m0nocle · December 4, 2011 14:53
diff --git a/main.go b/main.go
 package main

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

 var addr = flag.String("addr", ":8080", "http service address")

 func main() {
 	flag.Parse()
 	go hub()
 	http.HandleFunc("/", homeHandler)
 	http.Handle("/ws", websocket.Handler(clientHandler))
 	if err := http.ListenAndServe(*addr, nil); err != nil {
 		log.Fatal("ListenAndServe:", err)
 	}
 }

 var messageChan = make(chan []byte)

 type subscription struct {
 	conn      *websocket.Conn
 	subscribe bool
 }

 var subscriptionChan = make(chan subscription)

 func hub() {
 	conns := make(map[*websocket.Conn]int)
 	for {
 		select {
 		case subscription := <-subscriptionChan:
 			if subscription.subscribe {
 				conns[subscription.conn] = 0
 			} else {
 				delete(conns, subscription.conn)
 			}
 		case message := <-messageChan:
 			for conn, _ := range conns {
 				if _, err := conn.Write(message); err != nil {
 					conn.Close()
 				}
 			}
 		}
 	}
 }

 func clientHandler(ws *websocket.Conn) {
 	defer func() {
 		subscriptionChan <- subscription{ws, false}
 		ws.Close()
 	}()

 	subscriptionChan <- subscription{ws, true}

 	for {
 		var b []byte
 		err := websocket.Message.Receive(ws, &b)
 		if err != nil {
 			break
 		}
 		messageChan <- b
 	}
 }

 // Handle home page requests.
 func homeHandler(c http.ResponseWriter, req *http.Request) {
 	homeTempl.Execute(c, req.Host)
 }

 var homeTempl = template.Must(template.New("home").Parse(`
 <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> `))
diff --git a/Makefile b/Makefile
 run: clean example
 	./example
 
 include $(GOROOT)/src/Make.inc

 TARG=example
 GOFILES=\
    main.go\

 include $(GOROOT)/src/Make.cmd
	package main

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

	var addr = flag.String("addr", ":8080", "http service address")

	func main() {
	flag.Parse()
	go hub()
	http.HandleFunc("/", homeHandler)
	http.Handle("/ws", websocket.Handler(clientHandler))
	if err := http.ListenAndServe(*addr, nil); err != nil {
	log.Fatal("ListenAndServe:", err)
	}
	}

	var messageChan = make(chan []byte)

	type subscription struct {
	conn *websocket.Conn
	subscribe bool
	}

	var subscriptionChan = make(chan subscription)

	func hub() {
	conns := make(map[*websocket.Conn]int)
	for {
	select {
	case subscription := <-subscriptionChan:
	if subscription.subscribe {
	conns[subscription.conn] = 0
	} else {
	delete(conns, subscription.conn)
	}
	case message := <-messageChan:
	for conn, _ := range conns {
	if _, err := conn.Write(message); err != nil {
	conn.Close()
	}
	}
	}
	}
	}

	func clientHandler(ws *websocket.Conn) {
	defer func() {
	subscriptionChan <- subscription{ws, false}
	ws.Close()
	}()

	subscriptionChan <- subscription{ws, true}

	for {
	var b []byte
	err := websocket.Message.Receive(ws, &b)
	if err != nil {
	break
	}
	messageChan <- b
	}
	}

	// Handle home page requests.
	func homeHandler(c http.ResponseWriter, req *http.Request) {
	homeTempl.Execute(c, req.Host)
	}

	var homeTempl = template.Must(template.New("home").Parse(`
	<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> `))
	run: clean example
	./example

	include $(GOROOT)/src/Make.inc

	TARG=example
	GOFILES=\
	main.go\

	include $(GOROOT)/src/Make.cmd