gRPC简介及简单使用(C++)

曾经终败给现在 2024-04-18 14:47 108阅读 0赞

gRPC是一个现代的、开源的、高性能远程过程调用(RPC)框架，可以在任何平台运行。gRPC使客户端和服务器端应用程序能够透明地进行通信，并简化了连接系统的构建。gRPC支持的语言包括C++、Ruby、Python、Java、Go等。

gRPC默认使用Google的Protocol Buffers，关于Protocol Buffers的介绍可以参考：[https://blog.csdn.net/fengbingchun/article/details/49977903][https_blog.csdn.net_fengbingchun_article_details_49977903]

gRPC的源码在[https://github.com/grpc/grpc][https_github.com_grpc_grpc]，最新版本的版本为v1.23.0，它的license是Apache-2.0。

关于RPC(Remote Procedure Call, 远程过程调用)的介绍可以参考：[https://blog.csdn.net/fengbingchun/article/details/92406377][https_blog.csdn.net_fengbingchun_article_details_92406377]

关于gRPC的安装可以参考：[https://blog.csdn.net/fengbingchun/article/details/100608370][https_blog.csdn.net_fengbingchun_article_details_100608370]

下面参考gRPC官方examples/cpp/helloworld中的**同步模式**例子，过程如下：

1. 创建IDL(interface definition language)描述文件helloworld.proto，通过protobuf定义服务端与客户端之间的RPC调用接口，通过protoc工具生成客户端和服务端代码。gRPC是需要先定义服务接口约定，才可以进行RPC调用，使用.proto可以同时定义客户端和服务端交换的数据格式以及RPC调用的接口。helloworld.proto文件内容如下：

// Copyright 2015 gRPC authors.
    
    syntax = "proto3";
    
    option java_multiple_files = true;
    option java_package = "io.grpc.examples.helloworld";
    option java_outer_classname = "HelloWorldProto";
    option objc_class_prefix = "HLW";
    
    package helloworld;
    
    // The greeting service definition.
    service Greeter {
      // Sends a greeting
      rpc SayHello (HelloRequest) returns (HelloReply) {}
    }
    
    // The request message containing the user's name.
    message HelloRequest {
      string name = 1;
    }
    
    // The response message containing the greetings
    message HelloReply {
      string message = 1;
    }

通过protoc工具生成服务端和客户端代码，执行命令(终端定位在demo/gRGC\_Test)如下：

./../../src/grpc/linux_install/bin/protoc --cpp_out=./ helloworld.proto
    ./../../src/grpc/linux_install/bin/protoc --grpc_out=./ --plugin=protoc-gen-grpc=./../../src/grpc/linux_install/bin/grpc_cpp_plugin helloworld.proto

会在当前目录下生成helloworld.pb.h, hellowrold.pb.cc, helloworld.grpc.pb.h, helloworld.grpc.pb.cc四个文件。使用IDL定义服务端方法、参数、返回类型，客户端和服务端都使用从服务端定义生成的接口代码。

2. 编写客户端代码，测试代码函数为test\_grpc\_client；

3. 编写服务端代码，测试代码函数为test\_grpc\_server；

#include "funset.hpp"
    #include <iostream>
    #include <memory>
    #include <string>
    #include <grpcpp/grpcpp.h>
    #include "helloworld.grpc.pb.h"
    
    // reference: grpc/examples/cpp/helloworld
    namespace {
    
    class GreeterClient {
    public:
    	GreeterClient(std::shared_ptr<grpc::Channel> channel) : stub_(helloworld::Greeter::NewStub(channel)) {}
    
    	// Assembles the client's payload, sends it and presents the response back from the server.
      	std::string SayHello(const std::string& user) {
        		// Data we are sending to the server.
        		helloworld::HelloRequest request;
        		request.set_name(user);
    
        		// Container for the data we expect from the server.
        		helloworld::HelloReply reply;
    
        		// Context for the client. It could be used to convey extra information to the server and/or tweak certain RPC behaviors.
        		grpc::ClientContext context;
    
        		// The actual RPC.
        		grpc::Status status = stub_->SayHello(&context, request, &reply);
    
        		// Act upon its status.
        		if (status.ok()) {
          			return reply.message();
        		} else {
          			fprintf(stderr, "error code: %d, error message: %s\n", status.error_code(), status.error_message().c_str());
          			return "RPC failed";
       		}	
      	}	
    
    private:
      	std::unique_ptr<helloworld::Greeter::Stub> stub_;
    };
    
    } // namespace
    
    int test_grpc_client()
    {
    	fprintf(stdout, "client start\n");
      	// Instantiate the client. It requires a channel, out of which the actual RPCs are created.
    	// This channel models a connection to an endpoint (in this case, localhost at port 50051).
    	// We indicate that the channel isn't authenticated(use of InsecureChannelCredentials()).
      	GreeterClient greeter(grpc::CreateChannel("localhost:50051", grpc::InsecureChannelCredentials()));
      	std::string user("world");
      	std::string reply = greeter.SayHello(user);
      	fprintf(stdout, "Greeter received: %s\n", reply.c_str());
    
    	return 0;
    }
    
    namespace {
    
    // Logic and data behind the server's behavior.
    class GreeterServiceImpl final : public helloworld::Greeter::Service {
      	grpc::Status SayHello(grpc::ServerContext* context, const helloworld::HelloRequest* request, helloworld::HelloReply* reply) override {
        		std::string prefix("Hello ");
        		reply->set_message(prefix + request->name());
        		return grpc::Status::OK;
      	}
    };
    
    void RunServer() {
      	std::string server_address("0.0.0.0:50051");
      	GreeterServiceImpl service;
    
      	grpc::ServerBuilder builder;
      	// Listen on the given address without any authentication mechanism.
      	builder.AddListeningPort(server_address, grpc::InsecureServerCredentials());
      	// Register "service" as the instance through which we'll communicate with clients.
    	// In this case it corresponds to an *synchronous* service.
      	builder.RegisterService(&service);
      	// Finally assemble the server.
      	std::unique_ptr<grpc::Server> server(builder.BuildAndStart());
      	fprintf(stdout, "Server listening on: %s\n", server_address.c_str());
    
      	// Wait for the server to shutdown. Note that some other thread must be
      	// responsible for shutting down the server for this call to ever return.
      	server->Wait();
    }
    
    } // namespace
    
    int test_grpc_server()
    {
    	fprintf(stdout, "server start\n");
    	RunServer();
    
    	return 0;
    }

4. 先在一个终端启动服务端程序，再在另一个终端启动客户端程序，执行结果如下：

![2019090813391865.png][]

![20190908133930206.png][]

**GitHub**：[https://github.com/fengbingchun/OpenSSL\_Test][https_github.com_fengbingchun_OpenSSL_Test]

[https_blog.csdn.net_fengbingchun_article_details_49977903]: https://blog.csdn.net/fengbingchun/article/details/49977903
[https_github.com_grpc_grpc]: https://github.com/grpc/grpc
[https_blog.csdn.net_fengbingchun_article_details_92406377]: https://blog.csdn.net/fengbingchun/article/details/92406377
[https_blog.csdn.net_fengbingchun_article_details_100608370]: https://blog.csdn.net/fengbingchun/article/details/100608370
[2019090813391865.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/18/64b6d9ce0557442aa03eb6f402f0460e.png
[20190908133930206.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/18/ec3173955afc4db49fad45abe1ce31cb.png
[https_github.com_fengbingchun_OpenSSL_Test]: https://github.com/fengbingchun/OpenSSL_Test