| # Dora C++ Dataflow Example | |
| This example shows how to create dora operators and custom nodes with C++. | |
| Dora does not provide a C++ API yet, but we can create adapters for either the C or Rust API. The `operator-rust-api` and `node-rust-api` folders implement an example operator and node based on dora's Rust API, using the `cxx` crate for bridging. The `operator-c-api` and `node-c-api` show how to create operators and nodes based on dora's C API. Both approaches work, so you can choose the API that fits your application better. | |
| ## Compile and Run | |
| To try it out, you can use the [`run.rs`](./run.rs) binary. It performs all required build steps and then starts the dataflow. Use the following command to run it: `cargo run --example cxx-dataflow`. | |
| For a manual build, follow these steps: | |
| - Create a `build` folder in this directory (i.e., next to the `node.c` file) | |
| - Build the `cxx-dataflow-example-node-rust-api` and `cxx-dataflow-example-operator-rust-api` crates: | |
| ``` | |
| cargo build -p cxx-dataflow-example-node-rust-api --release | |
| cargo build -p cxx-dataflow-example-operator-rust-api --release | |
| ``` | |
| - Compile the `dora-node-api-c` crate into a static library. | |
| - Run `cargo build -p dora-node-api-c --release` | |
| - The resulting staticlib is then available under `../../target/release/libdora-node-api-c.a`. | |
| - Compile the `node-c-api/main.cc` (e.g. using `clang++`) and link the staticlib | |
| - For example, use the following command: | |
| ``` | |
| clang++ node-c-api/main.cc <FLAGS> -std=c++14 -ldora_node_api_c -L ../../target/release --output build/node_c_api | |
| ``` | |
| - The `<FLAGS>` depend on the operating system and the libraries that the C node uses. The following flags are required for each OS: | |
| - Linux: `-lm -lrt -ldl -pthread` | |
| - macOS: `-framework CoreServices -framework Security -l System -l resolv -l pthread -l c -l m` | |
| - Windows: | |
| ``` | |
| -ladvapi32 -luserenv -lkernel32 -lws2_32 -lbcrypt -lncrypt -lschannel -lntdll -liphlpapi | |
| -lcfgmgr32 -lcredui -lcrypt32 -lcryptnet -lfwpuclnt -lgdi32 -lmsimg32 -lmswsock -lole32 | |
| -lopengl32 -lsecur32 -lshell32 -lsynchronization -luser32 -lwinspool | |
| -Wl,-nodefaultlib:libcmt -D_DLL -lmsvcrt | |
| ``` | |
| Also: On Windows, the output file should have an `.exe` extension: `--output build/c_node.exe` | |
| - Compile the `operator-c-api/operator.cc` file into a shared library. | |
| - For example, use the following commands: | |
| ``` | |
| clang++ -c operator-c-api/operator.cc -std=c++14 -o build/operator_c_api.o -fPIC | |
| clang++ -shared build/operator_c_api.o -o build/liboperator_c_api.so | |
| ``` | |
| Omit the `-fPIC` argument on Windows. Replace the `liboperator_c_api.so` name with the shared library standard library prefix/extensions used on your OS, e.g. `.dll` on Windows. | |
| **Build the dora coordinator and runtime:** | |
| - Build the `dora-coordinator` executable using `cargo build -p dora-coordinator --release` | |
| - Build the `dora-runtime` executable using `cargo build -p dora-runtime --release` | |
| **Run the dataflow:** | |
| - Start the `dora-coordinator`, passing the paths to the dataflow file and the `dora-runtime` as arguments: | |
| ``` | |
| ../../target/release/dora-daemon --run-dataflow dataflow.yml ../../target/release/dora-runtime | |
| ``` | |