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中文

Overview

This article will guide you start tRPC-Cpp with a simple example.

Environment requirments

In the C++ world, there is no universal accepted standard for managing project dependencies. Therefore, you need to install some developing toolkits before compiling and running the example. For details, please refer to Environment Setup. If you are new to tRPC-Cpp, we recommend using bazel to build project. It will reduce much of time spending on bootstraping C++ project. You will see how easy it can be when we lead you though the following guidance.

Compile and Run

Compile tRPC-Cpp

Clone the tRPC-Cpp repo:

git clone https://github.com/trpc-group/trpc-cpp

Compile the tRPC-Cpp source code:

cd trpc-cpp
./build.sh

If do cat build.sh, you will find this script just executs a simple command bazel build //trpc/.... It means compling all the targets in trpc subdirectory where all tRPC-Cpp framework source codes placed. It will take a minutes to do the progress for the first time. Once done, you will see a similar output:

INFO: 2629 processes: 2629 processwrapper-sandbox.
INFO: Build completed successfully, 5459 total actions

If failed, it might due to network error(eg. unable to download third-party libs that tRPC-Cpp needs), or environment requirments not satisfied(eg. gcc version is too low). Please refer to Environment Setup Faq to get detail solutions.

Compile HelloWorld

After the tRPC-Cpp is successfully compiled, the next step is to compile and run the HelloWorld example.

Compile the HelloWorld source code:

bazel build //examples/helloworld/...

Run HelloWorld

After the HelloWorld is successfully compiled, you can run the server:

./bazel-bin/examples/helloworld/helloworld_svr --config=./examples/helloworld/conf/trpc_cpp_fiber.yaml

Then, open another terminal and run the client to send RPC requests to server:

./bazel-bin/examples/helloworld/test/fiber_client --client_config=./examples/helloworld/test/conf/trpc_cpp_fiber.yaml

After client done, you will see the following output in client's terminal:

FLAGS_service_name:trpc.test.helloworld.Greeter
FLAGS_client_config:./examples/helloworld/test/conf/trpc_cpp_fiber.yaml
get rsp msg: Hello, fiber

At the same time, you can also check the server log file helloworld_fiber.log in project root directory of trpc-cpp:

cat helloworld_fiber.log

You will see the following output:

[2023-08-25 15:30:56.587] [default] [info] [greeter_service.cc:37] remote address: 127.0.0.1:46074
[2023-08-25 15:30:56.587] [default] [info] [greeter_service.cc:38] request message: fiber

Congratulations! You’ve just successfully run a client-server application with tRPC-Cpp.

How to add a new RPC method

Now you can do some modifcation to HelloWorld project, how about adding a new RPC method.

Update the service definition

First, let's update service definition. You can find it in the file examples/helloworld/helloworld.proto (using protocol buffers IDL). It shows that, for RPC method SayHello in service Greeter, server recives HelloRequest type message from client and sends back HelloReply type message as serving response.

syntax = "proto3";

package trpc.test.helloworld;

service Greeter {
  rpc SayHello (HelloRequest) returns (HelloReply) {}
}

message HelloRequest {
   string msg = 1;
}

message HelloReply {
   string msg = 1;
}

Add a new SayHelloAgain method, with the same message types as SayHello.

syntax = "proto3";
 
package trpc.demo.helloworld;

service Greeter {
  rpc SayHello (HelloRequest) returns (HelloReply) {}

  rpc SayHelloAgain (HelloRequest) returns (HelloReply) {}
}

message HelloRequest {
  string msg = 1;
}

message HelloReply {
  string msg = 1;
}

Update the server code

After adding a RPC method for service, you need implement it in server side.

Open the file examples/helloworld/greeter_service.h and add method declartion SayHelloAgain to GreeterServiceImpl.

class GreeterServiceImpl : public ::trpc::test::helloworld::Greeter {
 public:
  ::trpc::Status SayHello(::trpc::ServerContextPtr context,
                          const ::trpc::test::helloworld::HelloRequest* request,
                          ::trpc::test::helloworld::HelloReply* reply) override;

  ::trpc::Status SayHelloAgain(::trpc::ServerContextPtr context,
                               const ::trpc::test::helloworld::HelloRequest* request,
                               ::trpc::test::helloworld::HelloReply* reply) override;
};

Open the file examples/helloworld/greeter_service.cc and add method implementation of SayHelloAgain to GreeterServiceImpl.

::trpc::Status GreeterServiceImpl::SayHelloAgain(::trpc::ServerContextPtr context,
                                                 const ::trpc::test::helloworld::HelloRequest* request,
                                                 ::trpc::test::helloworld::HelloReply* reply) {
  // Your can access more information from rpc context, eg: remote ip and port
  TRPC_FMT_INFO("remote address: {}:{}", context->GetIp(), context->GetPort());
  TRPC_FMT_INFO("request message: {}", request->msg());

  std::string response = "Hello, ";
  response += request->msg();
  response += " Again";

  reply->set_msg(response);

  return ::trpc::kSuccStatus;
}

Update the client code

Now the server serves method SayHelloAgain, you can asscess it via do a RPC call in client.

The stub code auto-generated using updated proto file already contains SayHelloAgain function, you can simply invoke it. Referencing code snippets that calls SayHello, you can add below code in examples/helloworld/test/fiber_client.cc after DoRpcCall function:

int DoRpcCallAgain(const std::shared_ptr<::trpc::test::helloworld::GreeterServiceProxy>& proxy) {
  ::trpc::ClientContextPtr client_ctx = ::trpc::MakeClientContext(proxy);
  ::trpc::test::helloworld::HelloRequest req;
  req.set_msg("fiber");
  ::trpc::test::helloworld::HelloReply rsp;
  ::trpc::Status status = proxy->SayHelloAgain(client_ctx, req, &rsp);
  if (!status.OK()) {
    std::cerr << "get again rpc error: " << status.ErrorMessage() << std::endl;
    return -1;
  }
  std::cout << "get again rsp msg: " << rsp.msg() << std::endl;
  return 0;
}

Then, you should add code to invoke DoRpcCallAgain in the Run function, as below:

int Run() {
  auto proxy = ::trpc::GetTrpcClient()->GetProxy<::trpc::test::helloworld::GreeterServiceProxy>(FLAGS_service_name);

  int ret = DoRpcCall(proxy);

  ret = DoRpcCallAgain(proxy);

  return ret;
}

Run

Compile the updated HelloWorld code

bazel build //examples/helloworld/...

Run the updated HelloWorld server:

./bazel-bin/examples/helloworld/helloworld_svr --config=./examples/helloworld/conf/trpc_cpp_fiber.yaml

Open another terminal and run the client to send RPC requests to server:

./bazel-bin/examples/helloworld/test/fiber_client --client_config=./examples/helloworld/test/conf/trpc_cpp_fiber.yaml

After client done, you will see the following output in client's terminal:

FLAGS_service_name:trpc.test.helloworld.Greeter
FLAGS_client_config:./examples/helloworld/test/conf/trpc_cpp_fiber.yaml
get rsp msg: Hello, fiber
get again rsp msg: Hello, fiber Again

What's next