这篇文章将会简单的描述一下grpc+protobuf 的C++ service的搭建过程，告诉读者在linux系统下怎样实现一个service接口的流程。

一、.proto文件的

实现一个简单的helloworld回显功能，首先需要一个.proto文件，我将它命名为example.proto，文件内容如下：

[cpp] view plain copy

syntax = "proto3";  message SearchRequest
{  string Request = 1;
}  message SearchResponse
{  string Response = 2;
}  service SearchService {  rpc Search (SearchRequest) returns (SearchResponse);
}

二、自动生成代码

使用example.proto文件自动生成grpc和protobuf的代码

[cpp] view plain copy

protoc --cpp_out=./ examples.proto
protoc --grpc_out=./ --plugin=protoc-gen-grpc=/usr/local/bin/grpc_cpp_plugin examples.proto

这两个命令将会生成四个文件，examples.grpc.pb.cc、examples.grpc.pb.h、examples.pb.cc、examples.pb.h。

三、服务器代码

[cpp] view plain copy

#include <iostream>
#include <memory>
#include <string>  #include <grpc++/grpc++.h>
#include <grpc/grpc.h>
#include <grpc++/server.h>
#include <grpc++/server_builder.h>
#include <grpc++/server_context.h>  #include "examples.grpc.pb.h"  using grpc::Server;
using grpc::ServerBuilder;
using grpc::ServerContext;
using grpc::Status;  class SearchRequestImpl final : public SearchService::Service {  Status Search(ServerContext* context, const SearchRequest* request,  SearchResponse* reply) override {  std::string prefix("Hello ");  reply->set_response(prefix + request->request());  return Status::OK;  }
};  void RunServer() {  std::string server_address("0.0.0.0:50051");  SearchRequestImpl service;  ServerBuilder builder;  builder.AddListeningPort(server_address, grpc::InsecureServerCredentials());  builder.RegisterService(&service);  std::unique_ptr<Server> server(builder.BuildAndStart());  std::cout << "Server listening on " << server_address << std::endl;  server->Wait();
}  int main(int argc, char** argv) {  RunServer();  return 0;
}

四、客户端代码

[cpp] view plain copy

#include <iostream>
#include <memory>
#include <string>  #include <grpc++/grpc++.h>
#include <grpc/support/log.h>  #include "examples.grpc.pb.h"  using grpc::Channel;
using grpc::ClientAsyncResponseReader;
using grpc::ClientContext;
using grpc::CompletionQueue;
using grpc::Status;  class ExampleClient {  public:  explicit ExampleClient(std::shared_ptr<Channel> channel)  : stub_(SearchService::NewStub(channel)) {}  std::string Search(const std::string& user) {  SearchRequest request;  request.set_request(user);  SearchResponse reply;  ClientContext context;  CompletionQueue cq;  Status status;  std::unique_ptr<ClientAsyncResponseReader<SearchResponse> > rpc(  stub_->AsyncSearch(&context, request, &cq));  rpc->Finish(&reply, &status, (void*)1);  void* got_tag;  bool ok = false;  GPR_ASSERT(cq.Next(&got_tag, &ok));  GPR_ASSERT(got_tag == (void*)1);  GPR_ASSERT(ok);  if (status.ok()) {  return reply.response();  } else {  return "RPC failed";  }  }  private:  std::unique_ptr<SearchService::Stub> stub_;
};  int main(int argc, char** argv) {  ExampleClient client(grpc::CreateChannel(  "localhost:50051", grpc::InsecureChannelCredentials()));  std::string user("world");  std::string reply = client.Search(user);  // The actual RPC call!  std::cout << "client received: " << reply << std::endl;  return 0;
}

五、Makefile文件

[cpp] view plain copy

subdir = ./  export PKG_CONFIG_PATH=/usr/local/lib/pkgconfig  SOURCES = $(wildcard $(subdir)*.cc)
SRCOBJS = $(patsubst %.cc,%.o,$(SOURCES))
CC = g++  %.o:%.cc  $(CC) -std=c++11 -I/usr/local/include -pthread -c $< -o $@  all: client server  client: examples.grpc.pb.o examples.pb.o examples_client.o  $(CC) $^ -L/usr/local/lib `pkg-config --libs grpc++ grpc` -Wl,--no-as-needed -lgrpc++_reflection -Wl,--as-needed -lprotobuf -lpthread -ldl -lssl -o $@  server: examples.grpc.pb.o examples.pb.o examples_server.o  $(CC) $^ -L/usr/local/lib `pkg-config --libs grpc++ grpc` -Wl,--no-as-needed -lgrpc++_reflection -Wl,--as-needed -lprotobuf -lpthread -ldl -lssl -o $@
#chmod 777 $@  clean:  sudo rm *.o

六、运行

运行./server启动service，在另一个端口运行./client 打印出：client received: Hello world表示两边已通，grpc+protobuf 搭建完成。