How to try the sample
Assuming you have Web server (e.g. Apache) running at http://example.com/ .
- Download web-socket-ruby.
- Run sample Web Socket server (echo server) in example.com with: (#1) $ ruby web-socket-ruby/samples/echo_server.rb example.com 10081
- If your server already provides socket policy file at port 843, modify the file to allow access to port 10081. Otherwise you can skip this step. See below for details.
- Publish the web-socket-js directory with your Web server (e.g. put it in ~/public_html).
- Change ws://localhost:10081 to ws://example.com:10081 in sample.html.
- Open sample.html in your browser.
- After "onopen" is shown, input something, click [Send] and confirm echo back.
#1: First argument of echo_server.rb means that it accepts Web Socket connection from HTML pages in example.com.
How to use it in your application
- Copy swfobject.js, web_socket.js, WebSocketMain.swf to your application directory.
Put Flash socket policy file to your server unless you use web-socket-ruby or em-websocket as your WebSocket server. See "Flash socket policy file" section below for details.
If it doesn't work, try these:
Try Chrome and Firefox 3.x.
- It doesn't work on Chrome:
It's likely an issue of your code or the server. Debug your code as usual e.g. using console.log.
- It works on Chrome but it doesn't work on Firefox:
It's likely an issue of web-socket-js specific configuration (e.g. 3 and 4 below).
- It works on both Chrome and Firefox, but it doesn't work on your browser:
Check "Supported environment" section below. Your browser may not be supported by web-socket-js.
- It doesn't work on Chrome:
Add this line before your code: WEB_SOCKET_DEBUG = true; and use Developer Tools (Chrome/Safari) or Firebug (Firefox) to see if console.log outputs any errors.
Make sure you do NOT open your HTML page as local file e.g. file:///.../sample.html. web-socket-js doesn't work on local file. Open it via Web server e.g. http:///.../sample.html.
If you are NOT using web-socket-ruby as your WebSocket server, you need to place Flash socket policy file on your server. See "Flash socket policy file" section below for details.
Check if sample.html bundled with web-socket-js works.
Make sure the port used for WebSocket (10081 in example above) is not blocked by your server/client's firewall.
Install debugger version of Flash Player to see Flash errors.
It should work on:
- Google Chrome 4 or later (just uses native implementation)
- Firefox 3.x, 4.x, Internet Explorer 8, 9 + Flash Player 10 or later
It may or may not work on other browsers such as Safari, Opera or IE 6. Patch for these browsers are appreciated, but I will not work on fixing issues specific to these browsers by myself.
Limitations/differences compared to native WebSocket
- It requires Flash Player 10 or later unless the browser supports native WebSocket.
- Your server must provide Flash socket policy file, unless you use web-socket-ruby or em-websocket. See "Flash socket policy file" section below for details.
- It has limited support for Cookies on WebSocket. See "Cookie support" section below for details.
- It doesn't use proxies specified in browser config. See "Proxy support" section below for details.
Flash socket policy file
This implementation uses Flash's socket, which means that your server must provide Flash socket policy file to declare the server accepts connections from Flash.
If you use web-socket-ruby or em-websocket, you don't need anything special, because web-socket-ruby handles Flash socket policy file request. But if you already provide socket policy file at port 843, you need to modify the file to allow access to Web Socket port, because it precedes what web-socket-ruby provides.
If you use other Web Socket server implementation, you need to provide socket policy file yourself. See Setting up A Flash Socket Policy File for details and sample script to run socket policy file server. node.js implementation is available here.
Actually, it's still better to provide socket policy file at port 843 even if you use web-socket-ruby or em-websocket. Flash always try to connect to port 843 first, so providing the file at port 843 makes startup faster.
web-socket-js has limited supported for Cookies on WebSocket.
Note that it's technically possible that client sends arbitrary string as Cookie and any other headers (by modifying this library for example) once you place Flash socket policy file in your server. So don't trust Cookie and other headers if you allow connection from untrusted origin.
The WebSocket spec specifies instructions for User Agents to support proxied connections by implementing the HTTP CONNECT method.
The AS3 Socket class doesn't implement this mechanism, which renders it useless for the scenarios where the user trying to open a socket is behind a proxy.
The class RFC2817Socket (by Christian Cantrell) effectively lets us implement this, as long as the proxy settings are known and provided by the interface that instantiates the WebSocket. As such, if you want to support proxied conncetions, you'll have to supply this information to the WebSocket constructor when Flash is being used. One way to go about it would be to ask the user for proxy settings information if the initial connection fails.
How to host HTML file and SWF file in different domains
By default, HTML file and SWF file must be in the same domain. You can follow steps below to allow hosting them in different domain.
WARNING: If you use the method below, HTML files in ANY domains can send arbitrary TCP data to your WebSocket server, regardless of configuration in Flash socket policy file. Arbitrary TCP data means that they can even fake request headers including Origin and Cookie.
- Unzip WebSocketMainInsecure.zip to extract WebSocketMainInsecure.swf.
- Put WebSocketMainInsecure.swf on your server, instead of WebSocketMain.swf.
How to build WebSocketMain.swf
Install Flex 4 SDK.
$ cd flash-src $ ./build.sh
New BSD License.