gRPC初接触

18 May 2017

Go
gRPC

最近在学习Golang, 所以把自己了解的一些框架和知识进行一个总结. 简单来说gRPC是一个基于Probuf的RPC系统, 特点是支持多语言, 跨平台调用

gRPC的工作流程

由于默认的protobuf生成器并不能直接生成RPC的相关代码, 所以要安装protoc-gen-go插件

protoc -I helloworld helloworld/helloworld.proto --go_out=plugins=grpc:helloworld

定义通信的proto文件
编译生成.pb.go文件
编写服务端代码, 注册对应的RPC调用函数
编写客户端代码

示例代码

helloworld.proto

syntax = "proto3";

option java_multiple_files = true;
option java_package = "io.grpc.examples.helloworld";
option java_outer_classname = "HelloWorldProto";

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;
}

server.go

package main

import (
	"log"
	"net"

	"golang.org/x/net/context"
	"google.golang.org/grpc"
	pb "google.golang.org/grpc/examples/helloworld/helloworld"
	"google.golang.org/grpc/reflection"
)

const (
	port = ":50051"
)

// server is used to implement helloworld.GreeterServer.
type server struct{}

// SayHello implements helloworld.GreeterServer
// 实现对应RPC接口的逻辑
func (s *server) SayHello(ctx context.Context, in *pb.HelloRequest) (*pb.HelloReply, error) {
	return &pb.HelloReply{Message: "Hello " + in.Name}, nil
}

func main() {
	lis, err := net.Listen("tcp", port)
	if err != nil {
		log.Fatalf("failed to listen: %v", err)
	}
	s := grpc.NewServer()
	// 注册对应的RPC服务
	pb.RegisterGreeterServer(s, &server{}) // server在helloworld.pb.go里有对应的接口定义
	// Register reflection service on gRPC server.
	reflection.Register(s)
	if err := s.Serve(lis); err != nil {
		log.Fatalf("failed to serve: %v", err)
	}
}

client.go

package main

import (
	"log"
	"os"

	"golang.org/x/net/context"
	"google.golang.org/grpc"
	pb "google.golang.org/grpc/examples/helloworld/helloworld"
)

const (
	address     = "localhost:50051"
	defaultName = "world"
)

func main() {
	// Set up a connection to the server.
	conn, err := grpc.Dial(address, grpc.WithInsecure())
	if err != nil {
		log.Fatalf("did not connect: %v", err)
	}
	defer conn.Close()
	c := pb.NewGreeterClient(conn)

	// Contact the server and print out its response.
	name := defaultName
	if len(os.Args) > 1 {
		name = os.Args[1]
	}
	// 远程调用服务器的SayHello函数
	r, err := c.SayHello(context.Background(), &pb.HelloRequest{Name: name})
	if err != nil {
		log.Fatalf("could not greet: %v", err)
	}
	log.Printf("Greeting: %s", r.Message)
}

参考资料

https://developers.google.com/protocol-buffers/docs/proto3