Start Using HTML5 WebSockets Today
Tutorial Details
- Topic: WebSockets
- Difficulty: Easy
- Estimated Completion Time: 1 Hour
One of the coolest new features of HTML5 is WebSockets, which let us talk to the server without using AJAX requests. In this tutorial, we’ll review the process of running a WebSocket server in PHP, and then building a client to send and receive messages to it over the WebSocket protocol.
What are WebSockets?
WebSockets is a technique for two-way communication over one (TCP) socket, a type of PUSH technology. At the moment, it’s still being standardized by the W3C; however, the latest versions of Chrome and Safari have support for WebSockets.
What do WebSockets Replace?
Websockets can replace long-polling. This is an interesting concept; the client sends a request to the server – now, rather than the server responding with data it may not have, it essentially keeps the connection open until the fresh, up-to-date data is ready to be sent – the client next receives this, and sends another request. This has its benefits: decreased latency being one of them, as a connection which has already been opened does not require a new connection to be established. However, long-polling isn’t really a piece of fancy technology: it’s also possible for a request to time-out, and thus a new connection will be needed anyway.
Many Ajax applications makes use of the above – this can often be attributed to poor resource utilization.
Wouldn’t it be great if the server could wake up one morning and send its data to clients who are willing to listen without some sort of pre established connection? Welcome to the world of PUSH technology!
Step 1: Get the WebSocket Server
This tutorial will focus more on the client building rather than server implementation.
I’m using XAMPP on Windows 7 to run the PHP server locally. Grab a copy of phpwebsockets which is a WebSocket server in PHP. (Note: I experienced some problems with this version, I made some changes to it and will including it in the source files) There are various WebSocket implementations; if one doesn’t work, you can try another or just continue with the tutorial.
- jWebSocket (Java)
- web-socket-ruby (ruby)
- Socket IO-node (node.js)
Start the Apache server
Step 2: Change URLs and Ports
Change the server according to your setup, for example in setup.class.php:
public function __construct($host='localhost',$port=8000,$max=100)
{
$this->createSocket($host,$port);
}
Browse through the files and make changes where appropriate.
Step 3: Start Building the Client
Lets get a basic template up; this is my client.php file:
<!DOCTYPE html>
<html>
<head>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js"></script>
<title>WebSockets Client</title>
</head>
<body>
<div id="wrapper">
<div id="container">
<h1>WebSockets Client</h1>
<div id="chatLog">
</div><!-- #chatLog -->
<p id="examples">e.g. try 'hi', 'name', 'age', 'today'</p>
<input id="text" type="text" />
<button id="disconnect">Disconnect</button>
</div><!-- #container -->
</div>
</body>
</html>
So in this code we’re creating a simple template: we have a box for the chat log, an input box, and one disconnect button.
Step 4: Add Some CSS
Nothing fancy, just space some elements out.
body {
font-family:Arial, Helvetica, sans-serif;
}
#container{
border:5px solid grey;
width:800px;
margin:0 auto;
padding:10px;
}
#chatLog{
padding:5px;
border:1px solid black;
}
#chatLog p {
margin:0;
}
.event {
color:#999;
}
.warning{
font-weight:bold;
color:#CCC;
}
Step 5: WebSocket Events
First, let’s try and understand the idea of WebSocket events.
The Events
We’ll be using three events:
- onopen: When a socket has opened
- onmessage: When a message has been received
- onclose: When a socket has been closed
But how can we implement this?
First create a WebSocket object
var socket = new WebSocket("ws://localhost:8000/socket/server/startDaemon.php");
And checking for events is as simple as:
socket.onopen = function(){
alert("Socket has been opened!");
}
But what about when we receive a message?
socket.onmessage = function(msg){
alert(msg); //Awesome!
}
However, let’s avoid using alert boxes, and actually integrate what we’ve learned into the client page.
Step 6: JavaScript
Ok, so let’s get started. First we put our code in jQuery’s document ready function, then we check whether the user has a WebSockets-enabled browser. If they do not, we append a link to Chrome in the HTML.
$(document).ready(function() {
if(!("WebSocket" in window)){
$('#chatLog, input, button, #examples').fadeOut("fast");
$('<p>Oh no, you need a browser that supports WebSockets. How about <a href="http://www.google.com/chrome">Google Chrome</a>?</p>').appendTo('#container');
}else{
//The user has WebSockets
connect();
function connect(){
//the connect function code is below
}
});
As you can see, if the user has WebSockets then we call a connect() function. This is the core of the functionality: we’ll start with the open, close and receive events.
We’ll define the URL of our server
var socket; var host = "ws://localhost:8000/socket/server/startDaemon.php";
Wait, where’s the http in that URL? Oh right, it’s a WebSocket URL, so it’s using a different protocol. Here’s a breakdown of the pieces of our URL:
Let’s continue with our connect() function. We will put our code within a try/catch block; so if something goes wrong, we can let the user know. We create a new WebSocket, and pass the message to a message function which I’ll explain later. We create our onopen, onmessage and onclose functions. Note that we also show the user the socket status; this is not necessary, but I’m including it here as it can be helpful for debugging.
- CONNECTING = 0
- OPEN = 1
- CLOSED = 2
function connect(){
try{
var socket;
var host = "ws://localhost:8000/socket/server/startDaemon.php";
var socket = new WebSocket(host);
message('<p class="event">Socket Status: '+socket.readyState);
socket.onopen = function(){
message('<p class="event">Socket Status: '+socket.readyState+' (open)');
}
socket.onmessage = function(msg){
message('<p class="message">Received: '+msg.data);
}
socket.onclose = function(){
message('<p class="event">Socket Status: '+socket.readyState+' (Closed)');
}
} catch(exception){
message('<p>Error'+exception);
}
}
The message() function is fairly simple, it takes in some text that we want to show the user and appends it to the chatLog. We create the appropriate class for paragraph tags in the socket event functions which is why there is only one closing paragraph tag in the message function.
function message(msg){
$('#chatLog').append(msg+'</p>');
}
So Far…
If you’ve been following up to this point, well done! We’ve managed to create a basic HTML/CSS template, create and establish a WebSocket connection and keep the user updated as progress was made with the connection.
Step 7: Sending Data
Now rather than having a submit button, we can detect when the user presses return on their keyboard, and run the send function. The ’13′ you see below is the ASCII key for the enter button.
$('#text').keypress(function(event) {
if (event.keyCode == '13') {
send();
}
});
And here’s the send() function:
function send(){
var text = $('#text').val();
if(text==""){
message('<p class="warning">Please enter a message');
return ;
}
try{
socket.send(text);
message('<p class="event">Sent: '+text)
} catch(exception){
message('<p class="warning"> Error:' + exception);
}
$('#text').val("");
}
Remember what you see above may be a chunky bit of code, but in reality, the code we really need is:
socket.send(); //Thanks JavaScript
The extra code is doing a number of things: detecting if the user didn’t enter anything but still hit return, clearing the input box, and calling the message functions.
Step 8: Closing the Socket
Closing the socket is fairly straightforward: attach a click handler to our disconnect button and we’re done!
$('#disconnect').click(function(){
socket.close();
});
The Completed JavaScript
$(document).ready(function() {
if(!("WebSocket" in window)){
$('#chatLog, input, button, #examples').fadeOut("fast");
$('<p>Oh no, you need a browser that supports WebSockets. How about <a href="http://www.google.com/chrome">Google Chrome</a>?</p>').appendTo('#container');
}else{
//The user has WebSockets
connect();
function connect(){
var socket;
var host = "ws://localhost:8000/socket/server/startDaemon.php";
try{
var socket = new WebSocket(host);
message('<p class="event">Socket Status: '+socket.readyState);
socket.onopen = function(){
message('<p class="event">Socket Status: '+socket.readyState+' (open)');
}
socket.onmessage = function(msg){
message('<p class="message">Received: '+msg.data);
}
socket.onclose = function(){
message('<p class="event">Socket Status: '+socket.readyState+' (Closed)');
}
} catch(exception){
message('<p>Error'+exception);
}
function send(){
var text = $('#text').val();
if(text==""){
message('<p class="warning">Please enter a message');
return ;
}
try{
socket.send(text);
message('<p class="event">Sent: '+text)
} catch(exception){
message('<p class="warning">');
}
$('#text').val("");
}
function message(msg){
$('#chatLog').append(msg+'</p>');
}
$('#text').keypress(function(event) {
if (event.keyCode == '13') {
send();
}
});
$('#disconnect').click(function(){
socket.close();
});
}//End connect
}//End else
});
Step 9: Run the WebSocket Server
We will need command line access. Luckily, XAMPP has a handy shell option. Click ‘Shell’ on the XAMPP control panel, and type in:
php -q path\to\server.php
You have now started a WebSocket server!
Finished
When the page loads, a WebSocket connection will attempt to be established (try editing the code so the user has connect/disconnect option). Then, the user can enter messages and receive messages from the server.
That’s it!
Thanks for reading; I hope you enjoyed this tutorial! Remember, as exciting as WebSockets may be, things may change. You can refer here to keep up to date on the W3C WebSocket API.
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how to program socket
google frame?
tested but did not work which protocols are supported?
Hello, Can somebody help me??? I can’t make run this…
Safari
Socket status(0)
…5 seconds…
Socket status(3)(close)
The console:
Resurce id #9 CONNECTED!
Requesting handshake…
Handshaking…
Resource id #9 disconnected!
Chrome:
Socket status(0)
…. and never connect…
The console:
Resurce id #9 CONNECTED!
Requesting handshake…
Handshaking…
….. and never pass of this line.. :L…..
grounds of error is because the protocols used in this tutorial was 75
now changed to 76.
use this srvidor this site: http://bohuco.net/blog/2010/07/html5-websockets-example/
socket ainda é uma grande aventura talvez dor de cabeça por causa das atualizaçoes dos protocolos feto pelo webkit entao o melhor a se fazer é implementar socket js + xml + flash, senao voce vai sofrer com as atualizaçoes do chrome.
“Welcome to the world of PUSH technology!” Really? 1997 called… it wants its crappy ideas back – and the buzzwords that go with them!
Cute… now run along and let the grown ups play
Hey,
Im wondering if i shall try to implement this on our chat or wait some more years?
Are they planning to get this to work in the couple of month in all new browsers?
Have been watching some solution within comet ajax programming but this seems better if it just start to work well in the close future.
//Ben
I wish I had a better answer for you, but all I want to say is I’m really excited about WebSockets in a chat web app.
When coupled with node.js an extremely succinct, fast and scalable chat server or web app seems like it can be constructed with the utmost ease.
Quite exciting times!
I am using your complete package to connect with web socket but fail to implement.
My code is like this:
if( ($this->master=socket_create(AF_INET,SOCK_STREAM,SOL_TCP)) master));
}
when I run my php file which create connection with web socket, I got error
Fatal error: Call to undefined function socket_create() in the line
if( ($this->master=socket_create(AF_INET,SOCK_STREAM,SOL_TCP)) < 0 )
Therefore i am not able to connect web socket and also not able to get response message from socket because Socket Status: 3 (Closed) is displaying in my browser when run client page .
Have you got an idea what is missing?
Thank you in advance.
I run your scipt and have exception in code javascript:
try{
socket.send(text); // exception here
message(‘Sent: ‘+text)
catch(exception){
console.log(exception); ///~~~~> show exception : Error: INVALID_STATE_ERR: DOM Exception 11 …
message(”);
}
help me!
thanks!
Whats the use of websocket? if well just to have localhost. hastle free
Alright, I can’t seem to get it to connect to the websocket, i’m a complete noob with this websocket junk and could use some help. If anyone has got this tutorial to run successfully, please message me @ http://www.facebook.com/xymon.sinclair and we’ll have a chat, that’d be just beautiful thanks :)
how do I do javascript to javascript then?
The correct link to phpwebsocket is http://code.google.com/p/phpwebsocket/
Hello,
I tested your cod, but always get this message:
# php -q htdocs\socket\server\startDaemon.php
2011-09-26 08:03:30 System: Socket Resource id #7 created.
2011-09-26 08:03:30 System: Socket bound to localhost:8000.
2011-09-26 08:03:30 System: Start listening on Socket.
2011-09-26 08:03:40 WebSocket: Resource id #8 CONNECTED!
2011-09-26 08:03:40 WebSocket: Requesting handshake…
2011-09-26 08:03:40 WebSocket: Handshaking…
2011-09-26 08:03:40 WebSocket: Done handshaking…
2011-09-26 08:03:40 WebSocket: Resource id #8 disconnected!
How can I fix this?
Tks in advance
First off, thanks for the excellent write up. I am having the same problems as Flavio however… looking forward to some resolution!
Several mistakes in socketWebSocket.class.php. No arguments are passed in the __construct function, so if you try and change the host or port in startDaemon.php there is no effect. Headers returned are incorrect, and entirely missing handling of the Sec-WebSocket-Key header, which is why it isn’t working for anyone.
http://en.wikipedia.org/wiki/WebSocket#draft-ietf-hybi-thewebsocketprotocol-06
Fix the header to that, and you may have more luck.
Hello,
I tested your code but the websocket server connection is closing without any message transfer.
php -q C://AppServ/www/websocket/server/startDaemon.php
2011-11-04 08:03:30 System: Socket Resource id #7 created.
2011-11-04 08:03:30 System: Socket bound to localhost:8000.
2011-11-04 08:03:30 System: Start listening on Socket.
2011-11-04 08:03:40 WebSocket: Resource id #8 CONNECTED!
2011-11-04 08:03:40 WebSocket: Requesting handshake…
2011-11-04 08:03:40 WebSocket: Handshaking…
2011-11-04 08:03:40 WebSocket: Done handshaking…
2011-11-04 08:03:40 WebSocket: Resource id #8 disconnected!
How can i fix this problem…… please help to get the solution
Thanks & Regards.
New phpwebsocket with Hybi-17 protocol.
http://www.wilky.it/Shared/phpwebsocket.zip
WOW !!! Thank you so much for that… I was tearing my hairs off with websocket for 2 days now.
Got your source, launch it, worked perfectly in Chrome and Firefox.
Thx so much, I think I love you right now.
Yes! this one works! Thanks a lot. :)
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Websockets can replace long-polling, but it should not. In many cases, Server Side Events with EventSource should replace the push nature. WebSockets is used for a two-way (technically known as a full-duplex) connection. Where EventSource tells the client what’s going on, WebSockets allows for a conversation.
Thanks, right code source: http://code.google.com/p/phpwebsocket/
Question: for backward compatibility should the implemented website check what browser the user has in order to determine whether websockets is suitable for them, and if it is not suitable should their be an alternative (backward compatibility) such as long-polling? Thanks.