Web Sockets

Web Sockets is a technology providing for bi-directional, full-duplex communications channels, over a single Transmission Control Protocol (TCP) socket, designed to be implemented in web browsers and web servers. It is being standardized in its JavaScript API by W3C, and in its protocol by IETF.

Proxy traversal

Web Socket protocol client implementations try to detect if the user agent is configured to use a proxy when connecting to destination host and port and, if it is, uses HTTP CONNECT method to set up a persistent tunnel.

URL scheme

The Web Socket protocol specification defines two new URI schemes, ws: and wss:, for unencrypted and encrypted connections. Apart from the scheme name, the rest of the URI components are defined to use URI generic syntax.

Browser Implementations

• Google Chrome, client support since version 4.0.249.0
• Mozilla Firefox, client implementation of native Web Sockets Targeted release is Firefox 3.7.
• Apple Safari, based on Webkit. No new release announced.

Server Implementations

• Kaazing, Websocket Gateway, production since April 2009, including client-side Websocket emulation support for browsers without native implementation of Web Socket APIs. Runs on the Java software platform. Currently released version 9.06_7.
• jWebSocket, Open Source Java WebSocket Streaming and Communication Server, including a JavaScript Client for HTML 5 compliant browsers]
• APE, Comet server and client-side JavaScript framework that support both Websockets and other transport methods (long polling, xhrstreaming)
• Jetty, since version 7.0.1, the HTTP server and servlet container provides a Web Sockets server in Java
• Cramp, Realtime web application framework for Ruby, extends Thin/Rainbows to support Web Sockets handshaking and provides Jetty servlet like mechanism for sending/receiving data over Web Sockets.
• Netty, this patch provides support for upgrading an HTTP connection to the Web Sockets protocol and provides support for encoding and decoding Web Socket frames in Java
• phpwebsocket, a quick hack to implement Web Sockets client and server in PHP
• phpwebsockets, a bit more complex but still experimental Web Sockets Server PHP
• web-socket-js, an experimental client implementation based on Flash
• web-socket-ruby, an experimental client and server implementation in Ruby
• mod_pywebsocket, an experimental extension for the Apache HTTP Server

See also

• Push technology
• Comet

External Links

• WebSockets.de, a german web-site dedicated to Web Sockets
• The Web Socket protocol Internet-Draft submitted to IETF
• HTML5 Web Sockets W3C draft specification
• WebSockets.org, a web-site dedicated to Web Sockets
• IANA Uniform Resource Identifer (URI) Schemes
• WebSocket Games in Python with Tornado An explanation about how to build games using WebSockets and Python