package mainimport (	"net"	"strings"	"fmt"	"time"	"io"	"bytes"	"strconv"	"math"	"math/rand"	"sync")const (	SERVER_NETWORK = "tcp"	SERVER_ADDRESS = "127.0.0.1:8085"	DELIMITER = ‘\t‘)var wg sync.WaitGroupfunc main() {	wg.Add(2)	go serverGo()	time.Sleep(500 * time.Millisecond)	go clientGo(1)	wg.Wait()}func serverGo() {	defer wg.Done()	listener, err := net.Listen(SERVER_NETWORK, SERVER_ADDRESS)	if err != nil {		printServerLog("Listen Error: %s", err)		return	}	defer listener.Close()	printServerLog("Got listener for the server.(local address: %s)", listener.Addr())	for {		conn, err := listener.Accept()		if err != nil {			printServerLog("Accept Error: %s", err)		}		printServerLog("Established a connection with a client application,(remote address: %s)", conn.RemoteAddr())		go handleConn(conn)	}}func printLog(role string, sn int, format string, args ...interface{})  {	if !strings.HasSuffix(format, "\n") {		format += "\n"	}	fmt.Printf("%s[%d]: %s", role, sn, fmt.Sprintf(format, args...))}func printServerLog(format string, args ...interface{})  {	printLog("Server", 0, format, args...)}func printClientLog(sn int, format string, args ...interface{})  {	printLog("Cient", sn, format, args...)}func handleConn(conn net.Conn)  {	defer conn.Close()	for {		conn.SetDeadline(time.Now().Add(10 * time.Second))		// set read timeline 10s		strReq, err := read(conn)		if err != nil {			if err == io.EOF {				printServerLog("The connection is closed by another side.")			} else {				printServerLog("Read Error: %s", err)			}			break		}		printServerLog("Received request: %s", strReq)		intReq, err := strToInt32(strReq)		if err != nil {			n, err := write(conn, err.Error())			printServerLog("Sent error message (written %d bytes): %s", n, err)			continue		}		floatResp := cbrt(intReq)		respMsg := fmt.Sprintf("The cube root of %d is %f.", intReq, floatResp)		n, err := write(conn, respMsg)		if err != nil {			printServerLog("Sent response message (written %d bytes: %s).", n, respMsg)		}	}}func read(conn net.Conn) (string, error){	readBytes := make([]byte, 1)	var buffer bytes.Buffer	for {		_, err := conn.Read(readBytes)		if err != nil {			return "", err		}		readByte := readBytes[0]		if readByte == DELIMITER {			break		}		buffer.WriteByte(readByte)	}	return buffer.String(), nil}func strToInt32(str string) (int32, error){	i32, err := strconv.ParseInt(str, 10 ,32)	return int32(i32), err}func write(conn net.Conn, content string) (int, error) {	var buffer bytes.Buffer	buffer.WriteString(content)	buffer.WriteByte(DELIMITER)	return conn.Write(buffer.Bytes())}func cbrt(intReq int32) float64 {	return math.Cbrt(float64(intReq))}func clientGo(id int)  {	defer wg.Done()	conn, err := net.DialTimeout(SERVER_NETWORK, SERVER_ADDRESS, 2 * time.Second)	if err != nil {		printClientLog(id, "Dial Error: %s", err)		return	}	defer conn.Close()	printClientLog(id, "Connected to server.(remote address: %s,local address: %s)", conn.RemoteAddr(), conn.LocalAddr())	time.Sleep(200 * time.Millisecond)	requestNumber := 5	conn.SetDeadline(time.Now().Add(5 * time.Millisecond))	for i := 0; i< requestNumber; i++ {		req := rand.Int31()		n, err := write(conn, fmt.Sprintf("%d", req))		if err != nil {			printClientLog(id, "Write Error: %s", err)			continue		}		printClientLog(id, "Sent request (written %d bytes)", n)	}	for j := 0; j< requestNumber; j++ {		strResp, err := read(conn)		if err != nil {			if err == io.EOF {				printClientLog(id, "The connection is closed by another side.")			}else{				printClientLog(id, "Read Error: %s", err)			}			break		}		printClientLog(id, "Received response: %s", strResp)	}}