HTML5 WebSockets is a solution to drive the real time web. The common use case says a real time stock application, online collaboration (multi-user sketching)
Refer: http://websocket.org/quantum.html for the introduction of WebSockets.
Currently, only Google Chrome the client browser supports HTML5 WebSockets natively. There is also less server support for HTML5 WebSockets, since this specification still new. Jetty WebSocket Server is one of an open source solution built on top of Java EE.