go语言的RPC编程

服务端代码：服务端接收student分数，返回Performance成绩评级和评语。package mainimport (    "log"    "net"    "net/http"    "net/rpc")type Student struct {    Name  string    Score float64}type Performance struct {    Name    string    Grade   rune    Comment string}type RpcServer intfunc (r *RpcServer) SetGrade(s *Student, p *Performance) error {    p.Name = s.Name    if s.Score >= 80 {        p.Grade = 'A'        p.Comment = "Very good!"    } else if s.Score >= 60 && s.Score        p.Grade = 'B'        p.Comment = "Good!"    } else {        p.Grade = 'C'        p.Comment = "Bad!"    }    return nil}func main() {    rpcser := new(RpcServer)    rpc.Register(rpcser)    rpc.HandleHTTP()    listen, err := net.Listen("tcp", "172.16.1.28:1234")    if err != nil {        log.Fatal("Server starting error:", err)    }    http.Serve(listen, nil)}客户端：调用服务端方法，得到该student的成绩评级和评语。package mainimport (    "fmt"    "log"    "net/rpc")type Student struct {    Name  string    Score float64}type Performance struct {    Name    string    Grade   rune    Comment string}func main() {    var performance Performance    client, err := rpc.DialHTTP("tcp", "172.16.1.28:1234")    if err != nil {        log.Fatal("dialing:", err)    }    stu := &Student{        Name:  "Tom",        Score: 90,    }    err = client.Call("RpcServer.SetGrade", stu, &performance)    if err != nil {        log.Fatal("RpcServer error:", err)    }    fmt.Printf("%s:Grade:%c,Comment:%s\n", performance.Name, performance.Grade, performance.Comment)}