Simple PRC (Ping-Pong)

//  - proto/unary.proto - 
syntax = "proto3";

option go_package = "proto;unary_proto";

package ua.made.unary;

// The greeting service definition.
service Service {
  // Sends a greeting
  rpc Hello(Request) returns (Reply) {}
}

// The request message containing the user's name.
message Request { string message = 1; }

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

//  - server.go - 
// Package main implements a server for Greeter service.
package main

import (
	"context"
	"fmt"
	"log"
	"net"

	pb "github.com/butuzov/sandbox/grpc/simple-rpc/proto"
	"google.golang.org/grpc"
	"google.golang.org/grpc/reflection"
)

const (
	address = "localhost:4772"
)

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

var _ pb.ServiceServer = (*server)(nil)

// SayHello implements helloworld.GreeterServer
func (s *server) Hello(ctx context.Context, in *pb.Request) (*pb.Reply, error) {
	log.Printf("(incoming server) %#v \n", in.GetMessage())

	switch in.GetMessage() {
	case "Ping":
		return &pb.Reply{Message: "Pong"}, nil
	}

	return &pb.Reply{Message: "<echo>" + in.GetMessage()}, nil
}

func main() {
	listener, err := net.Listen("tcp", address)
	if err != nil {
		log.Fatalf("failed to listen: %v", err)
	}
	fmt.Println("SERVER RUNS@", listener.Addr().String())

	s := grpc.NewServer()
	pb.RegisterServiceServer(s, &server{})

	reflection.Register(s)

	log.Fatalf("failed to serve: %v", s.Serve(listener))
}

//  - client.go - 
package main

import (
	"context"
	"log"

	pb "github.com/butuzov/sandbox/grpc/simple-rpc/proto"
	"google.golang.org/grpc"
)

const (
	address = "localhost:4772"
)

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

	c := pb.NewServiceClient(conn)

	if response, err := c.Hello(context.Background(), &pb.Request{Message: "Ping"}); err != nil {
		log.Fatalf("Error connecting to server: %v", err)
	} else {
		log.Printf("(incoming client) %#v \n", response.GetMessage())
	}
}