如何通过邮递员进行远程过程调用？

syntax = "proto3";

service Greeter {
  rpc SayHello (HelloRequest) returns (HelloReply) {}
}

message HelloRequest {
  string name = 1;
}

message HelloReply {
  string message = 1;
}

protoc --go_out=. --go-grpc_out=. greeter.proto

package main

import (
    "context"
    "log"
    "net"

    "google.golang.org/grpc"
    pb "path/to/your/proto"
)

type server struct {
    pb.UnimplementedGreeterServer
}

func (s *server) SayHello(ctx context.Context, in *pb.HelloRequest) (*pb.HelloRequest, error) {
    return &pb.HelloReply{Message: "Hello " + in.Name}, nil
}

func main() {
    lis, err := net.Listen("tcp", ":50051")
    if err != nil {
        log.Fatalf("failed to listen: %v", err)
    }
    s := grpc.NewServer()
    pb.RegisterGreeterServer(s, &server{})
    log.Printf("server listening at %v", lis.Addr())
    if err := s.Serve(lis); err != nil {
        log.Fatalf("failed to serve: %v", err)
    }
}

package main

import (
    "context"
    "log"
    "time"

    "google.golang.org/grpc"
    pb "path/to/your/proto"
)

func main() {
    conn, err := grpc.Dial("localhost:50051", grpc.WithInsecure())
    if err != nil {
        log.Fatalf("did not connect: %v", err)
    }
    defer conn.Close()
    c := pb.NewGreeterClient(conn)

    ctx, cancel := context.WithTimeout(context.Background(), time.Second)
    defer cancel()
    r, err := c.SayHello(ctx, &pb.HelloRequest{Name: "World"})
    if err != nil {
        log.Fatalf("could not greet: %v", err)
    }
    log.Printf("Greeting: %s", r.Message)
}