AndreasBriese/A_WebSocket_Example.md

## A_WebSocket_Example.md

      
    Raw
  

              A_WebSocket_Example.md
            
          
    This gist is the source code for http://gary.beagledreams.com/page/go-websocket-chat.html
Copyright (c) 2013 Gary Burd
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.

  
## conn.go
package main

import (
	"github.com/gorilla/websocket"
	"net/http"
)

type connection struct {
	// The websocket connection.
	ws *websocket.Conn

	// Buffered channel of outbound messages.
	send chan []byte
}

func (c *connection) reader() {
	for {
		_, message, err := c.ws.ReadMessage()
		if err != nil {
			break
		}
		h.broadcast <- message
	}
	c.ws.Close()
}

func (c *connection) writer() {
	for message := range c.send {
		err := c.ws.WriteMessage(websocket.TextMessage, message)
		if err != nil {
			break
		}
	}
	c.ws.Close()
}

func wsHandler(w http.ResponseWriter, r *http.Request) {
	ws, err := websocket.Upgrade(w, r, nil, 1024, 1024)
	if _, ok := err.(websocket.HandshakeError); ok {
		http.Error(w, "Not a websocket handshake", 400)
		return
	} else if err != nil {
		return
	}
	c := &connection{send: make(chan []byte, 256), ws: ws}
	h.register <- c
	defer func() { h.unregister <- c }()
	go c.writer()
	c.reader()
}

## home.html
<html>
<head>
<title>Chat Example</title>
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js"></script>
<script type="text/javascript">
    $(function() {

    var conn;
    var msg = $("#msg");
    var log = $("#log");

    function appendLog(msg) {
        var d = log[0]
        var doScroll = d.scrollTop == d.scrollHeight - d.clientHeight;
        msg.appendTo(log)
        if (doScroll) {
            d.scrollTop = d.scrollHeight - d.clientHeight;
        }
    }

    $("#form").submit(function() {
        if (!conn) {
            return false;
        }
        if (!msg.val()) {
            return false;
        }
        conn.send(msg.val());
        msg.val("");
        return false
    });

    if (window["WebSocket"]) {
        conn = new WebSocket("ws://{{$}}/ws");
        conn.onclose = function(evt) {
            appendLog($("<div><b>Connection closed.</b></div>"))
        }
        conn.onmessage = function(evt) {
            appendLog($("<div/>").text(evt.data))
        }
    } else {
        appendLog($("<div><b>Your browser does not support WebSockets.</b></div>"))
    }
    });
</script>
<style type="text/css">
html {
    overflow: hidden;
}

body {
    overflow: hidden;
    padding: 0;
    margin: 0;
    width: 100%;
    height: 100%;
    background: gray;
}

#log {
    background: white;
    margin: 0;
    padding: 0.5em 0.5em 0.5em 0.5em;
    position: absolute;
    top: 0.5em;
    left: 0.5em;
    right: 0.5em;
    bottom: 3em;
    overflow: auto;
}

#form {
    padding: 0 0.5em 0 0.5em;
    margin: 0;
    position: absolute;
    bottom: 1em;
    left: 0px;
    width: 100%;
    overflow: hidden;
}

</style>
</head>
<body>
<div id="log"></div>
<form id="form">
    <input type="submit" value="Send" />
    <input type="text" id="msg" size="64"/>
</form>
</body>
</html>

## hub.go
package main

type hub struct {
	// Registered connections.
	connections map[*connection]bool

	// Inbound messages from the connections.
	broadcast chan []byte

	// Register requests from the connections.
	register chan *connection

	// Unregister requests from connections.
	unregister chan *connection
}

var h = hub{
	broadcast:   make(chan []byte),
	register:    make(chan *connection),
	unregister:  make(chan *connection),
	connections: make(map[*connection]bool),
}

func (h *hub) run() {
	for {
		select {
		case c := <-h.register:
			h.connections[c] = true
		case c := <-h.unregister:
			delete(h.connections, c)
			close(c.send)
		case m := <-h.broadcast:
			for c := range h.connections {
				select {
				case c.send <- m:
				default:
					delete(h.connections, c)
					close(c.send)
					go c.ws.Close()
				}
			}
		}
	}
}

## main.go
package main

import (
	"flag"
	"log"
	"net/http"
	"text/template"
)

var addr = flag.String("addr", ":8080", "http service address")
var homeTempl = template.Must(template.ParseFiles("home.html"))

func homeHandler(c http.ResponseWriter, req *http.Request) {
	homeTempl.Execute(c, req.Host)
}

func main() {
	flag.Parse()
	go h.run()
	http.HandleFunc("/", homeHandler)
	http.HandleFunc("/ws", wsHandler)
	if err := http.ListenAndServe(*addr, nil); err != nil {
		log.Fatal("ListenAndServe:", err)
	}
}
	package main

	import (
	"github.com/gorilla/websocket"
	"net/http"
	)

	type connection struct {
	// The websocket connection.
	ws *websocket.Conn

	// Buffered channel of outbound messages.
	send chan []byte
	}

	func (c *connection) reader() {
	for {
	_, message, err := c.ws.ReadMessage()
	if err != nil {
	break
	}
	h.broadcast <- message
	}
	c.ws.Close()
	}

	func (c *connection) writer() {
	for message := range c.send {
	err := c.ws.WriteMessage(websocket.TextMessage, message)
	if err != nil {
	break
	}
	}
	c.ws.Close()
	}

	func wsHandler(w http.ResponseWriter, r *http.Request) {
	ws, err := websocket.Upgrade(w, r, nil, 1024, 1024)
	if _, ok := err.(websocket.HandshakeError); ok {
	http.Error(w, "Not a websocket handshake", 400)
	return
	} else if err != nil {
	return
	}
	c := &connection{send: make(chan []byte, 256), ws: ws}
	h.register <- c
	defer func() { h.unregister <- c }()
	go c.writer()
	c.reader()
	}
	<html>
	<head>
	<title>Chat Example</title>
	<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js"></script>
	<script type="text/javascript">
	$(function() {

	var conn;
	var msg = $("#msg");
	var log = $("#log");

	function appendLog(msg) {
	var d = log[0]
	var doScroll = d.scrollTop == d.scrollHeight - d.clientHeight;
	msg.appendTo(log)
	if (doScroll) {
	d.scrollTop = d.scrollHeight - d.clientHeight;
	}
	}

	$("#form").submit(function() {
	if (!conn) {
	return false;
	}
	if (!msg.val()) {
	return false;
	}
	conn.send(msg.val());
	msg.val("");
	return false
	});

	if (window["WebSocket"]) {
	conn = new WebSocket("ws://{{$}}/ws");
	conn.onclose = function(evt) {
	appendLog($("<div><b>Connection closed.</b></div>"))
	}
	conn.onmessage = function(evt) {
	appendLog($("<div/>").text(evt.data))
	}
	} else {
	appendLog($("<div><b>Your browser does not support WebSockets.</b></div>"))
	}
	});
	</script>
	<style type="text/css">
	html {
	overflow: hidden;
	}

	body {
	overflow: hidden;
	padding: 0;
	margin: 0;
	width: 100%;
	height: 100%;
	background: gray;
	}

	#log {
	background: white;
	margin: 0;
	padding: 0.5em 0.5em 0.5em 0.5em;
	position: absolute;
	top: 0.5em;
	left: 0.5em;
	right: 0.5em;
	bottom: 3em;
	overflow: auto;
	}

	#form {
	padding: 0 0.5em 0 0.5em;
	margin: 0;
	position: absolute;
	bottom: 1em;
	left: 0px;
	width: 100%;
	overflow: hidden;
	}

	</style>
	</head>
	<body>
	<div id="log"></div>
	<form id="form">
	<input type="submit" value="Send" />
	<input type="text" id="msg" size="64"/>
	</form>
	</body>
	</html>
	package main

	type hub struct {
	// Registered connections.
	connections map[*connection]bool

	// Inbound messages from the connections.
	broadcast chan []byte

	// Register requests from the connections.
	register chan *connection

	// Unregister requests from connections.
	unregister chan *connection
	}

	var h = hub{
	broadcast: make(chan []byte),
	register: make(chan *connection),
	unregister: make(chan *connection),
	connections: make(map[*connection]bool),
	}

	func (h *hub) run() {
	for {
	select {
	case c := <-h.register:
	h.connections[c] = true
	case c := <-h.unregister:
	delete(h.connections, c)
	close(c.send)
	case m := <-h.broadcast:
	for c := range h.connections {
	select {
	case c.send <- m:
	default:
	delete(h.connections, c)
	close(c.send)
	go c.ws.Close()
	}
	}
	}
	}
	}
	package main

	import (
	"flag"
	"log"
	"net/http"
	"text/template"
	)

	var addr = flag.String("addr", ":8080", "http service address")
	var homeTempl = template.Must(template.ParseFiles("home.html"))

	func homeHandler(c http.ResponseWriter, req *http.Request) {
	homeTempl.Execute(c, req.Host)
	}

	func main() {
	flag.Parse()
	go h.run()
	http.HandleFunc("/", homeHandler)
	http.HandleFunc("/ws", wsHandler)
	if err := http.ListenAndServe(*addr, nil); err != nil {
	log.Fatal("ListenAndServe:", err)
	}
	}