia
460
608
1 105
1 527
464
Maldives
Myanmar
134
111
227
64
62
Nepal
Sri Lanka
NA
NA
NA
20
Thailand
542
236
1 007
179
290
Timor-Leste
SEA Region
1 136
955
2 339
1 779
836
Case-fatality rate
1.18
2.06
1.14
2.38
0.97
Figure 3: Trends in reported number of dengue cases and case-fatality rates (CFR) reported from countries of the SEA Region, 19852009
300 3
250
2.5
200
150
1.5
100
50
0.5
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
Years
Number of cases
The above figure shows that in countries of the SEA Region the trend of dengue cases is showing an increase over the years. The case-fatality rate (CFR), however, has registered a declining trend since 1985 and this could be attributed to better case management.
Category B (Bhutan, Nepal) Endemicity uncertain. Bhutan: First outbreak reported in 2004. Nepal: Reported first indigenous dengue case in 200411.
2009
Case-fatality rate %
3.
The transmission of dengue virus depends upon biotic and abiotic factors. Biotic factors include the virus, the vector and the host. Abiotic factors include temperature, humidity and rainfall.
3.1
The virus
The dengue viruses are members of the genus Flavivirus and family Flaviviridae. These small (50 nm) viruses contain single-strand RNA as genome. The virion consists of a nucleocapsid with cubic symmetry enclosed in a lipoprotein envelope. The dengue virus genome is 11 644 nucleotides in length, and is composed of three structural protein genes encoding the nucleocaprid or core protein (C), a membrane-associated protein (M), an envelope protein (E), and seven non-structural protein (NS) genes. Among non-structural proteins, envelope glycoprotein, NS1, is of diagnostic and pathological importance. It is 45 kDa in size and associated with viral haemagglutination and neutralization activity. The dengue viruses form a distinct complex within the genus Flavivirus based on antigenic and biological characteristics. There are four virus serotypes, which are designated as DENV-1, DENV-2, DENV-3 and DENV-4. Infection with any one serotype confers lifelong immunity to that virus serotype. Although all four serotypes are antigenically similar, they are different enough to elicit cross-protection for only a few months after infection by any one of them. Secondary infection with another serotype or multiple infections with different serotypes leads to severe form of dengue (DHF/DSS). There exists considerable genetic variation within each serotype in the form of phylogenetically distinct sub-types or genotypes. Currently, three sub-types can be identified for DENV-1, six for DENV-2 (one of which is found in non-human primates), four for DENV-3 and four for DENV-4, with another DENV-4 being exclusive to non-human primates.12 Dengue viruses of all four serotypes have been associated with epidemics of dengue fever (with or without DHF) with a varying degree of severity.
3.2
Vectors of dengue
Aedes (Stegomyia) aegypti (Ae. aegypti) and Aedes (Stegomyia) albopictus (Ae. albopictus) are the two most important vectors of dengue.b
Comprehensive Guidelines for Prevention and Control of Dengue and Dengue Haemorrhagic Fever
The subgenus Stegomyia has been upgraded to genus level, known as Stegomyia aegypti. However, for simplicity of reference, the name has been retained as Ae. aegypti Aedes versus Stegomyia. Trends Parasital, 2006, 22 (1): 8-9; Jr.Med. Entom. Policy on Names of Aedine Mosquito Genre and Subgenre]. The sub-genus, Stegomyia has been upgraded to genus level, called as Stegomyia albopictus. However for simplicity of reference, the name has been retained as Ae. albopictus --Aedes versus Stegomyia. Trends Parasital, 2006, 22 (1): 8-9; Jr.Med. Entom. Policy on Names of Aedine Mosquito Genre and Sub-genre).
10
Comprehensive Guidelines for Prevention and Control of Dengue and Dengue Haemorrhagic Fever
Source: Rogers D.J., Wilson, A.J., Hay, S.L. The global distribution of yellow fever and dengue. Adv. Parasitol. 2006. 62:181220.15
Source: Rogers D.J., Wilson, A.J., Hay, S.L. The global distribution of yellow fever and dengue. Adv. Parasitol. 2006. 62:181220.15
Both Ae. aegypti and Ae. albopictus carry high vectorial competency for dengue viruses.
Comprehensive Guidelines for Prevention and Control of Dengue and Dengue Haemorrhagic Fever
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Vectorial capacity Vectorial capacity is governed by the environmental and biological characteristics of the species, and thus these two species differ in their vectorial capacity. Ae. aegypti is a highly domesticated, strongly anthropophilic, nervous feeder (i.e. it bites more than one host to complete one blood meal) and is a discordant species (i.e. it needs more than one feed for the completion of the gonotropic cycle). These habits epidemiologically result in the generation of multiple cases and the clustering of dengue cases in cities. On the contrary, Ae. albopictus still maintains feral moorings and partly invades peripheral areas of urban cities, and thus feeds on both humans and animals. It is an aggressive feeder and a concordant species, i.e. the species can complete its blood meal in one go on one person and also does not require a second blood meal for the completion of the gonotropic cycle. Hence, Ae. albopictus carries poor vectorial capacity in an urban epidemic cycle.
3.3
Host
Dengue viruses, having evolved from mosquitoes, adapted to non-human primates and later to humans in an evolutionary process. The viraemia among humans builds up high titres two days before the onset of the fever (non-febrile) and lasts 57 days after the onset of the fever (febrile). It is only during these two periods that the vector species gets infected. Thereafter, the humans become dead-ends for transmission. The spread of infection occurs through the movement of the host (man) as the vectors movements are very restricted. The susceptibility of the human depends upon the immune status and genetic predisposition.16,17,18 Both monkeys and humans are amplifying hosts and the virus is maintained by mosquitoes transovarially via eggs.
3.4
(1)
(2)
(3)
Transmission of DF/DHF
For transmission to occur the female Ae. aegypti must bite an infected human during the viraemic phase of the illness that manifests two days before the onset of fever and lasts 45 days after onset of fever. After ingestion of the infected blood meal the virus replicates in the epithelial cell lining of
12
Comprehensive Guidelines for Prevention and Control of Dengue and Dengue Haemorrhagic Fever
the midgut and escapes into haemocoele to infect the salivary glands and finally enters the saliva causing infection during probing. The genital track is also infected and the virus may enter the fully developed eggs at the time of oviposition. The extrinsic incubation period (EIP) lasts from 8 to 12 days and the mosquito remains infected for the rest of its life. The intrinsic incubation period covers five to seven days.22
Comprehensive Guidelines for Prevention and Control of Dengue and Dengue Haemorrhagic Fever
13
There is no time-limit to sensitization after a primary infection. The 1997 Santiago de Cuba epidemic clearly demonstrated that with the introduction of DENV-2, DHF had occurred 1620 years after the primary infection with DENV-1.27 Transmission sites Due to the limited flight range of Ae. aegypti,13 DF/DHF spread is caused by human movement. Receptivity (high-breeding potential for Ae. aegypti) and vulnerability (high potential for importation of virus) need to be mapped. Any congregation at receptive areas will result in either transmission from infected mosquito to human or from viraemic human to the uninfected mosquito. Hospitals, schools, religious institutions and entertainment centres where people congregate become the foci of transmission on account of high receptivity and vulnerability for DF/DHF. Further human movement spreads the infection to larger parts of the city.28
3.5
Global climate change refers to large-scale changes in climate patterns over the years, including fluctuations in both rainfall- and temperature-related greenhouse effects (including the emission of carbon dioxide from burning fossil fuel and methane from paddy fields and livestock), whereby solar radiation gets trapped beneath the atmosphere. Global warming is predicted to lead to a 2.0 C4.5 C rise in average global temperatures by the year 2100,29 and this could have a perceptible impact on vector-borne diseases.30 The maximum impact of climate change on transmission is likely to be observed at the extreme end of the temperature range at which the transmission occurs. The temperature range for dengue fever lies between 14 C and 18 C at the lower end and 35 C and 40 C at the upper end. Although the vector species, being a domestic breeder, is endophagic and endophilic, it largely remains insulated by fitting into human ecological requirements. However, with a 2 C increase in temperature the extrinsic incubation period of DENV will be shortened and more infected mosquitoes will be available for a longer period of time.31 Besides that, mosquitoes will bite more frequently because of dehydration and thus further increase man-mosquito contact.
3.6
Other factors that facilitate increased transmission are briefly outlined below:
Urbanization
As per United Nations reports, 40% of the population in developing countries now lives in urban areas, which is projected to rise to 56% by 2030e largely due to ruralurban migration. Such migration from rural to urban areas is due to both push (seeking better earning avenues) and pull (seeking better amenities such as education, health care, etc.) factors. The failure of urban local governments to provide matching civic amenities and infrastructure to accommodate the influx generates unplanned settlements with inadequate potable water, poor sanitation including solid waste disposal, and poor public health infrastructure. All this raises the potential for Ae. aegypti breeding to a high level and makes the environment for transmission conducive.
UN Population Division. World Urbanization Prospects: The 2001 revision. 2002. New York, UN. p.182. m16chap1_1.shtml
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Comprehensive Guidelines for Prevention and Control of Dengue and Dengue Haemorrhagic Fever
3.7
Ae. albopictus has spread farther north compared with Ae. aegypti (Figures 4a and 4b). Its eggs are somewhat resistant to sub-freezing temperatures.32 This raises the possibility that Ae. albopictus could mediate a re-emergence of dengue in the United States of America or in Europe. This species survived the extreme winters in Italy33 and was recently implicated in an outbreak of chikungunya in Italy.34
3.8
Mathematical models project a substantial increase in the transmission of vector-borne diseases in various climate change situations. However, these models have been criticized on the grounds that they do not adequately account for rainfall, interaction between climate variables or relevant socioeconomic factors. The dengue vector Ae. aegypti is highly domesticated and breeds in safe clean waters devoid of any parasite, pathogen or predators. Similarly, adults feed on humans inside houses and rest in sequestered, dark places to complete the gonotropic cycles. In view of these ecological features, Ae. aegypti is least affected by climatic changes and instead maintains a high transmission potential throughout. In an empirical model35 vapour pressure which is a measure of humidity was incorporated to estimate the global distribution of dengue fever. It was concluded that the current geographical limits of dengue fever transmission can be modelled with 89% accuracy on the basis of long-term average vapour pressure. In 1990, almost 30% of the world population, i.e. 1.5 billion people, lived in regions where the estimated risk of dengue transmission was greater than 50%. By 2085, given the population and climatic change projections, it is estimated that 56 billion people (50%60% of the projected global population) would be at risk of dengue transmission compared with 3.5 billion people or 35% of the projected population if climate change would not set in. However, further research on this is needed.
Comprehensive Guidelines for Prevention and Control of Dengue and Dengue Haemorrhagic Fever
15
4.
4.1
Clinical manifestations only short-term cross-protection for the other serotypes. The clinical manifestation depends on the virus strain and host factors such as age, immune status, etc. (Box 5). Box 5: Manifestations of dengue virus infection
Undifferentiated fever
Infants, children and adults who have been infected with dengue virus, especially for the first time (i.e. primary dengue infection), may develop a simple fever indistinguishable from other viral
f This chapter was reviewed at the Consultative Meeting on Dengue Case Classification and Case Management held in Bangkok, Thailand, on 7-8 October 2010. The participants included experts from SEARO and WPRO Member States and one observer each from the University of Massachusetts Medical School, USA, and Armed Forces Research Institute of Medical Sciences, Thailand, and the secretariat comprised members of the WHO Collaborating Centre for Case Management of Dengue/DHF/DSS, QSNICH (Bangkok, Thailand).
Comprehensive Guidelines for Prevention and Control of Dengue and Dengue Haemorrhagic Fever
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infections. Maculopapular rashes may accompany the fever or may appear during defervescence. Upper respiratory and gastrointestinal symptoms are common.
Dengue fever
Dengue fever (DF) is most common in older children, adolescents and adults. It is generally an acute febrile illness, and sometimes biphasic fever with severe headache, myalgias, arthralgias, rashes, leucopenia and thrombocytopenia may also be observed. Although DF may be benign, it could be an incapacitating disease with severe headache, muscle and joint and bone pains (break-bone fever), particularly in adults. Occasionally unusual haemorrhage such as gastrointestinal bleeding, hypermenorrhea and massive epistaxis occur. In dengue endemic areas, outbreaks of DF seldom occur among local people.
4.2
Clinical features
Dengue fever
After an average intrinsic incubation period of 46 days (range 314 days), various non-specific, constitutional symptoms and headache, backache and general malaise may develop. Typically, the onset of DF is sudden with a sharp rise in temperature and is frequently associated with a flushed face36 and headache. Occasionally, chills accompany the sudden rise in temperature. Thereafter, there may be retro-orbital pain on eye movement or eye pressure, photophobia, backache, and pain in the muscles and joints/bones. The other common symptoms include anorexia and altered
18
Comprehensive Guidelines for Prevention and Control of Dengue and Dengue Haemorrhagic Fever
taste sensation, constipation, colicky pain and abdominal tenderness, dragging pains in the inguinal region, sore throat and general depression. These symptoms usually persist from several days to a few weeks. It is noteworthy that these symptoms and signs of DF vary markedly in frequency and severity. Fever: The body temperature is usually between 39 C and 40 C, and the fever may be biphasic, lasting 57 days in the majority of cases. Rash: Diffuse flushing or fleeting eruptions may be observed on the face, neck and chest during the first two to three days, and a conspicuous rash that may be maculopapular or rubelliform appears on approximately the third or fourth day. Towards the end of the febrile period or immediately after defervescence, the generalized rash fades and localized clusters of petechiae may appear over the dorsum of the feet, on the legs, and on the hands and arms. This convalescent rash is characterized by confluent petechiae surrounding scattered pale, round areas of normal skin. Skin itching may be observed. Haemorrhagic manifestations: Skin haemorrhage may be present as a positive tourniquet test and/or petechiae. Other bleeding such as massive epistaxis, hypermenorrhea and gastrointestinal bleeding rarely occur in DF, complicated with thrombocytopenia. Course: The relative duration and severity of DF illness varies between individuals in a given epidemic, as well as from one epidemic to another. Convalescence may be short and uneventful but may also often be prolonged. In adults, it sometimes lasts for several weeks and may be accompanied by pronounced asthenia and depression. Bradycardia is common during convalescene. Haemorrhagic complications, such as epistaxis, gingival bleeding, gastrointestinal bleeding, haematuria and hypermenorrhoea, are unusual in DF. Although rare, such severe bleeding (DF with unusual haemorrhage) are an important cause of death in DF. fever. Dengue fever with haemorrhagic manifestations must be differentiated from dengue haemorrhagic
Clinical laboratory findings In dengue endemic areas, positive tourniquet test and leukopenia (WBC 5000 cells/mm3) help in making early diagnosis of dengue infection with a positive predictive value of 70%80%.37,38 The laboratory findings during an acute DF episode of illness are as follows: Total WBC is usually normal at the onset of fever; then leucopenia develops with decreasing neutrophils and lasts throughout the febrile period. Platelet counts are usually normal, as are other components of the blood clotting mechanism. Mild thrombocytopenia (100 000 to 150 000 cells/mm3) is common and about half of all DF patients have platelet count below 100 000 cells/mm3; but severe thrombocytopenia (<50 000 cells/mm3) is rare.39 Mild haematocrit rise (10%) may be found as a consequence of dehydration associated with high fever, vomiting, anorexia and poor oral intake. Serum biochemistry is usually normal but liver enzymes and aspartate amino transferase (AST) levels may be elevated. It should be noted that the use of medications such as analgesics, antipyretics, anti-emetics and antibiotics can interfere with liver function and blood clotting.
Comprehensive Guidelines for Prevention and Control of Dengue and Dengue Haemorrhagic Fever
19
Differential diagnosis The differential diagnoses of DF include a wide variety of diseases prevalent in the locality (Box 6). Box 6: Differential diagnoses of dengue40
Arboviruses: Chikungunya virus (this has often been mistaken for dengue in South-East Asia). Other viral diseases: Measles; rubella and other viral exanthems; Epstein-Barr Virus (EBV); enteroviruses; influenza; hepatitis A; Hantavirus. Bacterial diseases: Meningococcaemia, leptospirosis, typhoid, melioidosis, rickettsial diseases, scarlet fever. Parasitic diseases: Malaria.
Chikungunya fever (%) 90.3 59.4 40.0 31.6 68.4 30.8 55.6a 23.3 33.3 6.5 59.6a 40.0a 11.1 0.0 15.6 3.1 0.0
21.5 21.5 12.8 12.1 12.0 8.3 6.7 6.4 6.3 3.0
a a
Source: Nimmannitya S., et al., American Journal of Tropical Medicine and Hygiene, 1969, 18:954-971.41 a Statistically significant difference.
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Comprehensive Guidelines for Prevention and Control of Dengue and Dengue Haemorrhagic Fever
A positive tourniquet test (10 spots/square inch), the most common haemorrhagic phenomenon, could be observed in the early febrile phase. Easy bruising and bleeding at venipuncture sites are present in most cases. Fine petechiae scattered on the extremities, axillae, and face and soft palate may be seen during the early febrile phase. A confluent petechial rash with small, round areas of normal skin is seen in convalescence, as in dengue fever. A maculopapular or rubelliform rash may be observed early or late in the disease. Epistaxis and gum bleeding are less common. Mild gastrointestinal haemorrhage is occasionally observed, however, this could be severe in pre-existing peptic ulcer disease. Haematuria is rare. The liver is usually palpable early in the febrile phase, varying from just palpable to 24 cm below the right costal margin. Liver size is not correlated with disease severity, but hepatomegaly is more frequent in shock cases. The liver is tender, but jaundice is not usually observed. It should be noted that the incidence of hepatomegaly is observer dependent. Splenomegaly has been observed in infants under twelve months and by radiology examination. A lateral decubitus chest X-ray demonstrating pleural effusion, mostly on the right side, is a constant finding. The extent of pleural effusion is positively correlated with disease severity. Ultrasound could be used to detect pleural effusion and ascites. Gall bladder oedema has been found to precede plasma leakage. The critical phase of DHF, i.e. the period of plasma leakage, begins around the transition from the febrile to the afebrile phase. Evidence of plasma leakage, pleural effusion and ascites may, however, not be detectable by physical examination in the early phase of plasma leakage or mild cases of DHF. A rising haematocrit, e.g. 10% to 15% above baseline, is the earliest evidence. Significant loss of plasma leads to hypovolemic shock. Even in these shock cases, prior to intravenous fluid therapy, pleural effusion and ascites may not be detected clinically. Plasma leakage will be detected as the disease progresses or after fluid therapy. Radiographic and ultrasound evidence of plasma leakage precedes clinical detection. A right lateral decubitus chest radiograph increases the sensitivity to detect pleural effusion. Gall bladder wall oedema is associated with plasma leakage and may precede the clinical detection. A significantly decreased serum albumin >0.5 gm/dl from baseline or <3.5 gm% is indirect evidence of plasma leakage.39 In mild cases of DHF, all signs and symptoms abate after the fever subsides. Fever lysis may be accompanied by sweating and mild changes in pulse rate and blood pressure. These changes reflect mild and transient circulatory disturbances as a result of mild degrees of plasma leakage. Patients usually recover either spontaneously or after fluid and electrolyte therapy. In moderate to severe cases, the patients condition deteriorates a few days after the onset of fever. There are warning signs such as persistent vomiting, abdominal pain, refusal of oral intake, lethargy or restlessness or irritability, postural hypotension and oliguria. Near the end of the febrile phase, by the time or shortly after the temperature drops or between 37 days after the fever onset, there are signs of circulatory failure: the skin becomes cool, blotchy and congested, circum-oral cyanosis is frequently observed, and the pulse becomes weak and rapid. Although some patients may appear lethargic, usually they become restless and then rapidly go into a critical stage of shock. Acute abdominal pain is a frequent complaint before the onset of shock. The shock is characterized by a rapid and weak pulse with narrowing of the pulse pressure 20 mmHg with an increased diastolic pressure, e.g. 100/90 mmHg, or hypotension. Signs of reduced tissue perfusion are: delayed capillary refill (>3 seconds), cold clammy skin and restlessness. Patients in shock are in danger of dying if no prompt and appropriate treatment is given. Patients may pass into a stage of profound shock with blood pressure and/or pulse becoming imperceptible (Grade 4 DHF). It is noteworthy that most patients remain conscious almost to the terminal stage. Shock is reversible and of short duration if timely and adequate treatment with volume-replacement is given.
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Without treatment, the patient may die within 12 to 24 hours. Patients with prolonged or uncorrected shock may give rise to a more complicated course with metabolic acidosis and electrolyte imbalance, multiorgan failure and severe bleeding from various organs. Hepatic and renal failure are commonly observed in prolonged shock. Encephalopathy may occur in association with multiorgan failure, metabolic and electrolyte disturbances. Intracranial haemorrhage is rare and may be a late event. Patients with prolonged or uncorrected shock have a poor prognosis and high mortality. Convalescence in DHF Diuresis and the return of appetite are signs of recovery and are indications to stop volume replacement. Common findings in convalescence include sinus bradycardia or arrhythmia and the characteristic dengue confluent petechial rash as described for dengue fever. Convalescence in patients with or without shock is usually short and uneventful. Even in cases with profound shock, once the shock is overcome with proper treatment the surviving patients recover within 2 3 days. However, those who have prolonged shock and multiorgan failure will require specific treatment and experience a longer convalescence. It should be noted that the mortality in this group would be high even with specific treatment.
4.3
DHF occurs in a small proportion of dengue patients. Although DHF may occur in patients experiencing dengue virus infection for the first time, most DHF cases occur in patients with a secondary infection.42,43 The association between occurrence of DHF/DSS and secondary dengue infections implicates the immune system in the pathogenesis of DHF. Both the innate immunity such as the complement system and NK cells as well as the adaptive immunity including humoral and cellmediated immunity are involved in this process.44,45 Enhancement of immune activation, particularly during a secondary infection, leads to exaggerated cytokine response resulting in changes in vascular permeability. In addition, viral products such as NS1 may play a role in regulating complement activation and vascular permeability.46,47,48 The hallmark of DHF is the increased vascular permeability resulting in plasma leakage, contracted intravascular volume, and shock in severe cases. The leakage is unique in that there is selective leakage of plasma in the pleural and peritoneal cavities and the period of leakage is short (2448 hours). Rapid recovery of shock without sequelae and the absence of inflammation in the pleura and peritoneum indicate functional changes in vascular integrity rather than structural damage of the endothelium as the underlying mechanism. Various cytokines with permeability enhancing effect have been implicated in the pathogenesis of DHF.49-53 However, the relative importance of these cytokines in DHF is still unknown. Studies have shown that the pattern of cytokine response may be related to the pattern of cross-recognition of dengue-specific T-cells. Cross-reactive T-cells appear to be functionally deficit in their cytolytic activity but express enhanced cytokine production including TNF-a, IFN-g and chemokines.54,55,56 Of note, TNF-a has been implicated in some severe manifestations including haemorrhage in some animal models.57,58 Increase in vascular permeability can also be mediated by the activation of the complement system. Elevated levels of complement fragments have been documented in DHF.59 Some complement fragments such as C3a and C5a are known to have permeability enhancing effects. In recent studies, the NS1 antigen of dengue virus has been shown to regulate complement activation and may play a role in the pathogenesis of DHF.46,47,48 Higher levels of viral load in DHF patients in comparison with DF patients have been demonstrated in many studies.60,61 The levels of viral protein, NS1, were also higher in DHF patients.62 The degrees of viral load correlate with measurements of disease severity such as the amount of
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pleural effusions and thrombocytopenia, suggesting that viral burden may be a key determinant of disease severity.
4.4
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4.5
Clinical manifestations
Laboratory findings
Thrombocytopenia (100 000 cells per mm3 or less)h. Haemoconcentration; haematocrit increase of 20%i from the baseline of patient or population of the same age.
The first two clinical criteria, plus thrombocytopenia and haemoconcentration or a rising haematocrit, are sufficient to establish a clinical diagnosis of DHF. The presence of liver enlargement in addition to the first two clinical criteria is suggestive of DHF before the onset of plasma leakage. The presence of pleural effusion (chest X-ray or ultrasound) is the most objective evidence of plasma leakage while hypoalbuminaemia provides supporting evidence. This is particularly useful for diagnosis of DHF in the following patients: anaemia. severe haemorrhage. where there is no baseline haematocrit. rise in haematocrit to <20% because of early intravenous therapy.
In cases with shock, a high haematocrit and marked thrombocytopenia support the diagnosis of DSS. A low ESR (<10 mm/first hour) during shock differentiates DSS from septic shock. The clinical and laboratory findings associated with the various grades of severity of DHF are shown in Box 7.
h i
The tourniquet test is performed by inflating a blood pressure cuff to a point midway between the systolic and diastolic pressures for five minutes. The test is considered positive when 10 or more petechiae per sq. inch are observed. In DHF the test usually gives a definite positive result with 20 petechiae or more. The test may be negative or only mildly positive in obese patients and during the phase of profound shock. It usually becomes positive, sometimes strongly positive after recovery from shock. This level is usually observed shortly before subsidence of fever and/or onset of shock. Therefore, serial platelet estimation is essential for diagnosis. A few cases may have platelet count above 100 000 mm3 at this period. Direct count using a phase-contrast microscope (normal 200 000-500 000/mm3). In practice, for outpatients, an approximate count from a peripheral blood smear is acceptable. In normal persons, 510 platelets per oil-immersion field (the average observed from 10 fields is recommended) indicate an adequate platelet count. An average of 23 platelets per oil-immersion field or less is considered low (less than 100 000/mm3).
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4.6
The severity of DHF is classified into four grades36,41(Table 4). The presence of thrombocytopenia with concurrent haemoconcentration differentiates Grade I and Grade II DHF from dengue fever. Grading the severity of the disease has been found clinically and epidemiologically useful in DHF epidemics in children in the South-East Asia, Western Pacific and America Regions of WHO. Experiences in Cuba, Puerto Rico and Venezuela suggest that this classification is also useful for adults.
4.7
Early in the febrile phase, the differential diagnoses include a wide spectrum of viral, bacterial and protozoal infections similar to that of DF. Haemorrhagic manifestations, e.g. positive tourniquet test and leucopenia (5000 cells/mm3)63 suggest dengue illness. The presence of thrombocytopenia with concurrent haemoconcentration differentiates DHF/DSS from other diseases. In patients with no significant rise in haematocrit as a result of severe bleeding and/or early intravenous fluid therapy, demonstration of pleural effusion/ascites indicates plasma leakage. Hypoproteinaemia/albuminaemia supports the presence of plasma leakage. A normal erythrocyte sedimentation rate (ESR) helps differentiate dengue from bacterial infection and septic shock. It should be noted that during the period of shock, the ESR is <10 mm/hour.64
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Fever and haemorrhagic manifestation Thrombocytopenia <100 000 cells/ (positive tourniquet test) and mm3; HCT rise 20% evidence of plasma leakage As in Grade I plus spontaneous bleeding. As in Grade I or II plus circulatory failure (weak pulse, narrow pulse pressure (20 mmHg), hypotension, restlessness). As in Grade III plus profound shock with undetectable BP and pulse Thrombocytopenia <100 000 cells/mm3; HCT rise 20%. Thrombocytopenia <100 000 cells/mm3; HCT rise 20%.
DHF DHF#
II III
DHF#
IV
4.8
Complications
DF complications
DF with haemorrhage can occur in association with underlying disease such as peptic ulcers, severe thrombocytopenia and trauma. DHF is not a continuum of DF.
DHF complications
These occur usually in association with profound/prolonged shock leading to metabolic acidosis and severe bleeding as a result of DIC and multiorgan failure such as hepatic and renal dysfunction. More important, excessive fluid replacement during the plasma leakage period leads to massive effusions causing respiratory compromise, acute pulmonary congestion and/or heart failure. Continued fluid therapy after the period of plasma leakage will cause acute pulmonary oedema or heart failure, especially when there is reabsorption of extravasated fluid. In addition, profound/prolonged shock and inappropriate fluid therapy can cause metabolic/electrolyte disturbance. Metabolic abnormalities are frequently found as hypoglycemia, hyponatremia, hypocalcemia and occasionally, hyperglycemia. These disturbances may lead to various unusual manifestations, e.g. encephalopathy.
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4.9
Unusual manifestations are uncommon. In recent years with the geographical spread of dengue illness and with more involvement of adults, there have been increasing reports of DF and DHF with unusual manifestations. These include: neurological, hepatic, renal and other isolated organ involvement. These could be explained as complications of severe profound shock or associated with underlying host conditions/diseases or coinfections. Central nervous system (CNS) manifestations including convulsions, spasticity, changes in consciousness and transient paresis have been observed. The underlying causes depend on the timing of these manifestations in relation to the viremia, plasma leakage or convalescence. Encephalopathy in fatal cases cause encephalitis. It should be noted that exclusion of concurrent infections has not been exhaustive. Table 5 details the unusual/atypical manifestations of dengue. The above-mentioned unusual manifestations may be underreported or unrecognized or not related to dengue. However, it is essential that proper clinical assessment is carried out for appropriate management, and causal studies should be done.
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Source: Gulati S., Maheshwari A. Atypical manifestations of dengue. Trop Med Int Health. 2007 Sep.; 12(9):1087 95.65
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Generally, the percentage of DHF in adults is lower than in children. Adults with DHF have a course similar to that in children. However, some studies have mentioned less severe plasma leakage in adult patients. Yet there are some countries where most deaths are seen in adults, which could be explained by the late recognition of DHF/shock and the higher incidence of bleeding with delayed blood transfusion. Adult patients with shock have been reported to be able to work until the stage of profound shock. In addition, patients self-medicate with analgesics such as paracetamol, NSAIDs, anti-emetic and other drugs that worsen liver and platelet functions. Sometimes fever may not be detected by adult patients themselves. They are more likely to have the risk factors for severe disease such as peptic ulcer disease and others as stated above. A summary of diagnosis of DF and DHF is presented in Box 8a-8c.39 Box 8a: Diagnosis of dengue fever and dengue haemorrhagic feverk Dengue fever Probable diagnosis: Acute febrile illness with two or more of the followingl:
headache, retro-orbital pain, myalgia, arthralgia/bone pain, rash, haemorrhagic manifestations, leucopenia (wbc 5000 cells/mm3), thrombocytopenia (platelet count <150 000 cells/mm3), rising haematocrit (5 10%);
and at least one of following: supportive serology on single serum sample: titre 1280 with haemagglutination inhibition test, comparable IgG titre with enzyme-linked immunosorbent assay, or tasting positive in IgM antibody test, and occurrence at the same location and time as confirmed cases of dengue fever.
Confirmed diagnosis: Probable case with at least one of the following: isolation of dengue virus from serum, CSF or autopsy samples. fourfold or greater increase in serum IgG (by haemagglutination inhibition test) or increase in IgM antibody specific to dengue virus. detection of dengue virus or antigen in tissue, serum or cerebrospinal fluid by immunohistochemistry, immunofluorescence or enzyme-linked immunosorbent assay. detection of dengue virus genomic sequences by reverse transcription-polymerase chain reaction.
Based on discussions and recommendations of the Consultative Meeting on Dengue Case Classication and Case Management held in Bangkok, Thailand, on 7-8 October 2010. .The participants included experts from SEARO and WPRO countries and one observer each from University of Massachusetts Medical School, USA and Armed Forces Research Institute of Medical Sciences, Thailand, and secretariat from the WHO Collaborating Centre for Case Management of Dengue/DHF/DSS, QSNICH (Bangkok, Thailand). Studies have shown that in endemic areas acute febrile illness with a positive TT and leucopenia (WBC5000 cells/mm3) has a good positive predictive value of 70% to 80%. In situations where serology is not available, these are useful for early detection of dengue cases.37,38 Comprehensive Guidelines for Prevention and Control of Dengue and Dengue Haemorrhagic Fever
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m If all the four criteria are met, the sensitivity and specificity is 62% and 92% respectively. Anon S. et al. Dengue Hemorrhagic Fever: The Sensitivity and Specificity of the World Health Organization Definition for Identification of Severe Cases of Dengue in Thailand, 19942005, Clin. Inf. Dis. 2010; 50 (8):1135-43. n If fever and significant plasma leakage are documented, a clinical diagnosis of DHF is most likely even if there is no bleeding or thrombocytopenia.
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5.
Laboratory Diagnosis
Rapid and accurate dengue diagnosis is of paramount importance for: (i) epidemiological surveillance; (ii) clinical management; (iii) research; and (iv) vaccine trials. Epidemiological surveillance requires early determination of dengue virus infection during the outbreak for urgent public health action towards control as well as at sentinel sites for detection of circulating serotypes/genotypes during the inter-epidemic periods for use in forecasting possible outbreaks. Clinical management requires early diagnosis of cases, confirmation of clinical diagnosis and for differential diagnosis from other flaviviruses/infection agents. The following laboratory tests are available to diagnose dengue fever and DHF: Virus isolation serotypic/genotypic characterization Viral nucleic acid detection Viral antigen detection Immunological response based tests IgM and IgG antibody assays Analysis for haematological parameters
5.1
Dengue viraemia in a patient is short, typically occurs 23 days prior to the onset of fever and lasts for four to seven days of illness. During this period the dengue virus, its nucleic acid and circulating viral antigen can be detected (Figure 5). Antibody response to infection comprises the appearance of different types of immunoglobulins; and IgM and IgG immunoglobulin isotypes are of diagnostic value in dengue. IgM antibodies are detectable by days 35 after the onset of illness, rise quickly by about two weeks and decline to undetectable levels after 23 months. IgG antibodies are detectable at low level by the end of the first week, increase subsequently and remain for a longer period (for many years). Because of the late appearance of IgM antibody, i.e. after five days of onset of fever, serological tests based on this antibody done during the first five days of clinical illness are usually negative. During the secondary dengue infection (when the host has previously been infected by dengue virus), antibody titres rise rapidly. IgG antibodies are detectable at high levels, even in the initial phase, and persist from several months to a lifelong period. IgM antibody levels are significantly lower in secondary infection cases. Hence, a ratio of IgM/IgG is commonly used to differentiate between primary and secondary dengue infections. Thrombocytopenia is usually observed between the third and eighth day of illness followed by other haematocrit changes.
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Figure 5 shows the timeline of primary and secondary dengue virus infections and the diagnostic methods that can be used to detect infection at a particular time of illness. Figure 5: Approximate timeline of primary and secondary dengue virus infections and the diagnostic methods that can be used to detect infection
NS1 detection Virus isolation RNA detection
Viraemia
IgM secondary
HIA
25
O.D
IgG secondary
60
80 0
-2
-1
0 1 2 3 4 5 6 7 Onset of symptoms
10
11
12
13
14
15
16-20
21-40
41-60
61-80
90 >90 Days
Source: WHO. Dengue Guidelines for Diagnosis, Treatment, Prevention and Control, New edition, 2009. WHO Geneva.66
5.2
An essential aspect of laboratory diagnosis of dengue is proper collection, processing, storage and shipment of clinical specimens. The type of specimens and their storage and shipment requirements are shown in Table 6. Table 6: Collection, storage and shipment requirements of specimens
Specimen type Acute phase blood (S1) Recovery (convalescent) phase blood (S2+S3) Tissue Time of collection 05 days after onset 1421 days after onset As soon as possible after death Clot retraction 26 hours, 4 C 224 hours, ambient Storage Serum 70 C Serum 20 C 70 C or in formalin Shipment Dry ice Frozen or ambient Dry ice or ambient
Source: Gubler D.J., Sather G.E.. Laboratory diagnosis of dengue and dengue haemorrhagic fever. Proceedings of the International Symposium on Yellow Fever and Dengue; 1988; Rio de Janeiro, Brazil.67
Serological diagnosis using certain methods is arrived at based on the identification of changes in specific antibody levels in paired specimens. Hence serial (paired) specimens are required to confirm or refute a diagnosis of acute flavivirus or dengue infection. Collection of specimens is done at different time intervals as mentioned below:
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Collect a specimen as soon as possible after the onset of illness, hospital admission or attendance at a clinic (this is called the acute phase specimen, S1). Collect a specimen shortly before discharge from the hospital or, in the event of a fatality, at the time of death (convalescent phase specimen, S2). Collect a third specimen, in the event hospital discharge occurs within 12 days of the subsidence of fever, 721 days after the acute serum was drawn (late convalescent phase specimen, S3).
The optimal interval between paired sera, i.e. the acute (S1) and the convalescent (S2 or S3) blood specimen, is 1014 days. Samples of request and reporting forms for dengue laboratory examination are provided in Annex 1. Blood is preferably collected in tubes or vials, but filter paper may be used if this is the only option. Filter paper samples are not suitable for virus isolation.
Whatman No. 3 filter paper discs 12.7 mm ( inch) in diameter are suitable for this purpose, or Nobuto type-1 blood-sampling paper made by Toyo Roshi Kaisha Ltd, Tokyo, Japan.
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Place the dried strips in plastic bags along with a silica bead sachet if possible, and staple them to the Laboratory Examination Request form. Store without refrigeration. Dried filter paper discs may be sent through postal mail.
Serum elution in the laboratory: One of the recommended methods for eluting the blood from filter paper discs is mentioned below: Elute the disc at room temperature for 60 minutes, or at 4 C overnight, in 1 ml of kaolin in borate saline (125 g/litre), pH 9.0, in a test-tube. After elution, keep the tube at room temperature for 20 minutes, shaking it periodically. Centrifuge for 30 minutes at 600 g. For haemagglutination inhibition (HI) test using goose erythrocytes, without removing the kaolin add 0.05 ml of 50% suspension of goose cells to the tube, shake without disturbing the pellet, and incubate at 37 C for 30 minutes. For IgG and IgM assays, elute discs/strips in phosphate buffered saline (PBS) containing 0.5% Tween 20 and 5% non-fat dried milk for two hours at room temperature. Centrifuge at 600 g for 10 minutes and decant the supernatant. The supernatant is equivalent to a 1:30 serum dilution.
Each laboratory must standardize the filter paper technique prior to using it in diagnostic services, using a panel of well characterized sera samples.
5.3
During the early stages of the disease (up to six days of onset of illness), virus isolation, viral nucleic acid or antigen detection can be used to diagnose infection. At the end of the acute phase of infection, immunological tests are the methods of choice for diagnosis.
Isolation of virus
Isolation of dengue virus from clinical specimens is possible provided the sample is taken during the first six days of illness and processed without delay. Specimens that are suitable for virus isolation include: acute phase serum, plasma or washed buffy coat from the patient, autopsy tissues from fatal cases (especially liver, spleen, lymph nodes and thymus), and mosquitoes collected from the affected areas. For short periods of storage (up to 48 hours), specimens to be used for virus isolation can be kept at +4 C to +8 C. For longer storage the serum should be separated and frozen at 70 C and maintained at such a temperature that thawing does not occur. If isolation from leucocytes is to be attempted, heparinized blood samples should be delivered to the laboratory within a few hours. Whenever possible, original material (viraemic serum or infected mosquito pools) as well as laboratory-passaged materials should be preserved for future study. Tissues and pooled mosquitoes are triturated or sonicated prior to inoculation. Different methods of inoculation and methods of confirming the presence of dengue virus are shown in Table 7.50 The choice of methods for isolation and identification of dengue virus will depend on local availability of mosquitoes, cell culture and laboratory capability. Inoculation of serum or plasma into mosquitoes is the most sensitive method of virus isolation, but mosquito cell culture is the most cost-effective method for routine virological surveillance. It is essential for health workers interested in making a diagnosis by means of virus isolation to contact the appropriate virology laboratory prior to the collection of specimens. The acquisition, storage and shipment of the samples can then be organized to have the best chances of successful isolation.
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Inoculation of insect cell cultures, namely C6/36, a clone of Ae. albopictus cells. Inoculation of mammalian cultures, namely vero cells, LLCMK2 and BHK21.
Source: Vorndam V., Kuno G.. Laboratory diagnosis of dengue virus infection. In: Gubler D.J., Kuno G., Editors. Dengue and dengue haemorrhagic fever. Wallingford, Oxon: CAB International; 1997. p. 313-34.68
In order to identify different dengue virus serotypes, mosquito head squashes and slides of infected cell cultures are examined by indirect immunoflourescence using serotype-specific monoclonal antibodies. Currently, cell culture is the most widely used method for dengue virus isolation. The mosquito cell line C6/36 or AP61 are the host cells of choice for isolation of dengue viruses. Inoculation of suckling mice or mosquitoes can be attempted when no other method is available. The isolation and confirmation of the identity of the virus requires substantial skills, competency and an infrastructure with BSL2/BSL3 facilities.
Disadvantages include hard work, need for insectaries to produce a large number of mosquitoes and the isolation precautions to avoid release of infected mosquitoes. However, Toxorhynchitis larvae can be used for inoculation to avoid accidental release of infected mosquitoes.
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Nested RT-PCR Nested RT-PCR assay involves using universal dengue primers targeting the C/prM region of the viral genome for an initial reverse transcription and amplification step, followed by a nested PCR amplification that is serotype-specific. One-step multiplex RT-PCR This test is an alternative to nested RT-PCR. A combination of the four serotype-specific oligonucleotide primers is used in a single reaction step in order to identify the serotype. The products of these reactions are separated by electrophoresis on an agarose gel, and the amplification products are visualized as bands of different molecular weights after staining the gel using ethidium bromide dye, and compared with standard molecular weight markers. In this assay, dengue serotypes are identified by the size of their bands. Real-time RT-PCR The real-time RT-PCR assay is also a one-step assay system using primer pairs and probes that are specific to each dengue serotype. The use of a fluorescent probe enables the detection of the reaction products in real time, in a specialized PCR machine, without the need for electrophoresis. Real-time RT-PCR assays are either singleplex (detecting only one serotype at a time) or multiplex (able to identify all four serotypes from a single sample). These tests offer high-throughput and hence are very useful for large-scale surveillance. Isothermal amplification method The NASBA (nucleic acid sequence-based amplification) assay is an isothermal RNA-specific amplification assay that does not require thermal cycling instrumentation. The initial stage is a reverse transcription in which the single-stranded RNA target is copied into a double-stranded DNA molecule that serves as template for RNA transcription. Amplified RNA is detected either by electrochemiluminescence or in real time with fluorescent-labelled molecular beacon probes. Compared with virus isolation, the sensitivity of the RT-PCR methods varies from 80% to 100% and depends upon the region of the genome targeted by the primers, the approach used to amplify or detect PCR products and the methods employed for subtyping. The advantages of this technology include high sensitivity and specificity, ease of identifying serotypes and early detection of the infection. It is, however, an expensive technology that requires sophisticated instrumentation and skilled manpower. Recently, Loop Mediated Amplification (LAMP) PCR method has been developed, which promises an easy-to-do and less expensive instrumentation alternative for RT-PCR and real-time PCR assays. However, its performance needs to be compared with that of latter nucleic acid methods.69
the illness. Commercial kits for the detection of NS1 antigens are now available; however, these kits do not differentiate between the serotypes. Besides providing an early diagnostic marker for clinical management, it may also facilitate the improvement of epidemiological surveys of dengue infection.
5.4
Five basic serological tests are used for the diagnosis of dengue infection.67,70 These are: haemagglutination-inhibition (HI), complement fixation (CF), neutralization test (NT), IgM capture enzyme-linked immunosorbent assay (MAC-ELISA), and indirect IgG ELISA. For tests other than those that detect IgM, unequivocal serological confirmation depends upon a significant (four-fold or greater) rise in specific antibodies between acute-phase and convalescent-phase serum samples. The antigen battery for most of these serological tests should include all four dengue serotypes, another flavivirus, such as Japanese encephalitis, a non-flavivirus such as chikungunya, and an uninfected tissue as control antigen, when possible.
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MAC-ELISA is slightly less sensitive than the HI test for diagnosing dengue infection. It has the advantage, however, of frequently requiring only a single, properly timed blood sample. Considering the difficulty in obtaining second blood samples and the long delay in obtaining conclusive results from the HI test, this low error rate would be acceptable in most surveillance systems. It must be emphasized, however, that because of the persistence of IgM antibody, MAC-ELISA positive results on single serum samples are only provisional and do not necessarily mean that the dengue infection is current. It is reasonably certain, however, that the person had had a dengue infection sometime in the previous two to three months. MAC-ELISA has become an invaluable tool for surveillance of DF, DHF and DSS. In areas where dengue is not endemic, it can be used in clinical surveillance for viral illness or for random, population-based serosurveys, with the certainty that any positives detected are recent infections.67 It is especially useful for hospitalized patients who are generally admitted at a late stage of illness after detectable IgM is already present in the blood.
IgG-ELISA
An indirect IgG-ELISA has been developed and compares well with the HI test.70 This test can also be used to differentiate primary and secondary dengue infections. The test is simple and easy to perform, and is thus useful for high-volume testing. The IgG-ELISA is very non-specific and exhibits the same broad cross-reactivity among flaviviruses as the HI test; it cannot be used to identify the infecting dengue serotype. These tests can be used independently or in combination, depending upon the type of the sample and test available in order to confirm the diagnosis as shown in Table 8. Table 8: Interpretation of dengue diagnostic test Highly suggestive One of the following: (1) (2) IgM+ve in a single serum sample. (1) Confirmed One of the following: RT-PCR+ve. Virus culture+ve. IgM seroconversion in paired sera. IgG seroconversion in paired sera or fourfold IgG titre increase in paired sera.
IgG+ve in a single serum sample with a HI (2) titre of 1280 or greater. (3) (4)
Source: Jaenisch T., Wills B. (2008) Results from the DENCO study. TDR/WHO Expert Meeting on Dengue Classification and Case Management. Implications of the DENCO study. WHO, Geneva, Sept. 30Oct. 1 2008.71
IgM/IgG ratio
The IgM/IgG ratio is used to distinguish primary infection from secondary dengue infection . A dengue virus infection is defined as primary if the capture IgM/IgG ratio is greater than 1.2, or as secondary if the ratio is less than 1.2. This ratio testing system has been adopted by select commercial vendors. However, it has been recently demonstrated that the ratios vary depending on whether the patient has a serological non-classical or a classical dengue infection, and the ratios have been redefined taking into consideration the four subgroups of classical infection with dengue.72 The adjusted ratios of greater than 2.6 and less than 2.6, established by these authors, correctly classified 100% of serologically classical dengue infections and 90% of serologically non-classical infections.
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Neutralization test
The neutralization test or NT is the most specific and sensitive serological test for dengue viruses used for determining the immune protection. The common protocol used in most dengue laboratories is the serum dilution plaque reduction neutralization test (PRNT). The major disadvantages of this technique are the expense and time required to perform the test, and the technical difficulty involved since it requires cell culture facility. It is, therefore, not routinely used in most laboratories. However, it is of great use in the development of vaccines and their efficacy trials.
5.5
A number of commercial rapid format serological test-kits for anti-dengue IgM and IgG antibodies have become available in the past few years, some of these producing results within 15 minutes.70 Unfortunately, the accuracy of most of these tests is uncertain since they have not yet been properly validated. Rapid tests can yield false positive results due to cross-reaction with other flaviviruses, malaria parasite, leptospires and immune disorders such as rheumatoid and lupus. It is anticipated that these test kits can be reformulated to make them more specific, thus making global laboratorybased surveillance for DF/DHF an attainable goal in the near future. It is important to note that these kits should not be used in the clinical setting to guide the management of DF/DHF cases because many serum samples taken in the first five days after the onset of illness will not have detectable IgM antibodies. The tests would thus give a false negative result. Reliance on such tests to guide clinical management could, therefore, result in an increase in case-fatality rates.q In an outbreak situation, if more than 50% of specimens test positive when rapid tests are used, dengue virus is then highly suggestive of being the cause of febrile outbreak.
For further details, refer to: Update on the Principles and Use of Rapid Tests in Dengue, Prepared by the Malaria, Other Vectorborne and Parasitic Diseases Unit of the Western Pacific Region of WHO for dengue programme managers and health practitioners (2009).
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5.6
Haematological tests
Standard haematological parameters such as platelet count and haematocrit are important and are part of the biological diagnosis of dengue infection. Therefore, they should be closely monitored. Thrombocytopenia, a drop in platelet count below 100 000 per l, may be occasionally observed in dengue fever but is a constant feature in DHF. Thrombocytopenia is usually found between the third and eighth day of illness often before or simultaneously with changes in haematocrit. Haemoconcentration with an increase in the haematocrit of 20% or more (for the same patient or for a patient of the same age and sex) is considered to be a definitive evidence of increased vascular permeability and plasma leakage.
5.7
Handling of blood and tissues exposes health-care workers to the risk of contracting serious communicable diseases. Improper disposal of clinical and laboratory materials containing pathogens is a health risk to individuals as well as the community. To minimize these risks, health-care workers need to be trained and provided with appropriate infrastructure, especially personal protective material and equipment.73
5.8
Quality assurance
Laboratories undertaking dengue diagnosis work need to establish a functional quality system so that the results generated are reliable. Strengthening internal quality control and checking the quality of diagnostics using a panel of well-characterized samples at regular intervals will ensure accurate diagnosis. Laboratories employing in-house diagnostics need to standardize the assay against wellcharacterized samples in order to ascertain sensitivity and specificity. Participating in an external quality assessment scheme can enhance the credibility of the laboratory and support the selection of appropriate public health action.
5.9
Network of laboratories
Every country should endeavour to establish a network of dengue diagnostic laboratories with a specific mandate for each level of the health laboratory. While the peripheral laboratories can undertake RDT and have the competence to collect, store and ship the material to the next higher level of laboratories, the national laboratories should perform genetic characterization of the virus, organize external quality assessment schemes, impart training and develop national guidelines. The national laboratories are also encouraged to join international networks such as the European Network for Diagnostics of Imported Viral Diseases (ENIVD) to draw support from the global community.
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6.
The clinical spectrum of dengue infection includes asymptomatic infection, DF and DHF, which is characterized by plasma leakage and haemorrhagic manifestations. At the end of the incubation period, the illness starts abruptly and is followed by three phases, the febrile, critical and recovery phase,74 as depicted in the schematic representation below (Figure 7): Figure 7: Course of dengue illness
Source: Nimmannitya S.. Clinical manifestations and management of dengue/dengue haemorrhagic fever. In: Thongcharoen, P Ed. . Monograph on dengue/dengue haemorrhagic fever. WHO SEARO 1993, p 4854, 5561.74
This chapter was reviewed at the Consultative Meeting on Dengue Case Classification and Case Management held in Bangkok, Thailand, on 78 October 2010. The participants included experts from Member States of the WHO SEA and WP Regions and observers from the University of Massachusetts Medical School, USA and the Armed Forces Research Institute of Medical Sciences, Thailand. The Secretariat comprised staff from the WHO Collaborating Centre for Case Management of Dengue/DHF/DSS, QSNICH, Bangkok, Thailand.
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6.1
During epidemics all hospitals, including those at the tertiary level, find a heavy influx of patients. Therefore, hospital authorities should organize a frontline Dengue Desk to screen and triage suspected dengue patients. Suggested triage pathways are indicated below in Box 9 and Box 10. Box 9: Steps for OPD screening during dengue outbreak
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Primary triage
Triage has to be performed by a trained and competent person. If the patient arrives in hospital in a severe/critical condition, then send this patient directly to a trained nurse/medical assistant (refer to number 3 below). For other patients, proceed as following: (1) History of the duration (number of days) of fever and warning signs (Box 11) of high-risk patients to be assessed by a trained nurse or staff, not necessarily medical. (2) Tourniquet test to be conducted by trained personnel (if there is not enough staff, just inflate the pressure to 80 mmHg for >12 years of age and 60 mmHg for children aged 5 to 12 years for five minutes). (3) Vital signs, including temperature, blood pressure, pulse rate, respiratory rate and peripheral perfusion, to be checked by trained nurse or medical assistant. Peripheral perfusion is assessed by palpation of pulse volume, temperature and colour of extremities, and capillary refill time. This is mandatory for all patients, particularly so when digital blood-pressure monitors and other machines are used. Particular attention is to be given to those patients who are afebrile and have tachycardia. These patients and those with reduced peripheral perfusion should be referred for immediate medical attention, CBC and blood sugar-level tests at the earliest possible. (4) Recommendations for CBC: all febrile patients at the first visit to get the baseline HCT, WBC and PLT. all patients with warning signs. all patients with fever >3 days. all patients with circulatory disturbance/shock (these patients should undergo a glucose check).
Results of CBC: If leucopenia and/or thrombocytopenia is present, those with warning signs should be sent for immediate medical consultation. (5) Medical consultation: Immediate medical consultation is recommended for the following: shock. patients with warning signs, especially those whose illness lasts for >4 days. Shock: Resuscitation and admission. Hypoglycemic patients without leucopenia and/or thrombocytopenia should receive emergency glucose infusion and intravenous glucose containing fluids. Laboratory investigations should be done to determine the likely cause of illness. These patients should be observed for a period of 824 hours. Ensure clinical improvement before sending them home, and they should be monitored daily. Those with warning signs. High-risk patients with leucopenia and thrombocytopenia.
(7) Patient and family advice should be carefully delivered before sending him/her home (Box 12). This can be done in a group of 5 to 20 patients by a trained person who may not be a nurse/doctor. Advice should include bed rest, intake of oral fluids or a soft diet, and reduction of fever by tepid sponging in addition to paracetamol. Warning signs should be emphasized, and it should be made clear that should these occur patients must seek immediate medical attention even if they have a scheduled appointment pending.
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(8) Follow-up visits: Patients should be aware that the critical period is during the afebrile phase and that follow-up with CBC is essential to detect early danger signs such as leucopenia, thrombocytopenia, and/or haematocrit rise. Daily follow-up is recommended for all patients except those who have resumed normal activities or are normal when the temperature subsides. Box 11: Warning signs Box 12: A. No clinical improvement or worsening of the situation just before or during the transition to afebrile phase or as the disease progresses. Persistent vomiting, not drinking. Severe abdominal pain. Lethargy and/or restlessness, sudden behavioural changes. Bleeding: Epistaxis, black stool, haematemesis, excessive menstrual bleeding, darkcoloured urine (haemoglobinuria) or haematuria. Giddiness. Pale, cold and clammy hands and feet. Less/no urine output for 46 hours. Handout for home care of dengue patients (information to be given to patients and/or their family member(s) at the outpatient department)
Home care advice (family education) for patients: Patient needs to take adequate bed rest. Adequate intake of fluids (no plain water) such as milk, fruit juice, isotonic electrolyte solution, oral rehydration solution (ORS) and barley/rice water. Beware of overhydration in infants and young children. Keep body temperature below 39 C. If the temperature goes beyond 39 C, give the patient paracetamol. Paracetamol is available in 325 mg or 500 mg doses in tablet form or in a concentration of 120 mg per 5 ml of syrup. The recommended dose is 10 mg/kg/dose and should be administered in frequencies of not less than six hours. The maximum dose for adults is 4 gm/day. Avoid using too much paracetamol, and aspirin or NSAID is not recommended. Tepid sponging of forehead, armpits and extremities. A lukewarm shower or bath is recommended for adults. Watch out for the warning signs (as in Box 11): No clinical improvement or worsening of the situation just before or during the transition to afebrile phase or as the disease progresses. Persistent vomiting, lack of water intake. Severe abdominal pain. Lethargy and/or restlessness, sudden behavioural changes. Bleeding: Epistaxis, black coloured stools, haematemesis, excessive menstrual bleeding, dark-coloured urine (haemoglobinuria) or haematuria. Giddiness. Pale, cold and clammy hands and feet. Less/no urine output for 46 hours.
B.
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6.2
The details of management of DF/DHF cases in hospital observation wards or upon admission are presented below:75,76,77
Monitoring of dengue/DHF patients during the critical period (thrombocytopenia around 100 000 cells/mm3)
The critical period of DHF refers to the period of plasma leakage which starts around the time of defervescence or the transition from febrile to afebrile phase. Thrombocytopenia is a sensitive indicator of plasma leakage but may also be observed in patients with DF. A rising haematocrit of 10% above baseline is an early objective indicator of plasma leakage. Intravenous fluid therapy should be started in patients with poor oral intake or further increase in haematocrit and those with warning signs. The following parameters should be monitored: General condition, appetite, vomiting, bleeding and other signs and symptoms. Peripheral perfusion can be performed as frequently as is indicated because it is an early indicator of shock and is easy and fast to perform. Vital signs such as temperature, pulse rate, respiratory rate and blood pressure should be checked at least every 24 hours in non-shock patients and 12 hours in shock patients. Serial haematocrit should be performed at least every four to six hours in stable cases and should be more frequent in unstable patients or those with suspected bleeding. It should be noted that haematocrit should be done before fluid resuscitation. If this is not possible, then it should be done after the fluid bolus but not during the infusion of the bolus. Urine output (amount of urine) should be recorded at least every 8 to 12 hours in uncomplicated cases and on an hourly basis in patients with profound/prolonged shock or those with fluid overload. During this period the amount of urine output should be about 0.5 ml/kg/h (this should be based on the ideal body weight).
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Box 13: Additional laboratory investigations Complete blood count (CBC). Blood glucose. Blood gas analysis, lactate, if available. Serum electrolytes and BUN, creatinine. Serum calcium. Liver function tests. Coagulation profile, if available. Right lateral decubitus chest radiograph (optional). Group and match for fresh whole blood or fresh packed red cells. Cardiac enzymes or ECG if indicated, especially in adults. Serum amylase and ultrasound if abdominal pain does not resolve with fluid therapy. Any other test, if indicated.
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Source: Holiday M.A., Segar W.E.. Maintenance need for water in parenteral fluid therapy. Pediatrics 1957;19: 823.78
Rate of intravenous fluids should be adjusted to the clinical situation. The rate of IV fluid differs in adults and children. Table 10 shows the comparable/equivalent rates of IV infusion in children and adults with respect to the maintenance. Table 10: Rate of IV fluid in adults and children
Note Half the maintenance M/2 Maintenance (M) M + 5% deficit M + 7% deficit M + 10% deficit
Source: Holiday M.A., Segar W.E.. Maintenance need for water in parenteral fluid therapy. Pediatrics 1957; 19:823.78
Platelet transfusion is not recommended for thrombocytopenia (no prophylaxis platelet transfusion). It may be considered in adults with underlying hypertension and very severe thrombocytopenia (less than 10 000 cell/mm3).
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note that the rate of plasma leakage is NOT even]. The rate of IV replacement should be adjusted according to the rate of plasma loss, guided by the clinical condition, vital signs, urine output and haematocrit levels. Figure 8: Rate of infusion in non-shock cases
Source: Kalayanarooj S. and Nimmannitya S. In: Guidelines for Dengue and Dengue Haemorrhagic Fever Management. Bangkok Medical Publisher, Bangkok 2003.79
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Source: Kalayanarooj S. and Nimmannitya S. In: Guidelines for Dengue and Dengue Haemorrhagic Fever Management. Bangkok Medical Publisher, Bangkok 2003.79
Laboratory investigations (ABCS) should be carried out in both shock and non-shock cases when no improvement is registered in spite of adequate volume replacement (Box 14). Box 14: Laboratory investigations (ABCS) for patients who present with profound shock or have complications, and in cases with no clinical improvement in spite of adequate volume replacement Abbreviation AAcidosis Laboratory investigations Note Blood gas (capillary or Indicate prolonged shock. Organ involvement venous) should also be looked into; liver function and BUN, creatinine. Haematocrit If dropped in comparison with the previous value or not rising, cross-match for rapid blood transfusion. Hypocalcemia is found in almost all cases of DHF but asymptomatic. Ca supplement in more severe/ complicated cases is indicated. The dosage is 1 ml/kg, dilute two times, IV push slowly (and may be repeated every six hours, if needed), maximum dose 10 ml of Ca gluconate. Most severe DHF cases have poor appetite together with vomiting. Those with impaired liver function may have hypoglycemia. Some cases may have hyperglycemia.
BBleeding
CCalcium
Electrolyte, Ca++
SBlood sugar
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It is essential that the rate of IV fluid be reduced as peripheral perfusion improves; but it must be continued for a minimum duration of 24 hours and discontinued by 36 to 48 hours. Excessive fluids will cause massive effusions due to the increased capillary permeability. The volume replacement flow for patients with DSS is illustrated below (Box 15). Box 15: Volume replacement flow chart for patients with DSSs
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If blood pressure is restored after fluid resuscitation with or without blood transfusion, and organ impairment is present, the patient has to be managed appropriately with special supportive treatment. Examples of organ support are peritoneal dialysis, continuous renal replacement therapy and mechanical ventilation. If intravenous access cannot be obtained urgently, try oral electrolyte solution if the patient is conscious or the intraosseous route if otherwise. The intraosseous access is life-saving and should be attempted after 25 minutes or after two failed attempts at peripheral venous access or after the oral route fails.
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Congenital and ischaemic heart diseases: Fluid therapy should be more cautious as they may have less cardiac reserves. For patients on steroid therapy, continued steroid treatment is recommended but the route may be changed.
Management of convalescence
Convalescence can be recognized by the improvement in clinical parameters, appetite and general well-being. Haemodynamic state such as good peripheral perfusion and stable vital signs should be observed. Decrease of HCT to baseline or below and dieresis are usually observed. Intravenous fluid should be discontinued. In those patients with massive effusion and ascites, hypervolemia may occur and diuretic therapy may be necessary to prevent pulmonary oedema. Hypokalemia may be present due to stress and diuresis and should be corrected with potassium-rich fruits or supplements. Bradycardia is commonly found and requires intense monitoring for possible rare complications such as heart block or ventricular premature contraction (VPC). Convalescence rash is found in 20%30% of patients.
Signs of recovery
Stable pulse, blood pressure and breathing rate. Normal temperature. No evidence of external or internal bleeding. Return of appetite. No vomiting, no abdominal pain. Good urinary output. Stable haematocrit at baseline level. Convalescent confluent petechiae rash or itching, especially on the extremities.
Management of complications
The most common complication is fluid overload.
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Detection of fluid overload in patients Early signs and symptoms include puffy eyelids, distended abdomen (ascites), tachypnoea, mild dyspnoea. Late signs and symptoms include all of the above, along with moderate to severe respiratory distress, shortness of breath and wheezing (not due to asthma) which are also an early sign of interstitial pulmonary oedema and crepitations. Restlessness/agitation and confusion are signs of hypoxia and impending respiratory failure.
Management of fluid overload Review the total intravenous fluid therapy and clinical course, and check and correct for ABCS (Box 14). All hypotonic solutions should be stopped. In the early stage of fluid overload, switch from crystalloid to colloid solutions as bolus fluids. Dextran 40 is effective as 10 ml/kg bolus infusions, but the dose is restricted to 30 ml/kg/day because of its renal effects. Dextran 40 is excreted in the urine and will affect urine osmolarity. Patients may experience sticky urine because of the hyperoncotic nature of Dextran 40 molecules (osmolarity about twice that of plasma). Voluven may be effective (osmolarity = 308 mosmole) and the upper limit is 50ml/kg/day. However, no studies have been done to prove its effectiveness in cases of DHF/DSS. In the late stage of fluid overload or those with frank pulmonary oedema, furosemide may be administered if the patient has stable vital signs. If they are in shock, together with fluid overload 10 ml/kg/h of colloid (dextran) should be given. When the blood pressure is stable, usually within 10 to 30 minutes of infusion, administer IV 1 mg/kg/dose of furosemide and continue with dextran infusion until completion. Intravenous fluid should be reduced to as low as 1 ml/kg/h until discontinuation when haematocrit decreases to baseline or below (with clinical improvement). The following points should be noted: These patients should have a urinary bladder catheter to monitor hourly urine output. Furosemide should be administered during dextran infusion because the hyperoncotic nature of dextran will maintain the intravascular volume while furosemide depletes in the intravascular compartment. After administration of furosemide, the vital signs should be monitored every 15 minutes for one hour to note its effects. If there is no urine output in response to furosemide, check the intravascular volume status (CVP or lactate). If this is adequate, pre-renal failure is excluded, implying that the patient is in an acute renal failure state. These patients may require ventilatory support soon. If the intravascular volume is inadequate or the blood pressure is unstable, check the ABCS (Box 14) and other electrolyte imbalances. In cases with no response to furosemide (no urine obtained), repeated doses of furosemide and doubling of the dose are recommended. If oliguric renal failure is established, renal replacement therapy is to be done as soon as possible. These cases have poor prognosis. Pleural and/or abdominal tapping may be indicated and can be life-saving in cases with severe respiratory distress and failure of the above management. This has to be done with extreme caution because traumatic bleeding is the most serious complication and leads to death. Discussions and explanations about the complications and the prognosis with families are mandatory before performing this procedure.
Management of encephalopathy
Some DF/DHF patients present unusual manifestations with signs and symptoms of central nervous system (CNS) involvement, such as convulsion and/or coma. This has generally been shown to be
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encephalopathy, not encephalitis, which may be a result of intracranial haemorrhage or occlusion associated with DIC or hyponatremia. In recent years, there has been an increasing number of reported cases with CNS infections documented by virus isolations from the cerebrospinal fluid (CSF) or brain. Most of the patients with encephalopathy report hepatic encephalopathy. The principal treatment of hepatic encephalopathy is to prevent the increase of intracranial pressure (ICP). Radiological imaging of the brain (CT scan or MRI) is recommended if available to rule out intracranial haemorrhage. The following are recommendations for supportive therapy for this condition: Maintain adequate airway oxygenation with oxygen therapy. Prevent/reduce ICP by the following measures: give minimal IV fluid to maintain adequate intravascular volume; ideally the total IV fluid should not be >80% fluid maintenance. switch to colloidal solution earlier if haematocrit continues to rise and a large volume of IV is needed in cases with severe plasma leakage. administer a diuretic if indicated in cases with signs and symptoms of fluid overload. positioning of the patient must be with the head up by 30 degrees. early intubation to avoid hypercarbia and to protect the airway. may consider steroid to reduce ICP Dexamethazone 0.15 mg/kg/dose IV to be . administered every 68 hours. give lactulose 510 ml every six hours for induction of osmotic diarrhoea. local antibiotic gets rid of bowel flora; it is not necessary if systemic antibiotics are given.
Maintain blood sugar level at 80100 mg/dl per cent. Recommend glucose infusion rate is anywhere between 46 mg/kg/hour. Correct acid-base and electrolyte imbalance, e.g. correct hypo/hypernatremia, hypo/ hyperkalemia, hypocalcemia and acidosis. Vitamin K1 IV administration; 3 mg for <1-year-old, 5 mg for <5-year-old and 10 mg for>5-year-old and adult patients. Anticonvulsants should be given for control of seizures: phenobarbital, dilantin and diazepam IV as indicated. Transfuse blood, preferably freshly packed red cells, as indicated. Other blood components such as as platelets and fresh frozen plasma may not be given because the fluid overload may cause increased ICP . Empiric antibiotic therapy may be indicated if there are suspected superimposed bacterial infections. H2-blockers or proton pump inhibitor may be given to alleviate gastrointestinal bleeding. Avoid unnecessary drugs because most drugs have to be metabolized by the liver. Consider plasmapheresis or haemodialysis or renal replacement therapy in cases with clinical deterioration.
more experienced in the care of these critically ill dengue patients. The following patients should be referred for closer monitoring and probably accorded special treatment at a higher tier of hospital care: infants <1 year old. obese patients. pregnant women. profound/prolonged shock. significant bleeding. repeated shock 23 times during treatment. patients who seem not to respond to conventional fluid therapy. patients who continue to have rising haematocrit and no colloidal solution is available. patients with known underlying diseases such as Diabetes mellitus (DM) , hypertension, heart disease or haemolytic disease. patients with signs and symptoms of fluid overload. patient with isolated/multiple organ involvement. patients with neurological manifestations such as change of consciousness, semi-coma, coma, convulsion, etc. Discussions and counselling sessions with families. Prior contact with the referral hospital; communicating with doctors and nurses responsible. Stabilizing patients before transfer. Ensuring that the referral letter must contain information about clinical conditions, monitoring parameters (haematocrit, vital signs, intake/output), and progression of disease including all important laboratory findings. Taking care during transportation. Rate of IV fluid is important during this time. It is preferable to be given at a slower rate of about 5 ml/kg/h to prevent fluid overload. At least a nurse should accompany the patient. Review of referred patients by a specialist as soon as they arrive at the referral hospital.
Referral procedure
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Clinical Practice Guidelines (CPG) (the above-named personnel should undergo a brief training on the use of CPG). Medicines and solutions: paracetamol. oral rehydration solution. IV fluid. crystalloid: 0.9% and 5% Dextrose in isotonic normal saline solution (D/NSS), 5% Dextrose Aectated Ringers (DAR), 5% Dextrose Lactated Ringers (DLR). colloid-hyperoncotic (plasma expander): 10% dextran40 in NSS. 20% or 50% glucose. vitamin K1. calcium gluconate. potassium Chloride (KCl) solution. sodium bicarbonate. IV fluids and vascular access, including scalp vein, medicut, cotton, gauze and 70% alcohol. oxygen and delivery systems. sphygmomanometer with three different cuff sizes. automate CBC machine (Coulter counter). micro-centrifuge (for haematocrit determination). microscope (for platelet count estimation). glucometer (for blood-sugar level). lactatemeter. Basic: Complete blood count (CBC): haematocrit, white blood cell (WBC) count, platelet count and differential count. More complicated cases: blood sugar. liver function test. renal function test (BUN, creatinine). electrolyte, calcium. blood gas analysis. coagulogram: partial thromboplastin time (PTT), prothrombin time (PT), thrombin time (TT). chest X-ray. ultrasonography.
Laboratory support:
Blood bank: fresh whole blood, packed red cell (platelet concentrate).
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7.
7.1
Epidemiological surveillance
Epidemiological surveillance is an ongoing systematic collection, recording, analysis, interpretation and dissemination of data for initiating suitable public health interventions for prevention and control.
Objectives of surveillance
The objectives of public health surveillance applicable to dengue are to: detect epidemics early for timely intervention; measure the disease burden; monitor trends in the distribution and spread of dengue over time; assess the social and economic impact of dengue on the affected community; evaluate the effectiveness of prevention and control programmes; and facilitate planning and resource allocation based on the lessons learnt from programme evaluation.
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differentiate the associated illnesses from those caused by other viruses, bacteria and parasites. Therefore, surveillance should be supported by laboratory diagnosis. However, the reporting of dengue disease generally has to rely on clinical diagnosis combined with simple clinical laboratory tests and available epidemiological information. Passive surveillance should require case reports from every clinic, private physician and health centre or hospital that provides medical attention to the population at risk. However, even when mandated by law, passive surveillance is insensitive because not all clinical cases are correctly diagnosed during periods of low transmission when the level of suspicion among medical professionals is low. Moreover, many patients with mild, non-specific viral syndrome self medicate at home and do not seek formal treatment. By the time dengue cases are detected and reported by physicians under a passive surveillance system, substantial transmission has already occurred and it may even have peaked. In such cases, it is often too late to control the epidemic. However, passive surveillance for DF/DHF has two problems. First, there is no consistency in reporting standards. Some countries report only DHF while others report both DF and DHF. Secondly, the WHO case definitions are also not strictly adhered to while reporting the cases. These problems lead to both underreporting and overreporting that actually weakens the surveillance systems. Active surveillance The goals of an active surveillance system allow health authorities to monitor dengue transmission in a community and tell, at any point in time, where transmission is occurring, which virus serotypes are circulating, and what kind of illness is associated with the dengue infection.4 To accomplish this, the system must be active and have good diagnostic laboratory support. Effectively managed, such a surveillance system should be able to provide an early warning or predictive capability for epidemic transmission. The rationale is that if epidemics can be predicted, they can be prevented. This type of proactive surveillance system must have at least three components that place emphasis on the inter- or pre-epidemic period. These are a sentinel clinic/physician network, a fever alert system that uses community health workers, and a sentinel hospital system (Box 16). Box 16: Components of laboratory-based, proactive surveillance for DF/DHF during interepidemic periodst
Type of surveillance Sentinel clinic/physician Samplesu Approach Blood from representative cases Representative samples taken of viral syndrome, taken 5 to 15 round the year and processed days after the onset of symptoms. timely for virus isolation and for IgM antibodies. Blood samples from representative cases of febrile illness. Blood and tissue samples taken during hospitalization and/or at the time of death. Increased febrile illness in the community is investigated immediately. All haemorrhagic disease and all viral syndromes with fatal outcome are investigated immediately.
Fever alert
Sentinel hospital
t u
During an epidemic, after the virus serotype(s) is known, the case definition should be more specific and surveillance focused on severe disease. All samples are processed weekly for virus isolation and/or for dengue-specific IgM antibodies.
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The sentinel clinic/physician and fever alert components are designed to monitor non-specific viral syndromes in the community. This is especially important for dengue viruses because they are frequently maintained in tropical urban centres in a silent transmission cycle, often presenting as non-specific viral syndromes. The sentinel clinic/physician and fever alert systems are also very useful for monitoring other common infectious diseases such as influenza, measles, malaria, typhoid, leptospirosis and others that present in the acute phase as non-specific febrile illnesses. In contrast to the sentinel clinic/physician component, which requires sentinel sites to monitor routine viral syndromes, the fever alert system relies on community health and sanitation and the alertness of other workers to any increase in febrile activity in their community, and to report this to the health departments central epidemiology unit. Investigations by the latter should be immediate but flexible. It may involve telephonic follow-up or active investigation by an epidemiologist who visits the area to take samples. The sentinel hospital component should be designed to monitor severe disease. Hospitals used as sentinel sites should include all facilities that admit patients for severe infectious diseases in the community. This network should also include the physicians for infectious disease who usually consult patients with such cases. The system can target any type of severe disease, but for dengue it should include all patients with any haemorrhagic manifestation; an admission diagnosis of viral encephalitis, aseptic meningitis and meningococcal shock; and/or a fatal outcome following a viral prodrome.19 An active surveillance system is designed to monitor disease activity during the inter-epidemic period prior to increased transmission. Box 16 outlines the active surveillance system for DF/DHF, giving the types of specimens and approaches required. It must be emphasized that once epidemic transmission has begun, the active surveillance system must be refocused on severe disease rather than on viral syndromes. Surveillance systems should be designed and adapted to the areas where they will be initiated. Event-based surveillance Event-based surveillance is aimed at investigating an unusual health event, namely fevers of unknown aetiology and clustering of cases. Unlike the classical surveillance system, event-based surveillance is not based on routine collection of data but should be an investigation conducted by an epidemiological unit supported by a microbiologist, an entomologist and other personnel relevant to the particular event to initiate interventions to control and prevent further spread of the infection.
7.2
The International Health Regulations (IHR) were formulated in 2005 (World Health Assembly resolution WHA58.3) and came into force in 2007. The purpose and scope of these Regulations are to prevent, protect against, control and provide a public health response to the international spread of disease in ways that are commensurate with and restricted to public health risks, and which avoid unnecessary interference with international traffic and trade.2 The IHR (2005) encompass dengue as a disease of concern to the international community because of its high potential for build-up of epidemics of DF and DHF. The IHR enjoin Member States to develop capabilities for detection, reporting and responding to global health threats by establishing effective surveillance systems. Core obligations for Member States and for WHO are outlined in the Decision Instrument for the assessment and notification of events that may constitute a public health emergency of international concern (PHEIC). These are also mentioned in Annex 2
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and 3 respectively. Thailand is the first country in the South-East Asia Region to have developed an IHR Action Plan for 20082012 (Box 17). Box 17: Thailand develops IHR Action Plan for 2008201280 The Ministry of Public Health, Royal Government of Thailand, has formulated national action plans to develop public health infrastructure and human resources to meet the core capacity requirements as envisaged under the International Health Regulations (2005). The Plan for 20082012 was approved by the Cabinet in December 2007. The objectives of the Plan focus on capacity-building of all institutions involved in surveillance and public health emergencies, including laboratories and hospitals, and the 18 points of entry, and also on building capacity to coordinate, among various related governmental and private institutions and the community, the implementation of IHR (2005) in an integrated manner.
7.3
Vector surveillance
Surveillance of Ae. aegypti is important in determining the distribution, population density, major larval habitats, and spatial and temporal risk factors related to dengue transmission, and levels of insecticide susceptibility or resistance,81 in order to prioritize areas and seasons for vector control. These data will enable the selection and use of the most appropriate vector control tools, and can be used to monitor their effectiveness. There are several methods available for the detection and monitoring of larval and adult populations. The selection of appropriate methods depends on surveillance objectives, levels of infestation, and availability of resources.
Larval surveys
For practical reasons, the most common survey methodologies employ larval sampling procedures rather than egg or adult collections. The basic sampling unit is the house or premise, which is systematically searched for water-storage containers. Containers are examined for the presence of mosquito larvae and pupae. Depending on the objectives of the survey, the search may be terminated as soon as Aedes larvae are found, or it may be continued until all containers have been examined. The collection of specimens for laboratory examination is necessary to confirm the species present. Three commonly used indices for monitoring Ae. aegypti infestation levels81,82 are presented in Box 18.
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Box 18: Indices used to assess the levels of Ae. aegypti infestations House Index (HI): Percentage of houses infested with larvae and/or pupae. HI = Number of houses infested Number of houses inspected X 100
Container Index (CI): Percentage of water-holding containers infested with larvae or pupae. CI = Number of positive containers X 100 Number of containers inspected Breateau Index (BI): Number of positive containers per 100 houses inspected. BI = Number of positive containers Number of houses inspected X 100
The House Index has been most widely used for monitoring infestation levels, but it neither takes into account the number of positive containers nor the productivity of those containers. Similarly, the container index only provides information on the proportion of water-holding containers that are positive. The Breateau Index establishes a relationship between positive containers and houses, and is considered to be the most informative, but again there is no reflection of container productivity. Nevertheless, in the course of gathering basic information for calculating the Breateau Index, it is possible and desirable to obtain a profile of the larval habitat characteristics by simultaneously recording the relative abundance of the various container types, either as potential or actual sites of mosquito production (e.g. number of positive drums per 100 houses, number of positive tyres per 100 houses, etc.). These data are particularly relevant to focus efforts for the management or elimination of the most common habitats and for the orientation of educational messages in aid of community-based initiatives.
Pupal/demographic surveys
The rate of contribution of newly emerged adults to the adult mosquito population from different container types can vary widely. The estimates of relative adult production may be based on pupal counts81 (i.e. counting all pupae found in each container). The corresponding index is the Pupal Index (Box 19). Box 19: Pupal Index: Number of pupae per house Pupal Index (PI) = Number of pupae Number of houses inspected X 100
In order to compare the relative importance of larval habitats, the Pupal Index can be disaggregated by useful, non-essential and natural containers, or by specific habitat types such as tyres, flower vases, drums, clay pots, etc. Given the practical difficulties faced and labour-intensive efforts entailed in obtaining pupal counts, especially from large containers, this method may not be used for routine monitoring or in every survey of Ae. aegypti populations, but may be reserved for
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special studies or used in each locality once during the wet season and once during the dry season to determine the most productive container types. The Pupal Index has been most frequently used for operational research purposes. In any community, if the classes of containers with the highest rates of adult emergence are known, their selective targeting for source reduction or other vector control interventions can be the basis for the optimized use of limited resources.83,84 The pupal/demographic survey is a method for identifying these epidemiologically most important container classes. Unlike the traditional indices described above, pupal/demographic surveys measure the total number of pupae in different classes of containers in a given community. In practice, conducting a pupal/demographic survey involves visiting a sampling of houses. The number of persons living in the house is recorded. At each location, and with the permission of the householder, the field workers systematically search for and strain the contents of each water-filled container through a sieve, and re-suspend the sieved contents in a small amount of clean water in a white enamel or plastic pan. All the pupae are pipetted into a labelled vial. Large containers are a significant problem in pupal/demographic surveys because of the difficulty of determining the absolute number of pupae. In such circumstances sweep-net methods have been developed with calibration factors to estimate the total number of pupae in specific container types. If there is container-inhabiting species in the area other than Ae. aegypti, on return to the laboratory the contents of each vial are transferred to small cups and covered with mosquito netting secured with a rubber band. They are held until adult emergence occurs and taxonomic identification and counts can be made. The collection of demographic data makes it possible to calculate the ratio between the numbers of pupae (a proxy for adult mosquitoes) and persons in the community. There is growing evidence to suggest that together with other epidemiological parameters, notably dengue serotype-specific seroconversion rates and temperature, it is possible to determine the degree of vector control needed in a specific location to inhibit virus transmission. This remains an important area for research and awaits validation.
Adult surveys
Adult vector sampling procedures can provide valuable data for specific studies such as seasonal population trends, transmission dynamics, transmission risk, and evaluation of adulticide interventions. However, the results may be less reproducible than those obtained from the sampling of immature stages. The collection methods also tend to be labour-intensive and heavily dependent on the proficiency and skill of the collector. Landing collections Landing collections on humans are a sensitive means of detecting low-level infestations, but are very labour-intensive. Both male and female Ae. Aegypti are attracted to humans. Since adult males have low dispersal rates, their presence can be a reliable indicator of proximity to hidden larval habitats. The rates of capture, typically using hand nets or aspirators as mosquitoes approach or land on the collector, are usually expressed in terms of landing counts per man hour. As there is no prophylaxis for dengue or other viruses transmitted by Aedes mosquitoes, the method raises safety and ethical concerns in endemic areas. Resting collections During periods of inactivity, adult mosquitoes typically rest indoors, especially in bedrooms, and mostly in dark places such as clothes closets and other sheltered sites. Resting collections require systematic
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searching of these sites for adult mosquitoes with the aid of a flashlight. A labour-intensive method is to capture the adults using mouth or battery-powered aspirators and hand-held nets with the aid of flashlights. Recently, a much more productive, standardized and less labour-intensive method using battery-operated backpack aspirators has been developed.85 Following a standardized, timed collection routine in select rooms of each house, densities are recorded as the number of adults collected per house (females, males or both) or the number of adults collected for every human-hour of effort. When the mosquito population density is low, the percentage of houses found positive for adults is sometimes used. Another means of collecting adult mosqutoes is through the use of the insecticide impregnated fabric trap86,87 (IIFT), wherein the mosquitoes resting on the fabric hung inside the trap get killed upon contact with the insecticide and are collected in the bottom tray of the trap. These can then be sorted according to species and checked for the presence of Aedes. These traps, however, need to be evaluated for their efficacy in different field settings.
Oviposition traps
Ovitraps are devices used to detect the presence of Ae. aegypti and Ae. albopictus where the population density is low and larval surveys are largely unproductive (e.g. when the Breateau Index is less than 5), as well as under normal conditions. They are particularly useful for the early detection of new infestations in areas from which the mosquitoes have been previously eliminated. For this reason, they are used for surveillance at international ports of entry, particularly airports, which comply with the International Health Regulations (2005) and which should be maintained free of vector breeding. An ovitrap enhanced with hay infusion has been shown to be a very reproducible and efficient method for Ae. aegypti surveillance in urban areas and has also been found to be useful to evaluate control programmes such as adulticidal space spraying on adult female populations.88 The standard ovitrap is a wide-mouthed, pint-sized glass jar, painted black on the outside. It is equipped with a hardboard or wooden paddle clipped vertically to the inside with its rough side facing inwards. The jar is partially filled with water and is placed appropriately in a suspected habitat, generally in or around homes. The enhanced CDC ovitrap has yielded eight times more Ae. aegypti eggs than the original version. In this method, double ovitraps are placed. One jar contains an olfactory attractant made from a standardized seven day-old infusion while the other contains a 10% dilution of the same infusion. Ovitraps are usually serviced on a weekly basis, but in the case of enhanced ovitraps are serviced every 24 hours. The paddles are examined under a dissecting microscope for the presence of Ae. aegypti eggs, which are then counted and stored. Where both Ae. aegypti and Ae. albopictus occur, eggs should be hatched and then the larvae or adults identified, since the eggs of those species cannot be reliably distinguished from each other. The percentage of positive ovitraps provides a simple index of infestation levels. Again, if the eggs are counted it can provide an estimate of the adult female population. Figure 10 illustrates assembled and non-assembled ovitraps.
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Plastic collar
Mosquito eggs
Assembled
Non-assembled
Source: National Environment Agency, Ministry of Environment and Water Resource, Singapore, 2008.89
The placement and use of this method is discussed in detail by Nathan M.B.. et al.84
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Larval surveillance The commonly-used larval indices (house, container and Breateau) are useful for determining general distribution, seasonal changes and principal larval habitats, as well as for evaluating environmental sanitation programmes. They have direct relevance to the dynamics of disease transmission. However, the threshold levels of vector infestation that constitute a trigger for dengue transmission are influenced by many factors, including mosquito longevity and immunological status of the human population. There are instances (e.g. in Singapore), where dengue transmission occurred even when the House Index was less than 2%.90 Therefore, the limitations of these indices must be recognized and studied more carefully to determine how they correlate with adult female population densities, and how all indices correlate with the disease-transmission risk. The development of alternative, practical and more sensitive entomological surveillance methodologies is an urgent need. The level and type of vector surveillance selected by each country or control programme should be determined by operational research activities conducted at the local level.
7.4
Sampling approaches
The sample size for routine larval surveys should be calculated using statistical methods based on the expected level of infestation and the desired level of confidence in the results. Annex 4 gives tables and examples on how to determine the number of houses to be inspected. Several approaches as in Box 20 can be used. Box 20: Sampling approaches Systematic sampling: Every nth house is examined throughout the community or along linear transects through the community. For example, if a sample of 5% of the houses is to be inspected, every 20th house would be inspected. This is a practical option for rapid assessment of vector population levels, especially in areas where there is no house numbering system. Simple random sampling: The houses to be examined are obtained from a table of random numbers (obtained from statistical textbooks or from a calculator or computer-generated list). This is a more laborious process, as detailed house maps or lists of street addresses are a prerequisite for identifying the selected houses. Stratified random sampling: This approach minimizes the problem of under- and over-representation by subdividing the localities into sectors or strata. Strata are usually based on identified risk factors, such as areas without piped water supply, areas not served by sanitation services, and densely-populated areas. A simple random sample is taken from each stratum, with the number of houses inspected being in proportion to the number of houses in that sector.
Frequency of sampling
The sampling frequency would depend on the objective of the control programme. It should be decided on a case-by-case basis taking into consideration the life-cycle of the mosquito.
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Control programmes using integrated strategies do not require sampling at frequent intervals to assess the impact of the applied control measures. This is especially true where the effect of the alternative strategies outlasts residual insecticides (example, larvivorous fish in large potable waterstorage containers, source reduction or mosquito-proofing of containers) or when larval indices are high (HI greater than 10%). On the other hand, feedback at least on a monthly basis may be desirable to monitor and guide community activities and to identify the issues that need more scrutiny, especially when the HI is 10% or lower. For specific research studies, it may be necessary to sample on a weekly, daily or even hourly basis (e.g. to determine the diurnal pattern of biting activity).
7.5
Information on the susceptibility of Ae. aegypti to insecticides is of fundamental importance for the planning and evaluation of control. The status of resistance in a population must be carefully monitored in a number of representative sentinel sites depending on the history of insecticide usage and eco-geographical situations, to ensure that timely and appropriate decisions are made on issues such as use of alternative insecticides or change of control strategies. During the past 40 years, chemicals have been widely used to control mosquitoes and other insects from spreading diseases of public health importance. As a result, Ae. aegypti and other dengue vectors in several countries91 have developed resistance to commonly-used insecticides, including DDT, temephos, malathion, fenthion, permethrin, propoxur and fenitrothion. However, the operational impact of resistance on dengue control has not been fully assessed.w In countries where DDT resistance has been widespread, precipitated resistance to currentlyused pyrethroid compounds that are being increasingly used for space spray is a challenge as well. Since both groups of insecticide have the same mode of action which acts on the same target site, the voltage-gated sodium channel and mutations in the kdr gene have been associated with resistance to DDT and pyrethroid insecticides in Ae. aegypti. It is, therefore, advisable to obtain baseline data on insecticide susceptibility before insecticidal control operations are started, and to continue periodically monitoring susceptibility levels of larval or adult mosquitoes. WHO kitsx for testing the susceptibility of adults and larval mosquitoes remain the standard methods for determining the susceptibility of Aedes populations.92 Biochemical and immunological techniques for testing individual mosquitoes have also been developed and are yet available for routine field use.
7.6
In addition to the evaluation of aspects such as vector density and distribution, community-oriented, integrated pest management strategies require that other parameters be periodically monitored. These include the distribution and density of the human population, settlement characteristics, and conditions of land tenure, housing styles and education. The monitoring of these parameters is relevant and of importance to planning purposes and for assessing the dengue risk. Knowledge of changes over time in the distribution of water supply
w x Ranson H, Burhani J, Lumjuan N, Black WC. Insecticide resistance in dengue vectors, 2010. TropIKA.net Journal; 1(1).. tropika.net/scielo.php?script=sci_arttext&pid=S2078-86062010000100003&lng=en&nrm=iso&tlng=en Instructions for testing and purchase of kits, test papers and solutions are available at en/WHO_CDS_CPE_PVC_2001.2.pdf
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services, their quality and reliability, as well as in domestic water-storage and solid waste disposal practices is also particularly relevant. Meteorological data are important as well. Such information aids in planning targeted source reduction and management activities, as well as in organizing epidemic interventions measures. Some of these data sets are generated by the health sector, but other sources of data may be necessary. In most cases, annual or even less frequent updates will suffice for programme management purposes. In the case of meteorological data, especially rainfall patterns, humidity and temperature, a more frequent analysis is warranted if it is to be of predictive value in determining seasonal trends in vector populations and their short-term fluctuations.
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8.
Dengue Vectors
8.1
In the South-East Asia Region of WHO, Aedes aegypti (or Ae. aegypti, and also known as Stegomyia aegypti)93 is the principal epidemic vector of dengue viruses. Aedes albopictus (Ae. albopictus) has been recognized as a secondary vector that is also important in the maintenance of the viruses.
Aedes aegypti
Taxonomic status Ae. aegypti exhibits a continuous spectrum of scale patterns across its range of distribution from a very pale form to a dark form, with associated behavioural differences.94 It is essential to understand the bionomics of the local mosquito population as a basis for its control (Figure 11). Figure 11: Ae. aegypti (female)
Source: D.S. Kettle, Medical and Veterinary Entomology. 2nd Edition. CAB International. 1995. p. 110.95
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Geographical distribution in South-East Asia Distribution Ae. aegypti is widespread in tropical and subtropical areas of South-East Asia. Its distribution appears to be related to the 20 C isotherm, which roughly correlates with the tropical zone between latitude 40N and 40S. It is most common in urban areas. The rural spread of Ae. aegypti is a relatively recent occurrence associated with developmental and infrastructural growth initiatives such as expansion of rural water supply schemes and improved transport systems (see Figure 4a). In semi-arid areas as in parts of India, Ae. aegypti is an urban vector and populations typically fluctuate with rainfall and water storage habits.96 In other countries of South-East Asia where the annual rainfall is generally greater than 200 cm, Ae. aegypti populations Figure 12: Life-cycle of are more stable and established in urban, semi-urban and rural Ae. aegypti areas. Because of traditional water storage practices in Indonesia, Myanmar and Thailand, their densities are higher in semi-urban areas than in urban areas. Urbanization tends to increase the number of habitats suitable for Ae. aegypti. In some cities where vegetation is abundant, both Ae. aegypti and Ae. albopictus occur together. But Ae. aegypti is generally the dominant species, depending on the availability and type of larval habitat and the extent of urbanization. The premise index for Ae. aegypti was the highest in slum houses, shop houses and multistoreyed flats. Ae. albopictus, on the other hand, did not seem to relate to the prevailing housing type in its distribution but tended to occur more commonly in areas with open spaces and vegetation. Altitude Altitude is an important factor in limiting the distribution of Ae. aegypti. In India, Ae. aegypti ranges from sea level to heights of approximately 1200 metres above sea level. Lower elevations (less than 500 metres) have moderate to heavy mosquito populations while mountainous areas (higher than 500 metres) have low populations.97 In countries of South-East Asia, an altitude of 1000 to 1500 metres appears to be the limit for Ae. aegypti distribution. In other regions of the world, it is found at even higher altitudes, for example, up to 2200 metres98 in Columbia. Life-cycle The mosquito has four distinct stages in its life-cycle: egg, larva, pupa and adult (Figure 12). Eggs The female Ae. aegypti lays about 50 to 120 eggs in small containers such as flower vases, water-storage jars and other indoor water recepticles, as well as in rainwater collected in small containers such as cups, tyres, etc. outdoors. Eggs are deposited
Source: Bruce-Chwatt L.J.. Essential Malariology. 1985, John Wiley and Sons New York. chapter5a.pdf
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singly on damp surfaces just above the waterline. Most female Ae. aegypti lay eggs in several oviposition sites during a single gonotrophic cycle. Embryonic development is usually completed in 48 hours in a warm and humid environment. Once the embryonic development is complete, the eggs can withstand long periods of desiccation (for more than a year). Eggs hatch once the containers are flooded, but not all eggs hatch at the same time. The capacity of eggs to withstand desiccation facilitates the survival of the species in adverse climatic conditions. Larvae and pupae The larvae pass through four developmental stages. The duration of the larval development depends on temperature, availability of food and larval density in the receptacle. Under optimal conditions, the time taken from hatching to the emergence of the adult can be approximatey 10 days and as short as seven days, including two days in the pupal stage. At low temperatures, however, it may take several weeks for adults to emerge. Throughout most of South-East Asia, Ae. aegypti oviposits almost entirely in domestic and man-made water receptacles.y These include a multitude of receptacles found in and around urban environments (households, construction sites and factories) such as water-storage jars, saucers on which flowerpots rest, flower vases, cement baths, foot baths, wooden and metal barrels, metal cisterns, discarded tyres, bottles, tin cans, polystyrene containers, plastic cups, discarded wet-cell batteries, glass containers associated with spirit houses (shrines), drainpipes and ant-traps in which the legs of cupboards and tables are often rested. Natural larval habitats are rare, but include tree holes, leaf axils and coconut shells. In hot and dry regions, overhead tanks and groundwater-storage tanks may be primary habitats. In areas where water supplies are irregular, inhabitants store water for household use, thereby increasing the number of available larval habitats. While such man-made water receptacles may be removed to deny the Ae. aegypti a breeding habitat, one must also be prepared to eliminate other unconventional breeding habitats that the mosquito would be forced to find. Adults Soon after emergence, the adult mosquitoes mate and the inseminated female may take a blood meal within 2436 hours. Blood is the source of protein essential for the maturation of eggs. Ae. aegypti, being a discordant species, takes more than one blood meal to complete one gonotropic cycle. This behaviour increases manmosquito contact and is of great epidemiological importance. Feeding behaviour Ae. aegypti is highly anthropophilic, although it may feed on other available warm-blooded animals. Being a diurnal species, females have two periods of biting activity: one in the morning for several hours after daybreak and the other in the afternoon for several hours before dark.99,100,101 The actual peaks of biting activity may vary with location and season. Ae. aegypti, being a nervous feeder, may feed on more than one person. This behaviour greatly increases its epidemic transmission efficiency. Thus, it is not uncommon to see several members of the same household with an onset of illness occurring within 24 hours, suggesting that they were infected by the same infective mosquito.19 Ae. aegypti generally does not bite at night, but it will feed at night in lighted rooms.100
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Resting behaviour More than 90% of the Ae. aegypti population rests on non-sprayable surfaces, namely dark, humid, secluded places inside houses or buildings, including bedrooms, closets, bathrooms and kitchens. Less often is it found outdoors in vegetation or other protected sites. The preferred indoor resting surfaces are the undersides of furniture, hanging objects such as clothes and curtains, and walls. Hence, indoor residual spray is not an option for its control as with malaria vectors. Flight range The dispersal of adult female Ae. aegypti is influenced by a number of factors including the availability of oviposition sites and blood meals, but appears to be often limited to within 3050 metres of the site of emergence. However, recent studies in Puerto Rico (USA) indicate that they may disperse more than 400 metres primarily in search of oviposition sites.102 Passive transportation can occur via desiccated eggs and larvae in containers. Longevity The adult Ae. aegypti has a lifespan of about 34 weeks. During the rainy season, when survival is longer, the risk of virus transmission is greater. More research is required on the natural survival of Ae. aegypti under various environmental conditions. Virus transmission A vector mosquito may become infected when it feeds on a viraemic human host. In the case of DF/ DHF, viraemia in the human host may occur 12 days before the onset of fever and lasts for about five days after the onset of fever.103 After an intrinsic incubation period of 1012 days, the virus grows through the midgut to infect other tissues in the mosquito, including the salivary glands. If it bites other susceptible persons after the salivary glands become infected, it transmits dengue virus to those persons by injecting the salivary fluid.
Aedes albopictus
Ae. albopictus (Figure 13) belongs to the same subgenus (Stegomyia) as Ae. aegypti. This species is widely distributed in Asia in both tropical and temperate countries. During the past two decades, the species has extended its range (Figure 4b) to North and South America including the Caribbean, Africa, Southern Europe and some Pacific islands.104 It is estimated that the northern limit for overwintering Ae. albopictus is the 0 0C isotherm, and in summer its northward expansion is 5 0C isotherm, much further north than Ae. aegypti can colonize.95 Figure 13: Aedes albopictus
Source:
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Ae. albopictus is primarily a forest species that has adapted to rural, suburban and urban human environments. It oviposits and develops in tree holes, bamboo stumps and leaf axils in forest habitats; and in artificial containers in urban settings. It is an indiscriminate blood feeder and more zoophagic than Ae. aegypti. Its flight range may be up to 500 metres. Unlike Ae. aegypti, some strains in northern Asia and America are adapted to the cold, with eggs that can spend the winter in diapause. In some areas of Asia and the Seychelles, Ae. albopictus has been occasionally incriminated as the vector of epidemic DF/DHF though it is much less important than Ae. aegypti. In the laboratory, both species can transmit dengue virus vertically from a female through the eggs to her progeny, although Ae. albopictus does so more readily.105 Taxonomic status Ae. alobopictus can be easily recognized from other stegomyia species by the following combination of characters: palpi with white scales, scutum with a long, medium longitudinal white stripe extending from the interior margin to about the level of wing root (Figure 13). Geographical distribution in South-East Asia Ae. alobopictus is widespread in all countries of South-East Asia. It is believed that the species originated from this region of the world.106 Altitude Basically Ae. albopictus is a feral species most commonly found in fringe areas of forests. The presence of this species deep inside the forest is questionable. In Thailand, Ae. albopictus has been collected in three forested habitats in elevations ranging from 430 metres to 1800 metres.107 Life-cycle The species has four distinct stages in its life-cycle: egg, larva, pupa and adult.106 Eggs The female mosquito lays about 100 eggs that can withstand desiccation for long periods. Eggs hatch on flooding. Larve and pupae Under laboratory conditions, the larval stages at 25 C and with optional food take 5 to 10 days to transform to the pupal stage, which takes two more days to emerge as an adult. At low temperatures, the development period get prolonged. Development, however, ceases at temperatures of 11 C and below. Being feral species the mosquito breeds in tree holes, bamboo stumps and coconut shells at forest fringes, although it invades peripheral areas of urban cities through man-made containers filled with rainwater. In parks and gardens in cities, the species breeds on flower beds and various other natural/man-made containers. While such man-made water receptacles may be removed to deny the Ae. aegypti a breeding habitat, one must be prepared to watch out for other more unconventional breeding habitats that the mosquito would be forced to find. Adults After emergence, mating occurs between adult mosquitoes and the inseminated females may take a blood meal within 2436 hours. Ae. albopictus is an aggressive feeder and takes the full blood meal in one go to complete genesis, as it is a concordant species. This behaviour as well as feeding
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on other mammals/birds reduces its vectorial capacity. Unlike Ae. aegypti, some strains are adapted to the cold of northern Asia with their eggs spending the winter in diapause. Ae. albopictus is an efficient bridge vector between enzootic and human cycles among the human population living near the forest fringes. It is also more efficient then Ae. aegypti in maintaining the virus transovarially (vertically) as a reservoir. Resting behaviour Ae. albopictus generally rests outdoors near the ground and in any part of a forest. Survival Results of laboratory research with Ae. albopictus at 25 C and relative humidity of 30% brought out that: i) females live longer than males; and ii) females usually live from four to eight weeks in the laboratory but may survive up to three to six months.
Vector identification
Pictorial keys to Aedes (Stegomyia) mosquitoes breeding in domestic containers are given in Annex 5. The keys include Culex quinquefasciatus, which may be found in the same habitats.108
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9.
Dengue fever/DHF control is primarily dependent on the control of Ae. aegypti, since no vaccine is yet available for the prevention of dengue infection and there are no specific drugs for its treatment. Dengue vector control programmes in the South-East Asia Region have, in general, recorded modest success. Earlier attempts relied almost exclusively on space spraying of insecticides for adult mosquito control. However, space spraying required specific operations that were often not adhered to, and most countries found its costs prohibitive as well. Subsequently, source reduction by clean-up campaigns and/or larviciding with insecticides has been promoted widely. However, their success has been limited on account of the variable degrees of compliance by communities and the nonacceptability of larvicidal treatment either due to the bad odour of the larvicide used or inherent misgivings about it that are prevalent in some communities. To achieve sustainability of a successful DF/DHF vector control programme it is essential to focus on the larval source reduction while closely cooperating with non-health sectorssuch as nongovernmental organizations, civic organizations and community groupsto ensure community understanding and involvement in implementation. There is, therefore, a need to adopt an integrated approach to mosquito control by including all appropriate methods (environmental, biological and chemical) that are safe, cost-effective and environmentally acceptable. A successful and sustainable Ae. aegypti control programme must involve partnerships between government agencies and the community. The approaches described below are considered necessary to achieve long-term and sustainable control of Ae. aegypti.
9.1
Environmental management
Environmental management involves planning, organization, execution and monitoring of activities for the modification and/or manipulation of environmental factors or their interplay with human beings with a view to prevent or minimize vector breeding and reduce human-vector-virus contact. The control of Ae. aegypti in Cuba and Panama in the early part of the 20th century was based mainly on environmental management.15,109 Such measures remain applicable wherever dengue is endemic. In 1982 the World Health Organization110 defined three kinds of environmental management (see Box 21). Environmental methods to control Ae. aegypti and Ae. albopictus and reduce man-vector contact include source reduction, solid waste management, modification of man-made breeding sites, and improved house design. The major environmental management methods used for controlling immature stages of vectors are summarized in Box 22.
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Box 21: Environmental management methods Environmental modification: This includes any long-lasting physical transformation of land, water and vegetation aimed at reducing vector habitats without causing unduly adverse effects on the quality of the human environment. Environmental manipulation: This incorporates planned recurrent activities aimed at producing temporary changes in vector habitats that involve the management of essential and non-essential containers, and the management or removal of natural breeding sites. Changes to human habitation or behaviour: These feature the efforts made to reduce man-vector-virus contact.
Box 22: Environmental measures for control of some Ae. aegypti production sites
Production site Empty, clean, scrubbed weekly Mosquitoproof cover Store under roof Modify design Fill (sand/ soil) Collect, recycle/ dispose Puncture or drain
Essential Water evaporation cooler Water storage tank/ cistern Drum (4055 gallons) Flower vase with water Potted plants with saucers Ornamental pool/ fountain Roof gutter/sun shades Animal water container Ant-trap Non-essential Used tyres Discarded large appliances Discarded buckets Discarded food and drink containers Natural Tree holes Rock holes + + + + + + + + + + + + + + + + + + + + + + + +
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Environmental modification
Improved water supply Whenever piped water supply is inadequate and available only at restricted hours or at low pressure, the storage of water in varied types of containers becomes a necessary practice that leads to increased Aedes breeding. The majority of such containers are often large and heavy (e.g. storage jars) and can neither be easily disposed of nor cleaned. In rural areas, unpolluted, disused wells become breeding grounds for Ae. aegypti. It is essential that potable water supplies be delivered in sufficient quantity, quality and consistency to reduce the necessity and use of water-storage containers that serve as the most productive larval habitats. Mosquito-proofing of overhead tanks/cisterns or underground reservoirs Where Ae. aegypti larval habitats include overhead tanks/cisterns and masonry chambers of piped waterlines, these structures should be mosquito-proofed.111 A suggested design is illustrated in Annex 6a. Similarly, mosquito-proofing of domestic wells and underground water-storage tanks should be ensured. Filling, land levelling and transformation of impoundment margins These are usually of permanent nature; however, correct operation and adequate maintenance are essential for their effective functioning.
Environmental manipulation
Draining water supply installations Water collection/leakages in masonry chambers, distribution pipes, valves, sluice valves, surface boxes for fire hydrants, water meters, etc. that serve as important Ae. aegypti larval habitats in the absence of preventive maintenance should be provided with soak pits (Annex 6b). Covering domestic water-storage containers The major sources of Ae. aegypti breeding in most urban areas of South-East Asia are containers storing water for household use, including clay, ceramic and cement water jars, metal drums, and smaller containers storing fresh water or rainwater. Water storage containers should be covered with tightly fitting lids or screens and care should be taken to replace them after water is used. An example of the efficacy of this approach has recently been demonstrated in Thailand.112 Cleaning flowerpots/vases and ant-traps Flowerpots, flower vases and ant-traps are common sources of Ae. aegypti breeding. Water that collects on the saucers that are placed below flowerpots should be removed every week. Water in flower vases should be removed and discarded weekly and vases scrubbed and cleaned before reuse. Alternatively, live flowers can be placed in a mixture of sand and water. Brass flowerpots, which make poor larval habitats, can be used in cemeteries in place of traditional glass containers. Ant-traps to protect food-storage cabinets should be cleaned on a weekly basis and treated with common salt or oil.
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Cleaning incidental water collections Desert (evaporation) water-coolers, condensation collection pans under refrigerators, and airconditioners should be regularly inspected, drained and cleaned. Desert water-coolers generally employed in arid/semi-arid regions113 of South-East Asia to cool houses during summer contain two manufacturing defects. These are as follows: The exit pipe at the bottom of the water-holding tray is generally fixed a few centimetres above the bottom. This exit pipe should be fitted at such a level that while emptying the tray, all the water should get drained off without any retention at the bottom. Desert coolers are normally fitted to windows with the exit pipe located on the exterior portion of the tray. These sites are usually difficult to access, and therefore, there is a need to change the design so that both the filling and emptying of the water-holding trays can be manipulated from the room, thus eliminating the need for climbing to approach the exit pipe from the exterior of the building.
Each country should develop regulatory mechanisms to ensure the application of the design specifications as outlined above for manufacturing desert coolers. Managing construction sites and building exteriors Water-storage facilities at construction sites should be mosquito-proof. Housekeeping should also be stepped up to prevent occurrence of water stagnation. The design of buildings is important to prevent Aedes breeding. Drainage pipes of rooftops, sunshades/porticos often get blocked and become breeding sites for Aedes mosquitoes. Roof gutters of industrial/housing sheds also get similarly blocked. Where possible, the design of such features should minimize the tendency for mosquito breeding. There is a need for periodic inspection of such structures during the rainy season to locate potential breeding sites. Managing mandatory water storage for fire-fighting Fire prevention regulations may require mandatory water storage in some countries.114 Such storage tanks need to be kept mosquito-proof. These drums should be kept covered with tight lids; failing which larvivorous fish or temephos sand granules (one part per million) can be used. Managing discarded receptacles Discarded receptacles namely tins, bottles, buckets or any other consumable packaged items such as plastic cups/trays and waste material, etc. scattered around houses should be removed and buried in landfills. Scrap material in factories and warehouses should be stored appropriately until disposal. Household and garden utensils (buckets, bowls and watering devices) should be kept upside down to prevent accumulation of rain water. Similarly, in coastal areas canoes and small boats should be emptied of water and turned upside down when not in use. Plant waste (coconut shells, cocoa husks, etc.) should be disposed of properly. Managing glass bottles and cans Glass bottles, cans and other small containers should be reused, recycled or buried in landfills. Tyre management Used automobile tyres are of significant importance as breeding sites for urban Aedes, and are therefore a public health problem. Imported used tyres are believed to be responsible for the introduction of Ae. albopictus into the United States of America, Europe and Africa.115 Tyres in depots should always be kept under cover to prevent collection of rainwater. New technologies for
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tyre recycling and disposal are continually coming into use, but most of them have proved to be of limited application or cost-intensive. It is recommended that each community should look at ways to recycle/reuse used tyres so that they do not become breeding habitats. Some examples of how used tyres can be reused are mentioned below: As soil erosion barriers, e.g. creation of artificial reefs in order to reduce beach erosion by wave action. As planters or traffic/crash barriers, after filling with earth or concrete. As sandals, floor mats, industrial washers, gaskets, buckets, garbage pails and carpet backing, etc. (after recycling). As durable, low-cost refuse containers by using larger tyres such as truck tyres.
Filling up of cavities of fences Fences and fence-posts made from hollow trees such as bamboo should be cut down to the node, and concrete blocks should be filled with packed sand or cement to eliminate potential Aedes larval habitats. Managing public places Municipalities should have in place a programme to inspect and maintain structures in public places such as street lamp posts, park benches and litter bins that may collect water if not regularly checked. Discarded receptacles that may hold water such as plastic cups, broken bottles and metal cans should be regularly removed from public areas.
Personal protection
Protective clothing Clothing reduces the risk of mosquito bite if the cloth material is sufficiently thick or loosely fitting. Long sleeves and trousers with stockings may protect the arms and legs, which are the preferred sites for mosquito bites. Schoolchildren should adhere to these practices whenever possible. Mats, coils and aerosols Household insecticidal products, namely mosquito coils and aerosols, are used extensively for personal protection against mosquitoes. Electric vaporizer mats and liquid vaporizers are more recent additions, and are marketed in practically all urban areas. Repellents Repellents are common means of personal protection against mosquitoes and other biting insects. These are broadly classified into two categories, natural repellents and chemical repellents. Essential oils from plant extracts are the main natural repellent ingredients, such as citronella oil, lemon grass oil and neem oil. Chemical repellents such as DEET (N, N-Diethyl-m-Toluamide) can provide protection against Ae. aegypti, Ae. albopictus and anopheline species for several hours. A new compound, picaridin [2-(2-hydroxyethyl)-1-piperidinecarboxylic acid 1-methylpropyl ester] is very effective against mosquitoes. It has low toxicity and efficacy levels comparable with that of DEET.116 Permethrin is an effective repellant when impregnated in cloth. Table 11 presents the names of the principal insect repellents and the duration of protection.
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Formulation Pump spray, aerosol, gel, lotion. Pump spray, aerosol, lotion, stick. Lotion, aerosol. Pump spray, lotion, oil, towelette. Lotion. Pump spray. Aerosol. Aerosol, pump spray.
Source: Katz T.M., Miller J.H., Hebert A.A.. Insect repellents: Historical perspectives and new developments. J Am Acad Dermatol. 2008 May; 58(5): 86571.116
Insecticide-treated materials: Mosquito nets and curtains Insecticide-treated mosquito nets (ITNs)117,118 have limited utility in dengue control programmes since the vector species bites during the day. However, treated nets can be effectively utilized to protect infants and night workers who sleep by day. They can also be effective for people who generally have an afternoon nap. Details of insecticide treatment of mosquito nets and curtains are explained in Annex 7. The long-lasting insecticidal net (LLIN) is a factory-treated mosquito net with insecticide (synthetic pyrethroids) either incorporated into or coated around the fibre. It is expected to retain its biological activity for a minimum number of WHO washes and a minimum period of time under field conditions. Currently, an LLIN is expected to retain its biological activity for at least 20 standard WHO washes under laboratory conditions and three years of recommended use under field conditions.119
9.2
Biological control
Biological control is based on the introduction of organisms that prey upon, parasitize, compete with or otherwise reduce populations of the target species.66 The application of biological control agents, which are directed against the larval stages of dengue vectors, in South-East Asia has been somewhat restricted to specific container habitats in small-scale field operations.. Importantly, the biological control organisms are not resistant to desiccation, hence their utility is mainly restricted to container habitats that are seldom emptied or cleaned, such as large water-storage containers or wells. However, the willingness of communities to accept the introduction of organisms into water containers is essential. Community involvement is also desirable in distributing the agents, and monitoring and restocking containers, as necessary.
z DEET, N,N-diethyl-3-methylbenzamide. aa Permethrin is not formulated for direct application to the skin.
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Fish
Larvivorus fish (Gambusia affinis and Poecilia reticulata) have been extensively used for the control of An. stephensi and/or Ae. aegypti in large waterbodies or large water containers in many countries in South-East Asia (for example, the community-based use of larvivorous fish Poecilia reticulata to control the dengue vector Ae. aegypti in domestic water-storage containers in rural Cambodia).120 The applicability and efficiency of this control measure depends on the type of containers used.
Bacteria
Two species of endotoxin-producing bacteria, Bacillus thuringiensis serotype H-14 (Bt.H-14) and Bacillus sphaericus (Bs), are effective mosquito control agents. They do not affect non-target organisms associated with mosquito larvae. Bt.H-14 has an extremely low-level mammalian toxicity and has been accepted for the control of mosquitoes in containers storing water for household use.121 Bt.H-14 has been found to be most effective against An. stephensi and Ae. aegypti, while Bs is the most effective against Culex quinquefasciatus which breeds in polluted water. There is a whole range of formulated Bti products produced by several major companies for the control of vector mosquitoes. Such products include wettable powders and various slow-release formulations including briquettes, tablets and pellets. Further developments are expected in slowrelease formulations. Bt.H-14 has an extremely low-level mammalian toxicity and has been accepted for the control of mosquitoes in containers storing water for household use.
Cyclopods
The predatory role of copepod crustaceansab was documented between 1930 and 1950. However, scientific evaluation was carried.122 Trials in crab burrows against Ae. polynesiensis and in water tanks, drums and covered wells met with mixed results. In Queensland, Australia, too, the results were mixed; but in Vietnam the results were more successful, contributing to the eradication of Ae. aegypti from one village.123 Although the lack of nutrients and frequent cleaning of some containers can prevent the sustainability of copepods, they could be suitable for large containers that cannot be cleaned regularly (wells, concrete tanks and tyres).123 Paya Lebar International Airport.124 In Thailand, the autocidal trap was further modified as an auto-larval trap using plastic material available locally. Unfortunately, under local conditions of water-storage practices in Thailand, the technique was not very efficient in reducing
ab Copepods should not be used in countries where Gnathostomiasis are endemic as they may act as intermediate hosts for these parasites.
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81 the population density of the vector has already taken place. However, successful application of autocidal ovitraps/ larval traps depends on the number placed, the location of placement, and their attractiveness as Ae. aegypti female oviposition sites.125
9.3
Chemical control
Chemicals have been used to control Ae. aegypti since the beginning of the 20th century. In the first campaigns against the yellow fever vector in Cuba and Panama, along with widespread clean-up campaigns, Aedes larval habitats were treated with oil and homes of applying insecticides include larvicide application and space spraying.125 to ensure maximum effectiveness. Control personnel distributing the larvicide should always encourage house occupants to control larvae by environmental sanitation, i.e source reduction. There are three insecticides that can be used for treating containers that hold drinking water.ac The WHO guidelines on drinking water quality126 provide guidance on the use of pesticides in drinking water. Temephos 1% sand granules One per cent temephos sand granules are applied to containers using a calibrated plastic spoon to administer a dosage of 1 ppm. This dosage has been found to be effective for 812 weeks, especially in porous earthen jars under normal water use patterns. The quantity of sand granules required to treat various sizes of water containers is presented in Annex 8. The susceptibility level of Aedes mosquitoes should be monitored regularly in order to ensure effective use of the insecticide. Insect growth regulators (IGR)/pyriproxyfen Insect growth regulators (IGRs) interfere with the development of the immature stages of the mosquito by interference of chitin synthesis during the moulting process in larvae or by disruption of the pupal and adult transformation processes. Pyriproxyfen is an insect-juvenile hormone analogue that has been found extremely effective against Ae. aegypti at concentrations as low as 1 ppb or less, while high concentration does not inhibit oviposition.127 Very low doses of pyriproxyfen can also sub-lethally affect adults by decreasing
ac
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fecundity or fertility and the contaminated adult female can transfer effective doses to any breeding sites subsequently visited by the female.128 New formulations of pyriproxyfen129 can retain efficacy for six months. However, the disadvantages include non-visibility since the mode of action prevents eclosion and larvae and pupae remain visibly active after treatment. As a result, suspicion among communities about the IGRs effectiveness regarding treatment of domestic water is yet another impediment. Bacillus thuringiensis H-14 (Bt.H-14) Bt.H-14, which is commercially available under a number of trade names, is a proven and environmentally non-intrusive mosquito larvicide. It is entirely safe for humans when the larvicide is used in drinking water in normal dosages.121 Slow-release formulations of Bt.H-14 have been developed. Briquette formulations that appear to have greater residual activity are commercially available and can be used with confidence in drinking water. The use of Bt.H-14 is described in the section on biological control. The large parabasal body that forms in this agent contains a toxin that degranulates solely in the alkaline environment of the mosquito midgut. The advantage of Bt.H-14 is that an application destroys larval mosquitoes but spares any entomophagus predators and other non-target species that may be present. Bt.H-14 formulations tend to rapidly settle at the bottom of water containers, and frequent applications are therefore required. The toxin is also photolabile and is destroyed by sunlight.
Space sprays
Space spraying involves the application of small droplets of insecticide into the air in an attempt to kill adult mosquitoes. It has been the principal method of DF/DHF control used by most countries in the South-East Asia Region for 25 years. Unfortunately, it has not been effective, as illustrated by the dramatic increase in DHF incidence in these countries during the same period. Recent studies have demonstrated that the method has little effect on the mosquito population, and thus on dengue transmission.130,131,132 Moreover, when space spraying is conducted in a community, it creates a false sense of security among residents, which has a detrimental effect on community-based source reduction programmes. From a political viewpoint, however, it is a desirable approach because it is highly visible and conveys the message that the government is taking action. This, however, is a poor justification for using space sprays. Space spraying of insecticides (fogging) should not be used except in an epidemic situation. that the application equipment is well maintained and properly calibrated. Droplets that are too small tend to drift beyond the target area while large droplets fall out rapidly. Nozzles for ultra-low volume ground equipment should be capable of producing droplets in the 527.
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Thermal fogs Thermal fogs containing insecticides are normally produced when a suitable formulation condenses after being vaporized at a high temperature. Generally, a thermal fogging machine employs the resonant pulse principle to generate hot gas (over 200 C) at high velocity. These gases atomize the insecticide formulation instantly so that it is vaporized and condensed rapidly with only negligible formulation breakdown. Thermal fogging formulations can be oil-based or water-based. The oilbased (diesel or kerosene) formulations produce dense clouds of white smoke, whereas water-based formulations produce a colour Ultra-low volume 1015 micron range, although the effectiveness changes little when the droplet size range is extended to 525 microns. The droplet size should be monitored by exposure on Teflon or silicone-coated slides and examined under a microscope. Aerosols, mists and fogs may be applied by portable machines, vehicle-mounted generators or aircraft equipment. House-to-house application using portable equipment: Portable spray units can be used when the area to be treated is not very large or in areas where vehicle-mounted equipment cannot be used effectively. This equipment is meant for restricted outdoor use and for enclosed spaces (buildings) of not less than 14 m3. Portable application can be made in congested low-income housing areas, multi-storeyed buildings, warehouses, covered drains, sewage tanks and residential or commercial premises. Operators can treat an average of 80 houses per day, but the weight of the machine and the vibrations caused by the engine make it necessary to allow the operators to rest adequately and hence two or three operators are required per machine. Vehicle-mounted fogging: Vehicle-mounted aerosol generators can be used in urban or suburban areas with a good road system. One machine can cover up to 15002000 houses (or approximately 80 ha) per day. It is necessary to calibrate the equipment, vehicle speed and swath width (6090 m) to determine the coverage obtained by a single pass. A good map of the area showing all roads is of great help in undertaking the application. Advocacy and communication efforts may be required to persuade residents to cooperate by opening their doors and windows. The speed of the vehicle and the time of day of application are important factors to consider when insecticides are applied by ground vehicles. The vehicle should not travel faster than 16 kilometres per hour (kph) [10 miles per hour (mph)]. The insecticide should not be applied when the wind speed is greater than 16 kph or when the ambient air temperature is greater than 28 C (82 F).133,134 The best time for application is in the early morning (approximately 06000830 hours) or late afternoon (17001930 hours). Details of procedures, timing, frequency of thermal fogging and ULV space operation are given in Annex 9. Performance of fogging machines Estimates have been made of the average coverage per day with certain aerosol and thermal fog procedures (Box 23).
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Box 23: Average coverage per day with space spraying procedures Equipment 1. Vehicle-mounted cold fogger 2. Vehicle-mounted thermal fogger 3. Back-pack ULV mist blower 4. Hand-carried thermal fogger swing fog 5. Hand-carried ULV aerosol generators litres per hectare. Apart from the above-mentioned formulations, a number of companies produce pyrethroid formulations containing either permethrin, deltamethrin, lambda-cyhalothrin or other compounds which can be used for space spray applications. It is important not to under-dose during operational conditions. Low dosages of pyrethroid insecticides are usually more effective indoors than outdoors. Also, low dosages are usually more effective when applied with portable equipment (close to or inside houses) than with vehicle-mounted equipment, even if wind and climatic conditions are favourable for outdoor applications. Outdoor permethrin applications without a synergist should be applied at concentrations ranging from 0.5% to 1.0%, particularly in countries with limited resources and a paucity of staff experienced in routine spraying operations. Regardless of the type of equipment and spray formulations and concentrations used, an evaluation should be made from time to time to check if effective vector control is being achieved. Insecticides suitable as cold aerosols and for thermal fogging for mosquito control are described in Table 12. Possible daily coverage 225 ha 150 ha 30 ha 5 ha 5 ha or 250 houses
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Table 12: Some insecticides suitable for cold aerosol or thermal fog applications against mosquitoes Dosage of a.iad (g/ha) Insecticide Fenitrothion Malathion Pirimiphos-methyl Bioresmethrin Cyfluthrin Cypermethrin Cyphenothrin d,d-transCyphenothrin Deltamethrin D-Phenothrin Etofenprox -Cyhalothrin Permethrin Resmethrin Chemical Organophosphate Organophosphate Organophosphate Pyrethroid Pyrethroid Pyrethroid Pyrethroid Pyrethroid Pyrethroid Pyrethroid Pyrethroid Pyrethroid Pyrethroid Pyrethroid Cold aerosols 250300 112600 230330 5 12 13 25 12 0.51.0 520 1020 1.0 5 24 Thermal fogsae 250300 500600 180200 10 12 510 2.55 0.51.0 1020 1.0 10 4 II III III U II II II NA II U U II II III WHO hazard classification of Ai
Source: WHO 2006/2. Pesticides and their application for the control of vectors and pests of public health importance. WHO/CDS/ WHOPES/GCDPP/2006.1.
ad a.iActive ingredient; Class II, moderately hazardous; class III, slightly hazardous; class U, unlikely to pose an acute hazard in normal use; NA: not available. Label instructions must always be followed when using insecticides. ae The strength of the finished formulation when applied depends on the performance of the spraying equipment used.
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Box 24: Example of monitoring and evaluation of space spray and secondary transmission of DF/DHFaf Evaluation of timeliness, coverage and effectiveness of space spray for DF/DHF control were evaluated using the geographical information system (GIS) and an attempt was made to describe the spatial-time patterns of DF/DHF secondary case. A longitudinal monitoring of DF/DHF cases and spray activities in Songkhla municipality in Thailand was conducted. After a case was detected, subsequent cases occurring within a radius of 100 metres from the venue of the case up to a period of between 16 and 35 days were considered potential secondary cases. Poisson regression was used to identify risk factors for the secondary attack during the period May 2006April 2007. In the study period, 140 cases residing in Songkhla municipality were detected. Of these, 25 were potential secondary cases contracted from 20 index cases. Where combine secondary cases occurred, the mean secondary attack rate was 2.7 per 1000 population. Houses in the neighbourhood of all the index cases were sprayed, but only once. The median lag time of spray was 17.3 hours. Average percentage of the total area sprayed was 5.6%. It was concluded that space spray in the study area was inadequate and often failed to prevent secondary cases of DF/ DHF. Further investigation with a larger sample was, however, underscored. For effective space spray for DF/DHF outbreak control, increasing the spray area to cover a radius of 100 metres from the patients house and doubling the time of spray at an interval of every seven to ten days in addition to a control programme focusing on the houses of the poorer sections of the community was suggested. The use of insecticides for the prevention and control of dengue vectors should be integrated into environmental methods wherever possible. During periods of little or no dengue virus activity, the routine source reduction measures described earlier can be integrated into the larvicide application processes in containers that cannot be eliminated, covered, filled or otherwise managed. For emergency control to suppress a dengue virus epidemic or to prevent an imminent outbreak, a programme of rapid and massive destruction of the Ae. aegypti population should be undertaken involving both insecticides and source reduction and using the techniques described in these guidelines in an integrated manner.
af Suwich T. et al.: Space Spray and Secondary Transmission of DF/DHF in an Urban Area, Southern Thailand. (Manusript) ag For additional information refer to section on Outbreak Response in the Asia-Pacific Dengue Strategic Plan (20082015) and Chapter 13 of this document. ah Source: National Environment Agency, Singapore, 2009.
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Box 25: Preparedness programme in Singapore To reduce dengue transmission Singapore has adopted an integrated evidence-based approach. This comprises vector surveillance and control, intersectoral collaboration, public education and community outreach, law enforcement and research. The approach is reviewed periodically to ensure its relevance and effectiveness in addressing new challenges which arise from a number of factors including changing dengue serotypes, Aedes mosquito adaptation, transboundary transmission, low herd immunity, increasing population density and rapid urbanization. Before to the beginning of each year, areas at potential risk for dengue outbreaks are identified for intensive source reduction exercises (ISRE) to be conducted two months before the traditional dengue season, which falls between May and October. Based on this risk assessment, resources for vector control operations are deployed in a targeted manner to achieve maximum impact. In addition to the ISRE, through intersectoral collaboration the various land agencies will also be alerted to conduct intensive source reduction exercises on their properties. The public is also regularly reminded about the need for preparedness against dengue through outreach initiatives on different local media and through community events at the grassroots level. This helps to keep the subject of dengue fresh and the public on alert. By taking a proactive stance with a preparedness programme, this integrated evidence-based approach has been successful in curbing the spread of dengue in Singapore. The dengue situations in 2008 and 2009 have shown downward trends: from 7031 cases in 2008 to 4497 in 2009. This is in sharp contrast with a high of 14 209 cases reported during Singapores worst ever dengue outbreak in 2005. This is the first time in three decades that such a downward trend has been observed in Singapore notwithstanding the global surge in dengue cases.
9.4
The geographical information system (GIS) is an automated computer-based system with the ability to capture, retrieve, manage, display and analyse large quantities of spatial and temporal data in a geographical context. The system comprises hardware (computer and printer), software (GIS software), digitized base maps, information and a whole set of procedures such as data collection, management and updating. Specific diseases and public health resources can be mapped in relation to their surrounding environment and existing health and social infrastructures. Such information when mapped together creates a powerful tool for monitoring and management of disease. GIS provides a graphical analysis of epidemiological indicators over time, captures spatial distribution and severity of the disease, identifies trends and patterns, and indicates if and where there is a need to target extra resources. Various potential usages and constraints of GIS for dengue control were described by a Scientific Working Group on Dengue in 2006.135
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GIS, global positioning system (GPS) and remote sensing (RS) technologies provide dengue programme staff with additional types of data such as latitude-longitude coordinates for locations of breeding sites, and cases and transmission sources according to house lot, block and neighbourhood. Digital imagery from satellites and aerial photographs provide additional details to the map and improve the accuracy of the information. GIS technology encourages the formation of data partnerships and data sharing at the community level. Spatial analysis capability of GIS (distance, proximity, containment measures) can be used to improve entomological/vector control activities and interventions such as focal treatment, and to search for and destroy transmission sources. GIS technology enables work on multiple scales in space and other dimensions (time, individual and aggregated data). GIS capabilities for spatial and spatialtemporal statistical analysis can improve the information system by providing better support to planning, monitoring, evaluation and decision-making in the dengue control programme. GIS capability allows for synthesizing and visualizing information in maps.
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of hot spots by using hand-held terminals (HHT) for collection of field surveillance data in the field itself,137 unlike the previous approach of collecting information on paper forms in the field and then feeding the same into the computer for analysis. Currently, Singapore uses GIS in its dengue surveillance and control programme to process, map and analyse huge amounts of epidemiological, entomological and environmental data.138 A fully automated dengue model is run daily using GIS to conduct spatial and temporal analysis of the dengue cases (Figure 14). With this information, swift vector control action can be taken to prevent further dengue transmission within the affected area. Figure 14: Density mapping of dengue cases in Singapore
Through the use of GIS, the distribution of Aedes mosquitoes breeding, dengue cases, dengue serotypes and environmental factors such as construction sites, vacant premises and congregation areas could be monitored and analysed. Risk assessment is conducted to develop areas of potential risk for dengue outbreaks based on the principles of dengue epidemiology and Aedes ecology and behaviour. Taking into consideration the predominant serotype and the populations past exposures to that serotype, the areas identified as having relatively higher epidemic potential are marked out as focus areas (Figure 15). More resources and intensive vector control will be carried out in these focus areas, and this information assists the programme managers in their deployment of scarce resources in accordance with the risks and operational needs.
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Figure 15: Focus areas identified using GIS to prioritize resource allocation for dengue surveillance
Coupled with the timely availability of information, GIS has been found useful for planning vector control operations, and managing and deploying resources for dengue control (Figure 16). Figure 16: Planning, managing and deploying resources for vector control operations using GIS
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Alert system for informing environmental risk of dengue infections The Ovitrap Index has been in use in many countries. This is a measurement of mosquito eggs in specified geographical locations, which in turn reflects the distribution of Aedine mosquitoes, the vector for dengue. Using GIS application, an alert system was created from a synthesis of geospatial data on ovitrap indices in Hong Kong. The inter-relationship between ovitrap indices and temperature was established. This forms the rationale behind the generation of weighted overlays to define risk levels. The weighting could be controlled to set the sensitivity of the alert system. This system can be operated at two levels: one for the general public to assist the evaluation of dengue risk in the community and the other for professionals and academia in support of technical analysis. The alert system offers one objective means to define the risk of dengue in a society, which would not be affected by the incidence of the infection itself.ai Dengue spatial and temporal patterns, French Guiana, 2001 To study a 2001 dengue fever outbreak in Iracoubo, French Guiana, the locations of all patients homes were recorded along with the dates when symptoms were first observed. A GIS was used to integrate the patient-related information. The Knox test, a classic space-time analysis technique, was used to detect spatiotemporal clustering. Analysis of the relative-risk (RR) variations when space and time distances differed highlighted the maximum space and time extent of a dengue transmission focus. The results showed that heterogeneity in the RR variations in space and time corresponds to known entomological and epidemiological factors such as the mosquito feeding cycle and hostseeking behaviour. This finding demonstrates the relevance and potential of the use of GIS and spatial statistics in elaborating a dengue fever surveillance strategy.140
ai
Sze W.N., Yan L.C., Kwan L.M., Shan L.S., Hui L.. An alert system for informing environmental risk of dengue infections.
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Box 26: The key elements of IVM 1. Advocacy, awareness generation, social mobilization and legislation: Promotion and embedding of IVM principles in the development policies of all relevant agencies, organizations and civil society. Establishment of or bolstering regulatory and legislative controls for public health to ensure access to necessary services and health information and communication materials. Empowerment of communities and their active participation for advocating local policy changes, resolution of demand-side issues and challenges and inculcating appropriate practices for long-term prevention and control. Consideration of all options for collaboration within and between public and private sectors, which should be optimal and necessary in times of high alert. Application of the principles of subsidiarity in planning and decision-making. Necessary capacity-building of partners to address health equity, surveillance, control and prevention of vector-borne diseases. Strengthening channels of communication among policy-makers, managers of vectorborne disease control programmes and other IVM partners. Mobilization of additional resources, especially at the local levels. Ensuring the rational use of available resources through the application of a multidisease-control approach. Integration of non-chemical and chemical vector-control methods. Integration with other disease-control measures. Establishment of specific integrated bodies/mechanisms to ensure rapid response/ action to tackle an outbreak or epidemic.aj Adapting strategies and interventions to local vector ecology, epidemiology and resources. Guidance by operational research and routine monitoring and evaluation. Information management and research evidence to introduce and advocate for policy change. Local authorities, policy-makers and planning officers should be involved in information management to build ownerships and sustainable response. Developing essential physical infrastructure. Financial resources and adequate human resources at the national and local level to manage IVM programmes based on situation analysis/needs assessments.
2.
3.
Integrated approach:
4.
Evidence-based decision-making:
5.
Capacity-building
aj
A Disease Control Task Force led by community/area-based CDC; a Health promotion and preventive medicine unit in the Primary Health Care Unit; a Community Task Force led by full participation of people who are empowered with technical support from the health sectors; a community surveillance mechanism which can be used in other health alert systems as an integral part of vector-borne disease control.
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The SEA Regional IVM Strategy recommended IVM approval for malaria, dengue and kala azar control.142 This was prompted by promising results achieved in malaria control in Sri Lanka by empowering communities through the involvement of Farmers Field Schools.143
10.2 Approach
The urban and peri-urban eco-epidemiological paradigm is home to vectors of dengue and chikungunya, where they proliferate in diverse types of water-storage containers both indoors and outdoors (see Chapter 8). The IVM approach for dengue control is a classic example of multiple disease control, thus making control of three infections (namely. dengue, chikungunya and urban malaria) possible in a most cost-effective manner.ak For example, in the Indian subcontinent, urban malaria transmitted by Anopheles stephensi is also endemic. An. stephensi, also being a container habitat species, shares breeding sites with Ae. aegypti. However, the urban disease control programme suffers from lack of: (i) social mobilization of communities; (ii) intersectoral coordination; (iii) public health infrastructure (especially experts in vector ecology for mapping of breeding sites and for selection of appropriate mix of interventions); (iv) capacity-building; (v) administrative, financial and logistic support; and (vi) monitoring and evaluation. Over the last few decades, efforts to promote community-oriented activities for dengue control in an IVM mode have increased. A comprehensive review of community-based programmes for dengue control144 was carried out. The review found a tangible need to strengthen such programmes. The essential steps to improve the outcome and sustainability of control activities on a long-term basis are described below.
Community participation
Community participation has been defined as a process whereby individuals, families and communities are involved in the planning and conduct of local vector control activities so as to ensure that the programme meets the local needs and priorities of the people who live in the community, and promotes the communitys self-reliance in respect to development.145 In short, community participation entails the creation of opportunities that enable all members of the community and extended society to actively contribute to it, influence its development, and share equitably the fruits of accrued benefits. The objectives of community participation in dengue prevention and control are to: Extend the coverage of the programme to the whole community by creating community awareness. This, however, often requires intensive inputs. Make the programme more efficient and cost-effective, with greater coordination of resources, activities and efforts pooled by the community. Make the programme more effective through joint community efforts to set goals, objectives and strategies for action. Promote equity through the sharing of responsibility, and through solidarity in serving those in greatest need and at greatest risk. Promote self reliance and self-care among community members and increase their sense of control over their own health and destiny.
ak More details can be seen in the Report of the WHO Consultation on Integrated Vector Management, Geneva, 14 May 2007.1462
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Community participation approaches By showing concern: Community and government organizers should reflect true concern for human suffering, i.e. in this case morbidity and mortality due to dengue in the country, economic loss to families and the nation on account of it, and how the benefits of the dengue prevention and control programme fit into the peoples needs and expectations. Initiating dialogue: Community organizers and opinion leaders or other key personnel in the power structure of the community, namely womens groups, youth groups and civic organizations, should be identified. Dialogue should be carried out through personal contacts, group discussions and film/audiovisual shows, etc. Interaction should generate mutual understanding, trust and confidence, enthusiasm and motivation. The interaction should not be a one-time affair but should be a continuing dialogue to achieve sustainability. Creating community ownership: Organizers should use community ideas and participation to initiate the programme, community leaders to assist the programme, and community resources to fund the programme. The partnership of the community with mosquito control and abatement agencies should be strong and the latter should provide technical guidance and expertise. Health education (HE): Health education should not be based on telling people the dos and donts through a vertical, top-down communication process. Instead, health education should be based on formative research to identify what is important to the community and should be implemented at three levels, i.e. the community level, the systems level and the political level. Community level: People should not only be provided with knowledge and skills on vector control, but relevant educational material should empower them with the knowledge that allows them to make positive health choices and gives them the ability to act individually and collectively. A participatory approach in community health communication is imperative. Systems level: To enable people to mobilize local action and social forces beyond a single community, i.e. health, development and social services. Political level: Mechanisms must be made available to allow people to articulate their health priorities to political authorities. This will facilitate placing vector control high on the priority agenda and effectively lobby for suitable policies and actions. Defining community actions: The following community actions are essential to sustain DF/DHF prevention and control programmes: At the individual level, encourage each household to adopt routine health measures that will help in the control of DF/DHF, including source reduction and implementation of proper personal protection measures. At the community level, organize clean-up campaigns two or more times a year to control the larval habitats of the vectors in public and private areas of the community. Some key factors for the success of such campaigns include: extensive publicity via media-mix including audiovisuals, posters, pamphlets, etc.; and proper planning, precampaign evaluation of foci, execution in the community as promised, and follow-up evaluations. Participation by municipal/public sector sanitation services and agencies should be ensured. Where community-wide participation is difficult to arrange for geographical, occupational or demographic reasons, arrange community participation through nongovernmental/ voluntary/community-based/faith-based associations and organizations. The people in these organizations may interact daily at work or institutional settings, or come
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together for special purposes, i.e. religious activities, civic clubs, womens groups and schools, etc. Emphasize school-based programmes targeting children and parents to eliminate vector breeding at home and at school. Challenge and encourage the private sector to participate in the beautification and sanitary improvement of the community as sponsors, emphasizing source reduction of dengue vectors. Combine community participation in DF/DHF prevention and control with other priorities of community development. Where services such as refuse collection, waste water disposal, provision of potable water, etc. are either lacking or inadequate, the community and its partners can be mobilized to improve such services and at the same time reduce the larval habitats of Aedes vectors as part of an overall effort at community development. Combine dengue vector control with the control of all species of disease-bearing and nuisance mosquitoes as well as other vermin, to ensure greater benefits for the community, and consequently greater participation in neighbourhood campaigns. Arrange novel incentives and/or service recognition programmes for those who participate in community programmes for dengue control. For example, a nationwide competition can be promoted to identify the cleanest communities or those with the lowest larval indices within an urban area.
Over the years, community participation in controlling dengue vector is being increasingly applied in many countries. Box 27 illustrates an example of how dengue prevention and control in Indonesia has evolved from a vertical, government-controlled programme to a more horizontal, community-based approach.
Model development
Development of a model for dengue control through the community participation approach should be initiated in order to define potential prime-movers in the communities and to study ways to persuade them to participate in vector control activities. Social, economic and cultural factors that promote or discourage the participation of these groups should be intensively studied to enhance participation from the community. Mapping of community resources and infrastructure physically and socially would help shape up the model development for dengue control. Mapping will also identify key change agents that mobilize communities to change their behaviour towards and compliance of vector-borne disease control. Different models in different settings should be applied: In rural areas, where an acute sense of community exists, community participation is needed and has to be encouraged in addition to training and capacity-building. In urban and semi-urban areas, civil society groups, nongovernmental organizations and municipalities can act as prime movers for change and need to be mobilized to involve the community.
Model development focusing on schoolchildren has been studied in several countries (Box 28) and this strategy should be modified and introduced in each country.
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Box 27: Together Picket: Community activities in dengue source reduction in Purwokerto city, Central Java, Indonesia146 In Purwokerto, Central Java, Indonesia, a partnership has been established between the local government, the Rotary Club, the Family Welfare Empowerment Organization (PKK), and municipal health services. Leadership and commitment from these partners, with strong technical support from the National Health Research Department, has enabled the development of an effective community-based integrated vector control project in Purwokerto, which has a population of 220 000. This project operates at the level of neighbourhood associations. Each neighbourhood consists of between 25 and 50 households. Within each neighbourhood, houses are grouped into sets of 10, called dasawisma. Each dasawisma has a leader, usually a woman cadre from the PKK, trained in DF/DHF prevention and control. The leader is known as the source reduction cadre. Usually, being bestowed this title itself is an honour to be proud of. Each dasawisma gets a source reduction kit containing a flashlight (for checking for the presence of larva in containers stored in dark areas), simple record forms, and a health education booklet. The dasawisma arrange schedules within which one house inspects the other nine houses. Known as Piket Bersama (Picket Together), these house-to-house inspections are conducted on a weekly basis so that each household takes its turn every 10 weeks. The dasawisma leader collects the weekly record forms and reports the results to the next administrative level. The success of this project can be measured by the reduction in the House Index from 20% before activities began to 2% once the activities were on a roll. This project has now been expanded to 14 cities in Indonesia through grants from the Rotary International and CDC, Colorado.
Box 28: Health education in elementary school147 A child-focused approach to dengue prevention and control has been an important component of a broader public health programme in Puerto Rico since 1985. The highlights include health education in elementary schools with collaboration between the departments of Health and Education, among other initiatives. In elementary schools, an activity booklet was developed that contained 28 activities about dengue and its prevention and was accompanied by a guide to aid teachers in the presentation of the various activities. After several years of use and following suggestions from teachers and external programme reviewers, the booklet and teachers guides were revised. Each year, an estimated 50 000 fourth-grade students use the booklet in their social studies classes and it has now been incorporated into the public school curriculum. An important aspect of this programme has been the provision of training programmes for teachers, school nurses and school nurse supervisors by staff of the Center for Disease Control and Prevention, Puerto Rico.
Social mobilization
Advocacy meetings should be conducted for policy-makers for garnering political commitment to mass clean-up campaigns and environmental sanitation. Intersectoral coordination meetings should be conducted to explore possible donors/partners for mass antilarval control campaigns and
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measures and to help finance the programme. Reorientation training of health workers should be conducted to improve their technical capability, and their ability to supervise prevention and control activities. A DF/DHF month should be identified twice a year, during the pre-transmission and peak transmission period.
Health education
Health education is very important in achieving community participation. It is a long-term process to achieve human behavioural change, and thus should be carried out on a continuous basis.al Though countries may have limited resources, health education should be given priority in endemic areas and in areas at high risk for DF/DHF. Health education is conducted through the channels of interpersonal communication, group educational activities, mid-media activities such as wall writing, and mass media broadcasts. Health education can be implemented by womens groups, school teachers, formal and informal community leaders, and health workers/volunteer networks. Health education efforts should be intensified before the period of dengue transmission as one of the components of social mobilization. The main target groups are school children, women and other influencers at the community level in addition to the community in general.
Intersectoral coordination
Developing economies in the South-East Asia Region have identified many social, economic and environmental problems that promote mosquito breeding. The dengue control issue thus exceeds the capabilities of the ministries of health. The prevention and control of dengue requires collaboration and partnerships between the health and non-health sectors (both government and private), nongovernmental organizations (NGOs) and local communities. During epidemics such cooperation becomes even more critical since it requires the pooling of resources from all groups to check the spread of the disease. Intersectoral cooperation involves at least two components: Resource sharing. Policy adjustments and activities among various ministries and nongovernment sectors.
Resource sharing: Resource sharing should be sought wherever the dengue control coordinator can make use of underutilized human resources, e.g. for local manufacture of required tools, seasonal government labourers for water supply improvement activities, or community and youth groups to clean up discarded tyres and containers in neighbourhoods. The dengue control programme should seek the accommodation or adjustment of existing policies and practices of other ministries, sectors and municipal governments to incorporate public health as a central focus of their goals. For instance, the public works sector could be encouraged to accord first priority to water supply improvements for communities at the highest risk of dengue. In return, the Ministry of Health could consider authorization of the use of some of its field staff to assist the ministry responsible for public works to repair water supply and sewerage systems, as appropriate.
al
Refer to Chapter 12 for additional details (Communication for Behavioural Impact) on responsive behaviour within an enabling environment.
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Activities by government ministries/departments and NGOs The role of the ministry(ies)/department(s)/municipalities responsible for public works/roads and the buildings sector: The key roles to be performed by these sectors pertaining to dengue prevention and control include: reduction at source (storage containers) by providing a safe and as well as formulate or update public health by-laws. During the construction of roads and buildings, efforts need to be made to merge pits by breaking bunds, making excavations in line with the natural slope or gradient and making arrangements for the water to flow into natural depressions, ponds or rivers. Follow-up action after each excavation is also critical. The role of the ministry/department responsible for water supply: The key roles for this ministry/department pertaining to dengue prevention and control include: repair of leakages to prevent pooling of water, restoration of taps, diversion of waste water to ponds/ pits, staggering of water supply, mosquito-proofing of water harvesting devices and repair of sluice valves. Role of the ministry/department responsible for urban development: The key roles for this ministry/department pertaining to dengue prevention and control include: implementation of building by-laws, improved designs to avoid undue waterlogging, securing correct building use permission after clearance by the health department. Role of the ministry/ department responsible for education: The Ministry of Health should work closely with the Ministry of Education to develop a health education (health communication) component targeted at schoolchildren that will design interventions to promote community sanitation, waste characterization studies) to dengue control programmes. Role of the ministry/department responsible for environment/forests: The Ministry of Environment can help the Ministry of Health collect data and information on ecosystems and habitats in or around cities at high risk of dengue. Data and information on local geology and climate, land usage, forest cover, surface water and human populations are useful in planning control measures for specific ecosystems and habitats. The Ministry of Environment may also be helpful in determining the beneficial and adverse impacts of various Ae. aegypti control tactics (chemical, environmental and biological). These may include appropriate environment management policies and pesticide management policies. Other roles could be the reclamation of swampy areas and social forestry.
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Role of the ministry/department responsible for information, communication and mass media: Information directed at the community at large is best achieved through the media/channel-mix, including such mass media as television, radio and newspapers. Therefore, the ministry responsible for information, communication and the mass media should be approached to coordinate the release of messages on the prevention and control of dengue developed by public health specialists. Role of the ministry/department responsible for water resources: The key roles for this ministry/department pertaining to dengue prevention and control include development and maintenance of a canal system, intermittent irrigation, design modifications and lining of canals, weeding for proper flow, creating small check-dams away from human settlements and health impact assessment (HIA). Role of the ministry/department responsible for industry/mining: The key roles for this ministry/department pertaining to dengue prevention and control include improving drainage/sewerage systems, safe disposal of solid waste/used containers, mosquitoproofing of dwellings, safe water storage/disposal and use of ITN/ LLIN. Other roles may include: R&D in relation to the development of new, safer and more effective insecticides/formulations, and promoting safe use of public health pesticides. Role of the ministry/department responsible for agriculture: The key roles for this ministry/department pertaining to dengue prevention and control include the utilization of Farmers Field Schools to implement IVM, popularizing the concept of dry-wet irrigation through extension education, and pesticide management. Role of the ministry/department responsible for fisheries: The key roles for this ministry/department pertaining to dengue prevention and control include institutional help/training in mass production of larvivorous fish, and the promotion of composite fish farming schemes at the community level. Role of the ministry/department responsible for railways: The key roles for this ministry/department pertaining to dengue prevention and control include proper excavations, maintenance of yards and dumps and anti-larval activities within their jurisdiction, and HIA for health safeguards. Role of the ministry/department responsible for remote sensing/GIS: The key roles with regard to remote sensing and GIS pertaining to dengue prevention and control include technical support and training in mapping environmental changes and disease risks using GIS. Role of the ministry/department responsible for planning: The key roles for this ministry/department pertaining to dengue prevention and control include the active involvement of health authorities at the planning stage for HIA and the incorporation of appropriate mitigating actions in development projects.
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Role of nongovernmental organizations (NGOs): NGOs can play an important role in promoting community organization and mobilization for implementing environmental management for dengue vector control and to improve health-seeking behaviour. This will most often involve health education, source reduction and improvement of housing related to vector control. Community NGOs may be informal neighbourhood groups or formal private voluntary organizations, service clubs, churches or other religious groups, as well as environmental and social action groups. After adequate training on source reduction methods is provided by the Ministry of Health staff, NGOs can contribute actively by collecting discarded containers (tyres, bottles, tins, etc.), cleaning drains and culverts, filling depressions, removing abandoned cars and roadside junk, and distributing sand or cement to fill tree holes. NGOs may play a key role in developing a regimen of recycling activity to remove discarded containers from yards and streets. Such activities must be coordinated with the environmental sanitation service. NGOs may also be able to play a specific, but as yet not fully explored, role in environmental management during epidemic control. With guidance from the Ministry of Health, NGOs could concentrate on the physical control of locally identified, key breeding sites such as water drums, accumulated waste tyres and cemetery flower vases. The NGOs can be involved in village-level training, distribution of BCC/IEC materials, and ITN promotion and distribution. Clubs such as Rotary International have supported DF/DHF prevention and control programmes in the American Region for over 15 years. In Asia and the Pacific, programmes have been initiated by them in Sri Lanka, Philippines, Indonesia and Australia to provide economic and political support for successful community-based campaigns. A new grant from the Rotary Foundation has been made to study the possibility of upscaling this project to a global programme. Womens clubs and associations in many countries have contributed to Ae. aegypti control by conducting household inspections for foci and carrying out source reduction. There are many opportunities, mostly untapped, for environmental organizations and religious groups to play similar roles in Ae. aegypti-infested communities.
Legislative support
Legislative support is essential for the success of dengue control programmes. Many countries in the SEA Region have formulated and enacted legislation to address the control of epidemic diseases which authorize health officers to take necessary action within the community for the control of epidemics. Some municipalities/local governments have also adopted legislative provisions related to dengue control. All Member countries of the SEA Region are signatories to the International Health Regulations (IHR) 2005. These Regulations have a specific provision for the control of Ae. aegypti and other disease vectors at sea/air/land entry points. The formulation of legislation on dengue/Ae. aegypti control should take into consideration the following points: Legislation should be a necessary component of all dengue/Ae. aegypti prevention and control programmes. Dengue should be made a notifiable disease. Legislation should cover all aspects of environmental sanitation in order to effectively contribute to the prevention of all transmissible diseases and should aim at developing human resources within the institutional framework. In countries where sanitary regulations are primarily the responsibility of agencies other than the Ministry of Health, there should be coordinated plan of action with all the ministries and agencies concerned.
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Legislation should contemplate intersectoral coordination among the ministries involved in national development in order to prevent isolated implementation of individual programmes and the triggering of harmful environmental changes that could create potentially hazardous public health conditions. Ministries should be advised on the best ways to encourage disease prevention.
10.5 Budgeting
Like any other plan, the IVM implementation plan also will require an estimation of the resources required and then a budget covering all possible anticipated activities and keeping the time frame in mind.148
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In the absence of vaccines and drugs, the strategies for the prevention and control of dengue include prompt diagnosis of fever cases, providing appropriate clinical management, and reducing humanvector contact through vector control and personal protection methods. For effective reduction of human-vector contact, particular emphasis has to be placed on the management or elimination of larval habitats in and around homes, work settings, schools, and in other less obvious places such as informal dump-sites and playgrounds.an Community awareness generation and community and intersectoral participation in addition to disease and vector surveillance, emergency preparedness, capacity-building and training, and research are essential ingredients of prevention and control efforts. Though carefully researched and meticulously planned advocacy, mobilization and communication initiatives with high levels of community engagement are recognized as fundamental to the promotion of healthy behaviour and social change, yet till date few national DF/DHF programmes and international funding agencies have invested soundly in such initiatives.149,ao Adequate prevention and control methods exist, but many national programmes are unable to deliver them effectively.150,ap Many programmes struggle to achieve and sustain behavioural impact at the household, workplace, urban planning, and policy levels.130,151157,aq Further, translation of knowledge to practice often varies.157164 This is on account of reasons as diverse as lack of resources, irregular application and ineffectiveness of methods/interventions for vector control that have been promoted (example, methods promoted for cleaning water containers).165,166 Even with good levels of knowledge, people may resist household or personal practices to control the vector and view such actions to be the responsibility of the government.167,168 In addition, people do not change their behaviour all of a sudden and stay the changed way from that moment. Instead, peoples behaviour gradually moves through subtle stages of change: from becoming aware to becoming informed, then becoming convinced, followed by the decision to take action, then the actual taking of relevant action the first time, then repeating the same, and finally maintaining that action (Box 29) continuously.
an WHO. Report of the Consultation on: key issues in dengue vector control, toward the operationalization of a global strategy, CTD/ FIL(DEN)/IC/96.1, 2001. ao Cited from: Parks, et al. International Experiences in Social Mobilization and Communication for Dengue Prevention and Control. Dengue Bulletin Vol 28, 2004 (Suppl.): 1-7. ap ibid. aq ibid.
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Box 29: HICDARM and Behaviour Adoptionar First, we Then, we become And later In time, We make the And later we take We next await and if all is well, we H ear about the new behaviour. I nformed about it. C onvinced that it is worthwhile. D ecision to do something about our conviction. A ction on the new behaviour. R e-confirmation that our action was good. M aintain the behaviour!
Most programmes usually manage to increase awareness and inform, educate and convince individuals about what needs to be done (the HIC phase). Prompting people to take the necessary steps towards adopting and maintaining an effective and feasible new behaviour (the DARM phase) remains a challenge. Human recall is very short: communities may actively respond to a crisis situation but once that phase is over they tend to retire into the restive phase. Hence, the success and sustainability of the programmes depend upon continued motivation and mobilization of communities, till the threat of disease (for example, DF/DHF) exists. Constraints in various community-based prevention programmes in general have been documented.169 Major constraints identified to come in the way of achieving modest success in community-based programmes include the following: Designs have a strong educational component but without the motivational elements that set off community participation and inculcate a sense of ownership. Insufficient and intermittent efforts and inadequate resources. Inadequate intersectoral convergence in terms of time and resource sharing. Indifferent attitude of the upper strata of society wherein there is the inherent belief that dengue control is the responsibility of the government, and that the urban poor, who are mostly illiterate and too busy securing the minimum daily earnings, can perhaps live with the presence of mosquitoes. Security concerns and inconvenience caused often prevent the entry of health workers into households. Prevailing superstitions, beliefs and faiths [for example, children suffering from AIDS, malaria and other diseases are prime targets of witchcraft accusations, in Angola.170 Once accused of practising witchcraft, a child is punished, beaten, starved and sometimes killed to cleanse her or him of supposed magical powers].
Kyle and Harris30 summed up the performance of community-based programmes saying that the key to promote such programmes is to close the motivational gap between the communitys knowledge and sustainable practices (namely reducing mosquito breeding sites). The rationale for community-based health promotion is the notion that individuals cannot be considered separately from their social milieu and context and that programmes incorporating multiple interventions extending beyond the individual level have the potential to be more successful in the context of changing behaviours.171,172
ar Hosein, E. (cited from: Parks W., Lloyd L.. Planning Social Mobilization and Communication for Dengue Fever Prevention and Control: A step-by-step guide. WHO, Geneva 2004 (WHO/CDS/WMC/2004.2 and TDR/STR/SEB/DEN/04.1).
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It is only during the last decade that emphasis on a community-based integrated approach (bottom up rather than top down) started gaining attention,130 moving away from the biomedical approach, although change is often resisted.as The supportive activities included an understanding of prevalent knowledge, attitudes and practices (KAP) and the development and dissemination of material related to information, education and communication (IEC) focusing mostly on preventionoriented messages towards actions taken to be taken by the communities. Since then, there is a growing body of evidence to prove that social mobilization and communication are critical to sustainable dengue prevention and control. A review of the use of community participation for controlling Ae. aegypti via larval source reduction and of the effectiveness and sustainability of programmes in four countries concluded that a combination of vertically structured centralized and community-based approaches should provide short-term success as well as long-term sustainability.173 Considerable importance is placed on negotiating behaviour and social change as opposed to education for knowledge change; resources and decision-making are decentralized; targeted government and private sector advocacy is deployed to increase political and financial commitment; extensive partnerships and support networks are developed through intensive mobilization; and greater focus is given to environmental improvements such as through better urban planning and services, including refuse disposal and water supply management, with the active involvement of communities.174 Apart from individual/family/community behaviour change, an enabling environment, i.e. one that supports, for example, new appropriate behaviours perhaps by providing improved services, better housing/infrastructure construction techniques or superior policies and more effective legislation is also imperative.175 Communication for behavioural impact (COMBI), espoused by WHO, is an innovative approach that refers to the task of mobilizing all societal and personal influences on an individual and family to (ensure) prompt individual and family action.at COMBI focuses on and is informed by behavioural outcomes that are made explicit, while health education and promotion may be dedicated to behavioural outcomes stated implicitly.au COMBIs premise is that while knowledge of effective tools and technologies, availability of services, etc. needs to be introduced or reinforced, that alone is not enough, since knowing what to do is in reality different from doing or adopting appropriate activities without the necessary motivation and an enabling environment. In other words, an informed and educated individual is not necessarily a behaviourally responsive one. COMBIs process blends strategically a variety of communication interventions intended to engage individuals and families in considering recommended healthy behaviours and to encourage the adoption and maintenance of those behaviours.av COMBI thus entails purposive and tailor-made strategic communication solutions intended to engage a specific target audience to translate information into responsive action and integrate it with advocacy and social mobilization initiatives to create an enabling environment. Such an environment will result in desired behavioural outcomes and impact. Developed and tested over several years, COMBI incorporates the lessons learnt from five decades of public health communication and draws substantially from the experience of private sector consumer communication.176 In effect, COMBI represents a neat coalescence of a variety of marketing, communication, education, promotion, advocacy and mobilization approaches that
as Changes that are frequently resisted have been described in chapter 12. at World Health Organization, Mobilizing for Action: Communication-for-Behavioural-Impact (COMBI). 2004. WHO. au av ibid.
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generally aim to do the same thing: have an impact on behaviour and foster programmecommunity partnerships by integrating principles and techniques of health education and promotion. Furthermore, it is almost an article of faith that locating programmes in the community and involving community members in planning, implementation and evaluation can be an effective strategy for improving population health.177 Using participatory methods to include people in the designing, implementation and evaluation can be a productive way to start understanding the motivational gaps and barriersaw and ensuring sustainability, which are integral to COMBI planning and implementation as well. New evidence-based methodologies focus on furnishing community members with key concepts and evidence-based training so that they gather their own data, evaluate the control programme and generate and implement their own improved interventions based on the successes and challenges encountered in their settings.
(10) Strengthen staff skills. (11) Set up a system to manage and share information. (12) Structure the programme. (13) Write a Strategic Implementation Plan. (14) Determine budget. (15) Conduct a pilot test and revise the Strategic Implementation Plan.
aw A classification derived by a literature review by Mefalopulos (2003) includes (1) passive participation, when stakeholders attend meetings to be informed; (2) participation by consultation, when stakeholders are consulted but the decision-making rests in the hands of the experts; (3) functional participation, when stakeholders are allowed to have some input, although not necessarily from the beginning of the process and not in equal partnership; and (4) empowered participation, when relevant stakeholders take part throughout the whole cycle of the development initiative and have an equal influence on the decision-making process. Cited from: Mefalopulos, P Development Communication Source Book: Broadening the boundaries of communication. 2008. World Bank. ..
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Each organizations planning/processes include different names for the steps but there are common elements. Most key steps should engage the participation of members of the intended audience and other key stakeholders.ax Following the 15 steps of COMBI planning, starting with establishing clear behavioural objectives (and not just knowledge change), the strategic roles of a variety of social mobilization and communication actions (Box 31) and their integrated application as suitable is determined.ay Box 31: COMBIs integrated actions (1) Public relations/advocacy/administrative mobilization: to place the particular healthy behaviour on the agenda of the business sector and administrative/programme management via the mass media (news coverage, talk shows, soap operas, celebrity spokespersons and discussion programmes); meetings/discussions with various categories of government and community leadership, service providers, administrators and business managers; official memoranda; and partnership meetings. Community mobilization: including the use of participatory research, group meetings, partnership sessions, school activities, traditional media, music, song and dance, road shows, community drama, leaflets, posters, pamphlets, videos and home visits. Sustained appropriate advertising: in M-RIP (massive, repetitive, intense and persistent) mode via the radio, television, newspapers and other locally available media, to engage people in reviewing the merits of the recommended behaviour vis--vis the cost of carrying it out. Personal selling/interpersonal communication/counselling: involving volunteers, schoolchildren, social development workers and other field staff at the community level, in homes and particularly at service points, with appropriate information and literature and additional incentives, and allowing for careful listening to peoples concerns and addressing them. Point-of-service promotion: emphasizing easily accessible and readily available vector control measures and fever treatment and diagnosis.
(2)
(3)
(4)
(5)
ax Johns Hopkins Bloomberg School of Public Health. Center for Communication Programs. Knowledge for Health Project, The Tools for Behaviour Change Communication. January 2008 Issue No. 16. ay For additional information, refer to the Parks W., Lloyd L.. Planning social mobilization and communication for dengue fever prevention and control: A step-by-step guide. WHO, Geneva 2004 (WHO/CDS/WMC/2004.2 and TDR/STR/SEB/DEN/04.1). Additional literature include: 1) SEPA (Socializing Evidence for Participatory Action) programme based on CIET methods (http://); 2) Parks W. et al., International Experiences in Social Mobilization and Communication for Dengue Prevention and Control. Dengue Bulletin 2004; 28 (Supplement): 17; 3) Mefalopulos, P Development communication source book: .. Broadening the boundaries of communication. 2008. World Bank. DevelopmentCommSourcebook.pdf; 4) Carbanero-Versoza, C.. Strategic communication for development projects: A toolkit for task team leaders. 2003. World Bank.
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through IVM) on the one hand and the diversity of cultures, literacy and degree of poverty of urban and rural populations on the other hand to evolve suitable strategies. The terms of reference should include the following: Determining preliminary behavioural objectives (see Step 2). Recruiting principal investigators and field workers (as required) to design and conduct formative research (see Step 3). Organizing feedback on the formative research findings (see Step 4). Finalizing behavioural objectives (see Step 5) on the basis of research findings. Designing the strategy (see Steps 6 and 7). Overseeing pre-testing of messages, materials and behaviours (see Step 8). Ensuring that monitoring and evaluation activities are conducted and relevant reports written (see Steps 9 and 11). Supervising/participating in relevant training activities (see Step 10). Writing a Strategic Implementation Plan that details the social mobilization and communication strategies required to achieve the stated behavioural objectives (see Step 13). Seeking financial and other support in kind for the proposed project/activity (see Step 14). Identifying the location of a pilot project and discussing subsequent design and implementation with the relevant community and civic authorities (see Step 15). Presenting the programme progress to community groups, relevant national committees, donor agencies and the national media, as required. Presenting programme results at relevant forums (meetings, symposiums, etc.).
Step 2: State preliminary behavioural objectives Achievement of specific behavioural results vis--vis behavioural objects is the essence of COMBI planning. Hence, at the very start enunciation of preliminary behavioural objectives is absolutely imperative. In developing the preliminary objectives, the planning team must discuss the following questions:az Whose behaviour should be changed to bring about the desired outcomes? Who is the target audience? What is required to be done? Is it feasible? Is it effective? Why are they not doing it now? What are the barriers and motivators? What activities can address the factors most influential to change behaviour? Are materials/products/services needed to support those activities? If yes, are those easily available? If not, what should be done?
az Drawn from: Parks, W. and Lloyd L.. Planning social mobilization and communication for dengue fever prevention and control: A step-by-step guide. WHO. 2004.178
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Step 3: Plan and conduct formative research Formative research (also known as market or intervention or communication research) is conducted primarily at the start of the programme and includes all research that helps to inform the development of a new, or refinement of an existing, social mobilization and communication strategy. The key focus areas of research are described in Box 32. Box 32: Formative research Formative research: Identifies key socioeconomic issues, gaps in knowledge and health education, and key resource- and non-resource-related constraints that impede existing prevention or control programmes. Provides in-depth information about attitudes, beliefs and practices about health and the factors affecting health behaviours among the target audience and ascertains the degree of access to information, services and other resources. Highlights the felt needs in the community that could be shared by programme priorities. Keeps those developing the strategies informed about what local populations are doing, thinking, and saying about focal issues, behaviours, technologies and service staff. Discovers key cultural analogies that can be used for effective health education messages and materials. Identifies behaviours that, after modification, could become more effective in removing or reducing health risks; and examines what obstacles may come in the way of adopting new behaviours and how to resolve them. Investigates barriers, motivations and opportunities for change and identifies the stage people are at in the behaviour change process. Points out the degree of access to information, services and other resources, and basic media habits. Examines recent and current programmes and policies, assesses structures, scope and capabilities of programme planners and implementers, and provides details on how best to implement the strategy (who, when, where, how). Records the availability of communication channels and their strengths and weaknesses in terms of reaching the target audience. Pre-tests behaviours, messages, and materials with representative samples of intended target groups. Assesses health workers and/or policy-makers perceptions and practices. Lists the stakeholders and partners for planning, implementation and monitoring of COMBI programmes and the motivations, skills and resources required to ensure their active involvement to make dengue prevention and control everyones business. Monitors community response to interventions over time, enabling mid-course correction.
A specific body of research in addition to a series of practices to induce change through specific methods and media is essential in development communication. While there is vast literature about planning, production and strategic use of media in development, there is significantly less material
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about the dialogic communication to investigate issues at the beginning of development projects and programmes. It is well recognized that communication is a horizontal process aimed, first of all, at building trust, then assessing risks, exploring opportunities, and finally facilitating the sharing of knowledge, experiences and perceptions among stakeholders. The aim of this process is to probe each situation through communication in order to reduce or eliminate risks and misunderstandings that could negatively affect project design and success. Only after this exploratory and participatory research has been carried out does communication regain its well-known role of communication of information to specific groups and trying to influence voluntary change among stakeholders.ba For carrying out research, research design and protocol must be developed at the outset. Emphasis should be on qualitative research while quantitative information should also be gathered. In-depth interviews, focused group discussions, and observations, etc. should be considered. Institutional capabilities must be assessed to carry out research and identify who will conduct it. Selection and contracting should be executed as necessary. Questionnaire/interviewer guides must be developed, pre-tested and revised and a field plan for the research (responsibilities, schedules, etc.) should be prepared. Research staff (from the contracted organization) must be trained and conducted to facilitate/support research. Information should be carefully collated and analysed and a final formative research report with findings and implications for programme activities prepared. The key steps are presented in Box 33. Box 33: Key steps for conducting a formative research The following steps provide an idea of what to schedule for. Time estimates given are for a full study investigating all issues rather than for a specialized study: (1) (2) (3) (4) (5) (6) planning the research (4 weeks). training (3 weeks). field work (6 weeks). analysis and writing summary report of findings (6 weeks). final report writing (3 weeks). dissemination.
The cost of the research will vary depending mainly on how many communities need to be visited (sampled) and the cost incurred on personnel and transport. The larger the geographical area and the more diverse the population, the greater the number of days required in the field and more expensive the research. Engagement of target audience/community/group/individual: Sensitize and discuss the objectives and purpose with the target. Select participants who work with or represent those most affected by the health issue and ensure fair representation of vulnerable segments such as women and marginalized groups. Encourage response regarding their felt needs and involve them and other key stakeholders in analysis of concerns. Various participatory methods should be employed. These may include preference ranking, scoring of various problems and solutions (for example, programme interventions for vector control) in addition to mapping the availability of various programmes and prioritizing the best mode/place for implementation.
ba Mefalopulos, P Development communication source book: Broadening the boundaries of communication. 2008. World Bank. ..
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Step 4: Invite feedback on formative research On the basis of formative research, the planners and decision-makers should make suitable recommendations for action by different segments of the programme. Step 5: Analyse, prioritize and finalize behavioural objectives Examine critically. Alterations of the objectives originally set should respond to the outcome of formative research. Target a few behaviour items. Choose not more than three behavioural objectives at a time.
COMBI objectives are different from the objectives to which one is used to because it includes: the clear identification of the target audience (e.g. housewives who store water rather than households). a detailed description of the behaviour being promoted and the frequency of the behaviour (e.g. scrub the interior walls of water-storage drums twice a week with a rigid bristle brush and laundry detergent rather than scrub water-storage containers to prevent mosquito production). the measurable impact that is desired over a specific time period (e.g. 60% of women who store water will scrub the interior walls of after the first year of the programme rather than all women will scrub water-storage drums).
In other words the objectives should be SMART (specific, measurable, appropriate, realistic, time-bound). Specific: who or what is the focus; what change(s) are intended. Measurable: specified quantum (e.g. % change intended). Appropriate: based on target needs and aimed at specific health-related benefits. Realistic: can be reasonably achieved. Time-bound: specific time period to realize the objectives.
Step 6: Segment target groups In view of the diversity of the thinking processes of the community, perceptions about a particular message may differ. In contrast, if the messages are segment-specific, it is then seen as concerning that segment alone. There are two main advantages to segmentation: Meeting the needs of the smaller segments is better than targeting everyone. Since operation is often attempted with very limited resources, one can become more efficient and effective if it is determined as to which segments demand more resources than others and strategies are tailored accordingly.
Step 7: Develop strategy A strategy is the broad approach that the programme takes to achieve its behavioural objectives. Strategies are made up of specific social mobilization and communication activities that on their
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own or in combination lead to the achievement of the objectives. Box 34 gives an example of how objectives, strategies and activities may be linked. Box 34: Objectives, strategies, activities Objective To prompt 1000 householders in [location] to prevent any tyre that is not in use for a car from accumulating water during the next 12 months. Strategy (one of several, each aimed at different target groups). To drill holes in discarded tyres to stop them from collecting water. The strategy will be delivered in two ways: A field team of 30 volunteers and five vector control programme staff will visit households and drill holes into tyres with hand-held battery-driven drills. Tyre replacement centres and gas stations and the like will provide an ongoing drilling service when old tyres are exchanged for new ones but are still wanted by householders, and before storing unwanted tyres at a public dump site. Training workshop for field team on communication skills and the drilling of old tyres. Field team to visit 1000 households and drill holes in old tyres as well as disseminate information on vector control. Interpersonal communication (IPC) with householders supported by information dissemination pamphlets. Pamphlets handed out to drivers by sales staff and cashiers at tyre replacement centres and gas stations. Radio and TV spots to raise awareness about the mosquito breeding problem in used/ dumped tyres and drilling those for channelling out water. Letters and follow-up telephone calls and visits to tyre replacement centres and gas stations.
Activities
Strategy development requires creativity. Frequently, it is not the lack of funds, knowledge, technology, skilled employees, or motivated communities that is the principal impediment; what programmes lack most is a supply of new ideas. No effective dengue control programme can exist without an innovative approach to social mobilization and communication because everything must change on a regular basis. An example of creativity at work is illustrated in Box 35.
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Box 35: Dengue Bicycle-Riders in Johor Bahru, Malaysia178 As part of a carefully integrated social mobilization and communication campaign in Johor Bahru in Malaysia, bicycle-riding teams (DRIDERS) were formed to undertake tours of the district every Sunday during the three-month campaign. These riders were local youths who volunteered for this activity. Each team consisted of 20 riders. Every Sunday morning, the team toured selected areas on bicycles accompanied by a van equipped with a public announcement system to promote the campaign. They rode on mountainterrain bikes clad in special T-shirts with the two behavioural objectives of the campaign printed on the back (Every family should carry out a house inspection once a week for 30 minutes and Anyone with fever should seek immediate treatment in a clinic). At each location, the team was greeted by local community leaders and residents and the atmosphere was carnival-like. There were speeches delivered, along with distribution of health education materials, refuse-collection activities, traditional dances and singing, and occasionally some competitions. Refreshments were also served.
Designing strategies depends on the objectives to be achieved and the resources available. A number of resources are necessary to ensure four important design features of good strategies: consideration given to more than just the message; the careful blending of communication actions; gender sensitivity; and the timing of interventions to coincide with local events and calendars. Effective communication is central to achieving behavioural outcomes and impact. Communication is the process in which a Message from a Source is sent via a Channel to a Receiver with a certain Effect intended with opportunities for Feedback, all taking place in a particular Setting (MS.CREFS)bb [Table 13]. Table 13: MS.CREFS components
Components Message Important considerations Ensure that the language is clear and easily understandable. That it is not too technical. Giving too many messages confuses the audience. Be clear about what is the main central message. Use a credible person to deliver the message. For example, people may not pay attention if a local shopkeeper was giving advice about dengue, but it would be more credible if a well-known doctor was delivering the same. In other cases, a young teenager would be more likely to persuade other teenagers to take action rather than a figure seen as authoritarian. Remember, appearances make a difference in how the source is perceived. Identifying the most appropriate channel is important, either using the mass media through radio, television and newspaper and/or interpersonal channels such as door-to-door visits, traditional theatre, group meetings, etc. The right channel must be used for the right target audience and generally the most effective is a selective mix of channels. Note the importance of non-verbal channels such as gesticulation, facial expressions and posture.
Source
Channel
bb Everold Hosein
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Components Receiver
Important considerations The receiver filters and interprets the world through the cultural lens with which they view the world. An understanding of this world is crucial to effective communication. Therefore, how you would explain the need to correctly protect water containers to a rural farmer may be different from how one would deal with urban schoolchildren and housewives. This is the end result of communication. The effect is the behavioural focus through improving knowledge, skills and providing prompts/triggers that could have an impact on ultimate behavioural outcomes. This is the point of departure for COMBI planning. One must be clear about the communication effect(s) desired that would lead to behavioural results. It is important to ensure that communication interventions are appropriate, effective and engage the receiver to provide feedback. Feedback allows for such assurance. With it one can fine-tune communication actions. This can facilitate or hinder communication. If there is too much noise, or the timing is wrong, or the setting is inappropriate to the subject being discussed, or there are too many distractions, or it is too hot, or too cold, all these factors affect how messages are heard and interpreted. Locations such as religious venues, health centres, cafes, marketplaces and schools provide their unique features that can affect the dynamics of communication and must be considered in the planning of communication actions.
Effect
Feedback
Setting
Source: Parks W., Lloyd L.. Planning social mobilization and communication for dengue fever prevention and control: A step-by-step guide. WHO, Geneva 2004 (WHO/CDS/WMC/2004.2 and TDR/STR/SEB/DEN/04.1)178
Engagement of the target audience/community/group/individual: Involve targets, stakeholders and/or facilitate their involvement in strategy design consultations or workshops that should include deliberations on MS.CREFS . Such events should be held at locations preferred by the community and at times that are convenient for them. The workshops should arrive at a consensus regarding strategic planning. The stakeholders should buy in by agreeing to take on responsibilities as appropriate. Step 8: Pre-test behaviours, messages and materials Pre-testing is the hallmark of a well-designed social mobilization and communication strategy. The study should be designed and carried out by social scientists. The subject matter for pre-testing includes: (i) product testing, (ii) behavioural trials, and (iii) message and material testing. (i) Product testing helps avoid what could be called the product mindset. In this mindset, it is presumed that if any Aedes breeding control measure (example, e.g. larvicide, water container cover) is offered to the community it will be accepted/followed/used. However, in the absence of visibility, i.e. if dengue is not perceived to be a problem or if dengue cases occur despite vector control or if people continue to be bitten by mosquitoes despite Aedes control or if mosquito breeding is thought to be in areas such as swamps and drains (not in cleaner household water containers), or use of certain measures is thought to contaminate water supplies, Aedes control measures often have no clear advantage for the communities, in general. So, decision-makers have to generate evidence for the acceptance of the product. Behavioural trial is a small-scale test of a new behaviour with a representative sample of the target group to determine its abilities to effectively adopt a different practice (sometimes, behavioural trials and product tests are combined). A behavioural trial can help to:
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(ii)
analyse those parts of the desired behaviour that are, and are not, readily adopted; identify material or behavioural barriers to the adoption of the new behaviour; identify what works best to reinforce learning of the new behaviour; and refine communication to reinforce the desired behaviour.
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(iii) Pre-testing messages and materials including brochures, booklets, flipbooks, information cards, scripts for plays/skits/story boards as relevant for entertainment education/infotainment (information through entertainment), print, radio or TV advertisements, audiotapes or videotapes, packaging of technical products, etc. These help to: assess whether messages are clear and compelling; identify unintended messages; detect totally unpredictable audience responses and other aspects of materials that may require modification; select from among a range of potential messages and materials and provide some insight into whether these messages and materials will generate the desired behavioural impact.
Effective messages should be clearly stated and specific to the desired action(s)/behaviour(s), technically correct, consistently repeated, easy to understand, command attention; and should appeal to both the heart and the head, build trust and call for action. Engagement of the target audience/community/group/individual: Form a group of key stakeholders close to or representing the audience. Advisory groups can provide useful advice about developing appropriate messages and materials and can help with suggesting revisions after pre-testing. Invite members of the audience to suggest messages and materials. Step 9: Establish a monitoring system Monitoring of any programme is continuous and enables the desired modification of the strategy to achieve the desired goals. Evaluation is either periodic or a terminal activity. Monitoring and evaluation (M&E) demonstrate if a particular intervention/medium has reached/served its goal/purpose or not. M&E also helps obtain guidance for programme decisions and determine if improvements in health outcomes are causally linked to a given intervention or a given behavioural change.bc There are two ways to monitor strategy progress: (i) (ii) (i) Behavioural impact monitoring (or surveillance), and Process evaluation.
Individual behaviour change will be reflected by an increase or decrease in (i) production of adults of Ae. aegypti mosquitoes; (ii) the risk of other members of the family being bitten by Aedes mosquitoes; and (iii) the risk of acquiring dengue virus infection. (ii) Process evaluation: Making decisions about refining the strategys objectives, activities, behaviours, products, services and so on. Documenting and justifying how resources have been spent. Making a compelling case for continued or additional funding (especially if combined with behavioural impact data).
bc For additional information, refer to: Tools for Behaviour Change Communication. INFO project. Center for Communication Programs. Johns Hopkins Bloomberg School of Public Health. 2008. Issue No. 8. BCCTools.pdf
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Process evaluation may be carried out by way of tracking planned activities, field supervision and monitoring by using the standardized supervision checklist. Regular supervision ensures that any gap or problem with knowledge, skills or attitude is readily recognized and corrected. Mid-term and end-term evaluations, as appropriate, should be planned and conducted. These should be a component of the overall programme evaluations or may be conducted independently, as necessary and appropriate. The information generated through formative research should serve as the baseline. Both quantitative and qualitative methods should be applied. Engagement of the target audience/community/group/individual: Comparison of outputs, outcomes with shared vision and original objectives is important. For purposes of continued motivation and reward, it is important that most of the community/stakeholders participate in the M&E process so that lessons learnt about what worked and why are shared and the way forward discussed. Include the target audience and other stakeholders (as part of steering committees, etc.) to track the progress of implementation, make recommendations and ensure action to improve activities. Involve the target audience in evaluating the programme(s) against the parameters they set themselves (participatory evaluation). Discuss their involvement in conducting the evaluation, and how the results will be used. Encourage the sharing of evaluation findings within the community and with others, as well as advocate further activities. In 2005, an evaluation of 11 WHO-supported dengue communication and mobilization programmes using the COMBI planning tool was conducted in six South Asian and Latin American and Caribbean countries.179 Certain key issues from the conclusions derived from this evaluation, as well as from the review of recent programmes,bd are presented in Box 36. Box 36: Key Issues from COMBI evaluation from South Asian and Latin American and Caribbean countries Key issues: Programme leadership and planning for sustainable community participation and involvement. Transfer of technical knowledge and skills in planning participatory behavioural interventions to health workers, community volunteers and other partners at the local level. Creation and maintenance of monitoring and feedback systems at the local and national levels, including the development of behavioural indicators. Judicious mix of communication channels (interpersonal, mass media, publicity, etc.) to support programme behavioural goals over time, based not just on available funding but also on effectiveness in the local context.
Step 10: Strengthen staff skills Long-term sustainability of social mobilization and communication will be difficult unless the organization and orientation of government-run services emphasizes the development of communitybased programmes with genuine decision-making at the local level. Where programmes have undergone decentralization or are currently being decentralized, capacity at provincial, district and
bd Achieving Behaviour Change For Dengue Control: Methods, Scaling Up and Sustainability Working Paper for the Scientific Working Group, Report on Dengue, 15 October 2006, Geneva, Switzerland, World Health Organization on behalf of the Special Programme for Research and Training in Tropical Diseases, 2007.
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sub-district levels to plan, manage and implement social mobilization and communication strategies is often far from sufficient. It is, therefore, essential to provide opportunities for service personnel/ volunteers involved in the programme to learn how to plan and implement appropriate social mobilization and communication strategies, how to listen and work with community members, and how to link their plans and activities with local perceptions, conditions and resources. Training programmes should have feedback, and pre- and post-test sessions in addition to brainstorming on the major challenges in planning and implementing social mobilization and communication programmes for malaria. Further, group work should be organized on various prevention and control components with the exercises focusing on related current behaviours, desired behaviours, target audience, communication, objectives, key benefits, key barriers, draft messages, interventions, monitoring and evaluation, etc., thereby ensuring that skills are developed or refreshed. These should draw from the experiences of trainees/trainers. Step 11: Set up systems to manage and share information Programmes can no longer rely on their former practices to sustain dengue prevention and control. The ability to change requires an ability to learn. Dengue programmes need to become learning organizations, with information management systems that enable rapid understanding of trends and developments affecting the behaviour of target groups. Such systems would include carefully filed or electronically stored data on target groups and programme partners, drawing from formative research (see Step 3) as well as from pre-testing (see Step 8), monitoring (see Step 9), and negotiations with programme partners (see Step 12). This information system may be called Community Profiles or Consumer Information System or the Formative Research Databank. In essence, a COMBI database is needed as equivalent to a health information system or entomological surveillance system. Such database and archived research findings and lessons learned should be used in future programmes and/or for revising/redesigning communication, behaviour change objectives, channels, messages, tools, materials, indicators, etc. and for restarting the strategic designing/planning, till the desired behavioural objectives are achieved. The programmes should plan and prepare information products for dissemination among key stakeholders, partners, news media, funding agencies and the like. Step 12: Structure of the programme Social mobilization and communication are usually accorded low priority in most programmes and are often developed and implemented at the lowest levels (by junior staff or staff with no relevant background/experience). The obvious implication of this structural location is that senior management doesnt consider it to be very important. Organizational or structural change is often required. Strategies for organizational change may include: forming multidisciplinary teams and intersectoral committees to help managers work through the tasks required; training, mobilizing and supervising a field workforce; establishing management procedures, benchmarks (indicators that show whether the programme is moving towards a particular goal), and feedback or tracking mechanisms (e.g. monthly reports or newsletters shared at all levels and regular meetings); and designing a modified organizational structure by identifying and delineating new responsibilities, creating new positions (when necessary), modifying working hours, and covering the expenses that increased field work generates.
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Four basic organizational structures (not mutually exclusive) can be used to enable programmes to practise social mobilization and communication. They are: Functional organization (namely involving a number of staff and consultants, and the creation of working groups). Programme-centred organization (namely an identified staff given the responsibility of coordinating all functions). Community-centred organization (namely structuring the programme in accordance with how the interventions are perceived by community groups, i.e. on the basis of how they use them and what they think about them, and not on how the programme promotes them). Organizing strategic alliances (namely involving partner organizations such as NGOs, other ministries, advertising agencies, etc.).
Step 13: Write a strategic implementation plan The purpose of strategic planning for social mobilization and communication is to devise a plan that is appropriate to the health problem and target audience, takes into account the resources available, and has the best chance of bringing about sustainable behavioural impact. It should be locale- and context-specific and ensure implementation in a socioculturally and economically appropriate way. Plansbe can be short-term and long-term. While short-term normally refers to a period of one year or less, long-term plans usually extend to three to five years. The plan should focus on enhancing awareness among the targeted at-risk and affected groups about source and transmission risk reduction, treatment and availability of services. It should also address and promote attitudinal and value changes among target groups that would lead to informed decision-making and modified behaviour (such as the adoption of timely and appropriate practices at the individual, family and community levels), and stimulate an increased and sustained demand for quality prevention and care services and optimal utilization of available services. The plan should be discussed and debated by the multidisciplinary planning team and by other stakeholders. Ideally, there should be three basic sections, as enunciated in Box 37. Box 37: Basic sections of a strategic implementation plan178 1. INTRODUCTION
1.1 Principal findings from formative research: Prepare a summary of existing data and results of the formative research on the behavioural and programme environments, including a list of issues requiring further formative research. 1.2 Behavioural analysis: Write down a detailed description of the behaviours selected for attention through the analysis process (for example, problem analysis, risk factor analysis, force-field analysis, BEHAVE framework analysis, priority analysis, SMART objective analysis). State the behavioural objective(s) [ensure that the objectives are SMART: specific, measurable, appropriate, realistic and time-bound]. Explain the significance of the objective/s. 1.3 Target group segmentation: Describe target groups (classified by behavioural segments and primary and secondary audiences).
be
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2.1 Overall goal: Define the overall goal, for example: to contribute to the reduction in morbidity and mortality from dengue fever/dengue haemorrhagic fever in [location] by the year [date]. 2.2 Behavioural objective(s): Define the behavioural objective(s). Re-state the specific objective/s as presented in 1.2. For example: Within one year from the start of the programme, to increase the percentage, from 30% to 60%, of women in [place name] who vigorously scrub the interior walls of water-storage drums twice a week using a rigid bristle brush and laundry detergent. 2.3 Strategy(ies): A general overview of the social mobilization and communication strategy stating the key messages, their sequencing (if any), the overall tone of the strategy, the blend of communication actions (administrative mobilization, community mobilization, advertising, personal selling, point-of-service), and the relationships between different communication actions and an overview of how the plan will be managed. The strategy should focus on delivering the right messages to the right audience at the right time through the right channel mix. 3. THE IMPLEMENTATION PLAN (explaining the what, when, where, who, how much)
3.1 Communication actions: Detail specifications of communication actions outlined in the Strategy section, including descriptions and plans for production, procurement, pricing and distribution of any technological products, services, incentives (such as bags, caps, T-shirts, prizes) and other materials, as well as identifying what training and supervision activities are required for staff and/or partner agencies (for whom, what, when, where, why, and facilitated by whom). Drawing from the formative research, a locale- and context-specific media mix should be considered. Reach, credibility and costs should be discussed. 3.2 Monitoring and evaluation: Determine the details of the behavioural monitoring and process evaluation to be used, outline the methods for data collection and analysis, prepare a description of the system for managing and sharing monitoring information (community feedback, programme reports, etc.), and ready an explanation of how the plan will be modified as a result of monitoring. Also included here would be a description of any midterm or final evaluations of behavioural impact (alongside other areas of interest such as entomological impact, social and organizational impact, impact on morbidity and mortality, environmental impact, costbenefit analyses, and other unintended impacts). 3.3 Management: Describe the management team (e.g. the multidisciplinary planning team), including specific staff or collaborating agencies (e.g. local advertising firms and research institutions), designated to coordinate communication actions and other activities (such as monitoring). Also consider including any technical advisory group or government body from which the management team is to receive technical support or to which it will report.
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3.4 Workplan: Develop a detailed workplan with time schedules for the preparation and implementation of activities required to execute each communication action as described in Section 3.1. The workplan could take the form of a table with column headings such as Activities, Completion date, Responsibility (staff member, partner agency, and so on), etc.. A tabular flowchart (or Gantt Chart) with column headings for weeks, months, quarters or years along the top and specific activities being listed as row headings down the lefthand side is also useful. Cells within the table can be shaded to indicate the week or month during which a particular activity is scheduled. Such a diagram allows instant comprehension of when different activities begin and end, whether preparatory activities have been given enough time, whether communication actions that need to be integrated have indeed been integrated, and highlights periods of peak activity. 3.5 Budget: Work out a detailed list of costs for the various activities (see Step 14). Engagement of target audience/community/group/individual: Ensure that discussions are held with the target audience prior to finalization of the plan and encourage them to understand various roles and responsibilities in programme implementation and share their views on participation and self-monitoring. Step 14: Determine the budget Dengue is basically a problem of domestic and workplace water management and sanitation, and the behaviours required to improve this management are considerably cheaper than largescale application of insecticide. But it would be a mistake to believe that the problem can be addressed with little or no investment of funds and commitment of other resources (e.g. staff and time). It is a huge challenge to find ways of transferring to the community the desired degree of responsibility, capability and sense of motivation for the prevention and control of dengue. An appropriate budget should be allocated for these important activities. Step 15: Conduct a pilot test and revise the strategic implementation plan While a lot of attention needs to be devoted to the objectives, strategies, activities and monitoring procedures of the strategic implementation plan, and the resources needed for its implementation, the process of social mobilization and communication implementation is often overlooked. Pilottesting represents an important first step in implementing a social mobilization and communication plan. During piloting, formative research is again used to obtain feedback from participants involved in the plans implementation as well as from the staff on the quality of the activities covering all dimensions from educational materials to the competence of the personnel chosen to deliver the activities. Pilot-testing serves at least three basic functions: Ensuring that the chosen strategies have no obvious major deficiencies. Fine-tuning possible approaches so that they speak to target audiences in the most effective ways. Convincing staff and partners.
No matter how the behavioural results from the pilot test are captured, stored or analysed, the next important task is to determine whether the strategy can proceed to full implementation or whether modifications are needed. Here, the community-centred view of planning must dominate.
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In other words, the focus of learning should be on what primary and secondary audience members said, what they did, what additional information and resources they wanted and in what form, and so on. A pilot-test may reveal the need for re-setting the behavioual objectives, as well as redesigning strategy and approaches and also the plan of implementation itself. Engagement of target audience/community/group/individual: Mobilize the target audience and other stakeholders in the pilot-test while including a control group/community among whom nothing beyond routine activities have been conducted. The above-mentioned 15 steps of COMBI planning will accomplish three essential managerial tasks: First, to establish clear behavioural objectives. Second, to determine the strategic roles of a variety of social mobilization and communication disciplines; for example, public relations, advocacy, administrative mobilization, community mobilization, advertising, interpersonal communication, and point-of-service promotion, in achieving and sustaining these objectives. And third, to combine these disciplines into a comprehensive plan that provides clarity, consistency and maximum behavioural impact to the social mobilization and communication efforts.
The overall process or cycle of development communication, as in COMBI, too illustrates four main phases: research, is the first phase communication-based assessment (CBA) for obtaining inputs for strategy design, makes up the second phase. The next phase concerns the production of the materials and implementation of the planned activities. Finally, the fourth phase is concerned with evaluation. Proper evaluation of the impact of the communication intervention requires the definition of monitoring and evaluation indicators during the initial research phase.bf It is well acknowledged that social mobilization and communication is an ongoing process, which is mostly non-linear and cyclical. Examples of non-linear models have been developed and applied across the world.bg Sustainable behaviour change requires time and repeated effort. The results and lessons from evaluation are utilized for refinement of the strategy (Step 7). The other steps, namely, developing and pre-testing messages and materials, the strategic implementation plan, M&E, etc. continue till the desired behavioural objective/s is/are achieved.
bf Mefalopulos, P Development Communication Sourcebook: Broadening the boundaries of communication. 2008. World Bank. . bg P-Process by the Johns Hopkins Bloomberg School of Public Health/Center for Communication Programs (. org/Publications/P-Process.pdf); Planning and Implementing a Communication Program by the World Bank (. worldbank.org/EXTDEVCOMMENG/Resources/toolkitwebjan2004.pdf)
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(iii) preparation: the person plans to change the behaviour; (iv) (v)
The initiative focused on one day a week (i.e. Thursday) when residents were to seek and destroy the sites where the Aedes aegypti mosquito might occur and breed. On this day, communication and educational actions were used to mobilize and motivate people. Following this approach, innovative printed communication materials were designed and disseminated. This resulted in a massive mobilization of students, housekeepers and other members of the public. Materials and a methodology of interpersonal communication were additionally produced that generated partnerships with the private sector and community groups. Another innovative feature included a mobile dengue exhibit with interactive educational games. The evaluation found that 94% of the teachers and 96% of the students knew about the calendar and 88% of the teachers and 77% of the students used it. The impact on households of message broadcast on radio in 20022003 recorded a score of 27% associating Thursday as Dengue Prevention Day and the same percentage practising specific actions to look for and control Ae. Aegypti breeding sites on that day of the week. The number of houses and schools with immature Ae. aegypti was found to be fewer during the post-intervention evaluation compared with the pre-intervention survey. To monitor behavioural impact among housewives and the rest of the population, the House Index was measured every three months. The results showed the index had decreased from 18% in 1998 to 5% in 2003. The three most important lessons learnt from this exercise included: (i) (ii) (iii) Objectives should be based on results from research that combine appropriate qualitative and quantitative methods. It is necessary to generate a critical mass of committed persons acting in different roles to prevent dengue. In order to develop a behaviour change project, it is necessary to have at least three years of continuous work done before any significant changes are observed.
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Box 39: Application of COMBI in Sri Lanka183 Sri Lanka initiated COMBI for dengue prevention and control in 2009 in 12 high-risk districts on a campaign mode. The overall goal has been to reduce the incidence of DF/DHF in the high-risk districts by 50% by the end of 2006 (i.e. from 2000 to 2005). The behaviour objectives for the period of 16 weeks from March and 12 weeks from September in select high-risk areas were to: 1) prompt housewives in 80%90% of homes to remove breeding sites in their houses and surroundings every Sunday for 30 minutes; 2) motivate 80%90% of tyre traders to keep their premises free of breeding sites; and 3) prompt school principals and teachers of 80%90% of schools to keep their school premises free of dengue breeding sites through inspections conducted every Friday for 30 minutes. Appropriate messages were disseminated through the channel mix of administrative mobilization/public relations/advocacy; community mobilization; advertising; personal selling and interpersonal communication; and point-of-service promotion. The M&E plan included monitoring during the planning and preparatory phase and during the implementation phase as well as preand post-intervention surveys. Evaluation of the COMBI plan was carried out in 2009 through key informant interviews (with supervisors of the implementers of the COMBI plan), focus group discussions (with the target audience), entomological surveys, and by testing the consistency of the messages. However, certain constraints such as lack of commitment, and paucity of human resources and funds, however, needed resolution for sustaining COMBI activities.
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12. The Primary Health Care Approach to Dengue Prevention and Control
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The Millennium Development Goals that were adopted by UN Member States in 2000bn provided continuity to the values of social justice and fairness articulated at Alma-Ata in 1978 and further affirmed the central and pivotal position of health on the development agenda as a key driver of social and economic productivity and a route to poverty alleviation. One can consider the health-related MDGs as the principal mission or primary objectives of HFA till the target year of 2015. They also simultaneously serve as proxy indicators for HFA.
Community participation
Community participation involves active voluntary engagement of individuals and groups to change problematic conditions and influence policies and programmes that affect the quality of their lives or the lives of others.188,bo Community participation can lead to initiatives on the part of the community and allow members to assume ownership of the development process.189 Regarding DF/DHF control, community participation is extremely important as can be gauged from the fact that even those households which do follow the recommended actions for prevention may still harbour Ae. aegypti or other mosquitoes in their homesteads and, worse still, may suffer dengue infections if their neighbours do not participate in controlling domestic breeding sites. Members of such households may also get infected outside their homes or at their place of work or study. Therefore, the issue regarding vector control is not about whether source reduction is effective but whether and how community participation can be a part of that source reduction effort.173,190
whr08_en.pdf bn United Nations General Assembly. Resolution 55.2. United Nations Millennium Declaration. 2000. declaration/ares552e.pdf bo Refer to Chapter 11 on IVM for definition and additional details on community participation.
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In rural areas, frontline public health workers working in peripheral health units play a significant role, with technical and material support from district and provincial authorities, in securing the participation from the community in dengue control. In urban areas community lifestyle is quite different. Together with primary health-care services offered through organizations responsible for urban health such as health centres and health units in municipalities, the basic principles of health promotion such as health-promoting schools, healthy communities and cities, and healthy workplaces should be applied. This is because, unlike in rural areas, most urban people are engaged in the formal sector or institutions such as schools, factories, offices and workplaces, marketplaces and the like. Furthermore, many of them migrate from rural areas to work in cities and live in slums where the environment and sanitary conditions are often poor or decrepit. Vector proliferation in urban areas in particular is often associated with human activities that aggravate the rate of deterioration of environmental sanitation. A change in human behaviour and lifestyle is, therefore, a pressing and felt need. This can be achieved if individuals, families and communities are made aware of the detrimental effect that careless and irresponsible behaviour has on their health and are then empowered with the necessary skills. Securing community participation in urban areas is important for the success of the programme and requires a similar, yet different, approach from that adopted for rural areas. Adopting a more structured approach at various levels from the policy to the individual would be more appropriate for urban areas. Once initiated, community participation requires continuous government and organizational support, failing which it will not last long. The governments responsibility towards developing health-care services and facilities is, therefore, not diminished. Community participation needs both guidance and active interest from the government and can be sustained only through the constant motivation that is derived from the successes of their joint efforts and/or with support from relevant organizations and agencies. The political will of the government is of vital importance in this connection. It is extremely important that the government should adopt community participation as integral to the national policy for promoting health development. Community organization and social mobilization Despite constraints,bp organizing and mobilizing the community and other community-level stakeholders is a critical element in an effective and sustainable dengue control programme. This entails several tasks: Raising community awareness: bq Use different communication channels and an appropriate media-mix such as local radio, community theatres, posters, leaflets, group sessions/civic forums, etc. to inform the community about the morbidity and mortality due to dengue in a particular area and elsewhere and the related economic and opportunity losses incurred by both the family as well as the community/country. How the benefits of the programme can be dovetailed with the needs and expectations of the people must also be explained to the community. Initiating community dialogue: The key steps should include: recognizing the dengue prevention and control issue(s)/problem(s); initiating a discussion among community members; clarifying perceptions to reach a common understanding; expressing individual and shared needs; and sharing a vision for the future that includes an ideal picture of how the community wants to see itself in the context of the dengue problem.
bp For additional details, refer to Chapter 11. bq For additional details, see section on Health Promotion and Prevention Activities below.
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Identifying and involving community health volunteers/workers: Identify and select community health volunteers/workers who will be instrumental to the success of the programme, and who will in particular galvanize the community into action. They will serve as health educators, communicators, problem-detectors and problem-solvers, community organizers, and leaders for health to enhance individual and family self-care and responsibility as integral components of everyday life.185 They will also serve as the link between the community and the health workers at the peripheral health units of the health-care delivery system. Dengue control should evolve as a natural component of the overall mixture of health services that a community chooses for itself. This should not involve the adding on of new tasks for the community health volunteers/workers, which leave them exhausted and fosters programme inefficiency. The issue of overburdening the community health volunteers/workers will not arise if the community is truly involved in the planning of and taking responsibility for their own health and environment.
Identifying key stakeholders for local planning and actions: With community health volunteers/workers taking the lead, local leaders both formal and informal should take part in the planning process so that their knowledge of the local culture and their experiences in mobilizing community action can be used to their advantage. The planning exercise may begin by motivating key stakeholders such as local administrative authorities, community and opinion leaders (village elders, religious leaders, teachers, womens group leaders, youth groups and civic organizations, traditional healers, etc.) and forming a local group/committee for planning and action following needs assessment. Ensure real community representatives are identified as leaders since they will serve as good role models and as change agents for the community in dengue prevention and control. Dialogue with local leaders to galvanize them to participate in dengue control should be undertaken through personal contact, group discussions and use of audiovisual materials. Interaction should generate mutual understanding, trust and confidence, as well as enthusiasm and motivation. The interaction should not be a one-time affair and should continue to achieve sustainability. The local committees should describe the importance of the uptake of interventions/services offered to the community and assist in building their capacity to identify their problems. The seriousness of the identified problems should be explained and that should include site/field visits for exposure. A sense of ownership among the local committees should be promoted and local resources mobilized as much as possible. Efforts should be made to grant recognition to the successes and best practices of local stakeholder committees by designating them as model committees.
Empowering stakeholders by building capacity: To facilitate the contribution of stakeholders to the programme, they should be empowered to possess necessary knowledge and skills, at least in the following: Simple methods of planning and evaluation of dengue control, namely survey of larvae and different methods of larvicides, COMBI.br With regard to leadership, many communities leave leadership in vector control entirely to professionals. This does not mean that the community lacks leadership from within itself. In fact, for primary health care to succeed, the existing and potential leadership pool must be enhanced. Local leadership may emerge from many sources, such as traditional healers and birth attendants, elders and religious leaders as well as from serving officials of the local community. Leadership development requires that the
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health professional indentify and collaborate with local leaders. The community health worker is an important link in this process. Community-level management systems for acquiring, monitoring and distributing vector control supplies and equipment, appropriate action as well as timely case detection and proper treatment-seeking can grow from the development of local primary health-care leadership. Baseline data collection An assessment of current status tells the community where they stand in relation to the problem today. Simple tools should be developed by the members of the planning committee with the help of health workers and supported by technical experts to collect baseline data on the nature and extent of vector problems, breeding sites, location of human habitats, disease outbreaks, the number of dengue cases which turned severe and complicated within a certain period, and sociobehavioural data related to disease transmission, treatment-seeking, etc. Both quantitative and qualitative assessments are necessary to get a comprehensive picture. Analysis of such data should be simplified to suit the group. Discussions on the results of the survey should be held among members. Programme planning Baseline data should be used in planning dengue control programme activities. The key strategies are: Set feasible objectives: These must be specific, measurable, achievable, realistic and timebound, and should create a high level of individual/community motivation that is required for taking appropriate action to resolve problem(s). Determine appropriate strategies and tools including those for community education and mobilization, making use of stakeholder knowledge and experiences about the social, cultural and behavioural aspects of the community. Develop an implementation plan with clearly defined actions. Design a basic monitoring, evaluation and surveillance system. Establish indicators to measure progress and outputs vis--vis the objectives. Identify resource needs (materials, financial, equipment, supplies, expertise, etc.) and indicate those that can be procured locally as against those that have to be procured externally. Clarify roles and responsibilities of stakeholders including local committee members. Seek collaborative support and involvement from relevant agencies and voluntary organizations at the district and community levels.
For planning, it is critical to engage the community and stakeholders in various activities, as appropriate. Implementation/community actions: A specific workplan/timetable for each activity should be discussed among the community or stakeholders to achieve consensus, understand timelines and to determine who does what, when and how and with what kind of support from local health personnel. The more the community participates in such discussions and views the proposed actions as their own the more likely are they to take tangible and successful action. Any programme directed towards the community will not work without the essential elements of community awareness and community involvement at its planning and implementation stage.191,192
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Achieving a consensus on action can at times lead to conflict between interest groups or reveal a degree of lack of commitment on the part of some groups. The leadership needs to explore options and evaluate them from the standpoint of conflict and its resolution. The plan should cover the whole range of activities from health promotion and disease prevention which include changing health behaviours and ensuring household and surrounding environmental sanitation to monitoring the outbreak of disease, referring patients to the nearest primary care unit, and M&E of the programme using simple indicators such as household index, container index, number of cases, etc. Activities should be tailored to fit the community lifestyle and the prevailing social, cultural and economic conditions. A key element that community actions need to keep in mind is the involvement of individuals who are the most vulnerable or most disadvantaged in the community. Not everyone will experience the problem(s) with the same degree of severity. For example, economically affluent families with means of personal protection and adequate access to quality heath care may not have to cope with health problems regularly and, therefore, perceive such problems to be individual issues. If any conflict arises, the leaders are to resolve it first before progressing with the problem. To resolve any conflict, more clarification may be needed or new leaders/stakeholders may have to get involved so that the majority can convince a reluctant minority to go along with them. (a) Promotion and prevention activities:
From a health promotion perspective, gaining the trust of the entire community is often difficult, and without trust it is hard to convince people to adopt healthier lifestyles.193 The desired changes in a community as well as in the supportive structures necessary for community-based health promotion are often slow. There are a number of changes that are frequently resisted and these are:194 changes that are not clearly understood; changes that the community or their representatives have no part in bringing about; changes that threaten vested interests and security; changes advocated by those whom the community do not like or trust; and, changes that do not fit into the cultural values of the community.
Community capacity should be developed and fostered with different components of the community working together as well as through capacity-building and the involvement of health promotion workers as mentioned above. Health education and empowerment:bs Health education should raise awareness about the magnitude, severity, transmission and control of the disease, and initiate/sustain appropriate behavioural changebt at both the community and individual levels. The behaviour change needed for vector control which often involves changing old and familiar habits or methods with regard to water storage, solid waste disposal (junk, etc.), proper personal protection measures and action to be taken when having fever should be aimed at. The broad categories of factors that may influence individual and community health behaviours must be taken into account when planning for health education activities. These include knowledge, beliefs, values, attitudes, skills, finance, materials and time, and the influence of family members, friends, co-workers, opinion leaders as well as the health workers themselves.
bs For details, refer to chapter on communication on behavioural impact. bt For details, refer to chapter on communication on behavioural impact.
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Health education should use locale- and context-specific communication channels (such as mass media including local radio stations, cable TV networks, newspapers; community outreach programmes such as community/group sessions by community health volunteers/workers, theatre/ folk media, public announcements; interpersonal communication; and posters, leaflets, activity booklets with guides, etc.) in a synergistic manner. Different methods of education and skill development such as group discussions, slide presentations, demonstrations, role play, role models, participatory learning and problem solving should be used to address factors influencing individual and community health behaviours. In other words, an understanding of the local sociocultural and economic characteristics, together with consultation with stakeholders should make it possible to select suitable methods for health education. In addition to improving knowledge and awareness, the necessary skills in dengue prevention and control such as elimination of breeding sites, methods of larvicide use, and actions to be taken during fever should be inculcated among the target groups. At the community level, the task to increase peoples awareness and develop necessary skills for the desired environmental and sanitation changes can be effectively shifted to the womens groups, self-help groups, NGOs including faithbased organizations, formal and informal community leaders, community health volunteers, school students/teachers, and the like. Targeting children and their families to eliminate vector breeding at home and at school together with the rest of the community should be emphasized. Health education can be implemented in a campaign mode and/or as part of a routine programme. The campaigns/routine programmes could be implemented in an integrated manner with other necessary community development programmes, especially those with health implications. The activities should be intensified before and during the period of dengue transmission while continuing on a regular basis to reinforce message dissemination for sustaining appropriate actions. This is quite a challenging endeavour. Campaigns: Organize clean-up campaigns two or more times a year to control the larval habitats of the vectors in public and private areas of the community. One such campaign should be timed prior to the transmission season. These could be coincided with significant national or community events such as the observance of the National Day, Earth Day, other religious days and so on. These campaigns should be supported by appropriate communication activities for the dissemination of messages designed to change individual behaviour or promote collective action. Integrated programmes: Community programmes for dengue prevention and control could be integrated with other priorities of community development. Where municipal services related to refuse collection, waste water disposal, provision of potable water, etc. are either lacking or inadequate, the community and partners could be mobilized to improve such services. At the same time larval habitats of vectors can be reduced, thereby contributing to the overall effort. Some key factors for the success of such programmes include the use of the Champion, who is considered to be the catalyst or change agent or key influencer. Community involvement in planning and implementation with the support of health personnel and related sectors, extensive publicity via various communication channels and follow-up evaluations are also of crucial importance. Children should be encouraged to participate from the planning stage till the end. Participation by municipal authorities in cities and appropriate local bodies in rural areas should be promoted. Novel incentives and reward schemes for those who participate in community programmes for dengue control should be designed to recognise their services and motivate them into continual engagement.
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(b)
About once a week trained community health volunteers/workers and/or community leaders and/ or schoolchildren and teachers should visit households, schools, etc. in their respective catchment areas to check mosquito breeding sites and apply control interventions as locally appropriate. Other preventive behaviours such as using bednets or screens on doors and windows and mosquito repellants, and adoption of suitable water-storage and household and environmental sanitation measures should also be discussed with the householders. During the period of dengue transmission, the community health volunteers/workers and/or community leaders should visit households to make sure that any fever case, particularly children or at-risk, are properly taken care of and referred on time to the primary health care centre or other referral health facilities for proper treatment. Communication and transportation for referring patients must be ensured. Positive cases must immediately be reported to the agency concerned and action taken to control the disease. (c) Containment of disease
In an outbreak of dengue, health staff at the peripheral health unit together with community health volunteers will be notified to join the Surveillance and Rapid Response Team as members to carry out disease investigation and control measures. Health education must also be imparted along with case investigation and insecticide spraying. (d) Monitoring and evaluation
People are willing to continue their activities if they see the results of their efforts. Therefore, evaluation of the prevention and control programme is an important element in making the programme sustainable. A monitoring system should be designed to collect and analyse necessary data (entomological and epidemiological) as well as review ongoing programme activities through supportive supervision. Feasible indicators should be set to measure progress in outputs and outcomes. Participation by the community in monitoring and evaluation should be ensured. The results are also to be shared with the community. In urban areas, efforts should be made to set up a databank with all the information obtained from surveys and the studies carried out in areas that either have foci of infestation or are capable of generating them. The databank should also contain information on the underlying causes of such foci, vector density per residential unit, block or hectare, seasonal fluctuations and oscillations, and the relationship between indicators and the incidence of diseases associated with or transmitted or borne by such vectors. (e) Social support and social network
In order to make the programme sustainable, social support from community health volunteers/ workers should be provided to the community on a regular basis. Social networks should be encouraged about joint activities to both sustain and expand the dengue control programme.
Intersectoral collaboration
The dengue control programme cannot be successfully implemented or accomplished by the health sector alone. Contributions from other sectors (non-health departments of the governments such as education, public works, information and mass media, environment, urban and rural development and the like, and nongovernment organizations, the private sector, and local self-government institutions such as the municipalities) are also required to participate and/or contribute to make the programme effective and sustainable.
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Intersectoral collaboration is another key element of primary health care in addition to community participation. Hence, any programme should ensure that the health sector interacts with sectors involved with national development or that impact the health and well-being of the people, in both urban and rural areas. The Ministry of Health must have a focal point responsible for coordinating and convincing other related sectors to take health aspects into consideration during their policy formulation. Intersectoral task forces or committees that meet periodically for strategic planning, implementation and oversight should be formed as well. High-level intersectoral meetings that are held at least once a year are useful in establishing the principle of sustainable intersectoral cooperation. Intersectoral collaboration is and should be an important feature of vector control programmes.bu It is well known that the activities of other sectors and the community contribute to the breeding and spread of vectors and that is why such collaboration can help limit and control vectors in both rural and urban areas. Improved intersectoral collaboration requires that vector control be better integrated in the developmental plans of other sectors, or in other words, incorporated into healthy public policy. [Healthy public policy aims at creating a supportive environment to enable people to lead healthy lives. In the pursuit of healthy public policy, government sectors concerned with trade, agriculture, education, industry, and communications, etc. need to take into account health as an essential factor when formulating policy. These sectors should be accountable for the health consequences of their policy decisions: Second International Conference on Health Promotion, Adelaide, South Australia, 5-9 April 1988]. Health development must not compete with the social and economic goals associated with rural, industrial and urban development; it must evolve as an essential requirement on its own. One starting point for intersectoral collaboration is the exchange of information between sectors to determine priorities. Since vector propagation is linked with planned activities such as roadbuilding, the opening up of new land for agriculture and urban development and the like, it is possible to evolve an information system that graphically depicts and forecasts important developments. Vector control in urban areas should also include urban planning. The planning of urban settlements and planned urbanization can help enhance the quality of life on the whole as well as the health and general well-being of urban populations and that of migrants to the cities. Planning should be undertaken by a multidisciplinary group that can provide the necessary guidance as well as establish guidelines for consistent and adequate policy decisions. Three distinct situations associated with vector proliferation need to be considered in the planning process: (i) the construction of a new city; (ii) the expansion of a neighbourhood or an existing part of a city; and (iii) the growth of small pockets in different parts of the city. It is easier to plan for a completely new city and it is moderately difficult to forecast the needs of a new neighbourhood or sector of a city, but it is extremely difficult to foresee what preventive or coercive measures will be needed for small areas. The multidisciplinary group in charge of urban planning or of studies to serve as the input for urban planning activities must include physicians, public health personnel, vector control specialists, sanitary engineers and architects specialized in urban planning. The ministries of health and urban development as well as the municipalities should organize regular meetings with architects, builders sssociations and institutions such as RWAs (residents welfare associations); and enact and implement building by-laws/act, civic by-laws for preventing mosquito breeding conditions. Public health engineers must be involved to design mosquito-proof water-coolers, lids for water tanks and such utilities as well as initiate technology exchanges for effective and wide implementation. Health impact assessment of all development projects must also be undertaken by the authorities concerned.bv
bu Also refer to Chapter 10. bv For additional detals refer to Chapter 10.
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In community settings in urban and rural areas, the organizations responsible for providing health-care services such as the ministry of health or the municipality must ensure that quality primary health-care services are accessible and available to the community and effective referral systems from the community to the health-care unit are in place. The ministry responsible for public works and their municipal counterparts in urban areas and the ministry of rural development and allied entities, including nongovernmental organizations, in rural areas should be involved in preparing appropriate development programmes that preclude mosquito breeding. They can contribute to source reduction by providing a safe and dependable water supply, adequate sanitation and effective solid waste management. In addition, through the adoption and enforcement of housing and building codes, a municipality may mandate the provision of utilities such as individual household piped water supply or sewerage connections and rainwater run-off control for new housing developments, or forbid open surface wells. In communities, health personnel should carry out a survey and map out the area to familiarize themselves with it and identify key stakeholders and NGOs working in the community there and secure their cooperation for the dengue control programme. NGOs can play an important role in promoting community organization and participation and implementing environmental management for dengue control. This will most often involve health education, breeding source reduction and housing sanitation improvement. Community NGOs may even be informal neighbourhood groups or formal private voluntary organizations, service clubs such as Rotary or womens clubs, churches or other religious groups, or environmental and social action groups. If needed, they should be trained by staff of the Ministry of Health in breeding source reduction methods, recognizing signs and symptoms of dengue fever, undertaking appropriate action thereof, and other related issues. They can help in mobilizing and working with the community to collect discarded containers, clean drains and culverts, fill depressions, remove abandoned cars and roadside junk, and distribute sand or cement to fill tree holes. They may also play a key role in the formulating recycling activities and removing discarded containers from yards and streets. Such activities must be coordinated with the environmental sanitation services. In schools, a health education component targeted at schoolchildren should be developed and appropriate health messages devised and communicated. It must be kept in mind that the school is an excellent medium to reach out to the main target groups, children and families (Box 28). Health education models can be jointly developed, tested, implemented and evaluated for various age groups by the Ministry of Education and Ministry of Health. Such cooperation between the two ministries will facilitate health personnel to work with schools in dengue control through the principles of primary health care and health promotion in schools. Several activities should be encouraged, such as monthly cleanliness drives in different neighbourhoods supported by give-away BCC materials (leaflets, hand outs, etc.), and projects, debates and competitions. The ministry of education should consider the inclusion of topics and practical work related to dengue prevention and control in the curriculum and the printing of appropriate messages in textbooks, as appropriate. To make the programme sustainable, teachers must be equipped with the necessary knowledge and skills in dengue control through training and by working closely with health personnel so that they will be able to independently continue the programme in the future. The concept of volunteers and peer support can be applied with schoolchildren to encourage them to actively participate in the programme. These young volunteers should be provided with leadership and dengue control training so that they can be efficient as change agents for others in their schools and communities. As part of leadership training and enhancement of self-efficacy, these children should be involved in planning, implementing and evaluating the programme.
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At the workplace/factory/industry, health personnel of the area should work with the management/unions of organizations to put dengue control through the concept of healthy workplace. Raising the knowledge and awareness levels about the importance of dengue control could be done through the Champions who are easily recognized by the community and command respect for their capacity to inform, convince, reinforce and advocate on the basis of evidence. However, convincing the management is the most challenging task because the programme may eat into the working hours of employees and improvement of waste management and sanitation can cost both time and money. Hence, government policies, laws and regulations concerning environmental sanitation and sanitizing workplaces and industries will be needed. Once agreed by the management of the workplace, primary health care and healthy workplace can be effectively applied. In a large organization, there is at least one occupational health personnel who is responsible for the health and safety of employees. Government health personnel should work closely with the workplace authority, occupational health personnel, and leaders of employees in matters of planning, implementing and evaluating dengue control programmes. For sustainability of the programme, these stakeholders should be empowered with the necessary knowledge and skills, including leadership skills, to enable them to completely take over the programme in the future while retaining technical support from government health personnel. Examples of successful community participation and intersectoral involvement the core elements of PHC approach for dengue control are illustrated below (Box 40). Box 40: Dengue control through community/intersectoral involvement in Thailand, Malaysia and Cuba In Thailand,183 PHC was initiated in 1980 and currently there are has 900 000 village health volunteers (VHVs) with one VHV for every 10 households. The VHV is selected by community and health staff and trained for two weeks. After that self-learning with the help of books and other media is encouraged. The key roles and responsibilities of VHVs for dengue control include: IEC by means of interpersonal communication, village-level broadcasts, etc. supported by larval surveys and subsequent control with temephos, cleaning day campaigns, as well as dengue fever control by advising patients to take essential drugs and refer to hospitals if there is no improvement. Warning the community about disease outbreaks as informed and screening case(s) in respective catchment areas; coordinating with school or housewives groups to take care of children; producing herbbased repellents (for example, citronella); and conducting monthly meetings with health staff to exchange information on situations and new IEC materials are other responsibilities. According recognition to VHVs to sustain their commitment is a critical aspect of the programme. In Thailand, health volunteers are identified in the workplace, schools, and other places. The local administrative organizations that have the financial resources and regulations to support dengue control encourage VHV activities. The Bangkok Municipal Administration (BMA) has also taken a lead role to control dengue in the national capital. Generating public awareness, keeping the environment clean and eliminating breeding places as well as space-spraying in outbreak situations are the major responsibilities.
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In Malaysia178 (Johore State), a campaign motivated householders to seek prompt diagnosis for any fever, destroy any larval breeding site found around their premises, and organize voluntary teams to inspect and control larval breeding sites in public spaces such as community halls, parks and vacant lots. Dengue volunteer inspection teams (DeVIT) were formed in 48 localities with 615 volunteers. During the three-month campaign, DeVIT teams proferred advice to 100 956 people, distributed 101 534 handouts, and inspected 1440 vacant lots. The campaign resulted in a dramatic drop in the occurrence of dengue in the district; three months after the campaign tracking surveys revealed that 70% householders were still inspecting their household premises regularly. Today, 95% of DeVIT volunteers continue with their work. The government of the state of Johore has decreed that the campaign be implemented throughout the state. The experience showed that a group of committed and dedicated people can plan and execute a project; and that communities and households will readily get involved if the behavioural targets set are reasonable and achievable. However, sustaining the interest of the volunteers is fundamental. In Cuba195achieving sustainability is one of the major challenges currently in disease control programmes. In 20012002, a community-based dengue control intervention was developed in three health zones of Santiago de Cuba. New structures (heterogeneous community working groups and provincial/municipal coordination groups inserted in the vertical programme) were formed, and constituted a key element to achieve social mobilization. In three control zones, routine programme activities were intensified. Sustainability of the intervention strategy over a period of two years following the withdrawal of external support was evaluated. The interventions evaluated through larval indices and behavioural change indicators were found to have been maintained during the two years of follow-up. In the intervention area, 87.5% of the water-storage containers remained well covered in 2004 and 90.5% of the families continued to use a larvicide correctly as against 21.5% and 63.5% respectively in the control area. The house indices declined from 0.35% in 2002 to 0.17% in 2004 in the intervention area, while in the control area they increased from 0.52% to 2.25%. Institutionalization of the intervention was reaching a saturation point by the end of the study. Key elements of the intervention had lost their separate identity and become part of the control programme's regular activities. The host organization adapted its structures and procedures accordingly. Continuous capacity-building in the community led to participatory planning, implementation and evaluation of the Aedes control activities. It was concluded that in contrast with intensified routine control activities a community-based intervention approach promises to be sustainable.
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These two components should be implemented concurrently. The response will also differ depending on the endemicity in countries. For endemic countries, the overall aim is to reduce the risk of dengue outbreaks and strengthen control measures for any future outbreak in order to minimize the clinical, social and economic impact of the disease. Receptive countries (i.e. dengue vectors present without circulating virus), ensure interruption of transmission.
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Technical: This involves the process of planning for laboratory materials, specimen collection, and storage and transportation techniques. A sample case investigation form may be prepared. Logistics: Administrative procedures including travel plans and other arrangements should be worked out. Investigators should establish and build partnerships whenever possible. The team should plan for further necessary steps to deal with media and other communities in the locality. Coordination: Before starting the investigation all team members should agree on the plan and their roles stipulated and responsibilities.
Note: If the physician submitted samples to any appropriate laboratory facility, the case investigation form may already be completed or started. Try to obtain a copy. Identify if the patient was ill with symptoms of dengue fever. Refer to Box 8. Record onset date of first symptom. Examine the laboratory testing that was done; if not yet reported. Record date of serum specimen(s) and/or tissue (specify) collection. Record or obtain copies of serology results and virus isolation and PCR tests, if done. Collect demographic data and contact information of case [full name, date of birth, country, sex, race/ethnicity, home address, occupation and work address, relevant phone number(s)]. Record hospitalization details: location, admission and discharge dates. Record outcomes: recovery or date of death; any mental status changes.
bw Adapted from: Dengue Fever, Dengue Haemorrhagic Fever, Dengue Shock Syndrome Investigation Guidelines. Version 01/ 2010. Kansas, USA.
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Community-based investigation:bx Interview the case or proxy to determine source and risk factors; focus on incubation period of two weeks prior to illness onset. Travel history:by Travel outside town/city: list the places visited and dates. Travel outside country: list country, date of departure and return (to the country of origin). Any exposure to mosquitoes (include dates and places). Collect information from case for the contact investigation (see below). Investigate epidemiology links among cases (clusters, household, co-workers, etc.) Contacts are those who have exposure. Exposure is defined as: travel to a dengue endemic country or presence at a location with ongoing outbreak within previous two weeks of dengue-like illness; or association in time and place with a confirmed or probable dengue case. Identify other individuals who may have had contact with the source in the two weeks prior to the case becoming ill to find unreported or undiagnosed cases. If travel by the case occurred as part of a commercial travel group, investigate travel companions. Follow blood and body fluid precautions as prescribed by physician. Prevent access of mosquitoes to the case until fever subsides through the use of screened sickrooms, spraying with insecticides, and bednets. Educate all contacts on the symptoms of dengue fever. Investigate symptomatic contacts with dengue-like illness as suspect cases, collect acute and convalescent specimens and coordinate testing at the appropriate laboratory facility. Symptomatic contacts should be instructed to rest, drink plenty of fluids, and consult a physician. If they feel worse (example, develop vomiting and severe abdominal pain) 24 hours after the fever declines, they should immediately seek medical evaluation with their physician or hospital/clinic.
Contact investigation:bz
Contact management:
bx Adapted from: Dengue Fever, Dengue Haemorrhagic Fever, Dengue Shock Syndrome Investigation Guidelines. Version 01/2010. Kansas, USA. by Travel to an active dengue fever area is a crucial element. bz Adapted from: Heymann, D. L. (Ed.): Control of Communicable Diseases Manual. 18th edition. 2004. American Public Health Association. Washington DC, USA. ca It is important to have an idea about what specimens will be collected, stored and shipped to the appropriate laboratory. Refer to Chapter 5.
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It is not necessary to confirm the diagnosis of all cases detected during an outbreak. It is sufficient to confirm diagnosis in a sample of cases at the beginning, the interim period and the resolution of the outbreak. Containment measures should not be delayed by lack of laboratory diagnosis. Ae. aegypti is the primary vector, which is a container habitat species and well entrenched in urban areas. Entomological indices of container index (CI), house or premise index (HI) and Breateau Index (BI) should be determined for the affected areas. Similarly, types of containers, both indoors and outdoors, should be mapped for control of vector breeding.
Step Six: Communication with authorities concerned and recommendation of control measures
Findings should be communicated to appropriate decision-makers and control measures recommended. The following action is to be carried out by local health authorities. An Emergency Action Committee (EAC) (see Annex 11) may be constituted to coordinate activities aimed at emergency vector control measures and management of serious cases. The committee may comprise administrators, epidemiologists, entomologists, clinicians and laboratory specialists, social scientists, school health officers, health educators and representatives of other related sectors including civil society. The functions of the EAC will be to: take all administrative actions and coordinate activities aimed at the management of serious cases in all medical care centres and undertake emergency vector control measures; draw urgent plans of action and resource mobilization in respect of medicines, intravenous fluids, blood products, insecticides, equipment and vehicles; form a rapid action team comprising epidemiologists, entomologists and laboratory specialists to undertake urgent epidemiological investigations and provide on-the-spot technical guidance required and logistic support; liaise with inter-sectoral committees to mobilize resources from non-health sectors, namely Urban Development, Ministry of Education, Ministry of Information, Legal Department, Water Supply Department, Waste Disposal Department and share and disseminate information for the elimination of the breeding potential of Ae. aegypti; and interact with the media and NGOs for health education and community participation.
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people think that the government is active in disease control when space sprays are carried out. This often creates a false sense of security and prevents/slows down community as well as individual efforts for vector control. Hence, communities need to be engaged appropriately. Indoor space spray with pyrethrum 2% extract (0.2% ready to spray solution with kerosene oil) is applied where the case(s) is/are detected and in surrounding houses. Public education must continue to reinforce how important it is for people to seek medical attention if they have dengue symptoms, reduce larval habitats and use options for personal protection. During an epidemic the aim of risk communication, generally through the media, is to build public trust. It is done by announcing the epidemic early, communicating openly and honestly with the public (transparency), and particularly by providing accurate and specific information about what people can do to make themselves and their community safer. This gives people a sense of control over their own health and safety, which in turn allows them to react to the risk with more reasoned responses.35 In endemic countries, involving the media before the occurrence of the seasonal increase in dengue enhances the opportunity to increase public awareness about the disease and the personal and community actions that can be taken to mitigate the risk.
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It is essential to monitor and evaluate the progress of DF/DHF prevention and control programmes. They enable the programme manager to assess the effectiveness of control initiatives and must be continuous operational processes. The specific objectives of programme evaluation are to: measure overuse progress and specific programme achievements; detect and solve problems as they emerge; assess programme effectiveness and efficiency; guide the allocation of programme resources; collect information needed for revising policy and replanning interventions; and assess the sustainability of the programme.
Monitoring
Monitoring or concurrent evaluation involves the continuous collection of information during programme implementation. It allows immediate assessment and identification of deficiencies that can be rectified without delaying the programmes progress. Monitoring provides the type of feedback that is important to programme managers. Most monitoring systems follow the quantum and timing of various programme elements such as activities undertaken, staff movements, service utilization, supplies and equipment, and budgeting. Focus should also be given to the process of implementation of the dengue control strategy in time and space and the quality of implementation, seeking reasons for successes and failures. Monitoring should be undertaken by persons involved in the programme at various levels. This exercise by programme managers will give a better and deeper understanding of the programmes progress, strengths and weaknesses. The information collected should help programme managers strengthen the weaker links and optimize output.
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Formal evaluation
In addition to regular monitoring, which is generally built-in, there is also a need for more formal evaluation at different intervals to obtain a precise picture of the progress of the programme. This type of evaluation is even more essential when the programme is failing to achieve its targets or goals or when it has become static. This type of special evaluation should be done systematically and should take into account all programme elements. The main idea of such a study is to determine whether the programme is moving on course towards its targets and goals, to identify new needs particularly for increased inputs (e.g. additional manpower, money, materials, IEC activities, capacity-building) and to identify operational research areas for maximum operationalization. Formal evaluation, therefore, should systematically assess the elements outlined below. However, the evaluation can cover one or more other processes depending on the objectives of the evaluation. Evaluation of need, i.e. evaluation of the relative need for the programme. Evaluation of plans and design, i.e. evaluation of the feasibility and adequacy of programme plans or proposals. Evaluation of implementation, i.e. evaluation of the conformity of the programme to its design. Does the programme provide the goods and services laid down in the plan in terms of both quality and quantity? Evaluation of outcomes, i.e. evaluation of the more immediate and direct effects of the programme on relevant knowledge, attitudes and behaviour. For training activities, for example, outcomes may relate to the achievement of learning objectives and changes in staff performance. Evaluation of impact, i.e. evaluation of the programmes direct and indirect effects on the health and socioeconomic status of individuals and the demography of the community.
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Collection of data: the objective of this step is to ensure that procedures are followed in such a way that data are collected in a reliable and timely manner. Interpretation and analysis of data: the decisions about the main approaches to data analysis will have been made when the indicators are selected and the detailed plan formulated. Re-planning: at this step the results of the evaluation are fed back into the managerial process. Unfortunately, it is often this re-planning step that is done the least correctly.
Various aspects of programme that can be monitored and evaluated are presented in Box 41. Box 41: Aspects of programme that can be evaluated
In Box 42, a scheme is suggested to identify expected results pertaining to any dengue prevention and control programme component (example, IVM146) and decide SMARTcb indicators for monitoring and evaluation of targets, which in turn, will require the development or use of available methods/ tools. Box 42: M&E framework
Expected results 1. Activity Objectively verifiable indicators 1. Process indicators 2. Outcome indicators 3. Impact indicators Means of verification Targets Year 1 Year 2 Assumptions/risks Resources required
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different control measures, and evaluating new methods. Examples of types of cost estimates that should be obtained are described below.
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(d) Surveillance
Guidelines for entomological and epidemiological surveillance methods are given in the chapter on surveillance. These can be used as a framework to estimate the size of the required surveillance system in a given city, state, province or country, as well as the cost of the surveillance that, in addition to laboratory costs and information exchange, includes expenditure for collecting and processing samples in the field.
cc
For further reading: Finsterbusch, K. and Wicklin III, W.A.V. (1989). Beneficiary participation in development projects: empirical tests of popular theories, Economic Development and Cultural Change, Chicago: the University of Chicago.
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15. Strategic Plan for the Prevention and Control of Dengue in the Asia-Pacific Region: A Bi-regional Approach (20082015)
15.1 Need for a biregional approach and development of a Strategic Plan for the Prevention and Control of Dengue in the Asia-Pacific Region
Dengue is emerging rapidly as one of the major public health problems in countries of the Asia-Pacific Region, where nearly 1.8 billion people are estimated to be at risk against a global total of 2.5 billion. Epidemics of dengue are being reported more frequently and in an explosive manner. The disease continues to spread to new areas, including rural settings, in affected countries. Rapid spread of dengue in the Asia-Pacific Region is attributed to globalization, rapid unplanned and unregulated urban development, poor water storage and unsatisfactory sanitary conditions. Increased travel has contributed to the spread of viraemia. In a region where ecological and epidemiological conditions are similar, effective control of dengue is not possible if the efforts are limited to one country or a few countries. Since dengue does not respect international boundaries, control efforts have to be coordinated regionally. In this direction, WHO took an initiative to develop a Strategic Plan for the Prevention and Control of Dengue in the Asia-Pacific Region. Development of such a strategic plan is also important in meeting the requirements of the International Health Regulations (IHR) 2005. Salient components of the Asia-Pacific Dengue Strategic Plan (20082015)200 are outlined below.
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uses evidence-based interventions and best practices in developing and implementing dengue prevention and control programmes. uses networking to optimize available resources. supports intersectoral and interprogrammatic collaboration to maximize the provision of integrated services; e.g. developing links with the Asia-Pacific Strategy for Emerging Diseases (APSED) to strengthen health systems for surveillance and thereby contribute to IHR (2005). promotes the adoption of evidence-based interventions while at the same time recognizing the need for vaccine development, improved diagnostics and drugs and other innovations and intensifying related efforts.
15.4 Objectives
The objectives are to enable Member countries to achieve the regional goal and realize the mission and vision of dengue prevention and control. Different countries will achieve these objectives and expected results in the context of their current capacities and policies.
General objective
To reduce incidence rates of dengue fever and dengue haemorrhagic fever.
Specific objectives
To increase the capacity of Member countries to monitor trends and reduce dengue transmission. To strengthen capacity to implement effective integrated vector management. To increase the health workers capacity to diagnose and treat patients and improve healthseeking behaviour of communities. To promote collaboration among affected communities, national health agencies and major stakeholders to implement dengue programmes for behavioural change. To increase capacity to predict, detect early and respond to dengue outbreaks. To address programmatic issues and gaps that require new or improved tools for effective dengue prevention and control.
Expected results
The summary of expected results vis--vis objectives is given in Table 14.
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Table 14: Summary of expected results related to objectives S. No. 1 Objectives To increase the capacity of Member States to monitor trends and reduce dengue transmission. Expected results 1. Existing standard dengue case definition adopted. 2. Laboratory surveillance strengthened. 3. Regional dengue information system developed. 4. Mechanisms for sharing timely and accurate data strengthened. 5. Regional/intercountry response to timely advisory and resource (personnel, financial, stockpiling) mobilization improved. 6. Incorporate dengue surveillance (case, vector and seroprevalence) into an integrated and strengthened disease surveillance system. 7. Monitoring Member States surveillance systems. 2 To strengthen capacity to implement effective integrated vector management. 1. Vectors fully described and vector indicators regularly monitored. 2. Regional IVM Strategy developed. 3. Evidence-based strategies to control vector populations adopted according to IVM principles. 4. Member State-level IVM strategy and guidelines developed. 5. Consistent with regional strategy. 6. Capacity to implement IVM, including training and recruitment of entomologists, strengthened. 7. Mechanisms to facilitate community involvement for vector control established. 8. Rational use of insecticides for vector control promoted. 9. Vector resistance monitoring strengthened. 3 To increase health workers capacity to diagnose and treat patients and improve healthseeking behaviour of communities. 1. Public awareness increased on the warning signs and actions to be taken for dengue. 2. Strengthen capacity of health-care providers to diagnose, treat or refer cases. 3. Laboratory support for case management improved. 4. Referral network system in public and private sectors established.
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S. No. 4
Objectives To promote collaboration among affected communities, national health agencies and major stakeholders to implement dengue programmes for behavioural change.
Expected results 1. COMBI resource group for COMBI implementation established. 2. Assessment, including situation analysis of current strategies (social mobilization/health education) and extent and success of COMBI if implemented (with respect to dengue and other vector-borne diseases). 3. COMBI training implemented. 4. COMBI approach disseminated and promoted. 5. Development and implementation of COMBI plan supported. 6. Partnerships set up with private sector/and other multistakeholders.
1. Early warning system/dengue surveillance system developed and scaled up. 2. Dengue outbreak standard operating system developed. 3. Coordination mechanisms within MoH and with other programmes and sectors established. 4. Intercountry coordination mechanisms in place. 5. A mechanism to incorporate rumour surveillance developed and implemented. 6. Regional outbreak response guidelines developed. 7. The ability of health workers to respond to the dengue outbreak strengthened. 8. Risk communication plan developed.
To address programmatic issues and gaps that require new or improved tools for effective dengue prevention and control.
1. Operational research capacity in dengue of existing academic/scientific institutions in Member States enhanced. 2. Disease burden estimated (epidemiological impact, social costs and cost of illness). 3. New knowledge gained, new tools developed, existing tools improved and new strategies created. 4. Evaluation of tools and strategies for dengue control and case management. 5. Translation of new improved tools into programmatic activities.
Source: World Health Organization. Asia-Pacific Dengue Strategic Plan (2008 2015). 2008. SEA/RC61/11 Inf. Doc. SEARO/WHO.200
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Mobilization of resources
Despite the growing threat from dengue, resources for the control of dengue have not increased. National and international support continues to fall far short of the needs, even though there are untapped resources at the national, regional and global levels. To mobilize additional resources, synchronized action is needed with support from partners and different stakeholders. Harmonization of the strategy with the Asia-Pacific Dengue Partnership (APDP) is also required to mobilize the additional resources needed. Countries need to prepare operational plans that identify funding gaps. In addition, an advocacy plan should be prepared and implemented for mobilizing the resources on a sustained basis.
cd.. int/LinkFiles/Tools_&_Guidelines_SEA-MAL-255__Bookfold.pdf. Healthy public policy is characterized by an explicit concern for health and equity in all areas of policy and by accountability for health impact. adelaide/en/index1.html Comprehensive Guidelines for Prevention and Control of Dengue and Dengue Haemorrhagic Fever
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National dengue control programmes in Member countries should be implemented as part of national policy. These programmes have to find a niche and visibility within the existing disease surveillance programmes and the vector-borne disease control programme. It has to be a part of the basic health services and be able to find a place within the policy of decentralization in the national programme. Linkage to the IHR (2005) should also be encouraged.
Community participation
Dengue prevention and control efforts will be successful only if it becomes everyones concern and responsibility. Sustained action is required at the individual, family and community levels. It has to be supported by the local self-government and the national government through the involvement of the health and other relevant sectors.ce At the level of the individual and the family, self-reliant actions are needed for effective vector control and personal protection. This includes regular cleaning of containers in which water is stored, safe disposal of solid waste and prevention of vector breeding. Other responsibilities include monitoring vector activity within households and observing a weekly dry day. Vector breeding sites in the community include public places such as schools, places of worship, cinema halls, hospitals and community centres. Besides supporting individuals and families, community actions can assist in monitoring and reducing vector breeding. Community groups can also work with industry that can help in dealing with the problem of used tyres, curing of plastic and cement water storage tanks and reducing the risk of vector breeding in refrigerators and water coolers. In addition, specific measures such as larviciding, insecticide spraying and biological control activities can be supported, subsequent to training and capacity-building. For initiating and sustaining community participation, a strategic communication plan should be developed. Adoption of a COMBI strategy has demonstrated success in many countries. Best practices are recommended for documentation and adoption.cf
Partnerships
The Asia-Pacific Dengue Partnership (APDP) for Dengue Prevention and Control was formed in March 2006.cg At a meeting of the Core Group organized by the Regional Offices for the South-East Asia and Western Pacific Regions and the Government of Singapore held during February 2007 in Singapore, the Strategic Framework for the APDP was finalized. A biregional plan and a road map for the establishment of an executive board, secretaries and working groups were also agreed upon, in addition to all other relevant administrative matters. The Asia-Pacific Strategic Plan for Dengue Prevention and Control recognizes that partnerships are required to strengthen collaboration between countries, establish networks within the country and across borders, enhance cooperation in access to innovations, and contribute to the discovery of improved tools. In addition, partnerships are crucial for mobilizing additional resources and showcasing the cause of dengue prevention and control through advocacy and sharing of quality knowledge on dengue widely.
ce For additional details, refer to Chapter 11. cf For additional information, refer to Chapter 13. cg WHO. Meeting of Partners on Dengue Prevention and Control in Asia-Pacific, Chiang Mai, Thailand, 2324 March 2006 (SEA-VBC-91).
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15.7 Duration
The Strategic Plan is prepared to cover the period 20082015.
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ch For additional information, refer to the Guidelines for Conducting a Review of a National Dengue Prevention and Control Programme (WHO/CDS/CPE/PVC/2005.13). ci Asia-Pacific Dengue Programme Managers Meeting in Singapore, May 5-9, 2008. Field Research Report. Asia-Pacific Dengue Programme Managers Meeting in Singapore, May 5-9, 2008. Prepared by Minako Jen Yoshikawa, 1 Kyoto University.. cseas.kyoto-u.ac.jp/staff/nishibuchi/2008/doc/field_Resarch080505_en.pdf
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16. References
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(169) Merzel C, DAfflitti J. Reconsidering community-based health promotion: promise, performance, and potential. Am J Pub Health. 2003; 93(4): 557574. (170) UNHCR. Witchcraft allegations, refugee protection and human rights: A review of the evidence. Geneva: 2009. (171) Schooler C, Farquhar JW, Flora JA. Synthesis of findings and issues from community prevention trials. Ann Epidemiol. 1997; 7(suppl 7): S54S68. (172) Elder JP Schmid TL, Dower P Hedlund S. Community heart health programmes: Components, , ., rationale, and strategies for effective interventions. J Public Health Policy. 1993; 14: 463479. (173) Gubler DJ, Clark GG. Community involvement in the control of Aedes aegypti. Acta Tropica. 1996; 61(2): 169179. (174) Parks WJ, Lloyd LS, Bulletin. 2004; 28 (Suppl): 17. (175) Halstead S. Successes and failures in dengue controlglobal experience. Dengue Bulletin. 2000; 24: 6070 (176) World Health Organization. Integrated marketing communication for behavioural results in health and social development summary of concepts. Geneva: New York University/WHO Integrated Marketing Communication/COMBIMalaysia, 2001. (177) Cheadle A, Beery W, Wagner E, Fawcett S, Green L, Moss D, Plough A, Wandersman A, Woods I. Conference report: community-based health promotionstate of the art and recommendations for the future. Am J Prev Med. 1997; 13: 240243. (178) Parks W, Lloyd L. Planning social mobilization and communication for dengue fever prevention and control: A step-by-step guide. Geneva: WHO, 2004. Document No. WHO/CDS/WMC/2004.2 and TDR/STR/SEB/DEN/04.1. (179) Elder JP Evaluation of communication for behavioural impact (COMBI) efforts to control Aedes aegypti . breeding sites in six countries. Tunis: WHO Mediterranean Centre for Vulnerability Reduction, 2005. (180) World Health Organization, Regional Office for the Pan America. Dengue and dengue hemorrhagic fever in the Americas: guidelines for prevention and control. Washington DC: WHO-PAHO, 1994. (Scientific Publication No. 548). (181) World Health Organization, Regional Office for the Americas. The blueprint for action for the next generation: dengue prevention and control. Washington DC: WHO-PAHO, 1999. (182) World Health Organization. Strengthening implementation of the global strategy for Dengue Fever/ Dengue Haemorrhagic Fever Prevention and Control: Report of the informal consultation, 1820. October 1999. Geneva: WHO, 2000. Document No. WHO/CDS(DEN)/IC/2000.1. (183) World Health Organization, Regional Office for South-East Asia. Report of the Regional Meeting on Dengue and Chikungunya Fever, Chiang Rai, Thailand. New Delhi: WHO-SEARO, 2010. (In press). (184) Luna JE, Chain I, Hernandez J, Clark GG, Bueno A, Escalante R, Angarita S, Martinez A. Social mobilization using strategies of education and communication to prevent dengue fever in Bucaramanga, Colombia. Dengue Bulletin. 2004; 28 (Suppl): 1721. (185) World Health Organization. A global review of primary health care: Emerging messages. Geneva: WHO, 2003. (186) Lloyd LS. Best practices for dengue prevention and control in the Americas. Washington DC: Environmental Health Project, 2003. (187) World Health Organization. Health promotion glossary. Geneva: WHO, 1998. (188) Gamble DN, Weil MO. Citizen participation. In: Edwards RL. Ed. Encyclopaedia of social work. 19th edn, vol. 1. Washington, DC: National Association of Social Workers/NASW Press, 1995. p. 483494. (189) Finsterbusch K. Wicklin III WAV. Beneficiary participation in development projects: Empirical tests of popular theories. Chicago: Economic Development and Cultural Change, 1989.
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Name of patient _________________________ Hospital No. ______________________________ Address ________________________________ Hospital __________________________________ Age ________________Sex _______________ Physician _________________________________ Date of admission _______________________ Admission complaint________________________ Date of onset ___________________________ Clinical findings: 1. 2. 3. 4. Fever _____________ C or F (max). Duration ______ days Tourniquet test __________ Petechiae ___________ Epistaxis ____________ Haematemesis/melaena _________ Other bleeding (describe) _____________________ Hepatomegaly _____________ (cm at right costal margin). Tenderness _____________ Shock ________ Blood pressure ________ (mmHg) Pulse _______ (per min.) Restlessness/Lethargy ___________ Coldness of extremities/body ______________
Clinical laboratory findings: Platelets (X103 ) _____________________/mm3 (on _____________________ day of illness) Haematocrit (%) _______________________ (max) _____________________________ (min) Blood specimens (Acute) Hospital admission Date___________ Hospital discharge Date__________ Convalescent Date__________
Instructions: Fill the form completely with all clinical findings in duplicate. Saturate the filter-paper discs completely so that the reverse side is saturated and clip them to the form. Obtain admission and discharge specimens from all patients. If the patient does not return for a convalescent sample, mail promptly.
Source: Dengue Haemorrhagic Fever: Diagnosis, treatment, prevention and control, Second edition, WHO, Geneva, 1995. Comprehensive Guidelines for Prevention and Control of Dengue and Dengue Haemorrhagic Fever
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2.
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Provide all Member States with public health information to enable Member States to respond to a public health risk. Issue temporary and standing recommendations on control measures in accordance with the criteria and the procedures set out under the Regulations. Respond to the needs of Member States regarding the interpretation and implementation of the IHR (2005). Collaborate and coordinate its activities with other competent intergovernmental organizations or international bodies in the implementation of the IHR (2005). Update the Regulations and supporting guides as necessary to maintain scientific and regulatory validity.
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3.
Source:
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4.
For Aedes larval surveys, the number of houses to be inspected in each locality depends on the level of precision required, level of infestation, and available resources. Although increasing the number of houses inspected leads to greater precision, it is usually impractical to inspect a large percentage of houses because of limited human resources. Table A shows the number of houses that should be inspected to detect the presence or absence of infestation. For example, in a locality with 5000 houses, in order to detect an infestation of >1%, it is necessary to inspect at least 290 houses. There is still a 5% chance of not finding any positive houses when the true House Index = 1%. Table A: Number of houses that should be inspected to detect Aedes larval infestation Number of houses in the locality 100 200 300 400 500 1000 2000 5000 10 000 Infinite True House Index >1% 95 155 189 211 225 258 277 290 294 299 >2% 78 105 117 124 129 138 143 147 148 149 >5% 45 51 54 55 56 57 58 59 59 59
Table B shows the number of houses that should be inspected in a large (>5000 houses) positive locality, as determined by the expected House Index and the degree of precision desired. For example, if the preliminary sampling has indicated that the expected House Index is approximately 10%, and a 95% confidence interval of 8%12% is desired, then 1000 houses should be inspected. If there are only sufficient resources to inspect 200 houses, the 95% confidence limits will be 6%14%. In other words, there is a 5% chance that the true House Index is less than 6% or greater than 14%. In small localities, the same precision may be obtained by inspecting fewer houses. For example, if the expected House Index is 50% and a 95% confidence interval of 44%56% is acceptable, then in a large locality it would be necessary to inspect 300 houses (Table B). However, as seen in Table C, if the locality consists of only 1000 houses, the same precision will be obtained by inspecting 231 houses.
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Table B: Precision of the Aedes House Index in large localities (>5000 houses)
House Index (%) 100 2 5 10 20 50 70 0.27.0 211 518 1329 4060 6079 95% confidence interval of the House Index Number of houses inspected 200 0.55.0 29 614 1626 4357 6276 300 0.74.3 38 714 1625 4456 6475 1000 1.23.1 47 812 1823 4753 6773
Source: Pan American Health Organization. Dengue and dengue haemorrhagic fever in the Americas: Guidelines for prevention and control. Washington: WHO/PAHO; 1994. (Scientific publication; no. 548).
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5.
Source: Adapted from: Yiau-Min Huang. The mosquitoes of Polynesia with a pictorial key to some species associated with filariasis and/or dengue fever. Mosquito Systematics, 1977, 9(3): 289-322.
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Annex 5 (contd)
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Annex 5 (contd)
(2) Comb scale with very strong denticles at base of apical spine
Saddle complete
Saddle incomplete
Aedes albopictus
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6.
Designs for overhead tank with cover, masonry chamber and soak pit
(a) Standard design for overhead tank with cover design for mosquito proofing of overhead tanks and cisterns
(b) Design for masonry chamber and soak pit for sluice valve and water meter
Source: Sharma R.S., Sharma G.K., Dhillon GPS, Epidemiology and control of malaria in India. 1996. Dte. of NMEP 22 Shamnath , Marg, Delhi 110 054, India.
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7.
The steps described below mainly refer to treatment of mosquito nets with permethrin. The net treatment technique can be easily used for curtains. (a) Calculate the area to be treated
Measure the height, length and width of the net. Assuming a rectangular mosquito net is 150 cm high, 200 cm long and 107 cm wide, the calculations are as follows: Area of one end = 107 x 150 = 16 050 cm2 Area of one side = 200 x 150 = 30 000 cm2 Area of top = 107 x 200 = 21 400 cm2 The sides and ends need to be multiplied by 2: 2 (16 050 + 30 000) = 92 100 + 21 400 = 113 500 cm2 (end) (side) (top)
If 10 000 cm2 = 1 m2 then 113 500/10 000 = 11.35 m2 area of net (b) Determine how much insecticide is needed
Assume that a permethrin emulsifiable concentrate will be used, and the dosage desired is 0.5 grams per square metre. To determine the total grams required, multiply the net size by the dosage: 11.35 x 0.5 = 5.67 grams of insecticide needed. (c) Determine the amount of liquid required to saturate a net In order to determine the percentage solution to be used for dipping, it is first necessary to determine the approximate fibre, a 1.5% solution can be tried. Add the net to the solution till it is thoroughly wet and then remove it. Allow the drips to fall into a bucket for 15 to 30 seconds. Set the net aside. Repeat the process with two other nets. Cotton nets can be lightly squeezed but not the synthetic ones. Measure the water or solution remaining in the dripping/soaking container and in the bucket to calculate the amount of liquid used per net.
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Assuming that one polyethylene net retained 280 ml of solution, the percentage concentration required for dipping is calculated as follows: grams required per net ml solution retained per net (d) = 5.67 280 = 2%
The general formula is: X = (A/B) 1 in which, X = parts of water to be added to one one part of concentrate are required, or one litre of concentrate to 11.5 litres of water.
Example: A 2.0% solution of permethrin for dipping nylon mosquito nets or curtains is to be prepared from a 50% concentrate. X = (50/2.0) 1 = 24 Therefore, 24 parts of water to one part of concentrate are required, or one litre of concentrate to 24 litres of water.
Example: A 0.3% solution of permethrin for dipping cotton mosquito nets or curtains is to be prepared from a 25% concentrate. X = (25/0.3) 1 = 83.3 1 = 82.3 or rounded to 82. Therefore, 82 parts of water to one part concentrate are required, or one litre of concentrate to 82 litres of water, or half a litre of concentrate to 41 litres of water to accommodate a smaller container.
Example: A 0.3% solution of permethrin for dipping cotton mosquito nets or curtains is to be prepared from a 50% concentrate. X = (50/0.3) 1 = 166.6 1 = 165.6 or rounded to 166.
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Therefore, 166 parts of water to one part of concentrate are required, or one litre of concentrate to 166 litres of water, or half a litre of concentrate to 83 litres of water to accommodate a smaller container. (e) Preparation of a 2% dipping solution using a one litre bottle of 25% or 50% permethrin emulsifiable concentrate for soaking polyethylene or other synthetic fibre nets or curtains. This operational approach minimizes detailed measurements in the field. For 25% concentrate: Add 11.5 litres water to a container (with premeasured marks to indicate volume). Add 1 litre (1 bottle) concentrate to the container. Total volume: 12.5 litres Grams permethrin: 250 % concentration: 2% For 50% concentrate: Add 24 litres water to a container. Add one litre (one bottle) concentrate to the container. Total volume: 25 litres Grams permethrin: 500 % concentration: 2% (f) Preparation of a 0.3% dipping solution using a one litre bottle of 25% or 50% permethrin emulsifiable concentrate for soaking cotton nets or curtains For 25% concentrate: Add 82 litres of water to a container. Add one litre (one bottle) concentrate to the container. Total volume: 83 litres Grams permethrin: 250 % concentration: 0.3% For 50% concentrate: Add 166 litres of water to a container. Add one litre (one bottle) concentrate to the container. Total volume: 167 litres Grams permethrin: 500 % concentration: 0.3%
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(g)
Drying of nets
Polyethylene and synthetic nets are dried in a horizontal position. Do not hang to dry. Drying the nets on mats removed from houses has proved to be convenient and acceptable. The nets should be turned over about once every hour for up to three or four hours. If the weather is good, the nets can be dried outside in the sun but for not more than several hours. Under rainy conditions, they can be placed in sheltered areas or inside and left overnight to dry. When dripping stops, they can be hung for completion of drying. Treated cotton nets which are not oversaturated and do not drip can be hung up to dry soon after the soaking procedure. (h) Treatment of one net in a plastic bag (soaking)
As shown in (a) above, if it is assumed that the net size is 11.35 m2, 5.67 grams of permethrin are needed to achieve a target dosage of 0.5 grams per square metre, and a net of this size absorbs 280 ml of solution. The amount of 25% permethrin emulsifiable concentrate to use is determined as follows: grams required x 100 = 5.67 x 100 = 22.68 ml (rounded to 23 ml) % concentrated used: 25. (i) Summary of treatment procedures
The important points in the treatment are summarized as follows: (1) Dipping is the preferred method of net treatment. A 2% solution is usually sufficient to achieve a target dosage of 0.5 grams per square metre of permethrin on polyethylene, polyester, nylon or other type of synthetic fibre net or curtain. The residual effect lasts for six months or more. A 2% solution can be prepared simply. Staff need to check on the dosage applied and refine the operation accordingly. With bamboo curtains or mats used over doors or windows, a higher dosage (1.0 gram per square metre) can be used. Dipping the nets in a permethrin solution is a fast and simple method for treating nets and curtains in urban or rural housing conditions. Community members can easily learn the technique required for follow-up treatment. A dish-pan type of plastic or aluminum container which holds 15 to 25 litres of solution has been found to be quite suitable. Normally, about one litre of solution can treat four to five double (10m2)-sized the open air. With one dipping station, about 150 nets or curtains can be treated in two hours or less.
(2)
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(3)
About 100 treated double-sized nets or an equivalent area of curtain material can protect 250 persons. It is not reasonable to expect every person in a crowded household to sleep under a net. It is important that every house in a community or village has one or two treated nets to kill mosquitoes so as to reduce the vector density. When used in this manner, protection is provided to those who do not even sleep under the nets. Infants and small children can sleep under the nets during the day.
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8.
Quantities of 1% temephos (abate) sand granules required to treat different-sized water containers to kill mosquito larvae
Table D: Quantities of 1% temephos (abate) sand granules required to treat different-sized water containers
Size of water jar, drum or other container (in litres) Less than 25 50 100 200 250 500 1000
Grams of 1% granules Number of teaspoons required, required assuming one teaspoon holds 5 grams Less than 5 5 10 20 25 50 100 Pinch: small amount held between thumb and finger 1 2 4 5 10 20
Methoprene (altosid) briquettes can also be used in large water drums or overhead storage tanks. One briquette is suitable to treat 284 litres of water. Briquettes of Bacillus thuringiensis H-14 can also be used in large cistern tanks.
Source: WHO/Western Pacific Region Background Document No. 16, 1995.
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9.
Procedure, timing and frequency of thermal fogging and ULV space spray operations
Basic steps
The steps listed below are to be followed in carrying out the space spraying of a designated area: The street maps of the area to be sprayed must be studied carefully before the spraying operation begins. The area covered should be at least 300 metres within the radius of the house where the dengue case was located. Residents should be warned before the operation so that food is covered, fires extinguished and pets are moved out together with the occupants. Ensure proper traffic control when conducting outdoor thermal fogging since it can pose a traffic hazard to motorists and pedestrians. The most essential information about the operational area is the wind direction. Spraying should always be done from downwind to upwind, i.e. going against the direction of the wind.
Vehicle-mounted spraying
Doors and windows of houses and buildings in the area to be sprayed should be opened. The vehicle is driven at a steady speed of 68 km/h (3.54.5 miles/h) along the streets. Spray production should be turned off when the vehicle is stationary. When possible, spraying should be carried out along streets that are at right angles to the wind direction. Spraying should commence on the downwind side of the target area and progressively move upwind. In areas where streets run parallel as well as perpendicular to the wind direction, spraying is only done when the vehicle travels upwind on the road parallel to the wind direction. In areas with wide streets with houses and buildings far away from the roadside, the spray head should point at an angle to the left side of the vehicle (in countries where driving is on the left side of the road). The vehicle should be driven close to the edge of the road. In areas where the roads are narrow, and houses are close to the roadside, the spray head should be pointed directly towards the back of the vehicle. In dead-end roads, the spraying is done only when the vehicle is coming out of the deadend, not while going in. The spray head should be pointed at a 45 angle to the horizontal to achieve maximum effect with droplets. Vector mortality increases downwind as more streets are sprayed upwind in relation to the target area.
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House-spraying technique
Do not enter the house. House spraying means spraying in the vicinity of the house. Stand 35 metres in front of the house and spray for 10 to 15 seconds directing the nozzle towards all open doors, windows and eaves. If appropriate, turn away from the house and, standing in the same place, spray the surrounding vegetation for 10 to 15 seconds. If it is not possible to stand three metres from the house due to the closeness of houses and lack of space, the spray nozzle should be directed towards house openings, narrow spaces and upwards. While walking from house to house, hold the nozzle upwards so that particles can drift through the area. Do not point the nozzle towards the ground. Spray particles drift through the area and into houses to kill mosquitoes which become irritated and fly into the particles. The settled deposits can be residual for several days to kill mosquitoes resting inside houses and on vegetation not exposed to the rain.
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This technique permits treatment of a house with an insecticide ranging from 1 gram to 25 grams in one minute. The dosage depends on the discharge rate, concentration of insecticide applied, and the time it takes to spray the house. For comparison, an indoor residual house spray may require 30 minutes of spraying to deposit 300 grams of insecticide. This assumes a dosage of two grams per square metre to 150 square metres of sprayable surface.
Timing of application
Spraying is carried out only when the right weather conditions are present and usually only at the prescribed time. These conditions are summarized below: For optimum spraying conditions (Table E), please note the following: In the early morning and late evening hours, the temperature is usually cool. Cool weather is more comfortable for workers wearing protective clothing. Also, adult Aedes mosquitoes are most active at these hours. In the middle of the day, when the temperature is high, convection currents from the ground will prevent concentration of the spray close to the ground where adult mosquitoes are flying or resting, thus rendering the spray ineffective. An optimum wind speed of between 3 km/h and 13 km/h enables the spray to move slowly and steadily over the ground, allowing for maximum exposure of mosquitoes to the spray. Air movements of less than 3 km/h may result in vertical mixing while winds greater than 13 km/h disperse the spray too quickly. In heavy rain, the spray generated loses its consistency and effectiveness. When the rain is heavy, spraying should stop and the spray head of the ULV machine should be turned down to prevent water from entering the blower. Spraying is permissible during light showers. Also, mosquito activity increases when the relative humidity reaches 90, especially during light showers.
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Table E: Conditions for spraying Most favourable conditions Time Early morning (06300830 hrs) or late evening Steady, between 313 km/h No rain Cool Average conditions Early to mid-morning or late afternoon, early evening 03 km/h Light showers Mild Unfavourable conditions Mid-morning to midafternoon Medium to strong, over 13 km/h Heavy rain Hot
Frequency of application
The commencement and frequency of spraying generally recommended is as follows: Spraying is started in an area (residential houses, offices, factories, schools) as soon as possible after a DF/DHF case from that area is suspected. At least one treatment should be carried out within each breeding cycle of the mosquitoes (seven to ten days for Aedes). Therefore, a repeat spraying is carried out within seven to ten days after the first spraying. Also, the extrinsic incubation period of dengue virus in the mosquito is 8 to 10 days.
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Safety measures for insecticide use are adopted to protect the health and lives of those applying insecticides. These measures seek to minimize the degree of poisoning by insecticides and exposure to insecticides, prevent accidental poisoning, monitor sub-acute poisoning, and provide adequate treatment for acute poisoning. These measures can be broken down into the four broad categories listed below. Four issues for safety measures: the choice of insecticides to be used; the safe use of insecticides; the monitoring of sub-acute insecticide poisoning; and the treatment of insecticide poisoning.
The human population exposed to insecticide treatment is of prime importance. It must be ensured that they are not exposed to health hazards.
1.
The choice of an insecticide for vector control is determined by the following factors:
In weighing the relative importance of the three factors above, the following are important aspects from a safety standpoint: An effective and/or cheap insecticide should not be used if the chemical is highly toxic to humans and other non-target organisms. Pyrethroids, generally, have very low mammalian toxicity when compared with other groups of insecticides such as carbamates. The liquid formulation of an insecticide is usually more dangerous than a solid formulation of the same strength. Certain solvents in liquid formulation facilitate skin penetration. With regard to occupational exposure, dermal exposure is more important than gastrointestinal or respiratory exposure. Thus, an insecticide with low dermal toxicity is preferred. The latest information on the safety aspect of insecticides being considered must be available before a wise choice can be made.
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2.
The key to the safe use of insecticides is to control and minimize the level of routine or accidental exposure of an individual to a given insecticide. The level of exposure is in turn dependent on many factors, as outlined in the box below. Level of exposure depends on: Insecticide storage conditions. Personal hygiene and attitude of workers. Knowledge and understanding of workers concerning insecticides. Equipment used. Method and rate of application. Environmental conditions such as prevailing winds, temperature and humidity. Duration of the work. Protective clothing and mask used.
In order to minimize the routine and accidental exposure of staff to insecticides, safety precautions must be observed at all stages of insecticide use. Safety precautions during storage Store insecticides in containers with the original label. Labels should identify the contents, nature of the material, preparation methods and precautions to be employed. Do not transfer insecticides to other containers, or to containers used for food or beverages. All insecticide containers must be sealed. Keep insecticides in a properly-designated place, away from direct sunlight, food, medicine, clothing, children and animals and protected from rain and flooding, preferably in a locked room with warning signs such as Dangerous: Insecticides; Keep Away posted prominently. To avoid unnecessary and prolonged storage of insecticides, order only sufficient amounts needed for a given operation, or order on a regular basis (e.g. every three months depending on routine needs), or order only when stocks get low. Stocks received first must be used first. This avoids prolonged storage of any batch of insecticide.
Steps before insecticide use Read the label carefully and understand the directions for preparing and applying the insecticides as well as the precautions listed, then follow the precise directions and precautions. Know the first-aid measures relevant and antidotes for the insecticides being used.
During mixing and spraying/fogging with insecticides Do not drink, eat or smoke while working. This prevents accidental inhalation or ingestion of insecticides. Mix insecticides in a well ventilated area, preferably outdoors.
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Mix only as much insecticide as is needed for each application. This will reduce the problem of storing and disposing of excess insecticide. Do not smell or inhale insecticides. Never mix insecticides directly with bare hands. Stand with the wind blowing from behind when mixing insecticides. Do not clear blocked spray nozzles by blowing with the mouth. Make sure that the spray equipment does not leak; check all joints regularly. Keep all persons not involved away from where the insecticides are being mixed. Exposure to spraying normally should not exceed five hours a day. When spraying is undertaken, the hottest and most humid period of the day should be avoided if possible. It is best to apply insecticides early in the morning or late in the evening. This minimizes excessive sweating and encourages the use of protective clothing. Also, high temperatures increase the absorption of insecticides. Those applying insecticides should always wear long-sleeved shirts and trousers. Wear protective clothing and headgear, where necessary, to protect the main parts of the body as well as the head and neck, lower legs, hands, mouth, nose and eyes. Depending on the insecticide and type of application, boots, gloves, goggles and respirators may be required. Mixers and baggers should wear rubber boots, gloves, aprons and masks, since they come in contact with technical material and concentrated formulations. Those engaged in thermal fogging and ULV spraying should be provided with overalls, goggles, hats and masks. Those engaged in larviciding (e.g. with temephos) need no special protective clothing because the risk of toxicity is low. To protect yourself and your family, never work with insecticides in your street clothes. Do not wear unwashed protective clothing. Make sure your gloves and boots have been washed inside and outside before you put them on. Take heed of the wind direction to avoid drift.
Steps after spraying/fogging of insecticides Wash all spray equipment thoroughly and return to the storeroom. It is important to maintain equipment in good working order after usage. Empty insecticide containers should not be used in the household to store food or drinking water. They should be buried or burned. Larger metal containers should be punctured so that they cannot be reused. Used containers can be rinsed two or three times with water, scrubbing the sides thoroughly. If a drum has contained an organophosphorus compound, an additional rinse should be carried out with washing soda, 50 g/l (5%), and the solution should be allowed to remain in the container overnight. A soakage pit should be provided for rinsing. All workers must wash thoroughly with soap and water. This removes deposits of insecticides on the skin. All protective clothing should be washed after each use. All use of insecticides must be recorded. Eat only after thoroughly washing hands with soap and water.
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3.
Regular medical surveillance of all spraying personnel may be required if space spray operations are done on a routine, long-term basis. Mixers, baggers and spraymen should be instructed to detect and report any early signs and symptoms of mild intoxication. Any undue prevalence of illness not associated with well recognized signs and symptoms of poisoning by a particular insecticide should be noted and reported. A regular medical examination, including the determination of blood cholinesterase for those applying organophosphorus compounds, should be conducted. If the level of cholinesterase activity decreases significantly (50% of a well-established pre-exposure value), the affected operator must be withdrawn from exposure until he recovers. Test kits for monitoring cholinesterase activity are available.
Symptoms of insecticide poisoning Field workers should be taught to recognize the following symptoms: DDT and other organochlorines Symptoms include apprehension, excitement, dizziness, hyperexcitability, disorientation, headache, muscular weakness and convulsions . These compounds are normally not used for DHF vector control. Malathion, fenitrothion and other organophosphates Early symptoms include nausea, headache, excessive sweating, blurred vision, lacrimation (tears from eyes), giddiness, hypersalivation, muscular weakness, excessive bronchial secretion, vomiting, stomach pains, slurred speech and muscular twitching. Later, advanced symptoms may include diarrhoea, convulsions, coma, loss of reflexes, and loss of sphincter control. (Note: Temephos has a very low toxicity rating and can safely be used in drinking water to kill mosquito larvae). Carbamates Symptoms include headache, nausea, vomiting, bradycardia, diarrhoea, tremors, convulsive seizures of muscles, increased secretion of bronchial, lacrimal, salivary and sweat glands . Pyrethroids (e.g. permethrin and S-bioallethrin) These insecticides have very low mammalian toxicity, and it is deduced that only single doses above 15 gm could be a serious hazard to an adult. In general, the effective dosages of pyrethroids for vector control are much lower when compared with other major groups of synthetic insecticides. Although pyrethroids may be absorbed by ingestion, significant skin penetration is unlikely. Symptoms, if they develop, reflect stimulation of the central nervous system. No cases of accidental poisoning from pyrethroids have been reported in humans. Some pyrethroids such as deltamethrin, cypermethrin and lambdacyhalothrin, can cause eye and skin irritation if adequate precautions are not taken. Bacterial insecticide bacillus thuringiensis H-14 and insect growth regulators (methoprene) These control agents have exceedingly low mammalian toxicity and cause no side-effects. They can be safely used in drinking water.
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4.
Eliminate the poison. Determine whether the insecticide is in water emulsion or petroleum solution, if possible. If the insecticide is dissolved in a water emulsion, induce vomiting by putting a finger or spoon down the throat. If this fails, give one tablespoon of salt in a glass of warm water until vomitus is clear. If the insecticide is dissolved in a petroleum product, have the doctor or nurse perform gastric lavage, sucking the insecticide out of the stomach with a tube to prevent the possibility of the petroleum product entering the lungs and causing pneumonia. Administer a laxative such as Epsom salts or milk of magnesia in water to eliminate the insecticide from the alimentary tract. Avoid oily laxatives such as castor oil, which may increase the absorption of insecticide. The insecticide container must be made available to the physician wherever possible. This will help in determining the group of insecticides involved in the poisoning. The label will indicate if it is a chlorinated hydrocarbon, an organophosphate, a carbamate, a pyrethroid or a bacterial insecticide. If the insecticide is an organophosphate, either airopine sulphate or a 2-PAM chloride (pralidoxime chloride) can be used as an antidote. An injection of 2 mg to 4 mg atropine sulfate is given intravenously. More atropine may be required depending on the severity of the poisoning. The dose of 2-PAM chloride is 1 gram for an adult and 0.25 gram for an infant. If the insecticide is a carbamate, atropine sulphate is used as an antidote; 2-PAM and other oximes are not to be used.
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11. Functions of Emergency Action Committee (EAC) and Rapid Action Team (RAT)
(A) Emergency Action Committee (EAC)
Constitution The EAC will comprise administrators, epidemiologists, entomologists, clinicians and laboratory specialists, school health officers, health educators and representatives of other related sectors. Functions (1) To take all administrative actions and coordinate activities aimed at the management of serious cases in all medical care centres and undertake emergency vector control intervention measures. To draw urgent plans of action and resource mobilization in respect of medicines, intravenous fluids, blood products, insecticides, equipment and vehicles. To liaise with intersectoral committees in order to mobilize resources from non-health sectors, namely the ministry/department of - urban development, education, information, law, water supply, waste disposal for the elimination of the breeding potential of Aedes aegypti. To interact with the news media and NGOs for dissemination of information related to health education and community participation.
(2) (3)
(4)
(B)
Constitution The RAT at the state or provincial levels will comprise epidemiologists, entomologists and a laboratory specialist (at state and local levels). Local levels Medical officer, public health officer, non-health staff, local government staff. Functions Undertake urgent epidemiological and entomological investigations. Provide required emergency logistical support, e.g. delivery of medical and laboratory supplies to health facilities. Provide on-the-spot training in case management for local health staff. Supervise the elimination of breeding places and application of vector control measures. Carry out health education activities. Sample the collection of serum specimens.
Source: Management of Dengue Epidemic, Report of a WHO Technical Meeting, New Delhi, 2830 November 1996, WHO Regional Office for South-East Asia, New Delhi (SEA/DEN/1, SEA/VBC/55, May 1997, 38 pp).
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ID no.:
Name of hospital/institution/clinic: Locality/town/city: Date: Case investigation: Name: Age: Sex: Fathers/mothers name:
Address: Whether visited any other area during last two weeks:
Signs and symptoms: Date of onset of fever: Date of admission: Course of fever: continuous/intermittent/remittent Presenting symptoms: Haemorrhagic manifestations: Yes/no Petechiae, parpura, ecchymosis, epistaxis, gum bleeding, haematemesis, malena Enlarged lever: Yes/no Torniquet test: Positive/negative/not done Rash: Yes/no Shock: Yes/no Condition of patient: stable/critical Any platelet or blood transfusion given: Laboratory findings:
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Haematocrit (percentage) Platelet count Differential leucocyte count Seroogical input: NS1, IgM, IgG Acute sera collected on date: Convalescent sera collected on date: Outcome of the patient:
1 1 1
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Comprehensive Guidelines for Prevention and Control of Dengue and Dengue Haemorrhagic Fever | https://fr.scribd.com/document/98073584/Dengue-DHF-Prevention-amp-Control-Guidelines-Rev | CC-MAIN-2019-26 | en | refinedweb |
How to manually stop video recording?
Hey guys, I am new to the world of programming, I am not from the computer science background. Currently, I am working on a project in which I am using raspberry pi 3 and a USB webcam (I am not using the Pi camera). My objective is to record a video using the webcam, I have interfaced a button switch with one of the GPIO pins, so if I press the push button once it should start recording the video and on the next press, it must stop recording. I used the example code to check whether I am able to record the video or not? I run the code using terminal and yes it works, but whenever I want to stop recording I have to press Ctrl+C, which terminates the entire process, I also want to execute some different operation once the video stops, but I have no idea how to do that. Please I need your guidance.
import numpy as np import cv2 cap = cv2.VideoCapture(0) #defining the webcam fourcc = cv2.cv.CV_FOURCC(*'XVID') out = cv2.VideoWriter('webcamOut.avi',fourcc,30.0,(640,480)) while True: ret, frame = cap.read() out.write(frame) cv2.imshow('frame',frame) if cv2.waitKey(1) & 0xFF ==ord('q'): break cap.release() out.release() cv2.destroyAllWindow()
Also, one more thing. If I set the resolution higher than 480 (i.e. 720 or 1080), the output video saved with 5kb file size. what to do in that case? thanks
your code clearly shows, that it will stop both capturing & recording, once you press the "q" key (in the gui window) , you probably did not notice it yet.
you could easily insert some code just before
cap.release()
if you want to do the same using gpio pins, you'll have to insert some logic for that into the while loop, unfortunately, this is totally off-topic, we can't help you with that. | https://answers.opencv.org/question/146991/how-to-manually-stop-video-recording/ | CC-MAIN-2019-26 | en | refinedweb |
Truffle Tricks for Ethereum Development: Dispelling 8 Myths & First Impressions
If you haven’t heard of Truffle, go get it. It’s a tool that makes developing Ethereum projects much easier. When people first interact with Truffle, they think they’re confined to fitting into the structure first provided, having a very rare scope that supports only specific types of projects. I’m here to dispel that myth — and many others — and show you some Truffle tricks you didn’t know were possible.
Myth #1: You must use the folders provided to you in the `app` directory
When you run `truffle init` and you’re given an app directory with “javascripts”, “stylesheets” and “images” within it, you might think you have to use those directories to take advantage of Truffle’s build process. You don’t. You can delete those folders, add new ones, or rename them to your heart’s content. Here’s an example build configuration where files have been renamed (notice no images directory):
Directory structure:
/app
— pages
— controls
— vendor
App configuration:
{
“build”: {
"app.js": [
"vendor/react.js", // structure is up to you
"controls/button.js",
"pages/page_one.jsx",
"pages/page_two.jsx"
]
},
// ...
}
Myth #2: Dependencies must live in the app directory
Paths are relative to the app directory, but that doesn’t mean dependencies have to live there. Here’s an example where the build process refers to dependencies that exist outside of “app”, allowing you to take advantage of package managers like npm:
{
“build”: {
"app.js": [
"../node_modules/jquery/dist/jquery.min.js",
// ...
]
},
// ...
}
Myth #3: Truffle can only build web apps
False. Here’s a great example of Truffle building a library, creating both a distributable and minified version.
Myth #4: Truffle can’t have multiple dependent build targets
Oh but it can. Taken from the same example as Myth #3, you can use build targets as they’re created, since each build target within app.json is created in order:
{
“build”: {
// The main library file.
“hooked-web3-provider.js”: “hooked-web3-provider.es6”,
// Note, the first one will be processed before this one,
// so we can refer to the built file.
“hooked-web3-provider.min.js”: {
“files”: [
“../build/hooked-web3-provider.js”
],
“post-process”: [
“uglify”
]
}
},
// ...
}
Myth #5: Like it or not, you must use Truffle’s build process
Nope — this is perhaps the biggest myth. Just delete the “build” configuration from your app.json if you need something more complex (or don’t want a build process at all). You can still use Truffle for contract compilation, testing and deployment.
Myth #6: Contract code requires lots of copy pasta
This isn’t so much a myth it is a lesser-known feature we added to Truffle. Solidity’s import statement leaves much to be desired, so we wrote our own. If you want to include one contract as a dependency of another, simply import it in the order you want it included; Truffle will take care of the rest.
import "Permissioned"; // Looks for ./contracts/Permissioned.sol
contract MyContract is Permissioned {
// ..
}
You can even import nested contract files:
import "tools/Hammer"; // Looks for ./contracts/tools/Hammer.sol
And viola! Mangeable, maintainable code separation, sans pasta.
Myth #7: Truffle doesn’t support different blockchains like development vs. staging vs. production, or a testnet vs. Olympic vs. Frontier)
Au contraire. Truffle has the concept of environments — pulled from Rails — that you can use to configure different blockchains and contracts deployed to those blockchains. By default you’re given development, staging, production and test, but they’re not required. If you don’t need one, just delete it and Truffle will respond accordingly. If you want to make your environments more tailored to you, then rename them. Here’s an example file structure with environment names tailored to the context the app will be deployed to:
Directory structure:
/config
— development
— consensys-testnet
— ethereum-mainnet
- app.json
Each of the directories within `config` should contain a `config.json` file that at minimum defines the network they connect to. You can also use this config file to overwrite the default configuration of any value within `app.json`:
{
"rpc": {
"host": "xx.xx.xx.xx",
"port": "1234"
}
}
Once in place, you can build your application as well as compile and deploy your contracts to use the environments you’ve specified:
// Both compile and deploy will write a contracts.json file to the
// environment specified:
$ truffle compile -e consensys-testnet
$ truffle deploy -e consensys-testnet
// Building will hook up the contracts in the specified environment
// to the frontend for use. If you keep the production environment,
// `truffle dist` will create a `dist` folder you can commit to
// your respository.
$ truffle build -e consensys-testnet
$ truffle dist
Myth #8: Truffle doesn’t support complex deployment processes
Truffle hasn’t taken a stance on the ideal contract deployment process, so you won’t see any advanced deployment options if you take a deep dive into the code. But complex deployment processes are possible, and can easily be scripted with `truffle exec`. Truffle’s `exec` command lets you run a Node script within the environment you specify (details below), interacting with your contracts the same way you would when writing your frontend or your tests.
Here’s an example script that can be run after `truffle deploy` that hooks up an AppStore contract with an AppFactory:
File Name: register_factories.js
-----------------------------------------------------
var store = AppStore.at(AppStore.deployed_address);
store.registerFactory(“app”, AppFactory.deployed_address)
.then(function(tx) {
console.log(“Registered AppFactory successfully.”);
process.exit(0)
}).catch(function(e) {
console.log(e);
process.exit(1);
});
To run this script, simply run the following. In this example, `truffle exec` will use the contracts that were already deployed to the “consensys-testnet” environment created above:
$ truffle exec ./register_factories.js -e consensys-testnet
Fin.
Truffle is still being actively developed, and has a ways to go before it solves all development and deployment problems in the young Ethereum Frontier. However, through the tricks above we hope you can get one step closer to a manageable, maintainable project. Your feedback is most welcome, and feel free to express any issues, feedback and feature requests in our Gitter as well as the Github issue tracker. Cheers, and happy developing! | https://medium.com/@timothyjcoulter/truffle-tricks-for-ethereum-development-dispelling-8-myths-first-impressions-880f66bf3320 | CC-MAIN-2019-26 | en | refinedweb |
This is my struts 2 flow where i am using action chaining
JSP--->Action1--->Action2--->ResultJsp
With action chaining , my understanding is that request is forwarded from
action1 to action2.So if i pass some parameter from action1 to action 2
it should be set in new action instance variable(/value stack created for
new action).But its not happening
Below is my code in action1
@Result(name = "displayEmployee",type = "chain",
params = {
"namespace", "/employee",
"actionName", "Employee-lookup!search",
"empMode", "true"
})
@Action("display-employee!displayEmployee")
public String displayEmployee() {
return "displayEmployee";
}
Now in Action 2 i.e display-employee , i have boolean property with name
empMode. But i get the value as false though i should get it true
because i am passing it as attribute in result annotation. As my
understanding in action chaining, all request paramaters are
forwarded from action1 to action2. Basically new value stack is created for
action2 which contains the variables which were present
in action1. So why value true is not set for empMode property in action 2? | http://mail-archives.us.apache.org/mod_mbox/struts-user/201303.mbox/%3CCAE_TDVg7WUX6Hg+B1L76o6AjeXpEbLEq62m+jYVusDKeeWHQJg@mail.gmail.com%3E | CC-MAIN-2019-26 | en | refinedweb |
Everything About Python — Beginner To Advanced
Everything You Need To Know In One Article
This article aims to outline all of the key points of Python programming language. My target is to keep the information short, relevant and focus on the most important topics which are absolutely required to be understood.
After reading this blog, you will be able to use any Python library or implement your own Python packages.
You are not expected to have any prior programming knowledge and it will be very quick to grasp all of the required concepts.
I will also highlight top discussion questions that people usually query regarding Python programming language.
Lets build the knowledge gradually and by the end of the article, you will have a thorough understanding of Python.
Here are 5 interesting Python exercises to help with your learning :
I highly recommend this article as it shows how you can use your Python knowledge which I will be explaining now to build a robust application:
This article contains 25 key topics. Let’s Start.
1. Introducing Python
What Is Python?
- Interpreted high-level object-oriented dynamically-typed scripting language.
- Python interpreter reads one line of code at a time, interprets it into low level machine language (byte code) and then executes it.
- As a result, run time errors are usually encountered.
Why Python?
- Python is the most popular language due to the fact that it’s easier to code and understand it.
- Python is object oriented programming language and can be used to write functional code too.
- It is a suitable language that bridges the gaps between business and developers.
- Subsequently, it takes less time to bring a Python program to market compared to other languages such as C#/Java.
- Additionally, there are a large number of python machine learning and analytical packages.
- A large number of communities and books are available to support Python developers.
- Nearly all type of applications, ranging from forecasting analytical to UI, can be implemented in Python.
- There is no need to declare variable types. Thus it is quicker to implement a Python application.
Why Not Python?
- Python is slower than C++, C#, Java. This is due to the lack of Just In Time optimisers in Python.
- Python syntactical white-space constraint makes it slightly difficult to implement for new coders.
- Python does not offer advanced statistical features as R does.
- Python is not suitable for low-level system and hardware interaction.
How Does Python Work?
This image illustrates how python runs on our machines:
The key here is the Interpreter that is responsible for translating high level Python language to low level machine language.
2. Variables — Object Types And Scope
- Variables store information that can be used in your program such as to hold user inputs, local states of your program etc.
- Variables are also known as names in Python.
Python supports numbers, strings, sets, lists , tuples and dictionaries. These are the standard data types.
Declare And Assign Value To Variable
Assignment sets a value to a variable:
myFirstVariable = 1
mySecondVariable = 2
myFirstVariable = "Hello You"
- Assigning a value is known as binding in Python.
Note how I assigned an integer value of 1 and then a string value of “Hello You” to the myFirstVariable variable. This is possible due to the fact that the data types are dynamically typed in python.
Numeric
- Integers, decimals, floats are supported.
value = 1 #integer
value = 1.2 #float with a floating point
- Longs are also supported. They have a suffix of L e.g. 9999999999999L
Strings
- Textual information. Strings are sequence of letters.
- String value is enclosed in quotation marks:
name = 'farhad'
- Strings are immutable. Once they are created, they cannot be changed e.g.
a = 'me'
a[1]='y'
It will throw a Type Error
- When string variables are assigned a new value then internally, Python creates a new object to store the value.
Variables can have local or global scope.
Local Scope
- Variables declared within a function, as an example, can only exist within the block.
- Once the block exists, the variables also become inaccessible.
def some_funcion():
TestMode = False
print(TestMode) <- Breaks as the variable doesn't exist outside
In Python, if else and for/while loop block doesn’t create any local scope.
for i in range(1, 11):
test_scope = "variable inside for loop"
print(test_scope)
Output:
variable inside for loop
With if-else block
is_python_awesome = True
if is_python_awesome:
test_scope = "Python is awesome"
print(test_scope)
Output:
Python is awesome
Global Scope
- Variables that can be accessed from any function have a global scope. They exist in the __main__ frame.
- You can declare a global variable outside of functions. It’s important to note that to assign a global variable a new value, you will have to use the “global” keyword:
TestMode = True
def some_function():
global TestMode
TestMode = False
some_function()
print(TestMode) <--Returns False
Removing the line “global TestMode” will only set the variable to False within the some_function() function.
Note: Although I will write more on the concept of modules later, but if you want to share a global variable across a number of modules then you can create a shared module file e.g. configuration.py and locate your variable there. Finally, import the shared module in your consumer modules.
Finding Variable Type
- If you want to find type of a variable, you can implement:
type('farhad')
--> Returns <type 'str'>
Comma In Integer Variables
- Commas are treated as sequence of variables e.g.
9,8,7 is three numeric variables
3. Operations
- Allows us to perform computation on variables
Numeric Operations
- Python supports basic *, /, +, -
- Python also supports floor division
1//3 #returns 0
1/3 #returns 0.333
- Additionally, python supports exponentiation via ** operator:
2**3 = 2 * 2 * 2 = 8
- Python supports Modulus (remainder) operator too:
7%2 = 1
String Operations
Concat Strings:
'A' + 'B' = 'AB'
Repeat String:
‘A’*3 will repeat A three times: AAA
Slicing:
y = 'Abc'
y[:2] = ab
y[1:] = bc
y[:-2] = a
y[-2:] = bc
Reversing:
x = 'abc'
x = x[::-1]
Negative Index:
If you want to start from the last character then use negative index.
y = 'abc'
print(y[:-1]) # will return c
Also used to remove any new line carriages/spaces.
Finding Index
name = 'farhad'
index = name.find('r')
#returns 2
name = 'farhad'
index = name.find('a', 2) # finds index of second a
#returns 4
For Regex, use:
- split(): splits a string into a list via regex
- sub(): replaces matched string via regex
- subn(): replaces matched string via regex and returns number of replacements
Casting
- str(x): To string
- int(x): To integer
- float(x): To floats
Set Operations
- Set is an unordered data collection. We can define a set variable as:
a = {1,2,3}
Intersect Sets
- To get what’s common in two sets
a = {1,2,3}
b = {3,4,5}
c = a.intersection(b)
Difference In Sets
- To retrieve the difference between two sets:
a = {1,2,3}
b = {3,4,5}
c = a.difference(b)
Union Of Collections
- To get a distinct combined set of two sets
a = {1,2,3}
b = {3,4,5}
c = a.union(b)
Ternary Operator
- Used to write conditional statements in a single line.
Syntax:
[If True] if [Expression] Else [If False]
For example:
Received = True if x = 'Yes' else False
4. Comments
Single Line Comments
#this is a single line comment
Multiple Line Comments
One can use:
```this is a multi
line
comment```
5. Expressions
Expressions can perform boolean operations such as:
- Equality: ==
- Not Equal: !=
- Greater: >
- Less: <
- Greater Or Equal >=
- Less Or Equal <=
6. Pickling
Converting an object into a string and dumping the string into a file is known as pickling. The reverse is known as unpickling.
7. Functions
- Functions are sequence of statements which you can execute in your code. If you see repetition in your code then create a reusable function and use it in your program.
- Functions can also reference other functions.
- Functions eliminate repetition in your code. They make it easier to debug and find issues.
- Finally, functions enable code to be understandable and easier to manage.
- In short, functions allow us to split a large application into smaller chunks.
Define New Function
def my_new_function():
print('this is my new function')
Calling Function
my_new_function()
Finding Length Of String
Call the len(x) function
len('hello')
prints 5
Arguments
- Arguments can be added to a function to make the functions generic.
- This exercise is known as generalization.
- You can pass in variables to a method:
def my_new_function(my_value):
print('this is my new function with ' + my_value)
- Optional arguments:
We can pass in optional arguments by providing a default value to an argument:
def my_new_function(my_value='hello'):
print(my_value)
#Calling
my_new_function() => prints hello
my_new_function('test') => prints test
- *arguments:
If your function can take in any number of arguments then add a * in front of the parameter name:
def myfunc(*arguments):
return a
myfunc(a)
myfunc(a,b)
myfunc(a,b,c)
- **arguments:
It allows you to pass varying number of keyword arguments to a function.
You can also pass in dictionary values as keyword arguments.
Return
- Functions can return values such as:
def my_function(input):
return input + 2
- If a function is required to return multiple values then it’s suitable to return a tuple (comma separated values). I will explain tuples later on:
resultA, resultB = get_result()
get_result() can return ('a', 1) which is a tuple
Lambda
- Single expression anonymous function.
- It is an inline function.
- Lambdas do not have statements and they only have one expression:
my_lambda = lambda x,y,z : x - 100 + y - z
my_lambda(100, 100, 100) # returns 0
Syntax:
variable = lambda arguments: expression
Lambda functions can be passed as arguments to other functions.
dir() and help()
- dir() -displays defined symbols
- help() — displays documentation
8. Modules
What is a module?
- Python is shipped with over 200 standard modules.
- Module is a component that groups similar functionality of your python solution.
- Any python code file can be packaged as a module and then it can be imported.
- Modules encourage componentised design in your solution.
- They provide the concept of namespaces help you share data and services.
- Modules encourage code re-usability and reduces variable name clashes.
PYTHONPATH
- This environment variable indicates where the Python interpreter needs to navigate to locate the modules. PYTHONHOME is an alternative module search path.
How To Import Modules?
- If you have a file: MyFirstPythonFile.py and it contains multiple functions, variables and objects then you can import the functionality into another class by simply doing:
import MyFirstPythonFile
- Internally, python runtime will compile the module’s file to bytes and then it will run the module code.
- If you want to import everything in a module, you can do:
import my_module
- If your module contains a function or object named my_object then you will have to do:
print(my_module.my_object)
Note: If you do not want the interpreter to execute the module when it is loaded then you can check whether the __name__ == ‘__main__’
2. From
- If you only want to access an object or parts of a module from a module then you can implement:
from my_module import my_object
- This will enable you to access your object without referencing your module:
print(my_object)
- We can also do from * to import all objects
from my_module import *
Note: Modules are only imported on the first import.
If you want to use C module then you can use PyImport_ImportModule
Use import over from if we want to use the same name defined in two different modules.
9. Packages
- Package is a directory of modules.
- If your Python solution offers a large set of functionalities that are grouped into module files then you can create a package out of your modules to better distribute and manage your modules.
- Packages enable us to organise our modules better which help us in resolving issues and finding modules easier.
- Third-party packages can be imported into your code such as pandas/sci-kit learn and tensor flow to name a few.
- A package can contain a large number of modules.
- If our solution offers similar functionality then we can group the modules into a package:
from packageroot.packagefolder.mod import my_object
- In the example above, packageroot is the root folder. packagefolder is the subfolder under packageroot. my_module is a module python file in the packagefolder folder.
- Additionally, the name of the folder can serve as the namespace e.g.
from data_service.database_data_service.microsoft_sql.mod
Note: Ensure each directory within your package import contains a file __init__.py.
Feel free to leave the files blank. As __init__.py files are imported before the modules are imported, you can add custom logic such as start service status checks or to open database connections etc.
PIP
- PIP is a Python package manager.
- Use PIP to download packages:
pip install package_name
10. Conditions
- To write if then else:
if a == b:
print 'a is b'
elif a < b:
print 'a is less than b'
elif a > b:
print 'a is greater than b'
else:
print 'a is different'
Note how colons and indentations are used to express the conditional logic.
Checking Types
if not isinstance(input, int):
print 'Expected int'
return None
You can also add conditional logic in the else part. This is known as nested condition.
#let's write conditions within else
else:
if a == 2:
print 'within if of else'
else:
print 'within else of else'
11. Loops
While
- Provide a condition and run the loop until the condition is met:
while (input < 0):
do_something(input)
input = input-1
For
- Loop for a number of times
for i in range(0,10)
- Loop over items or characters of a string
for letter in 'hello'
print letter
One-Liner For
Syntax:
[Variable] AggregateFunction([Value] for [item] in [collection])
Yielding
- Let’s assume your list contains a trillion records and you are required to count the number of even numbers from the list. It will not be optimum to load the entire list in the memory. You can instead yield each item from the list.
- xrange instead of range can be used to iterate over the items.
Combine For with If
- Let’s do a simple exercise to find if a character is in two words
name = 'onename'
anothername = 'onenameonename'
for character in name:
if character in anothername
print character
Break
- If you want to end the loop
for i in range(0,10):
if (i==5):
break
while True:
x = get_value()
if (x==1):
break
- Let’s write Fibonacci for loop:
def fib(input):
if (input <=1):
return(str(input))
else:
first = 0
second = 1
count = 0
for count in range(input):
result = first + second
print(first)
first = second
second = result
count = count+1
#print statement will output the correct fib value
fib(7)
12. Recursion
- A function calling itself is known as recursion.
Let’s implement a factorial recursive function:
Rules:
- 0! = 1 #Factorial of 0 is 1
- n! = n(n-1)! #Factorial of n is n * factorial of n-1
Steps:
- Create a function called factorial with input n
- If n = 0 return 1 else do n x factorial of n-1
def factorial(n):
if n==0:
return 1
else:
return n * factorial(n-1)
Another Example: Let’s write Fibonacci recursive function:
Rules:
- First two digits are 0 and 1
- Rest add last two digits
0, 1, 1, 2, 3, 5, 8…
Steps:
- Create a function called fibonacci that takes in an input n
- Create two variables first and second and assign them with values 0 and 1
- if n =0 return 0, if n = 1 return 1 else return (n-1) + (n-2)
def fibonacci(n):
if (n<=1):
return n
else:
return fibonacci(n-1)+fibonacci(n-2)
print(fibonacci(6))
It is important to have an exit check otherwise the function will end up in infinite loop.
13. Frames And Call Stack
- Python code is loaded into frames which are located into a Stack.
- Functions are loaded in a frame along with the parameters and variables.
- Subsequently, frames are loaded into a stack in the right order of execution.
- Stack outlines the execution of functions. Variables that are declared outside of functions are stored in __main__
- Stacks executes the last frame first.
You can use traceback to find the list of functions if an error is encountered.
14. Collections
Lists
- Lists are data structures that can hold a sequence of values of any data types. They are mutable (update-able).
- Lists are indexed by integers.
- To create a list, use square brackets:
my_list = ['A', 'B']
- To add/update/delete an item, use index:
my_list.append('C') #adds at the end
my_list[1] = 'D' #update
my_list.pop(1) # removes
or
del my_list[1:2] # removes
my_list.extend(another_list) # adds second list at end
- Addition, repetition and slices can be applied to lists (just like strings).
- List also supports sorting:
my_list.sort()
Tuples
- Tuples are like lists in the sense that they can store a sequence of objects. The objects, again, can be of any type.
- Tuples are faster than lists.
- These collections are indexed by integers.
- Tuples are immutable (non-update-able)
my_tuple = tuple()
or
my_tuple = 'f','m'
or
my_tuple = ('f', 'm')
Note: If a tuple contains a list of items then we can modify the list. Also if you assign a value to an object and you store the object in a list and then change the object then the object within the list will get updated.
Dictionaries
- Dictionary is one of the most important data structure in programming world. It stores key/value pair objects.
- It has many benefits e.g. optimised data retrieval functionality.
my_dictionary = dict()
my_dictionary['my_key'] = 1
my_dictionary['another_key'] = 2
- You can also create a dictionary as:
my_dictionary = {'my_key':1, 'another_key':2}
- Print dictionary contents
for key in dictionary:
print key, dictionary[key]
- Values of a dictionary can be of any type including strings, numerical, boolean, lists or even dictionaries.
dictionary.items() # returns items
#checking if a key exists in a dictionary
if ('some key' in dictionary):
#do something
Note: If you want to perform vectorised/matrix operations on a list then use NumPy Python package
15. Compilation And Linking
- These features can be utilised to use a file that is written in another language e.g. C or C++ etc.
- Once the code is written into a file then the file can be placed in the Modules directory.
- It is important to add a line in the Setup.local file to ensure that the newly created file can be loaded.
Compilation:
- Allows compilation of new extensions without any error
Linking:
- Once the extensions are compiled, they can be linked.
16. Iterators
Iterators
- Allow traversing through a collection
- All iterators contain __iter__() and __next__() functions
- Simply execute iter(x) on lists, dictionaries, strings or sets.
- Therefore we can execute next(iter) where iter = iter(list) as an instance.
- Iterators are useful if we have a large number of items in a collection and we do not intend to load all of the files in memory at once.
- There are common iterators which enable developers to implement functional programming language paradigm:
Filter
- Filter out values based on a condition
Map
- Applies a computation on each value of a collection. It maps one value to another value e.g. Convert Text To Integers
Reduce
- Reduces a collection of values to one single value (or a smaller collection) e.g. sum of a collection. It can be iterative in nature.
Zip
- Takes multiple collections and returns a new collection.
- The new collection contains items where each item contains one element from each input collection.
- It allows us to transverse multiple collections at the same time
name = 'farhad'
suffix = [1,2,3,4,5,6]
zip(name, suffix)
--> returns (f,1),(a,2),(r,3),(h,4),(a,5),(d,6)
17. Object Oriented Design — Classes
- Python allows us to create our custom types. These user-defined types are known as classes. The classes can have custom properties/attributes and functions.
- Object oriented design allows programmers to define their business model as objects with their required properties and functions.
- A property can reference another object too.
- Python classes can reference other classes.
- Python supports encapsulation — instance functions and variables.
- Python supports inheritance.
class MyClass:
def MyClassFunction(self): #self = reference to the object
return 5
#Create new instance of MyClass and then call the function
m = MyClass()
returned_value = m.MyClassFunction()
- An instance of a class is known as an object. The objects are mutable and their properties can be updated once the objects are created.
Note: If a tuple (immutable collection) contains a list (mutable collection) of items then we can modify the list. Also if you assign a value to an object and you store the object in a list and then change the object then the object within the list will get updated.
__init__
- __init__ function is present in all classes. It is executed when we are required to instantiate an object of a class. __init__ function can take any properties which we want to set:
class MyClass:
def __init__(self, first_property):
self.first_property = first_property
def MyClassFunction(self):
return self.first_property
#Create an instance
m = MyClass(123)
r = m.MyClassFunction()
r will be 123
Note: self parameter will contain the reference of the object, also referred to as “this” in other programming languages such as C#
__str__
- Returns stringified version of an object when we call “print”:
m = MyClass(123)
print m #Calls __str__
- Therefore, __str__ is executed when we execute print.
__cmp__
- Use the __cmp__ instance function if we want to provide custom logic to compare two objects of the same instance.
- It returns 1 (greater), -1 (lower) and 0 (equal) to indicate the equality of two objects.
- Think of __cmp__ like Equals() method in other programming language.
Overloading
- Methods of an object can be overloaded by providing more arguments as an instance.
- We can also overload an operator such as + by implementing our own implementation for __add__
Shallow Vs Deep Copy Of Objects
- Equivalent objects — Contains same values
- Identical objects — Reference the same object — same address in memory
- If you want to copy an entire object then you can use the copy module
import copy
m = MyClass(123)
mm = copy.copy(m)
- This will result in shallow copy as the reference pointers of the properties will be copied.
- Therefore, if one of the properties of the object is an object reference then it will simply point to the same reference address as the original object.
- As a result, updating the property in the source object will result in updating the property in the target object.
- Therefore shallow copy copies reference pointers.
- Fortunately, we can utilise deep-copy:
import copy
m = MyClass(123)
mm = copy.deepcopy(m)
- If MyClass contains a property that references MyOtherClass object then the contents of the property will be copied in the newly created object via deepcopy.
- Therefore, deep copy makes a new reference of the object.
18. Object Oriented Design — Inheritance
- Python supports inheritance of objects. As a result, an object can inherit functions and properties of its parent.
- An inherited class can contain different logic in its functions.
- If you have a class: ParentClass and two subclasses: SubClass1, SubClass2 then you can use Python to create the classes as:
class ParentClass:
def my_function(self):
print 'I am here'
class SubClass1(ParentClass):
class SubClass2(ParentClass):
- Consequently, both subclasses will contain the function my_function().
- Inheritance can encourage code re-usability and maintenance.
Note: Python supports multiple inheritance unlike C#
- Use Python’s abc module to ensure all subclasses contain the required features of the Abstract Base Class.
Multi-Inheritance:
class A(B,C): #A implments B and C
- If you want to call parent class function then you can do:
super(A, self).function_name()
19. Garbage Collection — Memory Management
- All of the objects in Python are stored in a heap space. This space is accessible to the Python interpreter.
- Python has an in-built garbage collection mechanism.
- It means Python can allocate and de-allocate the memory for your program automatically such as in C++ or C#.
- Its responsibility is to clear the space in memory of those objects that are not referenced/used in the program.
As multiple objects can share memory references, python employs two mechanisms:
- Reference counting: Count the number of items an object is referenced, deallocate an object if its count is 0.
- The second mechanism takes care of circular references, also known as cyclic references, by only de-allocating the objects where the allocation — deallocation number is greater than threshold.
- New objects are created in Generation 0 in python. They can be inspected by:
import gc
collected_objects = gc.collect()
- Manual garbage collection can be performed on timely or event based mechanism.
20. I/O
From Keyboard
- Use the raw_input() function
user_says = raw_input()
print(user_says)
Files
- Use a with/as statement to open and read a file. It is equivalent to using statement in C#.
- with statement can take care of closing of connections and other cleanup activities.
Open files
with open(file path, 'r') as my_file:
for line in my_file
#File is closed due to with/as
Note: readline() can also be executed to read a line of a file.
To open two files
with open(file path) as my_file, open(another path) as second_file:
for (line number, (line1, line2)) in enumerate(zip(my_file, second_file):
Writing files
with open(file path, 'w') as my_file:
my_file.write('test')
Note: Use os and shutil modules for files.
Note: rw — read-write mode and a — append mode.
SQL
Open a connection
import MySQLdb
database = MySQLdb.connect(“host”=”server”, “database-user”=”my username”, “password”=”my password”, “database-name”=”my database”)
cursor = database.cursor()
Execute a SQL statement
cursor.fetch("Select * From MyTable")
database.close()
Web Services
To query a rest service
import requests
url = ''
response = requests.get(url).text
To Serialise and Deserialise JSON
Deserialise:
import json
my_json = {"A":"1","B":"2"}
json_object = json.loads(my_json)
value_of_B = json_object["B"]
Serialise:
import json
a = "1"
json_a = json.dumps(a)
21. Error Handling
Raise Exceptions
- If you want to raise exceptions then use the raise keyword:
try:
raise TypError
except:
print('exception')
Catching Exceptions
- To catch exceptions, you can do:
try:
do_something()
except:
print('exception')
- If you want to catch specific exceptions then you can do:
try:
do_something()
except TypeError:
print('exception')
- If you want to use try/catch/finally then you can do:
try:
do_something()
except TypeError:
print('exception')
finally:
close_connections()
- finally part of the code is triggered regardless, you can use finally to close the connections to database/files etc.
Try/Except/Else
try:
do something
except IfTryRaisedException1:
do something else
except (IfTryRaisedException2, IfTryRaisedException3)
if exception 2 or 3 is raised then do something
else:
no exceptions were raised
- We can also assign exception to a variable by doing:
try:
do something
except Exception1 as my_exception:
do something about my_exception
- If you want to define user-defined constraints then use assert:
assert <bool>, 'error to throw'
Note: Python supports inheritance in exceptions
You can create your own exception class by:
class MyException(Exception): pass
22. Multi-Threading And GIL
- GIL is Global Interpreter Lock.
- It ensures that the threads can execute at any one time and allows CPU cycles to pick the required thread to be executed.
- GIL is passed onto the threads that are currently being executed.
- Python supports multi-threading.
Note: GIL adds overheads to the execution. Therefore, be sure that you want to run multiple threads.
23. Decorators
- Decorators can add functionality to code. They are essentially functions that call other objects/functions. They are callable functions — therefore they return the object to be called later when the decorated function is invoked.
- Think of decorates that enable aspect-oriented programming
- We can wrap a class/function and then a specific code will be executed any time the function is called.
- We can implement generic logic to log, check for security checks etc and then attribute the method with the @property tag.
24. Unit Testing In Python
- There are a number of unit testing and mocking libraries available in Python.
- An example is to use unittest:
1.Assume your function simply decrements an input by 1
def my_function(input):
return input - 1
2. You can unit test it by:
import unittest
class TestClass(unittest.TestCase):
def my_test(self):
self.assertEqual(my_function(1), 0)) #checking 1 becomes 0
We can also use doctest to test code written in docstrings.
25. Top Python Discussion Questions
Why Should I Use Python?
- Simple to code and learn
- Object oriented programming language
- Great Analytics and ML packages
- Faster to develop and bring my solution to market
- Offers in-built memory management facilities
- Huge community support and applications available
- No need to compile as it’s an interpreted language
- Dynamically typed — no need to declare variables
How To Make Python Run Fast?
- Python is a high level language and is not suitable to access system level programs or hardware.
- Additionally it is not suitable for cross-platform applications.
- The fact that Python is a dynamically typed interpreted language makes it slower to be optimised and run when compared to the low level languages.
- Implement C language based extensions.
- Create multi-processes by using Spark or Hadoop
- Utilise Cython, Numba and PyPy to speed up your Python code or write it in C and expose it in Python like NumPy
Which IDEs Do People Use?
- Spyder, PyCharm. Additionally various notebooks are used e.g. Jupyter
What Are The Top Python Frameworks And Packages?
- There are a large number of must-use packages:
PyUnit (unit testing), PyDoc (documentation), SciPy (algebera and numerical), Pandas (data management), Sci-Kit learn (ML and data science), Tensorflow (AI), Numpy (array and numerical), BeautifulSoap (web pages scrapping), Flask (microframework), Pyramid (enterprise applications), Django (UI MVVM), urllib (web pages scraping), Tkinter (GUI), mock (mocking library), PyChecker(bug detector), Pylint (module code analysis)
How To Host Python Packages?
- For Unix: Make script file mode Executable and first line must be:
#(#!/my account/local/bin/python)
2. You can use command line tool and execute it
3. Use PyPRI or PyPI server
Can Python and R be combined?
- A large number of rich statistical libraries have been written in R
- One can execute R code within Python by using Rpy2 python package or by using beaker notebook or IR kernel within Juputer.
Is there a way to catch errors before running Python?
- We can use PyChecker and PyLink to catch errors before running the code.
Summary
This article outlined the most important 25 concepts of Python in a short, relevant and focused manner. I genuinely hope it has helped someone get better understanding of Python.
I believe I have concentrated on the must know topics which are absolutely required to be understood.This knowledge is sufficient to write your own python packages in the future or using existing Python packages.
Rest, just practice as much as possible and you can implement your own library in Python because this article contains all the knowledge you need.
Here are 5 interesting Python exercises to test your knowledge :
I highly recommend this article as it shows how you can use your Python knowledge to build a robust application:
Hope it helps. | https://medium.com/fintechexplained/everything-about-python-from-beginner-to-advance-level-227d52ef32d2 | CC-MAIN-2019-26 | en | refinedweb |
Most Android applications pass data items between code excerpts.
Photos.com/PhotoObjects.net/Getty Images
Each screen in an Android application is represented within the code as an activity. When you create Android applications, you can create an activity class for each screen you need. If you need to pass data parameters into these activities when you launch them, you can use the "putExtra" and "getExtras" methods of the intent class. This way you can pass specific items of data between the activity classes in your Android apps, including numbers and text strings. This is a useful ability for most Android applications.
Create a new activity in your Android project. In Eclipse, select your project and then choose "File," "New" and "Class." Enter a name for your class and click "Finish." Make your class extend the activity class as in the following example code: public class DataActivity extends Activity { //class declaration here } Your class will need to import the activity class, so add the following line at the top of your class file if your Integrated Development Environment, or IDE, doesn't add it automatically: import android.app.Activity;.
Implement the "onCreate" method for your new class. Add the following outline for the method which will execute when an instance of the class is created: public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); //instantiate the Activity } This is the default outline for an activity class. Inside this method you can enter code to retrieve any passed data as well as creating any user interface elements you need.
Create a bundle object in your new activity class. In the "onCreate" method, add the following code declaring and instantiating an object of the bundle class: Bundle extras = getIntent().getExtras();. This calls the method of the intent class to create a bundle so that you can access any data passed to the activity from elsewhere in your application. To safeguard against errors, add the following outline of a conditional statement: if(extras !=null) { //get the passed data } Inside this conditional block your code can retrieve the data.
Retrieve your data parameters. Inside the conditional block, add code to retrieve the passed data items using the following syntax: String passedText = extras.getString(this.getPackageName() + ".dataString");. This demonstrates retrieving a string item with "dataString" as its reference. The reference for the item also includes the package name, to avoid any confusion if the variable names are used by more than one application.
Create an intent to launch your new activity. In another activity class within your application, launch the activity using the following syntax: Intent newIntent = new Intent(this, DataActivity.class); String someText = "hello"; newIntent.putExtra(this.getPackageName() + ".dataString", someText); this.startActivity(newIntent); This code creates a new intent, specifying the class name of the new activity. The code then creates a string variable and passes it to the intent, giving it the same name as the variable specified in the activity "onCreate" method within the "getString" method call. Finally the code starts the new intent.
Tip
- You can pass multiple items of data into an activity.
Warning
- If you're passing data between classes in your Android applications, test them thoroughly to ensure the data is always correctly received.
References (4)
Resources (3)
Photo Credits
- Photos.com/PhotoObjects.net/Getty Images | https://smallbusiness.chron.com/start-new-activity-parameters-android-33251.html | CC-MAIN-2019-26 | en | refinedweb |
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On 04/08/2013 23:42, Christian Mueller wrote:
> Hello list!
>
> Assume Apache Foo is publishing its artifacts to Maven central with the
> coordinates
> org.apache.foo:foo-core:1.0.0
>
> Assume there is a company Bar who builds his product based on Apache
> Foo. Do we allow Bar to publish its modified Apache Foo artifacts with
> the name
> org.apache.foo:foo-core:1.0.0-bar-001
> ?
No. org.apache.* is for the ASF only. Anyone else publishing into the
org.apache namespace would confuse end-users about the source of the
software.
> Make it a difference whether the artifacts are "only" published to a
> freely accessible Maven repository maintained by Bar (and not to Maven
> central)?
No.
> Excuse me, if this is not the appropriate mailing list for such kind of
> question and please forward me to the right one.
This belongs on (the private) [email protected] (I've moved it to that list)
I'm assuming that there is a specific issue here. If that is the case,
please make sure the details are made available to the private
[email protected] list
Mark
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected] | http://mail-archives.apache.org/mod_mbox/www-legal-discuss/201308.mbox/%[email protected]%3E | CC-MAIN-2019-26 | en | refinedweb |
A tasty bit of Swift to make writing device and/or screen size specific code easier.
Requirements
- iOS 7.0+ / OS X 10.9+
- Xcode 6.3+
While QuerySize supports iOS 7.0, frameworks are not supported for iOS 7.0 so you must manually embed the framework for non app store apps or integrate the source files directly.
Installing
The first thing you’ll need to do with QuerySize is get it installed into your project. We support three different integrations:
Cocoapods
CocoaPods is a dependency manager for Cocoa projects.
CocoaPods 0.36 adds supports for Swift and embedded frameworks. You can install it with the following command:
$ gem install cocoapods
To integrate QuerySize into your Xcode project using CocoaPods, specify it in your
Podfile:
source '' platform :ios, '8.0' use_frameworks! pod 'QuerySize', '~> 1.0 QuerySize into your Xcode project using Carthage, specify it in your
Cartfile:
github "robertjpayne/QuerySize" >= 1.0.0
Embedded Framework
- Add QuerySize as a submodule by opening the Terminal,
cd-ing into your top-level project directory, and entering the following command:
$ git submodule add
- Open the
QuerySizefolder, and drag
QuerySize.xcodeprojinto the file navigator of your app project.
- In Xcode, navigate to the target configuration window by clicking on the blue project icon, and selecting the application target under the "Targets" heading in the sidebar.
- Ensure that the deployment target of
QuerySize.frameworkmatches that of the application target.
- In the tab bar at the top of that window, open the "Build Phases" panel.
- Expand the "Target Dependencies" group, and add
QuerySize.framework.
- Click on the
+button at the top left of the panel and select "New Copy Files Phase". Rename this new phase to "Copy Frameworks", set the "Destination" to "Frameworks", and add
QuerySize.framework.
Usage
import QuerySize // ... QuerySize(.ByIdiom(.Phone)) { println("I am a phone") } QuerySize(.ByIdiom(.Pad)) { println("I am a pad") } QuerySize(.ByIdiom(.Phone), .ByScreenMinWidth(321)) { println("I am a phone at least 321pt wide") } QuerySize(.ByIdiom(.Phone), .ByScreenMaxWidth(320)) { println("I am a phone at most 320pt wide") } QuerySize(.ByIdiom(.Phone), .ByScreenMaxWidth(320), .ByScreenMaxHeight(480)) { println("I am a phone at most 320pt wide and 480pt high") } QuerySize(.ByIdiom(.Phone), .ByScreenMaxWidth(320), .ByScreenMinHeight(481)) { println("I am a phone at most 320pt wide and at least 481pt high") }
Latest podspec
{ "name": "QuerySize", "version": "1.0.0", "license": "Apache 2.0", "summary": "A tasty bit of Swift to make writing device and/or screen size specific code.", "homepage": "", "authors": { "Robert Payne": "[email protected]" }, "social_media_url": "", "source": { "git": "", "tag": "1.0.0" }, "platforms": { "ios": "8.0" }, "source_files": "QuerySize.swift", "requires_arc": true }
Sun, 06 Mar 2016 19:32:03 +0000 | https://tryexcept.com/articles/cocoapod/querysize | CC-MAIN-2019-26 | en | refinedweb |
PParse demonstrates progressive parsing.
In this example, the application doesn't have to depend upon throwing
an exception to terminate the parsing operation. Calling parseFirst() will
cause the DTD to be parsed (both internal and external subsets) and any
pre-content, i.e. everything up to but not including the root element.
Subsequent calls to parseNext() will cause one more piece of markup to
be parsed, and propagated from the core scanning code to the parser..
PParse parses an XML file and prints out the number of
elements in the file.
Usage:
PParse [options] <XML file>
This program demonstrates the progressive parse capabilities of
the parser system. It allows you to do a scanFirst() call followed by
a loop which calls scanNext(). You can drop out when you've found what
ever it is you want. In our little test, our event handler looks for
16 new elements then sets a flag to indicate its found what it wants.
At that point, our progressive parse loop exits.
Options:
-v=xxx - Validation scheme [always | never | auto*].
-n - Enable namespace processing [default is off].
-s - Enable schema processing [default is off].
-f - Enable full schema constraint checking [default is off].
-? - Show this help.
* = Default if not provided explicitly.
-v=always will force validation
-v=never will not use any validation
-v=auto will validate if a DOCTYPE declaration or a schema declaration is present in the XML document
Here is a sample output from PParse
cd xerces-c-3.1.4/samples/data
PParse -v=always personal.xml
personal.xml: 60 ms (37 elems, 12 attrs, 134 spaces, 134 chars)
Running PParse with the validating parser gives a different result because
ignorable white-space is counted separately from regular characters.
PParse -v=never personal.xml
personal.xml: 10 ms (37 elems, 12 attrs, 0 spaces, 268 chars)
Note that the sum of spaces and characters in both versions is the same. | http://xerces.apache.org/xerces-c/pparse-3.html | CC-MAIN-2017-17 | en | refinedweb |
I know that I need to @declared_attr when declaring columns with foreign keys on declarative mixin classes, however I would like to know the reason behind this.
thank you :)
#store traces
class ListContainer():
id = Column(Integer, primary_key=True)
# timestamp = Column(DateTime, default=datetime.now())
name = Column(String)
#endclass
#store flow in traces
def list_item(tablename):
class ListItem():
# @declared_attr
# def trace_id(cls):
# return Column(Integer, ForeignKey(tablename+'.id'))
trace_id = Column(Integer, ForeignKey(tablename+'.id'))
id = Column(Integer, primary_key=True)
item_pos = Column(Integer)
# start_ea = Column(BLOB)
# end_ea = Column(BLOB)
#endclass
return ListItem
Each model must have unique orm attributes. If the same attribute from a mixin was directly applied to each subclass, they would all have the same attribute. Copies of basic orm attributes are easy to create because they do not reference any other orm attributes. For more complex attributes, a function decorated with
@declared_attr ensures that a new instance is created for each subclass.
During instrumentation, SQLAlchemy calls each declared attr for each class, assigning the result to the target name. In this way, it can ensure complex mapping happens uniquely and correctly for each subclass.
See the documentation. | https://codedump.io/share/4DVHNrZ8HQe/1/sqlalchemy-mixins-foreignkeys-and-declaredattr | CC-MAIN-2017-17 | en | refinedweb |
WisetravellerLondon's Hua Hin, Thailand
19
Contributions
12 Reviews |
7 Photos
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La Paillote
174/1 Naresdamri Road
"A bit of let down"
We went for dinner and received good welcome from the staff but the food did not meet our expectatio...
read more
Father Ted's Irish Pub and Steakhouse
Damnernkaseam Rd., Soi 61
"Good venue for food and drink"
Excellent location if you are missing home cooking and ale. There is a good selection of both Irish ...
read more
Carlo Ristorante Italiano
174/1 Naresdamri Road
"Little Italy in Hua Hin"
What a place? You get a typical Italian welcome both on arrival and on leaving. Carlo makes sure he...
read more
Anantara Hua Hin Resort
43 / 1 Phetkasem Road
"8th visit and still love it!!!!!!!!!!!!!!"
It was great to be back "home" again although we did notice the changes in staff working in food/bev...
read more
Pony Cafe
Petchkasem Road
"If you want a change then ths is the place"
If you looking for something other then spicy food then visit Pony Cafe. It has a reasonable selecti...
read more
Anantara Hua Hin Resort
43 / 1 Phetkasem Road
"Fifth visit and still love the property"
This was our fifth return visit to this resort in the last 3 years. The resort has undertaken some r...
read more
Anantara Hua Hin Resort
43 / 1 Phetkasem Road
"Our return visit to a “Magnificent Refreshing Resort”"
We were very pleased to return (for our second visit) to this magnificent refreshing Anantara resort...
read more
El Murphy's Irish Pub
25, Sela Kam Rd.
"Irish welcome in Hua Hin"
Having eaten in various resturants in Hua Hin, where both the food and service has been just about ...
read more
La Grappa Ristorante
20/5 Poolsuk Road
"Customer care for chosen regulars???"
Accompanied by my wife, we visted the establishment recently (October 2013) for dinner. We chose to ...
read more | https://www.tripadvisor.com/members-citypage/WisetravellerLondon/g297922 | CC-MAIN-2017-17 | en | refinedweb |
Geeks With Blogs
Welcome to
Geeks with Blogs
Tim Hibbard
648 Posts
| 1732
June 2008 Entries
C# DateTime extension method
Currently DateTime.ToShortDateString will not include any "0" prefixes. I think this makes any vertical lists of dates look funky: Here is a very simple extension method that will append any needed leading "0" to the date: namespace ParaPlan.Extensions{ public static class DateHelper { public static string ToShortDateEqualLengthStrin... DateTime dt) { var rv = new StringBuilder(); if (dt.Month.ToString().Length ==1) { rv.Append("0"); } rv.Append(dt.Month.ToString... rv.Append("/"); if (dt.Day.ToString().Length ......
Posted On
Thursday, June 26, 2008 3:43? | http://geekswithblogs.net/thibbard/archive/2008/06.aspx | CC-MAIN-2017-17 | en | refinedweb |
Explain the Purpose & requirement for keeping financial records.
Published: Last Edited:
This essay has been submitted by a student. This is not an example of the work written by our professional essay writers.
Page | 1
Question: 1.1Explain the Purpose & requirement for keeping financial records.
Answer: Most of us do maintain some kind of a written record of our income and expenditure. The idea behind maintaining such records is to know the correct position regarding income and expenditure. The need for keeping a record of income and expenditure in a clear and systematic manner has given rise to the subject of book keeping.
It is all the more necessary for an organization or a concern to keep proper records. At the end of the year the true result of the economic activities of a concern must be made available otherwise it will not be possible to run the concern. In case of a business concern the profit or loss at the end of analyzed and appropriate measures taken for their rectification. But it is only possible if proper books of records are maintained in the business. There are several very good reasons for keeping different types of business and financial records. Records are required for tax preparation, filing and if needed for any audits. Lenders require certain financial information about the business before making any new loans or extending new credit. Managing the business including making plans and solving problems is much easier if records of past performance are available. Monitoring and evaluating business performance cannot be done without the important information, problems may be going undetected and opportunities missed. Records are needed to provide a paper trail or documentation. Records provide a sound basis for developing business agreements both with family members and with others. For taxes and for financial management purposes, records of sales, cash received and cash paid out records are needed. Records of accounts payable and receivable are needed to ensure timely payment and for cash flow management. Question: 1.2Analyse Techniques for recording financial information in a business organization.
Answer: Accountants have developed systematic and relatively simple techniques for recording financial information. The initial starting point for collecting financial information is to systematically collect records of financial transactions e.g. invoices, receipts etc and to enter these into some form of book keeping system.
Single Entry Book Keeping: A simple system in which transactions of accounting information are recorded only once is called Single entry book keeping. It is used primarily in simple applications such as check book balancing or in very small cash based business. It does not require keeping of journals and ledgers. It is incomplete, faulty, inaccurate, unsystematic and unscientific style of account keeping, generally less costly and the both aspects of debit and credit are not recorded. It is not possible to prepare trial balance, profit and loss account and balance sheet.
Double Entry Book Keeping:
Every business transaction causes at least two changes in the financial position of a business concern at the same time hence both the changes must be recorded in the books of account. Otherwise the books of accounts will remain incomplete and the result ascertained therefore will be inaccurate. For example we buy machinery for £100,000. Obviously it is a business transaction. It has brought two changes machinery increases by £100,000 and cash decreases by an equal amount. While recording this transaction in the books of account both changes must be recorded. In accounting language these two changes are termed as a debit change and a credit change.
We see that.
In this connection, the successive processes of the Double Entry System may be noted:
Journal:
First of all, transactions are recorded in a book known as Journal.
Ledger:
In the second process transactions are classified in a suitable manner and recorded in another book known as Ledger.
Trial Balance:
In the third process, the arithmetical accuracy of the books of account is tested by means of Trial Balance.
Final Accounts:
In the fourth and final process the result of the full year working is determined through the Final Accounts.
Journal:
The initial record of each transaction is evidenced by a business document such as invoice, cash voucher etc. As soon as a transaction takes place its debit and credited aspect are analyzed and first of all recorded in a book together with its short description. This book is known as Journal. Thus we see that the most important function of Journal is to show the relationship between the two accounts connected with a transaction. Since transactions are first of all recorded in Journal, so it is called Book of Original Entry.
Ledger:
All the changes for a single account are located in one place, in a ledger account. This makes it easy to determine the current of any account. The book in which accounts are maintained is called Ledger. Generally one account opened on each page of this book, but if transaction relating to a particular account numerous, it may extend to more than one page. All transactions relating to that account are recorded there. From journal each transaction is posted to at least two concerned accounts.
Remember that, if there are two accounts involved in a journal entry, it will be posted to two accounts in the ledger and if the journal entry consists of three accounts it will be posted to three different accounts in the ledger. But it must be remembered that transactions cannot be recorded directly in the ledger, they must be routed through journal.
Transactions ïƒ Journal ïƒ Ledger
So, the book in which all the transactions of a business concern are finally recorded in the concerned account in a summarized and classified form, is called Ledger.
Trial Balance:
The fundamental principle of Double entry system is that at any stage, the total of debits must be equal to the total of credits. If entries are recorded and posted correctly, the ledger will reflect equal debits and credits and the total credit balances will then be equal to the total debited balances. As we know that under Double entry system for each at every transaction one account is debited and another account is credited with an equal account. If all the transactions are correctly recorded strictly according to this rule, the total amount of debit side of all the ledger accounts must be equal to that of credit side of all the ledger accounts. This verification is done through Trial Balance.
If the trial balance agrees, we may reasonably assume that the books are correct. On the other hand if does not agree, it indicates that the books are not correct there are mistakes somewhere. The mistakes are to be detected and corrected otherwise correct result cannot be ascertained. The trial balance serves to check the equality of debit and credits or mathematical test of accuracy and to provide information for use in preparing Final accounts.
Thus in the light of above discussion a Trial Balance may be defined as ‘’an informal accounting schedule or statement that lists the ledger account balances at a point in time and compares the total of debited balances with the total of credit balances’’.
Computerised System: A system in which computers and software’s are used to maintain the records of a business or any other organisation is called Computerised System. In computerised system operations can be done with high pace and accuracy, there will be lot of time saved in maintaining accounts. It provides quick information when ever needed. Maintaining and installation of computerised system cost is high and its operation requires technical knowledge and training.
Manual System: A system under which the records are maintained manually by using pen and paper or account work is done by humans what has been sold and for how much is called Manual System. These days there is no using this of type. Pen and paper are very old school technique of writing and saving different types of information.
(Okay)
Question 1.3 and 1.4
Question:
2.1 Analyses components of working capital.
Answer:
Components of Working Capital:
Working capital constitutes various current assets and current liabilities.
Current Assets:
Assets which are short-lived and which can be converted into cash quickly to meet short term liabilities are called Current Assets, e.g. Stock, Debtors, Receivables, Prepaid expenses, Accrued income,.
Current or Short-Term Liabilities:
The debts which are repayable within a short period of time are called Current or Short-Term Liabilities, e.g. Creditors, Bills Payable, Bank overdraft, outstanding expenses, Dividend payable, Provision for taxation etc. Current liabilities may again be divided into two:
- Deferred Liabilities: Debts which are repayable in the course of less than one year but more than one month are called Deferred Liabilities, e.g. Short-Term Loan etc.
- Liquid or Quick Liabilities: Debts which are repayable in the course of a month are called Liquid or Quick Liabilities, e.g. Bank overdraft, outstanding expenses, creditors etc.
The main components of working capital are:
- Cash: Cash is one of the most liquid and main component of working capital. Holding cash involves cost because the value of cash held and a year later it will be less than the value of cash as on today. Excess of cash balance should not be held in reserve in business because cash is a non-earning asset. Hence a suitable and well judged cash management is of extreme importance in business.
Ok hay)
- Marketable Securities:
These securities also don't give much capitulate to the business because of two reasons:
- Marketable securities act as a replacement for cash.
- These are used are impermanent investments.
These are held not for provisional balances but only as a security against potential lack of bank credit.
- Accounts Receivable:
Lots of debtors always lock up the firm's assets particularly during inflationary tendencies. It is a two step account. When goods are sold, inventories are reduced and accounts receivables are formed. When payment is made, debtors reduce and cash level increases. Thus quantum of debtors depends on two things, volume of Credit sales and usual length of time between sales and collections. The capitalist should find out the most advantageous credit standards. An optimal credit policy should be established and the firm's operations should be always monitored to attain higher sales and minimum bad debt losses.
- Inventory:
Inventories stand for an important amount of firm's assets. Inventories must be properly managed so as to this investment doesn't become too large and it would result in blocked capital which could be put to productive use elsewhere. On the other hand having too little or small inventory could result in loss of sales or loss of customer goodwill. An optimum level of inventory therefore should be maintained.
Question:
2.2 Explain how business organizations can effectively manage working capital.
Answer:
Question:
3.1 Explain the difference between management accounting and financial accounting.
Question 3.2 and 3.3
Question 3.4
Evaluate the use of different costing methods for pricing purposes
- What are the effects of absorption and marginal costing on profit?
- Advantages and Disadvantages of Marginal Costing Technique.
Answer
Differenr costing methods are mentioned below:
Job Costing: A job is a cost unit which consists of a single order or contract. Job costing consists of a single order undertaken to customer special requirements and is usually for a short duration. Contract Costing:Contract costing is a form of job costing which applies where the job is on a large scale and for a long duration. The majority of costs relating to a contract are direct costs. Batch Costing:A batch is a cost unit where a quantity of identical items is manufactured. It consists of a separate, readily identifiable group of product unit which maintains their separate identity throughout the production process.
Operating Costing or Service Costing:Service costing can be used by companies operating in a service industry or by companies wishing to establish the cost of services carried out by some of their departments. Service costing is cost accounting for services or functions, e.g. canteen, maintenance, personnel. These may be referred to as service centers, departments or functions. Process Costing: Process costing is a costing method which is applicable or industries producing homogenous products in large quantities. The purpose of process costing is a typical one i-e, stock valuation.
(Okay hay)
- effects of absorption and marginal costing on profit:
The difference in profits reported under the two systems is due to the different stock valuation methods used.
- If stock level increases between the beginning and end of the period, absorption costing will report higher profit. This is due to some fixed production overhead is carried forward to next period in the closing stock value.
- If stock level decreases, then absorption costing shows lower profit than marginal costing due to fixed production overhead brought forward in the opening stock charged into the current period profit statement.
- If sales are constant and production fluctuates then the marginal costing profit is constant but the profit of absorption costing fluctuates.
- If the output volume is constant and the volume of sales fluctuates then both profits are different in the direction of sales.
(okay hay ye b)
- Advantages and Disadvantages of Marginal Costing Technique:
4.1: Demonstrate the main methods of project appraisal by explaining various investment appraisal techniques. State, in general terms, which method of investment appraisal you consider to be most appropriate for evaluating investment projects and why?
Answer
Key Methods of Project Appraisal:
Net present value:
The net present value method calculates the present value of all cash flows, and sums them to give the net present value. If this is positive, then the project is acceptable.
The net present value (NPV) method of evaluation is as follows.
- Determine the present value of costs.
In other words decide how much capital must be set aside to pay for the project. Let this be £C.
- Calculate the present value of future cash benefits from the project.
To do this we take the cash benefit in each year and discount it to a present value. This shows how much we would have to invest now to earn the future benefits, if our rate of return were equal to the cost of capital. By adding up the present value of benefits for each future year, we obtain the total present value of benefits from the project. Let this be £B.
- Compare the present value of costs £C with the present value of benefits £B.
The net present value is the difference between them: £ (B-C)
- NPV is positive.
The present value of benefits exceeds the present value of costs. This in return means that the project will earn a return in excess of the cost of capital. Therefore, the project should be accepted.. The NPV method should be always be used where money values over time need to be appraised.
Accounting Rate of Return –ARR:
A capital investment project may be assessed by calculating the return on investment (ROI) or accounting rate of return (ARR) and comparing it with a pre-determined target level. A formula for ARR which is common in practice is: ARR = Estimated average profits divided by Estimated average investment and multiply by 100% It allows owner of a business compare easily profit potential for investments and projects.
Internal Rate of Return (IRR):
The internal rate of return technique uses a trial and error method to discover the discount rate which produces the NPV of zero. The discount rate will be the return forecast for the project.
The internal rate of rate of return method involves two steps:
- Calculating the rate of return which is expected from a project.
- Comparing the rate of return with the cost of capital.
If a project earns a higher rate of return than the cost of capital, it will be worth undertaking (and its NPV would be positive). If it earns a lower rate of return, it is not worthwhile (and its NPV would be negative). If a project earns a return which is exactly equal to the cost of capital, its NPV will be 0 and it will only just be worthwhile.
The Payback:
This is the time taken to recover the initial outlay from the cash flows of the project. Payback period is the amount of time. It is expected to take for the cash inflows from a capital investment project to equal the cash outflows. Payback period is always calculated as:
Initial investment ÷ Annual cash inflows
If the cash inflows are for the same amount and incurs after the same time period.
Decision Rule: If payback period < Target, accept it and if payback period > Target then reject it.
Discounted Payback:
An alternative of the payback method is the discounted payback period. The discounted payback period is the amount of time that it takes to cover the cost of a project by adding the net positive discounted cash flows arising from the project. It is never the lone appraisal method used to measure a project but is a handy performance indicator to judge the projects expected performance.
4.3 Explain how finance might be obtained for a business project. | https://www.ukessays.com/essays/accounting/explain-the-purpose-requirement.php | CC-MAIN-2017-17 | en | refinedweb |
camera_disable_event()
Disable the specified event.
Synopsis:
#include <camera/camera_api.h>
camera_error_t camera_disable_event(camera_handle_t handle, camera_eventkey_t key)
Since:
BlackBerry 10.0.0
Arguments:
- handle
The handle returned by a call to the camera_open() function.
- key
The key value that was returned by a call to an enable event function.
Library:libcamapi (For the qcc command, use the -l camapi option to link against this library)
Description:
Use this function to disable an event when you no longer want to receive the event.
For more information, | http://developer.blackberry.com/native/reference/core/com.qnx.doc.camera.lib_ref/topic/camera_disable_event.html | CC-MAIN-2017-17 | en | refinedweb |
I am trying to write a program that keeps track of social security numbers (SSN) of customers of a bank. I have to assume that SSN is a four-digit number (e.g., 1234. 0123 is not allowed.). When the program runs,it has to prompt that the user should enter a 4-digit SSN number to record, or 0 (zero) to exit.
The program also needs to be able to give an error message if a certain number is entered more than once.
After all the numbers have been saved and you finally end it by pressing 0, it needs to be able to output all the entered SSN's.
Here is my code so far, I am kinda lost from what to do from here can anybody help explain? not sure how to approach the rest can somebody please help me finish this code?
#include <iostream>
#include <iomanip>
#include <cmath>
using namespace std;
bool isExist(int ssn, int records[], int numberOfRecords);
void listRecords(int records[], int numberOfRecords);
int main()
{
int records[32];
cout << "Please enter number or 0";
system("pause");
return 0;
}
bool isExist(int ssn, int records[], int numberOfRecords)
{
}
void listRecords(int records[], int numberOfRecords)
{
}
First, please use code tags when posting code. Without code tags, then code is unformatted and hard to read.
Here is my code so far, I am kinda lost from what to do from here can anybody help explain?
The code you posted does nothing really.
You are to read the number, and then search the array to see if the number appears in the array. If it doesn't then you store the number in the array at some spot (usually at the spot in the array after the last element that was added). The assignment states plainly what you're supposed to do.
can somebody please help me finish this code?
Again, you really didn't do any coding except write some function header. You have no search loop in the isExist() function, you have no code to store the value in the array, you basically have nothing.
But why were you able to at least write the empty function body, not knowing what to do next? Ok, so finish the internals of each of the functions that you wrote. If not, what specifically is stopping you from completing the isExist() and listRecords() functions? You are passed arguments, and regardless of the main() program, you should be able to finish those functions. Then you get main() to call these functions at the appropriate time.
Since you need to store the number, I can see where it may get tricky since you need to keep track of where the last element was added. But in no way does searching an array for a number be that difficult (the isExist() function), and printing the values of an array (the listRecords) functions be such a stumbling block. So again, what is the specific reason why you cannot complete these rather simple functions? (given that you wrote the function header, complete with parameters).
Regards,
Paul McKenzie
Last edited by Paul McKenzie; June 26th, 2013 at 09:49 PM.
So again, what is the specific reason why you cannot complete these rather simple functions? (given that you wrote the function header, complete with parameters).
Skeleton provided in the assigment?
All advice is offered in good faith only. You are ultimately responsible for the effects of your programs and the integrity of the machines they run on. Anything I post, code snippets, advice, etc is licensed as Public Domain
C, C++ Compiler: Microsoft VS2017
Forum Rules | http://forums.codeguru.com/showthread.php?538091-please-help-with-c-program-question-over-arrays!&mode=hybrid | CC-MAIN-2017-17 | en | refinedweb |
Scala Cats library for dummies — part 3
Welcome back to our series of cats library type classes. In this write up we’ll be looking at “applicative” , “semigroup” and “monoid” type classes.
Applicative
Firstly, the applicative type class is a descendant of the Apply type class we discussed briefly in our previous article, it basically comes with a function called “pure” which wraps a data type(Int, string, Boolean) into a context (Option, List , Future ). In other terms, it takes a single data type A and return a data type F[A](lifts any value into the applicative functor).
Below is the signature of the “pure” function.
def pure[A](x: A): F[A]
Applicative demo
scala> import cats._ , cats.implicits._ , cats.instances._
import cats._
import cats.implicits._
import cats.instances._
scala> Applicative[Option].pure(1)
res0: Option[Int] = Some(1)
scala> Applicative[List].pure(4)
res1: List[Int] = List(4)
Semigroup
A semigroup is an algebraic structure consisting of a set together with an associative binary operation.
The cats library semigroup implementation comes with a function “combine” which simply combines 2 values of the same data type(Int, List , string, Option, Map).
Associativity is the only principle(law) that the semigroup type class follows.
- (a x b) x c == a x (b x c) == (b x c) x a
When we add or multiply a list of variables regardless of their order of arrangement yields the same result.
Imagine the semigroup combine function like a git merge with on conflicts :)
scala> import cats._ , cats.instances._ , cats.implicits._
import cats._
import cats.instances._
import cats.implicits._
scala> 2.combine(3)
res0: Int = 5
scala> List(1,3,5).combine(List(1,25,6))
res1: List[Int] = List(1, 3, 5, 1, 25, 6)
scala> Option(4).combine(Option(6))
res2: Option[Int] = Some(10)
scala> Option(2).combine(None)
res3: Option[Int] = Some(2)
Remember that writing an express like “2.combine(3)” is possible because we have the implicits functions in scope “cats.implicits._” — cats library have provided a lot of primitive data type implicits readily available for use.
Semigroup also has a symbolic operator |+| which ease typing, I personally like this because its kinda of cleaner!
scala> 2 |+| 5
res4: Int = 7
scala> List(1,2,4) |+| List(3,5,6)
res5: List[Int] = List(1, 2, 4, 3, 5, 6)
scala> Map("a"-> 1 ) |+| Map("b"-> 2)
res6: Map[String,Int] = Map(b -> 2, a -> 1)
Monoid!
Hummmmm……. yet another scary word but is a great tool that can efficiently parallelize computations.
So what is a monoid ?
A monoid is an algebraic structure that follows these two basic rules(laws).
1. A binary associative operation that takes two values of type A and combines them into one.
2. A value of type A that is an identity for that operation.
Lets do a simple arithmetics, when adding 2 integers 3 + 7 we get 10, however, when we add zero(0) to any integer the result will be the same regardless of whether the value zero(0) comes in-front or behind, same applies to multiplication, multiplying an integer with one(1) returns the same result. So therefore we can call zero(0) an identity element of addition and one(1) an identity element for multiplication.
With the definition above we can implement the monoid signature.
trait Monoid[A]{
def combine(x: A , y: A): A
def empty: A
}
#for int addition the monoid will look this
val intAddition = new Monoid[Int]{
def combine(x:Int, y:Int) = x + y
def empty = 0
}
#for int multiplication we have
val intMultiplication = new Monoid[Int]{
def combine(x:Int, y:Int) = x*y
def empty = 1
}
#for string concatenation we have
val stringMonoid = new Monoid[String]{
def combine(x:String, y:String) = x + y
def empty = ""
}
As an exercise you should implement monoid for List, booleanOr and booleanAnd and Options.
But why monoids ? What do we stand to benefit from monoids ? Well, it turns out that we can write very interesting programs over any data type, knowing nothing about that type other than that it’s a monoid.
Secondly, the fact that a monoid’s operation is associative means that we have a great deal of flexibility in how we fold a data structure like a list, this means that we can split our data into chunks, fold them in parallel , and then combine the chunks with the monoid.
In the standard scala collections(Sequence, Vectors, Lists , Ranges etc) there exist these methods fold, foldLeft, foldRight — which are used to aggregate values together to return a single value, these methods takes monoids as input parameters.
Lets try out adding a list of integers using the intAddition monoid we defined.
scala> import intAddition._
import intAddition._
scala> List(1,2,4,5).fold(empty)(combine)
res1: Int = 12
scala> import intMultiplication._
import intMultiplication._
scala> List(1,2,4,5).fold(empty)(combine)
res2: Int = 40
Back to cats implementation of monoid
when you add an “empty” method(which is equivalent to identity element) to the semigroup combine method we discussed above, you simply get our monoid.(hummm, pretty simple!)
Also, we can find out ourselves that cats library already have predefined the “empty” method for primitive types.
scala> Monoid[Int].empty
res0: Int = 0
scala> Monoid[Float].empty
res1: Float = 0.0
scala> Monoid[String].empty
res3: String = ""
As stated in the cats documentation - the advantage of using these type class provided methods, rather than the specific ones for each type, is that we can compose monoids to allow us to operate on more complex types.
Monoid[Map[String,Int]].combineAll(List(Map("a" -> 1, "b" -> 2), Map("a" -> 4)))res0: Map[String,Int] = Map(b -> 2, a -> 5)
Lets take a break from here, our next discuss will be on the Monad type class. See you then.
If you like this writeup, click the💚 below so more people can see it here on Medium.
Big thanks to some catlords @fabianmeyer , @mgttlinger and @tkroman for reviewing this article. | https://medium.com/@abu_nadhr/scala-cats-library-for-dummies-part-3-fd3b185088f0 | CC-MAIN-2017-17 | en | refinedweb |
One of the most exciting starter activities to do with a Raspberry Pi is something you can't do on your regular PC or laptop—make something happen in the real world, such as flash an LED or control a motor. If you've done anything like this before, you probably did it with Python using the RPi.GPIO library, which has been used in countless projects. There's now an even simpler way to interact with physical components: a new friendly Python API called GPIO Zero.
Photo by Giles Booth. Used with permission
I recently wrote about Raspberry Pi Zero, the $5 computer and latest edition to the world of affordable hardware. Although the names are similar, the GPIO Zero and Raspberry Pi Zero projects are unrelated and are not coupled. The GPIO Zero library is made to work on all Raspberry Pi models, and is compatible with both Python 2 and Python 3.
The RPi.GPIO library is bare bones and provides all the essential functionality to do simple things with the Pi's GPIO pins—set up pins as inputs or outputs, read inputs, set outputs high or low, and so on. GPIO Zero is built on top of this and provides a collection of simple interfaces to everyday components, so rather than setting pin 2 high to turn on an LED, you have an LED object and you turn it on.
GPIO port label – from rasp.io/portsplus
Getting started
With GPIO Zero, you import the name of the interfaces you're using, for example:
from gpiozero import LED Also you must correctly wire up any components you're using and connect them to the GPIO pins. Note that some pins are allocated to 3V3, 5V, and GND; a few are special purpose and the rest are general purpose. Refer to pinout.xyz for more information, or use a port label:
Blink an LED with the following code:
from gpiozero import LED from time import sleep led = LED(17) while True: led.on() sleep(1) led.off() sleep(1)
Alternatively, use the LED's
blink() method, but make sure to keep the program alive with
signal.pause() like so:
from gpiozero import LED from signal import pause led = LED(17) led.blink() pause()
Output devices
As well as a basic LED interface, with the methods
on(),
off(),
toggle(), and
blink(), GPIO Zero also provides classes for Buzzer and Motor, which work in a similar way:
from gpiozero import Buzzer, Motor from time import sleep buzzer = Buzzer(14) motor = Motor(forward=17, backward=18) while True: motor.forward() sleep(10) motor.backward() buzzer.beep() sleep(10) buzzer.off()
There also are interfaces for PWMLED (control the brightness rather than just on/off), and for RGB LED, which is an LED comprising red, green, and blue parts using the brightness of each to provide full color control.
There's even an interface for TrafficLights. Provide the pin numbers the red, amber, and green lights are connected to, then control with:
lights = TrafficLights(2, 3, 4) lights.on() lights.off() lights.blink() lights.green.on() lights.red.on()
and so on.
Input devices
The simplest input device is a push button, and the interface provided makes it easy to control programs with button presses:
from gpiozero import Button button = Button(14) while True: if button.is_pressed: print("Pressed")
Another way to use button pressed to control programs is to use
wait_for_press:
button.wait_for_press() print("pressed")
This halts the program until the button is pressed, then continues. Alternatively, rather than polling the button state, you can connect actions to button presses:
button.when_pressed = led.on button.when_released = led.off
Here, the method
led.on is passed in as the action to be run when the button is pressed, and
led.off as the button is released. This means when the button is pressed, the LED comes on, and when it's released the LED goes off. In addition to using other GPIO Zero object methods, you can use custom functions:
def hello(): print("Hello") def bye(): print("Bye") button.when_pressed = hello button.when_released = bye
Now every time the button is pressed, the
hello function is called and prints "Hello". When the button is released it prints "Bye".
The use of custom functions in this way can be a good way to run a set of GPIO instructions, such as a traffic lights sequence:
def sequence(): lights.green.off() lights.amber.on() sleep(1) lights.amber.off() lights.red.on() sleep(20) lights.amber.on() sleep(1) lights.green.on() lights.amber.off() lights.red.off() lights.green.on() button.when_pressed = sequence
Now when the button is pressed, the traffic lights will go from green to red, then wait 20 seconds before turning back to red, in the usual way.
Sensors
Swapping out a button for another input device, such as a basic sensor, can open up a world of interesting projects. Instead of a button, use a motion sensor:
from gpiozero import MotionSensor sensor = MotionSensor(15)
Then use
sensor.if_motion,
sensor.wait_for_motion, and
sensor.when_motion. There is a similar interface provided for LightSensor.
Analogue devices
The Raspberry Pi has no native analogue input pins, but you can easily connect up an ADC (analogue-to-digital converter) and access analogue input devices (such as potentiometers) and read their value:
from gpiozero import MCP3008 pot = MCP3008() while True: print(pot.value)
The potentiometer returns values from 0 to 1, which means you can connect them up to output devices easily:
from gpiozero import PWMLED, MCP3008 led = PWMLED(4) pot = MCP3008() while True: led.value = pot.value
Now the LED's brightness is controlled directly by the potentiometer value.
Alternatively, a clever feature of GPIO Zero allows you to directly connect two devices together without continuously updating inside a loop. Every output device has a
source property, which can read an infinite generator of values. All devices (input and output) have a
values property, which is an infinite generator, yielding the device's current value at all times:
from gpiozero import PWMLED, MCP3008 led = PWMLED(4) pot = MCP3008() led.source = pot.values
This works exactly the same as the previous example, just without the need for a
while loop.
You can connect multiple analogue inputs to the same ADC (the MCP3008 chip provides 8 channels). This example uses three potentiometers allowing control of each color channel in an RGB LED using the same method:
This allows you to use the three potentiometers as a color mixer for the RGB LED.
Bundle interfaces
Like the TrafficLights interface, there are others for bundles of components, particularly for use in commonly used simple add-on boards.
Generic LED board or collection of LEDs, controlled together or individually:
from gpiozero import LEDBoard lights = LEDBoard(2, 3, 4, 5, 6) lights.on() lights.off() lights.leds[1].on() lights.leds[3].toggle() lights.leds[5].on() lights.leds[2].blink() lights.leds[4].blink()
The Ryanteck TrafficHAT:
from gpiozero import TrafficHat hat = TrafficHat() hat.on() hat.off() hat.lights.blink() hat.buzzer.on() hat.button.when_pressed = hat.lights.on hat.button.when_released = hat.lights.off
Note that the TrafficHat interface did not require a set of pin numbers, because they are already defined within the class.
Connect up two motors and make a chassis and you have yourself a Raspberry Pi robot:
from gpiozero import Robot robot = Robot(left=(4, 14), right=(17, 18)) robot.forward() robot.backward() robot.reverse() robot.left() robot.forward() robot.stop()
Zero all the things
Now that there's a suite of Zero-named projects, why not use them in conjunction? How about a Pi Zero-powered robot programmed with GPIO Zero and PyGame Zero?
GPIO Zero and PyGame Zero do work very well together—perfect for creating on-screen interfaces for GPIO components.
Photo by ItsAll_Geek2Me. Used with permission.
Try it now!
GPIO Zero has been included in the Raspbian Jessie image since December, so you can grab a copy from raspberrypi.org/downloads. If you have an older image, install it with:
sudo apt-get update sudo apt-get install python3-gpiozero python-gpiozero
Open up IDLE and prototype in the REPL, or create a file to save your scripts. You can also use the regular Python shell, or install IPython and use that.
More
Read more about GPIO Zero:
- Full documentation on readthedocs
- GPIO Zero source on GitHub
- GPIO Zero in The MagPi #39
- GPIO Zero: Developing a new friendly Python API for Physical Computing on bennuttall.com
- Getting Started with GPIO Zero learning resource
- GPIO Zero introduction on raspi.tv
- RasP.iO Pro HAT Kickstarter—perfect for GPIO Zero
- Keeping Physical computing simple—by Giles Booth
- GPIO Zero: By George, I think I've got it—by Mike Horne
3 Comments
Great read Ben! This is a great resource for educators and any makers!
Thank you for this it is a great set of resources.
great job :) good article | https://opensource.com/education/16/2/programming-gpio-zero-raspberry-pi | CC-MAIN-2017-17 | en | refinedweb |
There was a time when instruments sporting a GPIB connector (General Purpose Interface Bus) for computer control on their back panels were expensive and exotic devices, unlikely to be found on the bench of a hardware hacker. Your employer or university would have had them, but you’d have been more likely to own an all-analogue bench that would have been familiar to your parents’ generation.
So there you are, with an instrument that speaks a fully documented protocol through a physical interface you have plenty of spare sockets for, but if you’re a Linux user and especially if you don’t have an x86 processor, you’re a bit out of luck on the software front. Surely there must be a way to make your computer talk to it!
Let’s give it a try — I’ll be using a Linux machine and a popular brand of oscilloscope but the technique is widely applicable.
It’s easy with a VISA
We are fortunate in that National Instruments have produced a standard bringing together the various physical protocols and interfaces used, and their VISA (Virtual Instrument Software Architecture) is available as precompiled libraries for both Windows and Linux(x86). Talking to VISA is a well-trodden path, for example if you are a Python coder there is a wrapper called PyVISA through which you can command your instruments to your heart’s content. And if you’ve spotted the glaring gap for architectures with no NI VISA library, they’ve got that covered too. PyVISA-py is a pure Python implementation of VISA that replaces it.
As a demonstration, we’ll take you through the process of using PyVISA-py and PyVISA on a Raspberry Pi for basic communication with an instrument over USB. We’ve used both a Raspberry Pi Zero and a Raspberry Pi 3 each running the latest Raspbian distro, but a similar path should apply to most other Linux environments and like instruments. Our instrument here is a Rigol DS1054z oscilloscope.
We start by installing the Python libraries for USB, PyVISA-py, and PyVISA. We’re assuming you already have python and pip, if not here’s a page detailing their installation. Type the following lines at the command prompt:
sudo pip install pyusb
sudo pip install pyvisa
sudo pip install pyvisa-py
You should now be able to test the installation from the Python interpreter. Make sure the instrument is both turned on and connected via USB, and type the following:
sudo python
This should give you a version and copyright message for Python, followed by a three-arrow >>> Python interpreter prompt. Type the following lines of Python:
import visa
resources = visa.ResourceManager('@py')
resources.list_resources()
The first line imports the VISA library, the second loads a resource manager into a variable, and the third queries a list of connected instruments. The ‘@py’ in line 2 tells the resource manager to look for PyVISA-py, if the brackets are empty it will look for the NI VISA libraries instead.
If all is well, you will see it return a list of resource names for the instruments you have connected. If you only have one instrument it should be similar to the one that follows for our Rigol:
(u'USB0::6833::1230::DS1ZA123456789::0::INSTR',)
The part in the single quotes, starting with USB0:: is the VISA resource name for your instrument. It is how you will identify it and connect to it in further code you write, so you will either need to run the Python code above in your scripts and retrieve the resource name before you connect, or as we are doing in this demonstration copy it from the prompt and hard-code it in the script. Hard-coding is not in any way portable as the script may only work with your particular instrument, however it does provide a convenient way to demonstrate the principle in this case.
If you are still within the Python interpreter at this point, you can leave it and return to the command prompt by typing a control-D end-of-file character.
Towards Something More Useful
Assuming all the steps in the previous paragraphs went smoothly, you should now be ready to write your own code. We’ll give you a simple example, but first there are a couple of pieces of documentation you’ll want to become familiar with. The first is the PyVISA documentation, the same as we linked to earlier, and the second should be the programming reference for your instrument. The manufacturer’s website should have it available for download, in the case of our Rigol it can be found as a PDF file (Click on the “Product manuals” link at the top).
The PyVISA manual details all the wrapper functions and has a set of tutorials, while the product manual lists all the commands supported by the instrument. In the product manual you’ll find commands to replicate all the interface controls and functions, but the ones we are most interested in are the measurement (MEAS) set of commands.
For our example, we’ll be measuring the RMS voltage on channel 1 of our Rigol. We’ll connect to the instrument directly using its resource name and querying it for its model identifier, before selecting channel 1 and querying it for an RMS voltage reading.
Copy the following code into a text editor, replacing the resource identifier with that of your own instrument, and save it as a .py file. In our case, we saved it as query_rigol.py.
#Bring in the VISA library import visa #Create a resource manager resources = visa.ResourceManager('@py') #Open the Rigol by name. (Change this to the string for your instrument) oscilloscope = resources.open_resource('USB0::6833::1230::DS1ZA123456789::0::INSTR') #Return the Rigol's ID string to tell us it's there print(oscilloscope.query('*IDN?')) #Select channel 1 oscilloscope.query(':MEAS:SOUR:CHAN1') #Read the RMS voltage on that channel fullreading = oscilloscope.query(':MEAS:ITEM? VRMS,CHAN1') #Extract the reading from the resulting string... readinglines = fullreading.splitlines() # ...and convert it to a floating point value. reading = float(readinglines[0]) #Send the reading to the terminal print reading #Close the connection oscilloscope.close()
Enable the channel on the instrument – when you are familiar with the API you can do this with your software – and connect it to a signal. We used the ‘scope calibration terminal as a handy square wave source. You can then run the script as follows, and if all is well you will be rewarded with the instrument ID string and a voltage reading:
sudo python query_rigol.py
It’s worth noting, we have just run Python as root through the sudo command to use the USB device for the purposes of this demonstration. It’s beyond the scope of this page, but you will want to look at udev rules to allow its use as a non superuser.
With luck on this page we will have demystified the process of controlling your USB-connected instruments, and you should be emboldened to give it a go yourself. We’re not quite done yet though, the second part of this article will present a more complete example with a practical purpose; we’ll use our Raspberry Pi and Rigol to measure the bandwidth of an RF filter.
28 thoughts on “How to Control Your Instruments From A Computer: It’s Easier Than You Think”
PyVISA is fantastic for USB devices and I definitely recommend it if you want something crossplatform for your lab (unlike VB). Really nice for automating parametric sweeps. I had the misfortune of working in a lab that had old equipment that only had GPIB interfaces. In addition, PyVISA isn’t able to support USB-GPIB adapters very well, and Keysight and NI suites really only support RHEL in terms of Linux.
Those programming references can get a bit dense, especially for VNAs.
VISA obviously makes things easier, but don’t forget about SCPI (which is abstracted by VISA). If you’ve got GPIB you probably have SCPI compliance.
Indeed, very true. The purpose of the article though is a simple introduction rather than a comprehensive review.
National Instruments bloatware? no thanks! I prefer to keep my sanity!
I installed this VISA-stuff because i wanted to try communicate with my DS1102E and i had a bad surprise, it messed something up on my computer. Fixing wasn’t too difficult, just delete some stuff in the registry, but yeah, this shouldn’t happen. Once this was done i was able to communicate with the scope using Perl. I however had to write a little more code because some simplified Perl-module didn’t work. Don’t ask me about details, long time ago…
i wrote a visa app for windows for my rigol dm3058e dmm , i haven’t finished it since it covered the bits i wanted, still have a few things.. just noticed i also forgot to copy the C++ source code to github though, so i’ll add it.
Baahahaa, I skimmed this article earlier thinking it was a replacement for MIDI.
I thought there would be trumpets and drums!
I bet if your instrument has steppers you could squeeze Für Elise (or the Imperial March;if that’s your jam) out of it via SCPI.
Well this is the one to beat…
More than a few scanners and copiers had classical music Easter egg ‘calibration’ routines. e.g.
This works for Siglent scope´s also! Also work with the Visa sources.
Control commands can be found here : Manuals
Shameless plugs:
and
What’s the benefit of Visa, compared to simple SCPI through USBTMC protocol on Linux?
USBTMC let you talk very easily to your instrument, the most useful would be to abstract SCPI commands.
You can change between different physical layer like GPIB, RS232, USB, VXI or LXI.
I agree, but most recent instruments implements USBTMC then others will works with either GPIB or RS232.
For GPIB(with prologix USB dongle) and RS232 it may be exactly the same than USBTMC, you just write SCPI commands to /dev/ttyUSBX(GPIB or rs232) or /dev/usbtmcX(USBTMC) and read response from this same inode.
It should be the same. But with Visa you can use other connections like Ethernet. And a big plus it is interchangeable over different OS.
Probably its greater abstraction as a simple introduction to the topic, in the case of this article.
I’m about to google for an GPIB implementation on the Raspberry Pi, using it’s GPIO Pins (+levelshiftprotectioncircuitry, of course)…
Visa is nice, but the hole power comes with ivi. Then you can change all components in your setup, in theory :D
The only person I know who writes a HaD blog wherein complete instructions are given.
We aim to please :)
Can’t you just pull out the Commodore PET for a controller?
Legend has it that some of those computers were sold because thy were cheap controllers, so suddenly the labs with test equipment that had the bus could afford controllers.
I seem to recall the HP-150, the one from 1983 with the touch screen, it used the bus to interface to its external floppy drive.
And if course, there were HP calculators in later days which included the bus.
Michael
The was also the HP-8X and 98XX computers which often had a HPIB interface card which also was used to control the disk drives,hard drives, and printers on the system.
I have an old Tek scope with RS232, I think it was just intended to print. Can I capture the print with it?
I seem to remember doing this with a Tek TDS420 about 20 years ago. Just connected the serial to a laptop and used a terminal program to capture the output to a file. I think I might have had to set the output format to something that was printable ASCII to get the file to capture properly but I’m not sure about that.
GPIB was originally called HPIB. Standardized as IEEE-488. VISA is an abstraction to multiple physical layers, and a standardized API; for example VXI-11 is the LAN abstraction (later updated to LXI). VXI-11 is built on ONC-RPCs. Pretty much every HP computing device from the late 70’s to the late 90’s came with HPIB, and it was used to interface to all manner of peripherials as well as instruments.
The cheap usbgpib dongles, like Prologix are really just toys. They don’t abstract the entirety of IEEE-488 … for example, there’s no interrupt channel, so SRQs are poorly implemented. Most of the standards are online these days if you go digging. SCPI is an attempt to standardize command sets across like instruments. It’s only been partially successful at that.
Personally, I prefer to use Perl to control instruments with PDL to handle the data. Google perl VXI11::Client to find it. A really good and often cheap LANGPIB box is the HP E2050A. Beware of NI … they don’t implement VXI-11 and use a proprietary protocol.
Another shameless plug: The Syscomp instruments use an FTDI chip to interface to the USB connection, so the interface looks like a high-speed serial interface and you can talk to it with any language that can send ASCII strings to a serial port. We use Tcl, but you can even use a dumb terminal emulator to talk to the hardware. Makes debugging very straightforward. | http://hackaday.com/2016/11/16/how-to-control-your-instruments-from-a-computer-its-easier-than-you-think/ | CC-MAIN-2017-17 | en | refinedweb |
Jeff Turner wrote:
> What is out-of-band about <elaboration> in the FAQ?
Well, given the following
[inlining elaborations]
> That's a feature not a bug ;P
I think I got the intention a bit wrong. If you actually want
to inline elaborations, your approach is ok.
This raises the question why you wrote you needed an xsl:if.
I'd do
<xsl:template
<xsl:template
<!-- normal operation -->
<xsl:apply-templates/>
</xsl:template>
Am I missing something?
It might be an issue that <question> is expected to result
in a single text block. If <elaboration> may suddenly introduce
block-like stuff, like your <pre> above, things may become
interesting.
An alternative idea would be to keep the full info in <question>
and resort to a separate optional <title> for the index:
<qa>
<title>NullPointerException at Forrest startup</title>
<question>
I am trying to run Forrest v0.4 on a W2K box running JDK 1.3.1
and keep getting a NullPointerException on startup. The
stacktrace I get is:
<pre>
....
</pre>
What am I doing wrong?
</question>
<answer>
...
[snip]
> Optional metadata of course. If metadata has some obvious benefit, people
> will use it.
The problem is that the metadata is often only really beneficial
if it is consistently used. Take your example of the FAQ creation
date, mostly for the benefit of flagging new FAQs. Someone adds
an important FAQ in a hurry without supplying a date, or mistyping
it grossly, or the patch with a proper adding date wasn't applied
until the "new" period passed. The FAQ is not flagged. People get
upset, but probably no action is taken. The next FAQ is also added
without date. There is no longer an obvious benefit in providing an
adding date in patches. The feature falls into disuse.
Well, the demise is not inevitable, but I've often seen a small
fluktuation in available ressources causing it ("...will do later...").
Once a certain amount of data with unmaintained metadata accumulated,
not even the most dedicated fellows will bother to fix it.
If you want metadata to be useful:
1. Make it *mandatory*, not optional.
2. Provide automated plausibility checks.
3. Preferably provide some automation tools.
4. Fix all the old data.
5. Sell its advantages aggressively.
>>> <meta name="..."> ... </meta> tag allowed inside <faq>.
>>*Cough*! Do you want people asking why the encoding they
>>added to a FAQ "doesn't work"?
> Character encoding? Unsupported tags inside <meta>?
The possible problem I see is that <meta> for documents goes more
or less unchanged into the HTML (I may be wrong here), which might
cause people to think the FAQ <meta> has a very similar purpose,
and that the possible <meta> keys are basically to the ones often
seen in HTML.
This could be an interesting application for namespaces:
The document/XHTML schema defines stuff for general purpose layout
and closely associated stuff, like <xhtml:meta> or <doc:meta> for
general purpose document level metadata.
The FAQ schema could use <faq:meta> for FAQ metadata and faq:section
for structuring FAQs, compared to <xhtml:section> or <doc:section>
for structuring general purpose documents.
J.Pietschmann | http://mail-archives.apache.org/mod_mbox/forrest-dev/200305.mbox/%[email protected]%3E | CC-MAIN-2017-17 | en | refinedweb |
chown - change owner and group of a file
#include <sys/types.h> #include <unistd.h> int chown(const char *path, uid_t owner, gid_t group);
The path argument points to a pathname naming a file. The user ID and group ID of the named file are set to the numeric values contained in owner and group respectively.
On XSI-conformant systems {_POSIX_CHOWN_RESTRICTED} is always defined, therefore:
->.
If owner or group is specified as (uid_t)-1 or (gid_t)-1 respectively, the corresponding ID of the file is unchanged.
Upon successful completion, chown() will mark for update the st_ctime field of the file.
Upon successful completion, 0 is returned. Otherwise, -1 is returned and errno is set to indicate the error. If -1 is returned, no changes are made in the user ID and group ID of the file.
The chown().
- [ENAMETOOLONG]
- Pathname resolution of a symbolic link produced an intermediate result whose length exceeds {PATH_MAX}.
None.
Because {_POSIX_CHOWN_RESTRICTED} is always defined with a value other than -1 on XSI-conformant systems, the error [EPERM] is always returned if the effective user ID does not match the owner of the file, or the calling process does not have appropriate privileges.
None.
chmod(), <sys/types.h>, <unistd.h>.
Derived from Issue 1 of the SVID. | http://pubs.opengroup.org/onlinepubs/007908775/xsh/chown.html | CC-MAIN-2017-17 | en | refinedweb |
For the purposes of Remoting, you can divide all .NET classes into three types:
Remotable classes. Any class that derives directly or indirectly from MarshalByRefObject automatically gains the ability to be exposed remotely and invoked by .NET peers in other application domains.
Serializable classes. Any class that is marked with the <Serializable> attribute can be copied across application boundaries. Serializable types must be used for the parameters or return values of methods in a remotable class.
Ordinary classes. These classes can't be used to send information across application boundaries, and they can't be invoked remotely. This type of class can still be used in a remotable application, even though it doesn't play a part in Remoting communication.
Figure 3-1 shows both remotable and serializable types in action. Incidentally, it's possible for a class to be both serializable and remotable, but it's not recommended. (In this case, you could interact with a remote instance of the object or send a copy of it across the network.)
Figure 3-1 shows a good conceptual model of what takes place with Remoting, but it omits the work that takes place behind the scenes. For example, serializable types are not moved, but rather copied by converting them into a stream of bytes. Similarly, remotable types aren't accessed directly, but through a proxy mechanism provided by the CLR (see Figure 3-2). This is similar to the way that many high-level distributed technologies work, including web services and COM/DCOM.
With proxy communication, you interact with a remote object by using a local proxy that provides all the same methods. You call a method on the proxy class in exactly the same way that you would call a method on a local class in your application. Behind the scenes, the proxy class opens the required networking channel (with the help of the CLR), calls the corresponding method of the remote object, waits for the response, deserializes any returned information, and then returns it to your code. This entire process is transparent to your .NET code. The proxy object behaves just like the original object would if it were instantiated locally.
In the next two examples, we'll consider serializable and remotable types in more detail, and show you how to make your own.
A serializable type is one that .NET can convert to a stream of bytes and reconstruct later, potentially in another application domain. Serializable classes are a basic feature of .NET programming and are used to persist objects to any type of stream, including a file. (In this case, you use the methods of the BinaryFormatter in the System.Runtime.Serialization.Formatters.Binary namespace or the SoapFormatter in the System.Runtime.Serialization.Formatters.Soap namespace to perform manual serialization.) Serialized classes are also used with Remoting to copy objects from one application domain to another.
All basic .NET types are automatically serializable. That means that you can send integers, floating point numbers, bytes, strings, and date structures to other .NET clients without worry. Some other serializable types include the following:
Arrays and collection classes (such as the ArrayList). However, the content or the array or collection must also be serializable. In other words, an array of serializable objects can be serialized, but an array of non-serializable objects cannot.
The ADO.NET data containers, such as the DataTable, DataRow, and DataSet.
All .NET exceptions. This allows you to fire an exception in a remotable object that an object in another application domain can catch.
All EventArgs classes. This allows you to fire an event from a remotable object and catch it in another application domain.
Many, but not all .NET types are serializable. To determine if a given type is serializable, look it up in the class library reference and check if the type definition is preceded with the <Serializable> attribute.
You can also make your own serializable classes. Here's an example:
<Serializable> _ Public Class Message Public Text As String Public Sender As String End Class
A serializable class must follow several rules:
You must indicate to .NET that the class can be serialized by adding the <Serializable> attribute just before the class declaration.
Every member variable and property must also be serializable. The previous example works because the Message class encapsulates two strings, and strings are serializable.
If you derive from a parent class, this class must also be serializable.
Both the client and recipient must understand the object. If you try to transmit an unrecognized object, the recipient will simply end up with a stream of uninterpretable bytes. Similar problems can occur if you change the version of the object on one end.
Remember, when you send a serializable object you're in fact copying it. Thus, if you send a Message object to another peer, there will be two copies of the message: one in the application domain of the sender (which will probably be released because it's no longer important) and one in the application domain of the recipient.
When a class is serialized, every object it references is also serialized. This can lead to transmitting more information than you realize. For example, consider this revised version of the Message class that stores a reference to a previous message:
<Serializable> _ Public Class Message Public Text As String Public Sender As String Public PreviousMessage As Message End Class
When serializing this object, the Message referred to by the PreviousMessage member variable is also serialized and transmitted. If this message refers to a third message, it will also be serialized, and so on. This is a dangerous situation for data integrity because it can lead to duplicate copies of the same object in the remote application domain.
Finally, if there's any information you don't want to serialize, add the <NonSerialized> attribute just before it. The variable will be reinitialized to an empty value when the object is copied, as follows:
<Serializable> _ Public Class Message Public Text As String Public Sender As String <NonSerialized> Public PreviousMessage As Message End Class
This technique is useful if you need to omit information for security reasons (for example, a password), or leave out a reference that may not be valid in another application domain (for example, file handles).
A remotable type is one that can be accessed from another application domain. Following is an example of a simple remotable object. It's identical to any other .NET class, except for the fact that it derives from the System.MarshalByRefObject class.
Public Class RemoteObject Inherits MarshalByRefObject Public Sub ReceiveMessage(ByVal message As Message) Console.WriteLine("Received message: " & message.Text) End Sub End Class
Every public property, method, and member variable in a remotable class is automatically accessible to any other application. In the previous example, this means that any .NET application can call RemoteObject.ReceiveMessage(), as long as it knows the URL where it can find the object. All the ByVal parameters used by ReceiveMessage() must be serializable. ByRef parameters, on the other hand, must be remotable. (In this case, the ByRef parameter would pass a proxy reference to the original object in the sender's application domain.)
In this example, RemoteObject represents the complete, viable code for a remote object that writes a message to a console window. With the aid of configuration files, we'll develop this into a working example.
MarshalByRefObject instances have the ability to be invoked remotely. However, simply creating a MarshalByRefObject doesn't make it available to other applications. Instead, you need a server application (also called a component host) that listens for requests, and provides the remotable objects as needed. The component host also determines the URL the client must use to locate or create the remote object, and configures how the remote object is activated and how long it should live. This information is generally set in the component host's configuration file. Any executable .NET application can function as a component host, including a Windows application, console application, or Windows service.
A component host requires very little code because the Remoting infrastructure handles most of the work. For example, if you place your configuration information into a single file, you can configure and initialize your component host with a single line of code, as follows:
RemotingConfiguration.Configure(ConfigFileName)
In this case, ConfigFileName is a string that identifies a configuration file that defines the application name, the protocol used to send messages, and the remote objects that should be made available. We'll consider these settings in the next section.
Once you have called the RemotingConfiguration.Configure() method, the CLR will maintain a pool of threads to listen for incoming requests, as long as the component host application is running. If it receives a request that requires the creation of a new remotable object, this object will be created in the component host's application domain. However, these tasks take place on separate threads. The component host can remain blissfully unaware of them and continue with other tasks, or—more commonly—remain idle (see Figure 3-3).
This model is all well and good for a distributed enterprise application, but it's less useful in a peer-to-peer scenario. In an enterprise application, a component host exposes useful server-side functionality to a client. Typically, each client will create a separate object, work with it, and then release it. By using Remoting, the object is allowed to execute on the server, where it can reap a number of benefits including database connection pooling and the use of higher-powered server hardware.
In a peer-to-peer application, however, the component host and the remote component are tied together as one application that supports remote communication. This means that every peer in a peer-to-peer application consists of a remotable interface that's exposed to the world and a component host that contains the rest of the application. Figure 3-4 diagrams this approach.
These two models are dramatically different. Enterprise systems use a stateless approach. Communication is usually initiated by the client and all functionality is held at the server (much like the client-server model). Peer-to-peer applications use a stateful model in which independent peers converse through Remoting front-ends.
This difference between enterprise development and peer-to-peer applications becomes evident when you need to choose an activation type for a remote object. Remotable types can be configured with one of three activation types, depending on the configuration file settings:
SingleCall. This defines a stateless object that is automatically created at the start of every method invocation and destroyed at the end. This is similar to how web services work.
Client-activated. This defines a stateful object that is created by the client and lives until its set lifetime expires, as defined by client usage and configuration settings. Client-activated objects are the most similar to local.NET objects.
Singleton. This defines a stateful object that is accessible to the remote client, but has a lifetime controlled by the server.
Generally, SingleCall objects are perfect for enterprise applications that simply want to expose server resources. They can't be used in a peer-to-peer application as the basis for bidirectional communication between long-running applications. In a peer-to-peer application, you need to use the Singleton type, which associates an endpoint with a single object instance. No matter how many clients connect, there's only ever one remote object created. Or, to put it another way, a Singleton object points to a place where a specific object exists. SingleCall and client-activated addresses point to a place where a client can create its own instance of a remotable object. In this book, we'll focus on the Singleton activation type.
There is one other twist to developing with Remoting. In order for another application to call a method on a remote object, it needs to know some basic information about the object. This information takes the form of .NET metadata. Without it, the CLR can't verify your remote network calls (checking, for example, that you have supplied the correct number of parameters and the correct data types). Thus, in order to successfully use Remoting to communicate, you need to distribute the assembly for the remote object to the client and add a reference to it.
There are some ways of minimizing this inconvenience, either by pre-generating a proxy class or by using interfaces. We'll use the latter method in the next chapter when we develop a real Remoting example.
The configuration files use an XML format to define the channels and ports that should be used for communication, the type of formatting for messages, and the objects that should be exposed. In addition, they can specify additional information such as a lifetime policy for remotable objects. Here's the basic framework for a configuration file with Remoting:
<configuration> <system.runtime.remoting> <application> <service> <!-- Information about the supported (remotable) objects. --> </service> <channels> <!-- Information about the channels used for communication. --> </channels> <!-- Optional information about the lifetime policy (tag below). --> <lifetime /> </application> </system.runtime.remoting> </configuration>
You can create this configuration file outside of Visual Studio .NET, provided you place it in the bin directory where the compiled application will be executed. A simpler approach is to add your configuration file to the Visual Studio .NET project. Simply right-click on the project in the Solution Explorer and select Add → New Item. Then, choose Application Configuration File under the Utility node (see Figure 3-5).
The application configuration file is automatically given the name app.config. When Visual Studio .NET compiles your project, it will copy the app.config file to the appropriate directory and give it the full name (the name of the application executable, plus the .config extension). To see this automatically generated configuration file for yourself, select Project
Show All Files from the menu. Once you compile your project, you'll see the appropriate file appear in the bin directory (see Figure 3-6).
Configuration files are required for every application that needs to communicate using Remoting. This includes a component host and any client that wants to interact with a remote object. The next section shows specific configuration file examples. | http://www.yaldex.com/vb-net-tutorial/LiB0018.html | CC-MAIN-2017-17 | en | refinedweb |
Creative Boycotts CeBit Over MP3s 195
underwhelm writes "According to ZDNet, Creative Labs is boycotting CeBit because the trade show has banned all MP3-related devices, presumably at the behest of the 'content industry.'"
panic: kernel trap (ignored)
Re:Unverifiable (Score:2)
if you'll note carefully, that is a fault on all of their pages, currently. I'd send them an email telling them they have a problem but they 1) are probably aware of it 2) i can't access their email contact page because of the following error message:
Microsoft OLE DB Provider for ODBC Drivers error '80040e07' [Microsoft][ODBC SQL Server Driver][SQL Server] The conversion of a char data type to a datetime data type resulted in an out-of-range datetime value.
/global/inc/banner.asp, line 192
Unintentional Troll. (Score:1)
Re:MP3's are like guns (Score:1)
I like the way you threw my comments back at me. Very witty.
To put my original point in a more precise way -
Associating MP3s with guns is a fucked idea.
Sorry, this is about as off topic as I get. go molest someone else.
Re:MP3's are like guns (Score:1)
Re:...Or is it the other way around? (Score:1)
no make that, you got *the* point
:-)
Re:Not hardware...and BTW, blame Sony for this... (Score:1)
Here's 10 minidiscs and a player; here's an MP3 player with 64Mb of Ram for the same price. Now,
the minidisc gives 740 minutes of play time, and
the MP3 player, say 90minutes. Now, you can get
more expensive HD MP3 players but watch the price
shoot up. See... *price* *performance*...
Re:ONLY THE ORIGINAL ENCODER WAS "PROPRIETARY"! (Score:1)
Fraunhaufer is relatively benevolent right now, because MP3 users are armed with the power to change format, and so they have ot be. But the history of GIF and others (esp. trademarks) teaches us that as soon as the power shifts into the hands of the corporation, the benevolence will end. So that's why I say burn all mp3s.
ZD Net didn't do their homework? (Score:1)
Someone Put A Leash On The Music Industry (Score:1)
I think it's really sad when record companies are stifling technological innovation just because it means the end of the Big Five screwing artists and the consumers by getting fat on big profits. If CD's weren't the price they were today chances are you would be worrying less about piracy and the "threat" of MP3 to the current order of things.
MP3 is the format that puts the power back to the artist and the consumer where it belongs. You can't stop it, so the only smart thing to do is not to fight it but to roll with it. Take advantage of the MP3 explosion. If MP3 is so widespread then use it to spread word about new music (like MP3.com) and to make more money. But unless the Big Five pulls their head of their ass then they'll suffer the consequences.
Self Bias Resistor
"You'll never need more then 640k of memory." -Bill Gates
Re:Not hardware...and BTW, blame Sony for this... (Score:2)
No, but I'm not spreading FUD, unless by FUD you mean truth.
> Not true. You have 2 routes, convert to ATRAC, or wrap the file with a SDMI compliant
> wrapper which leaves the file in MP3 format but lets the player handle it like any other file.
Fine, so there is an alternative to the ATRAC conversion--an alternative which *STILL* requires an extra, unnecessary, step. So, my point stands, since either way it's adding unneeded complexity. Is there any reason that to use an mp3 you already have, you would have to wrap it in SDMI bullshit? Umm, no, since you already have the mp3 in a non-SDMI format, there is no logical reason to impose this highly useless step. Bah.
>>This takes time and effort and makes the files almost twice as large as a normal mp3.
>
> Nope. ATRAC is as efficent, if not more so than MP3 than file compression.
Yes, ATRAC is efficient; but you, evidently, are not. Had you been paying attention, you would have seen that I was talking about converting an existing mp3 file to ATRAC for use with Sony's badly designed mp3 players, mp3 players which do not in fact play standard mp3s since you have to either convert the mp3 file to ATRAC or, as you pointed out, give it an SDMI wrapper. Converting an mp3 file into an ATRAC file causes the file size to nearly double in many cases--I suppose this is a result of recompressing the file into an entirely different compression format.
> You are
> obviously repeating half remembered stuff from other
No, you are obviously not paying attention. I'm repeating what I know FROM PERSONAL KNOWLEDGE. I'd never buy one of these Sony monstrosities, but a friend of mine has one that I've played with. Yes, from personal experience, recompressing an mp3 into ATRAC can double file size. I didn't even know the option existed to put an SDMI wrapper around an mp3 file and use that instead of ATRAC, which means that the software is either extremely bad or the type of Sony player my friend had doesn't have this option (I believe Sony makes at least 3 "mp3" players).
> It can be suggested that
> it will take twice the space because you'd have 2 copies of the file, one wrapped/
> converted, one unwrapped.
No, as I said you're just not paying attention. Try to read *before* you flame, kay?
>>They obviously want to make it more complicated than necessary to use their mp3 players,
>
> Insert CD. Select autocheckout. Press record. Player loaded. Hey, maybe you should
> try using the stuff first?
I never mentioned ripping from CDs to the mp3 player, something fewer people would want to do than to just download to the player mp3s which are already on his HD. As I said, using existing mp3 files is a pain in the ass. Why should they have to be converted first? Because Sony wants to make it difficult to use mp3 players, so that everyone will stay with/switch to MiniDisc. Sony needs to make one themselves to compete with the other companies making mp3 players, but that doesn't mean that Sony wants to make them easy to use; Sony has a long history of discouraging products even as they make them, to try to get people to switch to formats they better approve of. Umm, remember Beta, and how Sony tried to get everyone to switch from VHS to that but prices were never on par since Sony demanded royalty fees for each Beta-format product, whereas VHS was more affordable because Sony wasn't milking everyone?
>> so that customers will switch back to CDs and MiniDiscs.
>
> You mean them minidiscs which offer better price performance than MP3?
Now you're just being retarded, comparing a type of media to a file format. Well, mp3s could easily be stored on MiniDiscs, you know. And, how pray tell do MiniDiscs offer better price/performance than mp3 players? Last time I went to Best Buy, MiniDiscs were pretty damned expensive. I could buy a whole spindle of quality Imation 12x 80min CD-Rs for the same price as a paltry few MiniDiscs, thanks to Sony's insane licensing fees. News flash: MiniDisc is losing, because of Sony's excessive royalty demands, just like consumer Beta lost for the same reason. MiniDisc devices have been out for far longer than mp3 players have, but with that huge advantage they haven't conquered the market. And, they won't, because of Sony's greed over their pet proprietary formats. mp3 players are getting cheaper and gaining larger capacities, but I have yet to see any significant evolutionary developments in MiniDic players. Sony's SACD format will fail for the same reason, especially since other companies are moving towards DVD-Audio; why should they pay Sony to license SACD, when they can use DVD-Audio for free (the major labels are all part of the DVD Consortium).
But, I digress. My point stands about Sony's mp3 players being unnecessarily complicated in requiring ATRAC or SDMI conversion for existing mp3 files, and I continue to support my statement that Sony is supporting mp3 players half-heartedly, to try to take marketshare away from real mp3 player manufacturers like Creative and Diamond, while simultaneously using a poor implementation to try to leave consumers with a bad taste in their mouths which they'll unfairly blame on mp3 devices in general instead of on Sony in particular.
What's the basis for making laws? (Score:1)
A good indicator of a corrupt government is the number of laws they pass - they gain a lot of power by making everybody a criminal in one form or another. Then, for example, if a group of people is peacefully protesting the government, they can shut them up by arresting them on other charges. This is a dangerous position to leave the government in. We need to speak up and have unjust laws overturned - the DCMA, UCITA, drug laws, encryption laws, and other vicimless crimes (including punching someone in the dark
--
Codecs are dangerous things! (Score:2)
Codec's are software, software is the implementation of an idea, and ideas are _very_ dangerous things if you are the status quo.
----
Remove the rocks from my head to send email
CeBIT did *not* ban Creative or MP3. (Score:5)
As someone who has worked on CeBIT as booth personnel, let me tell you that multimedia booths are a real problem. There are regulations against too loud exhibitors, but many companies on CeBIT don't care. The organizers are now trying to enforce these rules a little bit more.
CeBIT did *not* ban Creative, but *Creative* decided not to be there. Instead, Creative will be on next years' largest German consumer fair, the "Funkausstellung". This fair is not a specific IT business fair, but targets your average TV / vcr / dvd / stereo / videogame consumer.
I *am* getting a bit nervous about Slashdot's namecalling recently.
------------------
Re:Corporate bashing trash (Score:1)
Corperation's first responsibility is to thier sock holders. It is all well and good that they can be on the right side here but it is thier job to make money. Not to uphold the rights of computer users.
Horses (Score:1)
I bet that back in the day, the average person felt that Justice was on his side. Nowadays, Justice is half crap-shoot / half payola.
The real Threed's
--Threed
NOT a boycott, NOT a censorship case. (Score:1)
CeBIT [cebit.de] is a business-, not a consumer-oriented trade show, or at least the makers want it to be. Since Creative's plans involved (again) to have a very large, very loud booth praising their consumer-devices, CeBIT told them they couldn't do that. That specifically. Creative pulled out entirely, and booked IFA [ifa-berlin.de] instead.
CeBIT has since changed its mind, but Creative don't want to change their plans again, understandably enough.
Details at (for example, this is in German):
Re:MP3 we love thee (Score:1)
Following the same reasoning... (Score:1)
YEAH!
Re:BULLSHIT. MP3 IS EXPENSIVE. VERY. (Score:1)
For a player that fits into the world envisioned by Thomson & Fraunhofer IIS-A, it's really not that expensive to make a cool MP3 player...
...like this one that I've been working on lately [pjrc.com].
<shameless plug>
</shameless plug>
ONLY THE ORIGINAL ENCODER WAS "PROPRIETARY"! (Score:1)
Fraunhaufer had the original encoder. That's where the stickiness is. You can get non-proprietary encoder, which LAME is now. Maybe they renamed the program now it is its own encoder.
All the encoder really is is a piece of software that decides which parts of the signal should be represented in the compressed file.
The format decoders are totally free of proprietary IP and patents, IIRC. Some are shareware, freeware, GPL, although some are totally closed source payware, but no decoder pays royalties to read the format itself. Some might to use someone else's code tree though.
There is a significant difference. SDMI enabled formats are definitely proprietary in every way and are far worse in this respect.
Re:Go Creative! (Score:1)
Re:AUGH!! NO! (Score:1)
There are also plugins available for most mp3 players to use it, so you may want to give it a try. After all, it's completely unencumbered by patents, and it doesn't look like big business will try to get ahold of it just, so you can still feel like a rebel.
Re:Serious Case of Product Discrimination & Prejud (Score:2)
Re:ONLY THE ORIGINAL ENCODER WAS "PROPRIETARY"! (Score:1)
Are there any patent restricitions other than the Fraunhoffer encoder? I haven't heard about it.
AFAIK the Fraunhoffer encoder is the *only* proprietary thing about it, and Fraunhoffer *already* tried to crack down on its use. The encoder is only a human-psycho-acoustic model for stuffing the best bits into the file. Build your own psycho-acoustic model and encoder and you are set, AFIAK. Maybe you know more about the math than I do, but that's long been my impression.
I support a move to make a totally free audio format, but in my opinion, the only reason corporate pressure will be applied to removing MP3 is to move us to much more *closed* formats rather than try to milk the MP3 for cash, because they want to milk some closed format for even more cash.
Also, I was wrong on something else you didn't notice, I think it's an ISO standard, not IEEE, part of the MPEG-1 standard. Remember that? MPEG-1 Layer 3? The ISO reference code has some of Fraunhoffer's work and that's how these encoders got out in the first place, the reference code was freely available.
Banning a codec?! (Score:3)
I just can't believe it...What would you think if SIGGRAPH banned jpeg? This insane!
Beware the dangerous codec!!!
Re:ONLY THE ORIGINAL ENCODER WAS "PROPRIETARY"! (Score:1)
There is an MP3 IP FAQ [a-net.nl] which answers the question "16. If I don't use their source, can I make my own MP3 encoder without paying FhG?" with "If you infringe on their techniques, it is within their rights to seek recourse, whether or not you had help from them, or whether or not you intentionally or knowingly infriged."
As to my claim that it may not be mathematically possible to create an MP3 encoder without infringing Fraunhaufer's patents -- I was just repeating what I have heard from many knowledgeable people. I doubt anyone has proved that it is impossible, but the bottom line is that nobody has done it yet, and the best policy is probably to refrain from using MP3 until someone does, if someone does. Or how about this: just don't use any patented encoders. That includes all existing MP3 encoders, so you'd better stick with OGG!
For a complete overview of the MP3 patent situation see this page from mp3-tech.org mirrored on LAME's site: ht tp://javatest.a-net.nl/servlet/pedit.Main/http://
w ww.mp3-tech.org/patents.html [a-net.nl]. Select quote: "You can try to write an MP3 encoder without using this [Fraunhaufer's patented] encoding scheme, so in this case you will not have to pay, but it's obvious that it's nearly impossible."
the enemy of my enemy is my friend (Score:2)
Just watch your back.
Conspericy (Score:1)
At the time I was like "How could technology be illegal"..
Now I'm putting this all together...
That was the launch pad for a sinister plot to strip us of advanced technology. To allow government agentcys to deside what we can and can not have.
Eventually technology will be regulated by an agentcy like the FDA or FCC... Who will deside what medications you can have or who can brodcast and what they can broudcast.
They will strip you of your freedoms.. Deside you can not have things like encryption and eventually even deside you can not publish certen information on the Internet as it could be used to instruct terrorists.
They may even go so far as to require computers at ISPs so they can scan e-mail or implant back doors in software so that they may spy on other governments.
I tell you the day is comming when you don't buy software but rent it..
When you don't buy a computer but get it as part of a pacage deal with your Internet provider...
I tell you they may even go so far as change the way TV is broudcast...
We must stop this madness... log into your local BBS and send FidoNet mail to Presedent Ronald Regan about the potental treat to the future of techology...
I mean when they are able to have portable digital file players I want mine....
Note: This is a joke...
Please note the diffrence between what the slashdot editor says and what the artical submitor said...
In the case of this story... Slashdot didn't say a word...
Anyway... It looks to me CeBit is basicly saying "No more MP3s" as a way to make the booths quieter.
They are basicly trying to get rid of the consummer stuff and return to busness and kinda pushed Creative off to the home show... a smaller show that really isn't paying off...
It's not really about MP3s.. it's about being loud during a busness expo...
For the love of God , Mp3's are not illegal! (Score:1)
Must give kudos to Creative though, surely others will follow suit. What bullshit.
--
Re:Are there any computers at CeBit? (Score:1)
Electrical wiring... even structural technologys...
Hmm I guess we'll be holding this expo in a cave... animal skins only....
AUGH!! NO! (Score:3)
Please, think about the future. Consider Vorbis [vorbis.org] instead.
It's "out of the frying pan and into the fire" if you stick with MP3. [remember the patents?]
MP3 we love thee (Score:5)
Finally one of the panel stood up and said. I'm sorry, MP3s are here you're too late. There is hardware available, consumers like it and it has already been adopted as the defacto standard. You have no place to decide whether it gets adopted or not.
I stood up and clapped.
Re:MP3's are like guns (Score:1)
CeBit fair = professional NOT ENDCONSUMER (Score:1)
It seems that the fair agency tried to suppress the presentation of MP3 Players in relation to ENDCONSUMERS. Creative stated that a presentation for business purposeses is NOT LIKE CREATIVE WANTS TO PRESENT THEIR DEVICES.
I can understand this move pretty good. The fair agency wants to keep the CeBit fair as a "professional" fair for business to business relations. Several years ago the Cebit has become more and more a fair for games and the average age of visitors dropped. This lead to an inacceptable bias for any professional visitior. The solution was to split the Cebit up into CeBit (professional) and Cebit Home (Endconsumer).
Yey for the boycott! (Score:1)
$.02
Re:MP3's are like guns (Score:1)
I've owned guns and shot guns since I was 5 years old and never had an incedent where someone was harmed. I've owned and used a hammer since I was 5 years old and done more harm to my self with it than I care to mention. But then I've also killed more deer with a car than I've killed with a gun ( I only shoot competition ). So those are only my personal facts but it seems to me that mp3 are as safe as a gun to me. Neither has caused any harm when I was around. In fact both have caused me to spend money that I would not have otherwised spent.
Re:RIGHT ON CREATIVE! (Score:1)
Re:AUGH!! NO! (Score:1)
Re:Banning a codec?! (Score:1)
err... they banned DeCSS, why not MP3?
Re:Go Creative! (Score:1)
More modern drives have a "digital audio out", which does digitally encoded audio to the soundcard, but I'm not sure if it's really an exact copy of the CDDA data
It is an SPDIF output, thus a perfect copy of the digital data on the disc (there is a copybit thing though, but it's not difficult to get rid of it)
...Or is it the other way around? (Score:2)
I think I'll boycott Cebit too. (Score:3)
Re:MP3's are like guns (Score:5)
Not hardware...and BTW, blame Sony for this... (Score:3)
I myself got the Live! Value OEM, and am very happy with it. I just wish I could have afforded the Live! Platinum, since the LiveDrive is both cool and useful. I mean, having all those audio connections mounted on a front drive bay is just plain cool looking, plus I'm always reaching behind the computer to switch audio connections anyway since I use it for a DVD player (Hollywood+ cards rock).
But, the very idea of banning any mp3 players at CeBit is just disgusting. I mean, it's just a type of audio player, which you can use with your own paid-for CDs after all, just as you can legally make a mix tape or CD from CDs and tapes you bought. Funny how they're not banning MiniDisc devices, since they can be used to pirate music too with any soundcard that has an SP/DIF connector--just decompress the mp3s and burn them to MiniDisc. But, oh, wait, Sony makes a fortune from every MiniDisc device and media sold, so it's okay to have them present.
And yes, Sony makes mp3 players, but half-heartedly--after all, at least one of their "mp3 players" requires that mp3 files be converted to the proprietary Sony "ATRAC" format before downloading them to the player. This takes time and effort and makes the files almost twice as large as a normal mp3. They obviously want to make it more complicated than necessary to use their mp3 players, so that customers will switch back to CDs and MiniDiscs. And, am I the only one who notices the ironic sound of "ATRAC," so similar to the doomed "8-track" format? Arrgh, the more I learn about Sony, the more I start to think that they're the most evil corporation this side of the future "Disney's AOL/Time-Warner" which I'm convinced will happen one day... They introduce a proprietary format for everything, in the attempt to keep people from using better, open formats--like trying to get their new 1.3GB CDs to be used by consumers instead of the better DVD and DVD-R formats which they are actively trying to hamper.
But, I digress. All I can say is, you can bet that Sony had a hand in ensuring that mp3 devices would be banned from Cebit. I personally buy nothing Sony, and nothing by another brand which I know is made for them by Sony.
Re:Not about rights or freedom (Score:2)
Agreed.
Creative is doing the right thing for the wrong reasons, which in my mind is about the same as just doing nothing.
Except that doing the right thing for the wrong reason has the potential to actually accomplish something, whereas doing nothing doesn't. If Creative receives support from the people who want the right thing for the right reason, it will encourage other companies to join the boycott. That would be a good thing, even though those companies would also be doing it for the wrong reason.
TheFrood
Clap Clap (Score:2)
*applause*
I believe the geek/hacker/techie community is a great group of people for a company to have on their side - in general we have a large amount of disposable money to frivolously spend on expensive gadgets and gizmos, and I believe listen pretty well to word of mouth about the quality of a company's products.
MP3 format illegal? (Score:2)
I mean, if its in MP3 format, then i guess it should automatically be made illeagal [sic] right?
If you're not an MP3 patent licensee [mp3licensing.com], yes. But there's always the patent-free Vorbis [vorbis.com] codec.
<O
( \
XGNOME vs. KDE: the game! [8m.com]
I asked CeBIT; here's what they said (Score:3)
Thank you very much for your e-mail!
We would like to inform you that we in fact never banned MP3 Players or the MPEG storage format from CeBIT. There will be around 25 companies in hall 9 this yearshowing MP3 players.
ObviouslyCreativeLabs released a press article serveral days ago, saying that they are cancelling the CeBIT becausewe excluded MP3players from our nomenclature. This isdefinately not true and wedo not understand the reasons for such an article.
Sincerely
Deutsche Messe AG
Interesting, no?
BULLSHIT. MP3 IS EXPENSIVE. VERY. (Score:4)
Commercial decoding:
15k annual pre-pay + 2.50 / item shipped.
Commercial encoding:
Their object code:
15k annual
$250k minimum
$5.00/copy shipped
Their patents:
15k annual
$2.50/copy shipped.
This is US dollars. I hardly consider this "free" by any means. They have over 13 patents on the format alone, who cares if you can encode it? You can't USE it unless you pay!
Our project was scrapped because of these costs, and management's inability to grasp that there are other formats.
Vorbis is free. Period. You can get and change the code. You can make free players. You can make commerical players. You can use it in your other products. No one will come after you with a team of lawyers for not paying for Vorbis.
I get sick of hearing about how "open" mp3 is.
Re:MP3 we love thee (Score:2)
And the Clue Meter reads 11 (on a scale of 1 to 10 -- I borrowed Spinal Tap's meter).
CeBIT Website and Contact Info (Score:3)
--
Re:Why on earth.... (Score:2)
1. Old, slow executives who are too tired to learn a new way of doing business.
2. Young, cynical lawyers and consultants who are making a mint by telling those in group 1: "Yes, you can stop MP3s. By the way, here's my bill for last month."
It makes me wonder if anybody hung around on the Titanic, selling pails.
Francis Hwang
Don't forget... (Score:2)
Re:Not hardware...and BTW, blame Sony for this... (Score:2)
but its not a true spdif output. its resampled. meaning: the internals of the card force a resampling of even the most common rate (44.1k) to the internally required 48k.
yes, the spdif out will drive an outboard DAC or a DAT deck, etc. but regardless of what the input samplerate is, the output is ALWAYS 48k
;-(
the sample-rate conversion is a bit noisy and adds noticeable distortion.
don't ask me why they resample up to 48k when 99% of all the audio sources out there are cd-based which is 44.1. sigh...
--
Re:Go Creative! (Score:2)
the digital audio out (of most modern ide cdrom drives) is a bastardized form of spdif. its the spdif logical frame format but the physical levels are TTL rather than the real standard of 0.5v p-p.
but for most devices that take spdif-in, the TTL levels are ok and will work.
and yes, it is a bit-for-bit extraction of the audio frames; its just that its 1:1 speed; ie, realtime. for better than realtime, you need to use a drive that has dae (digital audio extraction).
its worth noting (for you power rippers out there) that very few cdrom changers will support DAE. I wonder why that is? is it because DAE is "just barely tolerated" by the bigWigs? and if you put the power of DAE into a changer, that could cause ALL SORTS OF CHAOS out there? makes me wonder..
but at any rate, you could use the spdif out of the ide cdrom drives as a last resort to get digital audio without an intermediate analog step.
--
Re:Why on earth.... (Score:4)
Exactly. Just like Marijuana is illegal, as are "bongs." And we know nobody uses those right....right?
There's only one thing more powerful than big business - and that's the will of the people. When the public is divided, politicians can do whatever they want. In this case, i think we all know where the public stands (the vast majority, at least) - all the corporate money in the world won't save a politician once he's been voted out of office.
FluX
After 16 years, MTV has finally completed its deevolution into the shiny things network
Re:Not hardware...and BTW, blame Sony for this... (Score:2)
Good, now let's tell Creative we're happy. (Score:2)
Oldthink thinkcrime doubleplus ungood
all mp3 related devices? (Score:3)
does this include sound cards, speakers, hard drives, RAM (which is evil because it loads mp3's partially into memory before playing them)??
FluX
After 16 years, MTV has finally completed its deevolution into the shiny things network
Re:MP3 we love thee (Score:2)
[ogg vorbis for digital audio] [xiph.org]
MP3's are bad mmmmkay! (Score:3)
This is not simply stupid, or careless, it's just plain WRONG!
This is just another case of people assuming that MP3's themselves are bad!
***NEWSFLASH - MP3 is just a FILE FORMAT***
Regardless of how people use it, MP3's and all their associated gadgets have done nothing wrong, they are a part of technology as much as anything else!
I say "go Creative", because it's about time that someone, or some company had the guts to take a stand!
In fact, we should all take a stand, because I've had about enough of this. I like to be able to listen to all my songs without changing CD's. I also like to be able to have a backup of them all on one CD and on my HDD!
It's time we showed some support for this move and all Boycott CeBit too, and instead use the time and money to go out and buy a Nomad!
Power to the People!
"How much truth can advertising buy?" - iNsuRge [insurge.com.au] - AK47
Good news for IFA (Score:2)
So does that mean... (Score:2)
A car analogy would be more appropriate (Score:2)
I would choose a car analogy instead because MP3 has much more in common with a vehicle (maybe a pizza delivery van
Also, I think most people can better identify with the ownership/usefulness of a vehicle.
numb
Re:Go Creative! (Score:3)
Did the VCR destroy the movie industry?
Sadly, no.
Did the tape recorder destroy the music industry?
Um... no. *Damn*
Did CD Burners kill the CD music business?
Nooooo! *SOB* Cease your cruel, cruel taunts!
Will the CD-ROM drives that allowed Digital Audio Extraction kill the CD market? Will MP3 do it either?
WE CAN DREAM, CAN'T WE?!
Seriously, these technologies are not "okay" because the music and film industries will still rake in bucketloads of money despite them. Rather, they are "okay", period-- even if Jack Valenti and Edgar Bronfman are left sharing a tin of tuna warmeded over a back-alley fire. Sorry, dreaming again.
Re:According to the local press... (Score:2)
In fact the splitting of CeBit didn't go exactly according to plan, most see the business part as the real thing and don't see sense in visiting what's mostly a big advertisement for the newest games/gadgets. So most people still go for CeBit (not "CeBit home") as can be seen from the fact, that there's really a lot of people there at Weekends while real business is done mostly in the week.
Re:MP3's are like guns (Score:2)
According to the local press... (Score:5)
CeBit is currently a large fair, in fact it is the larges computer trade show on earth. Hannover cannot longer take all the people.
CeBit tried to split the show into a consumer show called "CeBit Home" and tried to promote the curent CeBit as a strictly business tradeshow. They have not been doing well: CeBit Home is actually shrinking, and many consumer product specialists are showing on the main CeBit.
Specifically: Creative undermined their marketing strategy at the last CeBit by having a loud and gaming oriented booth at the supposedly business oriented main CeBit. CeBit directorate wanted Creative to switch over to CeBit home, but Creative was not interested into a shrinking low profile fair.
Re:Why on earth.... (Score:2)
> Just like Marijuana is illegal, as are "bongs." And we know nobody uses those right....right?
Which means that if you're carrying a bong which tests positive for once having had marijuana smoke passed through it, you get busted for "drug paraphenalia".
Likewise - owning an MP3 player will be fine. Owning a computer will be fine. But owning an MP3 player will be probable cause for an officer to seize the computer and examine it for MP3 files. Even if you've deleted the MP3 files, if they can recover evidence (e.g. old bytes in the FAT portion of the disk) that the MP3 files were there, you go to jail.
> In this case, i think we all know where the public stands (the vast majority, at least) - all the corporate money in the world won't save a politician once he's been voted out of office.
Support for marijuana legalization is remarkably high in the US. Please explain why no major political candidate supports legalization.
Even a small portion of the corporate money in the world appears to be quite sufficient to thwart the public's will.
Re:MP3's are like guns (Score:4)
Ohh, righty then, we better call for some new laws then
...
--
Why pay for drugs when you can get Linux for free ?
Well good for them (Score:3)
It's nice to see the larger players in the whole multimedia finally saying out loud that the whole MP3 thing is getting way out of hand.
The RIAA are doing everybody a massive dis-service by their actions. What I find very offensive is that an American company's whinging and bitching is telling me what I can and can't do here in Australia.
Still, money buys influence just as well in Australia as it does in the US, so I shouldn't be surprised.
Re:Why on earth.... (Score:2)
1) Never doubt the power of government(s) making something illegal. It would only take a couple of major governments together (the US, the EU, AU/NZ, and Japan) declaring that all A/V file formats MUST support digital rights management, possibly implemented under WIPO so countries have very little choice in passing laws to support it, for this format to be declared wiped from all servers. And when your shoices are A) Delete it or B) 5 years in jail... Lots of people will choose A. If it is not listed on US/EU search engines, it will drop off the public radar fairly quickly, and only be available on slower offshore servers. Still there if you search for it, but much less easily available.
2) Ditto with #1, declare the format illegal, and you cannot manufacture or import devices that support that format in(to) the country. Without a device to buy, consumers will find something else that fulfills the same basic purpose. There are 2 or 3 competing audio file formats that are suitable for consumer devices, and support DRM.
3) Frankly, businesses are more concerned with controlling what consumers want, through marketting/PR and other means, and selling controlled products, than in creating new markets... Large entrenched businesses, at least. Why do you think the first MP3 player wasn't from Sony?
The CeBit organizers are people that depend on the goodwill of the major electronics/entertainment industry firms. This means that when most of the big members of an organization like the MPAA or RIAA says "Don't support this format" the trade show organizers will listen. No overt threats, no bribery, just a large powerful organization making known its wishes.
ZD Net UK tells the story differently from the US (Score:2)
Re:Go Creative! (Score:2)
When you "play an audio CD" on a standard old-school CDROM in a machine with some old soundblaster, the CDROM drive itself processes the CDDA data into an analog audio signal, which is then passed to the soundcard through that little CD audio cable like any line-level audio signal.
More modern drives have a "digital audio out", which does digitally encoded audio to the soundcard, but I'm not sure if it's really an exact copy of the CDDA data.
There's there Digital Audio Extraction (DAE), which is the ability of a drive to allow software to directly read the bitstream of an audio file from the CD disc as if it were a file. While most newer CDROMs support this feature on their buzzword list, many have compatibility problems in the real world, which makes finding a "good" CDROM drive for DAE (for converting later to MP3) a bitch sometimes.
While we're talking about boycotts... (Score:2)
Bruce
Well, of course. (Score:4)
And everyone knows that MP3s and related technology are'nt enjoyed by people that will spend rediculously large percentages of their personal income buying gadgets, right?
Its just a fad, and its a good thing that the MPAA and its friends are keeping the research going on 8-tracks, as thats where its at.
-- Crutcher --
#include <disclaimer.h>
Re:MP3's are like guns (Score:2)
You are obviously properly trained in the use of guns. But lets take someone who isn't properly trained in guns, and isn't properly trained in MP3s. They could harm someone with a gun, but not with an MP3. That's why guns aren't as safe as MP3s.
---
RIAA wants to push SDMI? (Score:3)
MP3's are like guns (Score:3)
------------------------------------------
If God Droppd Acid, Would he see People???
Re:RIGHT ON CREATIVE! (Score:2)
Do as I say, not as I do. I have all those CDs on my shelf too
:P
Serious Case of Product Discrimination & Prejudice (Score:2)
Isn't this illegal somehow? If I have a product - a perfectly legal product - which I want to sell, why can't I showcase it an industry meeting?
I wonder what other past technologies this HIGHLY-QUESTIONABLE practice has been able to stifle? So, whoever owns CeBit gets to decide the course of the industry and not the industry itself?
This sticks to high heaven.
--
Ironic (Score:2)
It's ironic that you mention that--with your apparent Netscape background..
I was using Netscape 5PR2 for Windows
.. Your expertise required: Bug with Netscape 5PR2 returning a nonstandard header? or careless programming on Creative Labs' end?
Mozilla/5.0 (Windows; U; Win98; en-US; m17) Gecko/20000807 Netscape6/6.0b2
Re:Ironic (Score:2)
Sorry
..
Requested, not Required
Banned Shmanned (Score:2)
All I'm saying is instead of bitching, maybe we should all get up and start to do something. Lets organize a serious boycott of the companies who are pulling these tactics, bug our friends and family until they too participate, do whatever you can to squash these assholes. Look, Napster may be violating their rights to a degree (like they haven't been fucking us in the ass for years), but it's unstoppable, and to make these blanket attacks on consumers and even manufacturers is out of hand.
Re:MP3 we love thee (Score:2)
Just a quick question... (Score:2)
what kind of hold could RIAA have over CeBit (apart from Sony pulling out) to get CeBit to ban any and all MP3 related devices from the show?
Surely there are manufacturers other than Creative who have a vested interest in this as well...
M@T
Re:Not hardware...and BTW, blame Sony for this... (Score:2)
Why on earth.... (Score:3)
1) The software exists. There is no way mp3 encoding/playing software is going to go away.
2) The hardware exists. Plenty of mp3 players have been sold, and continue to be sold. There's no basis for a lawsuit against hardware manufacturers, as there's nothing remotely illegal about playing or creating mp3s.
3) Consumers *love* mp3. Isn't the whole point of business (and by extension, trade shows) to create, market, and sell products and services that consumers want?
This seems to indicate that either the CeBit organizers or some MAJOR participants had a very good motive to get mp3 devices off the floor. Bribery or stock deals (really just another form of bribery) wouldn't surprise me. Perhaps one of the exhibitors will be showing off some new audio encoding technology and use the fact that they're the only thing being shown to impress people?
Thank You Big Brother (Score:3)
Still, I feel a great need to send a big hug and kiss to the people at Creative Labs. Even if your beating on the bully for your own reasons... the little guy who got his milk money taken last week will still be there to laugh and enjoy it.
I'll start taking it like a man when I'm done crying
Not about rights or freedom (Score:2)
Creative is doing the right thing for the wrong reasons, which in my mind is about the same as just doing nothing.
Re:...Or is it the other way around? (Score:2)
Er, yeah, but ever heard of Creative's Nomad line of portable MP3 players? The most popular players out there? I suspect that's a bigger concern for them.
Re:Minidisc is expensive? (Score:2)
Getting media on a spindle doesn't mean it's not high-quality; Imation, for example, makes a very high quality disc, and uses the same discs on its spindles that it uses in its nice slimline cases. On sale, you can get them sometimes for as little as $30 for 50. And, the media will last in excess of fifty years, and probably closer to a century, without bit-rot. There was a story on
You're right that not all burners can use an 80-min CD-R to full capacity, but that's pretty much irrelevant since most people aren't using 4 year old 1-2x CD burners. My own Craetive burner was purchased two years ago, and has no problem with them. But, even very, very ancient CD players will be able to use an 80-min audio CD--I have a walkman from when I was in high school which plays them glitchlessly. Aside from which, a good CD burner and a decent portable CD player cost less new than a new MD player/recorder.
If you want to go the uber-cool route, you could shell out a few more $$ and instead of getting a plain-Jane CD player, get something like a portable Encino Voyager CD MP3 player--easily fitting 150 high-quality mp3 recordings (192kbps or greater) onto a single medium.
And contrary to the FUD surrounding the issue, mp3 sound is as high quality as most other compressed formats, probably including ATRAC. The key is to remember that bitrate affects audio quality immensely--a 128k mp3 will sound flat and dull on even a mid-range stereo system, if you're an audiophile; but, a 192k mp3 sounds as good as a CD on a high-end system, unless you have better hearing than most people do; and, anything greater than that sounds indistinguishable from CD audio even to highly skilled audiophiles with great hearing. I believe Ars Technica did an mp3 comparison which touched on these issues. Personally, I use HQ VBR mp3 encoding, which varies the bitrate up to 320kbps and down to 96kbps as necessary, depending on the demands of the stream at any given time. It produces absolutely flawless sound, as good as any CD.
So, claims of CD-quality sound are absolutely true, if you create a high quality file. I find plenty of them on Napster, too, so I'm not the only audiophile who's keen to this. The resulting files are usually about 6-10MB, depending on bitrate--HQ VBR can produce smaller files than 256kbps files, and often they're even smaller than 192kbps files. And, you can call it piracy if you want, but I gleefully download any songs older than 14 years without any concern for copyright since the Constitution specified a copyright term of 14 years, and the extensions to this have been gained by heavy-handed and too-powerful corporations acting against the interests of the people. I also don't feel *too* bad about downloading new stuff from companies who are responsible for the DMCA and other extensions of copyright against the public interest. The only CDs I purchase any more are from bands who actually deserve my support, like Kittie, Chuck D, and people affiliated with indie labels. The music industry--and by that I mean the big corporations who are witholding IP from the public domain indefinitely, whereas it was originally supposed to be public domain after a reasonable 14 year term--don't deserve my money for abusing and taking away the rights of the people to public domain IP, but we *do* deserve to take from them since they withold IP which should rightfully be in the public domain. As David Boies, Napster attorney who was instrumental in the DoJ's case against Microsoft, pointed out, if a company or group of companies abuses its copyrights to gain or illegally exploit a monopoly, they lose their legal rights to those copyrights.
I have nothing against the MD formet in itself--it's Sony's control of it I dislike, and that's why I will never use it. Sony tried to control us with Beta, they tried to prevent resale of CDs, and they're making a very flawed version of mp3 players, and they are among the worst offenders of the DVD Consortium and one of the multinationals responsible for the DMCA. I don't trust them, and in fact hate the world they want to create, where all content and IP is encrypted, rented, and no one can touch it but them.
I've been to CeBIT last year... (Score:2)
And the reason? To protect the content providers? That's absolutely crazy. Most people who buy MP3 players actually do mostly use them to play music from their own CD collection, or maybe one or two songs snatched from Napster.
I don't understand how a huge and influential organisation like CeBIT could possibly decide to ban all MP3-related stuff from their fair. Now that Creative is boycotting CeBIT, I'm pretty sure others like Diamond and Thomson may follow. And then suddenly CeBIT isn't the biggest computer fair anymore...
Oh, if anybody does go to CeBIT despite all this, don't forget to check out the Münchner Halle. Ugly waitresses, but good beer and a nice stereotypical German atmosphere
)O(
Never underestimate the power of stupidity
Re:Gotta watch it with them codecs (Score:2)
)O(
Never underestimate the power of stupidity
Ogg Vorbis (Score:2)
What I plan to do is rip the surrond tracks from my dvds when ogg reaches maturity, and encode them for playing through a computer. What I _really_ would like to see is a CAR STEREO that has surround sound cabability. I mean, they're ALREADY hooked up to front and rear left and right. If I had a car stereo that could play ogg AND was surround sound aware, that would be just spiffy.
"What a waste it is to lose one's mind. Or not to have a mind is being very wasteful. How true that is"
Re:RIAA wants to push SDMI? (Score:2)
Re:MP3 we love thee (Score:2)
Ogg works now in WinAmp, Sonique and XMMS. For WinAmp it's as easy as downloading a plugin and double clicking the
With plans to allow streaming ogg it can almost become a drop in replacement for MP3.
SDMI requires it's whole authentication sceme to play files.
The real barier to entry in a case like this is not the format but the changes the end users have to make. With Ogg there is little to none. With SDMI the end user is forced to adopt a new way of thinking about the music they listen to.
Re:short article (Score:2)
You can't even say that.
:) The Diamond Rio is by, well, Diamond. (Who have recently been absorbed into S3)
Creative's players are the Nomads.
Go Creative! (Score:2)
We don't have to take this crap from these steenking artists any more.
Did the VCR destroy the movie industry? Did the tape recorder destroy the music industry? Did CD Burners kill the CD music business? Will the CD-ROM drives that allowed Digital Audio Extraction kill the CD market? Will MP3 do it either? Isn't this crap obvious??????!?!@#!@#
RIGHT ON CREATIVE! (Score:2)
Represent the customers by declining to go to a trade show that doesn't want to display what they want.
Another sign that the RIAA will eventually have to bow to popular demand - we got our music, and we aren't going back to the stone age on account of "intellectual property" or "copy protection", regardless of what congress belches out or how illegal they make it. The revolution has begun!
-- | https://slashdot.org/story/00/09/12/2057216/creative-boycotts-cebit-over-mp3s | CC-MAIN-2017-17 | en | refinedweb |
A ReverseUnique model field implementation for Django
The ReverseUnique field can be used to access single model instances from the reverse side of ForeignKey. Essentially, ReverseUnique can be used to generate OneToOneField like behaviour in the reverse direction of a normal ForeignKey. The idea is to add an unique filter condition when traversing the foreign key to reverse direction.
To be able to use reverse unique, you will need a unique constraint for the reverse side or otherwise know that only one instance on the reverse side can match.
It is always nice to see actual use cases. We will model employees with time dependent salaries in this example. This use case could be modelled as:
class Employee(models.Model): name = models.TextField() class EmployeeSalary(models.Model): employee = models.ForeignKey(Employee, related_name='employee_salaries') salary = models.IntegerField() valid_from = models.DateField() valid_until = models.DateField(null=True)
It is possible to save data like “Anssi has salary of 10€ from 2000-1-1 to 2010-1-1, and salary of 11€ from 2010-1-1 to infinity (modelled as None in the models).
Unfortunately when using these models it isn’t trivial to just fetch the employee and his salary to display to the user. It would be possible to do so by looping through all salaries of an employee and checking which of the EmployeeSalaries is currently in effect. However, this approach has a couple of drawbacks:
- It doesn’t perform well in list views
- Most of all It is impossible to execute queries that refer the employee’s current salary. For example, getting the top 10 best paid employees or the average salary of employees is impossible to achieve in single query.
Django-reverse-unique to the rescue! Lets change the Employee model to:
from datetime import datetime class Employee(models.Model): name = models.TextField() current_salary = models.ReverseUnique( "EmployeeSalary", filter=Q(valid_from__gte=datetime.now) & (Q(valid_until__isnull=True) | Q(valid_until__lte=datetime.now)) )
Now we can simply issue a query like:
Employee.objects.order_by('current_salary__salary')[0:10]
or:
Employee.objects.aggregate(avg_salary=Avg('current_salary__salary'))
What did happen there? We added a ReverseUnique field. This field is the reverse of the EmployeeSalary.employee foreign key with an additional restriction that the relation must be valid at the moment the query is executed. The first “EmployeeSalary” argument refers to the EmployeeSalary model (we have to use string as the EmployeeSalary model is defined after the Employee model). The filter argument is a Q-object which can refer to the fields of the remote model.
Another common problem for Django applications is how to store model translations. The storage problem can be solved with django-reverse-unique. Here is a complete example for that use case:
from django.db import models from reverse_unique import ReverseUnique from django.utils.translation import get_language, activate class Article(models.Model): active_translation = ReverseUnique("ArticleTranslation", filters=Q(lang=get_language)) class ArticleTranslation(models.Model): article = models.ForeignKey(Article) lang = models.CharField(max_length=2) title = models.CharField(max_length=100) body = models.TextField() class Meta: unique_together = ('article', 'lang') activate("fi") objs = Article.objects.filter( active_translation__title__icontains="foo" ).select_related('active_translation') # Generated query is # select article.*, article_translation.* # from article # join article_translation on article_translation.article_id = article.id # and article_translation.lang = 'fi' # If you activate "en" instead, the lang is changed. # Now you can access objs[0].active_translation without generating more # queries.
Similarly one could fetch current active reservation for a hotel room etc.
The requirement for ReverseUnique is Django 1.6+. You will need to place the reverse_unique directory in Python path, then just use it like done in above example. The tests (reverse_unique/tests.py) contain a couple more examples. Easiest way to install is:
pip install -e git://github.com/akaariai/django-reverse-unique.git#egg=reverse_unique
You’ll need to have a supported version of Django installed. Go to testproject directory and run:
python manage.py test reverse. | https://pypi.org/project/django-reverse-unique/ | CC-MAIN-2017-17 | en | refinedweb |
* Linus Torvalds <[email protected]> wrote:> On Sat, 8 Nov 2008, Ingo Molnar wrote:> >> > Ingo Molnar (2):> > sched: improve sched_clock() performance> > sched: optimize sched_clock() a bit> > Btw, why do we do that _idiotic_ rdtsc_barrier() AT ALL?> > No sane user can possibly want it. If you do 'rdtsc', there's > nothing you can do about a few cycles difference due to OoO > _anyway_. Adding barriers is entirely meaningless - it's not going > to make the return value mean anything else.> > Can we please just remove that idiocy? Or can somebody give a _sane_ > argument for it?yeah, i had the same thinking, so i zapped it for everything but the vdso driven vgettimeofday GTOD method.For that one, i chickened out, because we have this use in arch/x86/kernel/vsyscall_64.c: now = vread(); base = __vsyscall_gtod_data.clock.cycle_last; mask = __vsyscall_gtod_data.clock.mask; mult = __vsyscall_gtod_data.clock.mult; shift = __vsyscall_gtod_data.clock.shift;which can be triggered by gettimeofday() on certain systems.And i couldnt convince myself that this sequence couldnt result in userspace-observable GTOD time warps there, so i went for the obvious fix first.If the "now = vread()"'s RDTSC instruction is speculated to after it reads cycle_last, and another vdso call shortly after this does another RDTSC in this same sequence, the two RDTSC's could be mixed up in theory, resulting in negative time?I _think_ i heard some noises in the past that this could indeed happen (and have vague memories that this was the justification for the barrier's introduction), but have to check the old emails to figure out what exactly the issue was and on what CPUs.It's not completely impossible for this to happen, as the vdso calls are really just simple function calls, so not nearly as strongly serialized as say a real syscall based gettimeofday() call.In any case, it failed my "it must be obvious within 1 minute for it to be eligible for sched/urgent" threshold and i didnt want to introduce a time warp.But you are right, and i've queued up the full fix below as well, as a reminder. Ingo----------------->From 2efe2c42e008a80ebe1992db63749386778f7df8 Mon Sep 17 00:00:00 2001From: Ingo Molnar <[email protected]>Date: Sat, 8 Nov 2008 19:46:48 +0100Subject: [PATCH] x86, time: remove rdtsc_barrier()Linus pointed out that even for vread() rdtsc_barrier() is pointlessoverhead - as due to speculative instructions there's no such thingas reliable cycle count anyway.Signed-off-by: Ingo Molnar <[email protected]>--- arch/x86/include/asm/system.h | 13 ------------- arch/x86/include/asm/tsc.h | 6 +----- 2 files changed, 1 insertions(+), 18 deletions(-)diff --git a/arch/x86/include/asm/system.h b/arch/x86/include/asm/system.hindex 2ed3f0f..1a1d45e 100644--- a/arch/x86/include/asm/system.h+++ b/arch/x86/include/asm/system.h@@ -409,17 +409,4 @@ void default_idle(void); #define set_mb(var, value) do { var = value; barrier(); } while (0) #endif -/*- * Stop RDTSC speculation. This is needed when you need to use RDTSC- * (or get_cycles or vread that possibly accesses the TSC) in a defined- * code region.- *- * (Could use an alternative three way for this if there was one.)- */-static inline void rdtsc_barrier(void)-{- alternative(ASM_NOP3, "mfence", X86_FEATURE_MFENCE_RDTSC);- alternative(ASM_NOP3, "lfence", X86_FEATURE_LFENCE_RDTSC);-}- #endif /* _ASM_X86_SYSTEM_H */diff --git a/arch/x86/include/asm/tsc.h b/arch/x86/include/asm/tsc.hindex 9cd83a8..700aeb8 100644--- a/arch/x86/include/asm/tsc.h+++ b/arch/x86/include/asm/tsc.h@@ -44,11 +44,7 @@ static __always_inline cycles_t vget_cycles(void) if (!cpu_has_tsc) return 0; #endif- rdtsc_barrier();- cycles = (cycles_t)__native_read_tsc();- rdtsc_barrier();-- return cycles;+ return (cycles_t)__native_read_tsc(); } extern void tsc_init(void); | http://lkml.org/lkml/2008/11/8/114 | CC-MAIN-2017-17 | en | refinedweb |
A colleague of mine recently called me out on the fact that I haven't blogged in … oh about a year and a half. Well it’s 2010 now and resolution season is in full swing so here’s my attempt at getting back on the ball (no promises though).
In a recent post Scott Hanselman described writing custom filters for ASP.NET Dynamic Data. Scott provides a nice overview of the Dynamic Data architecture and then gets his hands dirty with some custom filters using the advanced capabilities available in Dynamic Data Futures. However, he soon realizes that writing custom late-bound LINQ expressions is definitely not a trifle.
I started thinking about how this experience could be improved and so started writing some code. Things were going great and I was well on my way towards providing the “magic” code that would make Scott’s task that much easier when I started getting this déjà vu feeling that I had already seen something very similar. I scratched my head a bit and then remembered a long-lost sample for dynamically building LINQ queries written back when the original Visual Studio 2008 shipped.
It’s available as a download but it also comes bundled with your VS (both 2008 and 2010) installation under the following path in your VS installation directory:
Samples\1033\CSharpSamples.zip\LinqSamples\DynamicQuery\DynamicQuery
This sample implements a subset of the LINQ extension methods in a late-bound, string-based manner. So for example (using Scott’s model classes) instead of writing this:
IQueryable<Brick> bricks; // strongly-typed collection of bricks
var result = bricks.Select(p => p.Year).Distinct().OrderBy(i => i);
you can write this “magic” code:
using System.Linq.Dynamic; // you need to include this namespace
// for the extension methods to kick in
IQueryable bricks; // weakly-typed collection of bricks
var result = bricks.Select("Year").Distinct().OrderBy("it");
DynamicQueryable is quite powerful and includes the following
The only custom code that I had to write to support Scott’s scenario was the Distinct method, which is missing from what’s provided. Fortunately this was not that difficult:
public static class DynamicQueryableExtras {
public static IQueryable Distinct(this IQueryable q) {
var call = Expression.Call(typeof(Queryable),
"Distinct",
new Type[] { q.ElementType },
q.Expression);
return q.Provider.CreateQuery(call);
}
}
Other missing LINQ APIs could be added quite easily too.
Once I had the Distinct extension method it was easy to rewrite Scott’s code:());
}
}
as:
protected void Page_Init(object sender, EventArgs e) {
var items = Column.Table.GetQuery();
var result = items.Select(Column.EntityTypeProperty.Name)
.Distinct()
.OrderBy("it");
foreach (var item in result) {
if (item != null) DropDownList1.Items.Add(item.ToString());
}
}
Much simpler, wouldn’t you agree?
I hope this technique will save you time trying to figure out how to dynamically build LINQ expressions. The sample contains a detailed document describing all of the APIs and the features available in the expression language. You should definitely check it out because it is very powerful. Oh, and if this also looks familiar to you, that’s because it’s almost the same as the querying features in LinqDataSource. | http://blogs.msdn.com/b/marcinon/archive/2010/01.aspx | CC-MAIN-2014-23 | en | refinedweb |
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