gRPC-demo

gRPC是由google开发，是一款跨平台，跨语言，开源的远程过程调用(RPC)系统。Docker v1.12.3就是通过gRPC调用containerd的。所以本次笔记介绍基于官方例子改写的一个例子，分别用Go和Python实现。

环境搭建

略(由于google.golang.org被墙，所以我是通过containerd源码包中的src来解决依赖的，不方便)。

proto

gRPC的序列化由protobuf完成。我们先定义helloworld.proto文件，里面定义了Greeter service, HelloRequest message和HelloReply。其中HelloRequest message定义了普通变量，enum变量，数组变量及oneof和any变量。

syntax = "proto3";

option java_package = "io.grpc.examples";

package helloworld;
import "google/protobuf/any.proto";

// The greeter 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;
  enum Gender {
    FEMALE = 0;
    MALE = 1;
  }
  Gender gender = 2;
  repeated string hobbies = 3;
  oneof office {
    string school = 4;
    string company = 5;
  }
  map<string, string> phone = 6;
  google.protobuf.Any other = 7;
}

// The response message containing the greetings
message HelloReply {
  string message = 1;
}

使用protoc --go_out=plugins=grpc:. helloworld.proto可生成helloworld.pb.go文件，即Go语言需要调用的文件。
使用python -m grpc_tools.protoc -I. --python_out=. --grpc_python_out=. helloworld.proto可生成helloworld_pb2_grpc.py和helloworld_pb2.py文件，即Python语言需要调用的文件。

Go

server.go

package main

// server.go

import (
	"log"
	"fmt"
	"net"

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

const (
	port = ":50051"
)

type server struct {}

func (s *server) SayHello(ctx context.Context, in *pb.HelloRequest) (*pb.HelloReply, error) {
	name := fmt.Sprintf("%q", in.GetName())
	hobbies := fmt.Sprintf("%q", in.GetHobbies())
	gender := fmt.Sprintf("%q", in.GetGender())
	office := fmt.Sprintf("%q", in.GetOffice())
	phone := fmt.Sprintf("%q", in.GetPhone())
	other := fmt.Sprintf("%q", in.GetOther().GetValue())
	return &pb.HelloReply{Message: "Name: " + name + " , Gender: " + gender + " , Hobbies: " + hobbies + " , Office: " + office + ", Phone: " + phone + " , Other: " + other}, nil
}

func main() {
	lis, err := net.Listen("tcp", port)
	if err != nil {
		log.Fatal("failed to listen: %v", err)
	}
	s := grpc.NewServer()
	pb.RegisterGreeterServer(s, &server{})
	s.Serve(lis)
}

client.go

package main

//client.go

import (
	"log"
	"os"

	"golang.org/x/net/context"
	"google.golang.org/grpc"
	"github.com/golang/protobuf/ptypes/any"
	pb "helloworld/helloworld"
)

const (
	address     = "127.0.0.1:50051"
	defaultName = "Jack"
)

func main() {
	conn, err := grpc.Dial(address, grpc.WithInsecure())
	if err != nil {
		log.Fatal("did not connect: %v", err)
	}
	defer conn.Close()
	c := pb.NewGreeterClient(conn)

	name := defaultName
	if len(os.Args) >1 {
		name = os.Args[1]
	}
	gender := pb.HelloRequest_MALE
	hobbies := []string{"swimming", "running", "football"}
	office := &pb.HelloRequest_School{"Fudan University"}
	phone := map[string]string{"telephphone": "13900010001", "phone": "123456"}
	other := &any.Any{Value: []byte("This is my greet!")}
	request := pb.HelloRequest{Name: name, Gender: gender, Hobbies: hobbies, Office: office, Phone: phone, Other: other}
	r, err := c.SayHello(context.Background(), &request)
	if err != nil {
		log.Fatal("could not greet: %v", err)
	}
	log.Printf("Greeting from: %s", r.Message)
}

运行go run server.go和go run client.go，在client端，可得到：

2017/11/11 15:57:23 Greeting from: Name: "Jack" , Gender: "MALE" , Hobbies: ["swimming" "running" "football"] , Office: &{"Fudan University"}, Phone: map["phone":"123456" "telephphone":"13900010001"] , Other: "This is my greet!"

Python

server.py:

"""The Python implementation of the GRPC helloworld.Greeter server."""

from concurrent import futures
import time
import string

import grpc

from helloworld import helloworld_pb2
from helloworld import helloworld_pb2_grpc

_ONE_DAY_IN_SECONDS = 60 * 60 * 24


class Greeter(helloworld_pb2_grpc.GreeterServicer):
    def SayHello(self, request, context):
        name = request.name
        hobbies = request.hobbies
        gender = ""
        if request.gender == helloworld_pb2.HelloRequest.MALE:
            gender = "MALE"
        else:
            gender = "FEMALE"
        office = request.school
        phone = request.phone
        other = request.other.value
        message = "Name: " + name + " , Gender: " + gender + " , Hobbies: " + str(hobbies) + " , Office: " + office + ", Phone: " + str(phone.items()) + " , Other: " + other
        return helloworld_pb2.HelloReply(message=message)


def serve():
    server = grpc.server(futures.ThreadPoolExecutor(max_workers=10))
    helloworld_pb2_grpc.add_GreeterServicer_to_server(Greeter(), server)
    server.add_insecure_port('[::]:50051')
    server.start()
    try:
        while True:
            time.sleep(_ONE_DAY_IN_SECONDS)
    except KeyboardInterrupt:
        server.stop(0)

if __name__ == '__main__':
    serve()

client.py

from __future__ import print_function

import grpc

from helloworld import helloworld_pb2
from helloworld import helloworld_pb2_grpc
from google.protobuf import any_pb2

def run():
    channel = grpc.insecure_channel('127.0.0.1:50051')
    stub = helloworld_pb2_grpc.GreeterStub(channel)
    name = "Jack"
    gender = "MALE"
    hobbies = ["swimming", "running", "football"]
    school = "Fudan"
    phone = {"telephphone": "13900010001", "phone": "123456"}
    other = any_pb2.Any(value="This is my greet!")
    request = helloworld_pb2.HelloRequest(name=name, gender=gender, hobbies=hobbies, school=school, phone=phone, other=other)
    response = stub.SayHello(request)
    print(response.message)

if __name__ == '__main__':
    run()

运行python server.go和python client.go，在client端，可得到：

Name: Jack , Gender: MALE , Hobbies: [u'swimming', u'running', u'football'] , Office: Fudan, Phone: [(u'phone', u'123456'), (u'telephphone', u'13900010001')] , Other: This is my greet!

总结

protobuf的语法网上有很多资源。需要着重说明的是，上面的server.py和client.go也可以得到正确的结果，这充分说明了gRPC是跨语言的，很神奇。