edg3/experiment_software_csharp_12_net_8 · Datasets at Hugging Face

title stringlengths 3 46	content stringlengths 0 1.6k
21:825	Then, we deserialize the message body to get a PurchaseMessage instance and add it to the database:
21:826	var body = ea.Body.ToArray();
21:827	PurchaseMessage? message = null;
21:828	using (var stream = new MemoryStream(body))
21:829	{
21:830	message = PurchaseMessage.Parser.ParseFrom(stream);
21:831	}
21:832	var res = await statistics.Add(new Purchase {
21:833	Cost= message.Cost,
21:834	Id= Guid.Parse(message.Id),
21:835	Location = message.Location,
21:836	Time = new DateTimeOffset(message.Time.ToDateTime(), TimeSpan.Zero),
21:837	PurchaseTime = new DateTimeOffset(message.PurchaseTime.ToDateTime(), TimeSpan.Zero)
21:838	});
21:839
21:840	If the operation fails, the Add operation returns null, so we must send a Nack; otherwise, we must send an Ack:
21:841	if(res != null)
21:842	((EventingBasicConsumer)sender).Model
21:843	.BasicAck(ea.DeliveryTag, false);
21:844	else
21:845	((EventingBasicConsumer)sender).Model
21:846	.BasicNack(ea.DeliveryTag, false, true);
21:847
21:848	That’s all! The full code is in the GrpcMicroServiceRabbitProto subfolder of the ch15 folder in the GitHub repository of this book. You can test the code by setting both the client and server projects as the start project and running the solution. After 1–2 minutes, the database should be populated with new purchases and new daily totals. In a staging/production environment, you can run several copies of both the client and server.
21:849	The GrpcMicroServiceRabbit subfolder in the ch15 folder of the GitHub repository contains another version of the same application that uses the Binaron NuGet package for serialization. It is faster than ProtoBuf, but being .NET-specific, it is not interoperable. Moreover, it has no features to facilitate message versioning. It is useful when performance is critical and versioning and interoperability are not a priority.
21:850	The Binaron version differs in that it has no .proto files or other ProtoBuf stuff, but it explicitly defines a PurchaseMessage .NET class. Moreover, ProtoBuf serialization and deserialization instructions are replaced by the following:
21:851	byte[]? body = null;
21:852	using (var stream = new MemoryStream())
21:853	{
21:854	BinaronConvert.Serialize(purchase, stream);
21:855	stream.Flush();
21:856	body = stream.ToArray();
21:857	}
21:858
21:859	Together with:
21:860	PurchaseMessage? message = null;
21:861	using (var stream = new MemoryStream(body))
21:862	{
21:863	message = BinaronConvert.Deserialize<PurchaseMessage>(stream);
21:864	}.
21:865
21:866	Now that we have created a microservice connected to a message broker, it is also important to learn how to expose packages from WWTravelClub using web APIs. Let’s see this in the next section.
21:867	Exposing WWTravelClub packages using Web APIs
21:868	In this section, we will implement an ASP.NET REST service that lists all the packages that are available for a given vacation’s start and end dates. For didactic purposes, we will not structure the application according to the best practices we have described previously; instead, we will simply generate the results with a LINQ query that will be directly placed in the controller action method. A well-structured ASP.NET Core application has been presented in Chapter 18, Implementing Frontend Microservices with ASP.NET Core.
21:869	Let us make a copy of the WWTravelClubDB solution folder and rename the new folder WWTravelClubWebAPI80. The WWTravelClubDB project was built step by step in the various sections of Chapter 13, Interacting with Data in C# – Entity Framework Core. Let us open the new solution and add a new ASP.NET Core API project to it named WWTravelClubWebAPI80 (the same name as the new solution folder). For simplicity, select No Authentication. Right-click on the newly created project and select Set as StartUp project to make it the default project that is launched when the solution is run.
21:870	Finally, we need to add a reference to the WWTravelClubDB project.
21:871	ASP.NET Core projects store configuration constants in the appsettings.json file. Let’s open this file and add the database connection string for the database we created in the WWTravelClubDB project to it, as shown here:
21:872	{
21:873	`ConnectionStrings`: {
21:874	`DefaultConnection`: `Server=
21:875	(localdb)mssqllocaldb;Database=wwtravelclub;
21:876	Trusted_Connection=True;MultipleActiveResultSets=true`
21:877	},
21:878	...
21:879	...
21:880	}
21:881
21:882	Now, we must add the WWTravelClubDB entity framework database context to Program.cs, as shown here:
21:883	builder.Services.AddDbContext<WWTravelClubDB.MainDBContext>(options =>
21:884	options.UseSqlServer(
21:885	builder.Configuration.GetConnectionString(`DefaultConnection`),
21:886	b =>b.MigrationsAssembly(`WWTravelClubDB`)))
21:887
21:888	The option object settings that are passed to AddDbContext specify the usage of SQL Server with a connection string that is extracted from the ConnectionStrings section of the appsettings.json configuration file with the Configuration.GetConnectionString(`DefaultConnection`) method. The b =>b.MigrationsAssembly(`WWTravelClubDB`) lambda function declares the name of the assembly that contains the database migrations (see Chapter 13, Interacting with Data in C# – Entity Framework Core), which, in our case, is the DLL that was generated by the WWTravelClubDB project. For the preceding code to compile, you should add the Microsoft.EntityFrameworkCore namespace.
21:889	Since we want to enrich our REST service with OpenAPI documentation, let’s add a reference to the Swashbuckle.AspNetCore NuGet package. Now, we can add the following very basic configuration to Program.cs:
21:890	var builder = WebApplication.CreateBuilder(args);
21:891	...
21:892	builder.Services.AddSwaggerGen(c =>
21:893	{
21:894	c.SwaggerDoc(`v2`, new() { Title = `WWTravelClub REST API - .NET 8`, Version = `v2` });
21:895	});
21:896	var app = builder.Build();
21:897	...
21:898	app.UseSwagger();
21:899	app.UseSwaggerUI(c => c.SwaggerEndpoint(`/swagger/v2/swagger.json`, `WWTravelClub REST API - .NET 8`));
21:900	...
21:901	app.Run();
21:902
21:903	Now, we are ready to encode our service. Let’s delete WeatherForecastController, which is automatically scaffolded by Visual Studio. Then, right-click on the Controllers folder and select Add \| Controller. Now, choose an empty API controller called PackagesController. First, let’s modify the code as follows:
21:904	[Route(`api/packages`)]
21:905	[ApiController]
21:906	public class PackagesController : ControllerBase
21:907	{
21:908	[HttpGet(`bydate/{start}/{stop}`)]
21:909	[ProducesResponseType(typeof(IEnumerable<PackagesListDTO>), 200)]
21:910	[ProducesResponseType(400)]
21:911	[ProducesResponseType(500)]
21:912	public async Task<IActionResult> GetPackagesByDate(
21:913	[FromServices] WWTravelClubDB.MainDBContext ctx,
21:914	DateTime start, DateTime stop)
21:915	{
21:916	}
21:917	}
21:918
21:919	The Route attribute declares that the basic path for our service will be api/packages. The unique action method that we implement is GetPackagesByDate, which is invoked on HttpGet requests on paths of the bydate/{start}/{stop} type, where start and stop are the DateTime parameters that are passed as input to GetPackagesByDate. The ProduceResponseType attributes declare the following:
21:920
21:921	When a request is successful, a 200 code is returned, and the body contains an IEnumerable of the PackagesListDTO type (which we will soon define) containing the required package information.
21:922	When the request is ill formed, a 400 code is returned. We don’t specify the type returned since bad requests are automatically handled by the ASP.NET Core framework through the ApiController attribute.
21:923	In the case of unexpected errors, a 500 code is returned with the exception error message.
21:924

21:825

Then, we deserialize the message body to get a PurchaseMessage instance and add it to the database:

21:826

var body = ea.Body.ToArray();

21:827

PurchaseMessage? message = null;

21:828

using (var stream = new MemoryStream(body))

21:829

{

21:830

message = PurchaseMessage.Parser.ParseFrom(stream);

21:831

}

21:832

var res = await statistics.Add(new Purchase {

21:833

Cost= message.Cost,

21:834

Id= Guid.Parse(message.Id),

21:835

Location = message.Location,

21:836

Time = new DateTimeOffset(message.Time.ToDateTime(), TimeSpan.Zero),

21:837

PurchaseTime = new DateTimeOffset(message.PurchaseTime.ToDateTime(), TimeSpan.Zero)

21:838

});

21:839

21:840

If the operation fails, the Add operation returns null, so we must send a Nack; otherwise, we must send an Ack:

21:841

if(res != null)

21:842

((EventingBasicConsumer)sender).Model

21:843

.BasicAck(ea.DeliveryTag, false);

21:844

else

21:845

((EventingBasicConsumer)sender).Model

21:846

.BasicNack(ea.DeliveryTag, false, true);

21:847

21:848

That’s all! The full code is in the GrpcMicroServiceRabbitProto subfolder of the ch15 folder in the GitHub repository of this book. You can test the code by setting both the client and server projects as the start project and running the solution. After 1–2 minutes, the database should be populated with new purchases and new daily totals. In a staging/production environment, you can run several copies of both the client and server.

21:849

The GrpcMicroServiceRabbit subfolder in the ch15 folder of the GitHub repository contains another version of the same application that uses the Binaron NuGet package for serialization. It is faster than ProtoBuf, but being .NET-specific, it is not interoperable. Moreover, it has no features to facilitate message versioning. It is useful when performance is critical and versioning and interoperability are not a priority.

21:850

The Binaron version differs in that it has no .proto files or other ProtoBuf stuff, but it explicitly defines a PurchaseMessage .NET class. Moreover, ProtoBuf serialization and deserialization instructions are replaced by the following:

21:851

byte[]? body = null;

21:852

using (var stream = new MemoryStream())

21:853

{

21:854

BinaronConvert.Serialize(purchase, stream);

21:855

stream.Flush();

21:856

body = stream.ToArray();

21:857

}

21:858

21:859

Together with:

21:860

PurchaseMessage? message = null;

21:861

using (var stream = new MemoryStream(body))

21:862

{

21:863

message = BinaronConvert.Deserialize<PurchaseMessage>(stream);

21:864

}.

21:865

21:866

Now that we have created a microservice connected to a message broker, it is also important to learn how to expose packages from WWTravelClub using web APIs. Let’s see this in the next section.

21:867

Exposing WWTravelClub packages using Web APIs

21:868

In this section, we will implement an ASP.NET REST service that lists all the packages that are available for a given vacation’s start and end dates. For didactic purposes, we will not structure the application according to the best practices we have described previously; instead, we will simply generate the results with a LINQ query that will be directly placed in the controller action method. A well-structured ASP.NET Core application has been presented in Chapter 18, Implementing Frontend Microservices with ASP.NET Core.

21:869

Let us make a copy of the WWTravelClubDB solution folder and rename the new folder WWTravelClubWebAPI80. The WWTravelClubDB project was built step by step in the various sections of Chapter 13, Interacting with Data in C# – Entity Framework Core. Let us open the new solution and add a new ASP.NET Core API project to it named WWTravelClubWebAPI80 (the same name as the new solution folder). For simplicity, select No Authentication. Right-click on the newly created project and select Set as StartUp project to make it the default project that is launched when the solution is run.

21:870

Finally, we need to add a reference to the WWTravelClubDB project.

21:871

ASP.NET Core projects store configuration constants in the appsettings.json file. Let’s open this file and add the database connection string for the database we created in the WWTravelClubDB project to it, as shown here:

21:872

{

21:873

`ConnectionStrings`: {

21:874

`DefaultConnection`: `Server=

21:875

(localdb)mssqllocaldb;Database=wwtravelclub;

21:876

Trusted_Connection=True;MultipleActiveResultSets=true`

21:877

},

21:878

...

21:879

...

21:880

}

21:881

21:882

Now, we must add the WWTravelClubDB entity framework database context to Program.cs, as shown here:

21:883

builder.Services.AddDbContext<WWTravelClubDB.MainDBContext>(options =>

21:884

options.UseSqlServer(

21:885

builder.Configuration.GetConnectionString(`DefaultConnection`),

21:886

b =>b.MigrationsAssembly(`WWTravelClubDB`)))

21:887

21:888

The option object settings that are passed to AddDbContext specify the usage of SQL Server with a connection string that is extracted from the ConnectionStrings section of the appsettings.json configuration file with the Configuration.GetConnectionString(`DefaultConnection`) method. The b =>b.MigrationsAssembly(`WWTravelClubDB`) lambda function declares the name of the assembly that contains the database migrations (see Chapter 13, Interacting with Data in C# – Entity Framework Core), which, in our case, is the DLL that was generated by the WWTravelClubDB project. For the preceding code to compile, you should add the Microsoft.EntityFrameworkCore namespace.

21:889

Since we want to enrich our REST service with OpenAPI documentation, let’s add a reference to the Swashbuckle.AspNetCore NuGet package. Now, we can add the following very basic configuration to Program.cs:

21:890

var builder = WebApplication.CreateBuilder(args);

21:891

...

21:892

builder.Services.AddSwaggerGen(c =>

21:893

{

21:894

c.SwaggerDoc(`v2`, new() { Title = `WWTravelClub REST API - .NET 8`, Version = `v2` });

21:895

});

21:896

var app = builder.Build();

21:897

...

21:898

app.UseSwagger();

21:899

app.UseSwaggerUI(c => c.SwaggerEndpoint(`/swagger/v2/swagger.json`, `WWTravelClub REST API - .NET 8`));

21:900

...

21:901

app.Run();

21:902

21:903

Now, we are ready to encode our service. Let’s delete WeatherForecastController, which is automatically scaffolded by Visual Studio. Then, right-click on the Controllers folder and select Add | Controller. Now, choose an empty API controller called PackagesController. First, let’s modify the code as follows:

21:904

[Route(`api/packages`)]

21:905

[ApiController]

21:906

public class PackagesController : ControllerBase

21:907

{

21:908

[HttpGet(`bydate/{start}/{stop}`)]

21:909

[ProducesResponseType(typeof(IEnumerable<PackagesListDTO>), 200)]

21:910

[ProducesResponseType(400)]

21:911

[ProducesResponseType(500)]

21:912

public async Task<IActionResult> GetPackagesByDate(

21:913

[FromServices] WWTravelClubDB.MainDBContext ctx,

21:914

DateTime start, DateTime stop)

21:915

{

21:916

}

21:917

}

21:918

21:919

The Route attribute declares that the basic path for our service will be api/packages. The unique action method that we implement is GetPackagesByDate, which is invoked on HttpGet requests on paths of the bydate/{start}/{stop} type, where start and stop are the DateTime parameters that are passed as input to GetPackagesByDate. The ProduceResponseType attributes declare the following:

21:920

21:921

When a request is successful, a 200 code is returned, and the body contains an IEnumerable of the PackagesListDTO type (which we will soon define) containing the required package information.

21:922

When the request is ill formed, a 400 code is returned. We don’t specify the type returned since bad requests are automatically handled by the ASP.NET Core framework through the ApiController attribute.

21:923

In the case of unexpected errors, a 500 code is returned with the exception error message.

21:924