go get google.golang.org/grpc
go get google.golang.org/protobuf

syntax = "proto3";
package template;
option go_package = "../chat";
message Message{
  string body = 1;
}
service ChatService{
  rpc SayHello(Message) returns (Message){}
  rpc BroadcastMessage2(Message) returns (Message) {}
}

protoc --go_out=plugins=grpc:chat ./chat/chat.proto

package chat
import (
   "context"
   "log"
)
type Server struct {
}
func (receiver \*Server) SayHello(ctx context.Context, in \*Message) (*Message, error) {
   log.Printf("Receive message body from client: %s", in.Body)
   return &Message{Body: "Hello From the Server!"}, nil
}
func (receiver \*Server) Test(ctx context.Context, in \*Message) (*Message, error) {
   log.Printf("test new message from a client: %s", in.Body)
   return &Message{Body: "test message!"}, nil
}

package main
import (
   "fmt"
   "google.golang.org/grpc"
   "grpc-study/chat"
   "log"
   "net"
)
func main() {
   fmt.Println("Go gRPC Beginners Tutorial!")
   listen, err := net.Listen("tcp", ":9000")
   if err != nil {
      log.Fatalf("failed to listen: %v", err)
   }
   grpcServer := grpc.NewServer()
   s := chat.Server{}
   chat.RegisterChatServiceServer(grpcServer, &s)
   if err := grpcServer.Serve(listen); err != nil {
      log.Fatalf("failed to serve: %s", err)
   }
}

package main
import (
   "context"
   "google.golang.org/grpc"
   "grpc-study/chat"
   "log"
   "time"
)
func main() {
   var conn *grpc.ClientConn
   conn, err := grpc.Dial(":9000", grpc.WithInsecure())
   if err != nil {
      log.Fatalf("did not connect: %s \\n", err)
   }
   defer conn.Close()
   c := chat.NewChatServiceClient(conn)
   for true {
      response, err := c.SayHello(context.Background(), &chat.Message{Body: "66666"})
      if err != nil {
         log.Fatalf("Error when calling SayHello: %s", err)
      }
      log.Printf("Response from server: %s", response.Body)
      broadcastMessage, err := c.Test(context.Background(), &chat.Message{Body: "123"})
      if err != nil {
         log.Fatalf("Error when calling Broadcast Message: %s", err)
      }
      log.Printf("Response from server: %s", broadcastMessage.Body)
      time.Sleep(1*time.Second)
   }
}