Golang : Serving HTTP and Websocket from different ports in a program example

Problem:

For some reason you want to split the port use by your program to serve HTTP and Web-socket traffic. How to write one program that is able to listen and serve HTTP/Web-socket traffics on different ports?

Solution:

Setup a http.NewServeMux() and http.ListenAndServe() for one port and launch it as go-routine. For example, one go-routine for handling web socket traffic and main routine in the program to handle HTTP traffic.

NOTE : Instead of web-socket, can you use for another HTTP server? Yes, of course.

Here you go!

 package main

 import (
 "fmt"
 "golang.org/x/net/websocket"
 "io"
 "net/http"
 )

 func homeHandler(w http.ResponseWriter, r *http.Request) {
 html := `<!DOCTYPE html>
 <html>
 <head>
 <title>One HTTP and Websocket serve with different ports example</title>
 <script src="http://code.jquery.com/jquery-1.11.3.min.js"></script>
 <script>
 $(function() {
 var ws = new WebSocket("ws://localhost:8082/"); // use port 8082 instead of 8080
 var $ul = $('#msg-list');

 $('#sendBtn').click(function(){
 var data = $('#name').val();
 ws.send(data);
 console.log("Sending data to HTTP server via Websocket via port 8082 :" + data);
 $('<li>').text(data).appendTo($ul);
 });
 });
 </script>
 </head>
 <body>
 <input id="name" type="text" />
 <input type="button" id="sendBtn" value="send"></input>
 <ul id="msg-list"></ul>
 </body></html>`

 w.Write([]byte(fmt.Sprintf(html)))
 }

 func wsHandler(ws *websocket.Conn) {
 fmt.Println("Receive data from : ", ws.LocalAddr())
 fmt.Println("Sending data to : ", ws.RemoteAddr())

 // echo back
 io.Copy(ws, ws)
 }

 func main() {
 mxWS := http.NewServeMux()
 mxWS.Handle("/", websocket.Handler(wsHandler))
 fmt.Println("Listen and serve websocket on :8082")
 go func() {
 http.ListenAndServe(":8082", mxWS)
 }()

 mxHTTP := http.NewServeMux()
 mxHTTP.HandleFunc("/", homeHandler)
 fmt.Println("Listen and serve HTTP on :8080")
 http.ListenAndServe(":8080", mxHTTP)
 }

Run the code and point your browser to http://localhost:8080. Open up the developer view to see the console messages.

References:

https://www.socketloop.com/tutorials/golang-web-javascript-to-server-side-websocket-example

Golang : Serving HTTP and Websocket from different ports in a program example

By Adam Ng

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