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:
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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
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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
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#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
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[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
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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。