Golang : Simple client server example



Tags : golang client-server connection listening port

This a quick tutorial on creating a bare bone client-server program with Golang. We will start with the server part first and then followed by client part. You can use this as a foundation to create your own client-server program.

server.go

 package main

 import (
  "fmt"
  "log"
  "net"
 )

 func handleConnection(c net.Conn) {

  log.Printf("Client %v connected.", c.RemoteAddr())

  // stuff to do... like read data from client, process it, write back to client
  // see what you can do with (c net.Conn) at
  // http://golang.org/pkg/net/#Conn

  // buffer := make([]byte, 4096)

  //for {
  //  n, err := c.Read(buffer)
  //  if err != nil || n == 0 {
  // c.Close()
  // break
  //  }
  //  n, err = c.Write(buffer[0:n])
  //  if err != nil {
  // c.Close()
  // break
  //  }
  // }
  log.Printf("Connection from %v closed.", c.RemoteAddr())
 }

 func main() {
  ln, err := net.Listen("tcp", ":6000")
  if err != nil {
 log.Fatal(err)
  }

  fmt.Println("Server up and listening on port 6000")

  for {
 conn, err := ln.Accept()
 if err != nil {
 log.Println(err)
 continue
 }
 go handleConnection(conn)
  }
 }

compile the server.go and run it as a background process :

./server &

then run the client on a separate machine(if possible) and connect to the server

client.go

 package main

 import (
 "fmt"
 "net"
 )

 func main() {
 hostName := "example.com" // change this
 portNum := "6000"

 conn, err := net.Dial("tcp", hostName+":"+portNum)

 if err != nil {
 fmt.Println(err)
 return
 }

 fmt.Printf("Connection established between %s and localhost.\n", hostName)
 fmt.Printf("Remote Address : %s \n", conn.RemoteAddr().String())
 fmt.Printf("Local Address : %s \n", conn.LocalAddr().String())

 }

Sample output :

For client

./client-dial

Connection established between socketloop.com and localhost.

Remote Address : 162.243.5.230:6000

Local Address : 192.168.1.65:49774

For server

./server

Server up and listening on port 6000

2015/05/09 08:55:55 Client 14.192.213.197:8017 connected.

2015/05/09 08:55:55 Connection from 14.192.213.197:8017 closed.

This should be the basis of creating client-server programs with Golang. Hope you find this tutorial useful.

Check out this example as well on establishing secure(SSL/TLS) connection between client-server :

https://www.socketloop.com/references/golang-crypto-tls-listen-and-newlistener-functions-example

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Tags : golang client-server connection listening port

By Adam Ng

IF you gain some knowledge or the information here solved your programming problem. Please consider donating to the less fortunate or some charities that you like. Apart from donation, planting trees, volunteering or reducing your carbon footprint will be great too.


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