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Last active August 29, 2015 14:09
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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.

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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()
}
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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>
Raw
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()
}
}
}
}
}
Raw
main.go
package main
import (
"flag"
"go/build"
"log"
"net/http"
"path/filepath"
"text/template"
)
var (
addr = flag.String("addr", ":8080", "http service address")
assets = flag.String("assets", defaultAssetPath(), "path to assets")
homeTempl *template.Template
)
func defaultAssetPath() string {
p, err := build.Default.Import("gary.burd.info/go-websocket-chat", "", build.FindOnly)
if err != nil {
return "."
}
return p.Dir
}
func homeHandler(c http.ResponseWriter, req *http.Request) {
homeTempl.Execute(c, req.Host)
}
func main() {
flag.Parse()
homeTempl = template.Must(template.ParseFiles(filepath.Join(*assets, "home.html")))
go h.run()
http.HandleFunc("/", homeHandler)
http.HandleFunc("/ws", wsHandler)
if err := http.ListenAndServe(*addr, nil); err != nil {
log.Fatal("ListenAndServe:", err)
}
}
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