How do pages like Yahoo Finance update page without plugins etc? (HTTP PUSH)

I am interested in HTTP PUSH technologies. I am interested in the technology behind pages like Yahoo Finance etc, which are able to update the page with data in real time.

When I checked the FF console, there are no periodic POSTs from the client which suggests that the client is not polling, rather it is having data PUSHed to it.

I then checked the page source - (AFAICT) they are NOT:

• using a java applet
• using开发者_StackOverflow社区 a hidden iframe
• using any custom client side JS library (like APE etc)

So HOW are the pages being updated in real time?.

Can anyone explain the technolgies used to put together such a page - a link to a simple demo would be most useful.

The techniques for HTTP PUSH and the like are

• Comet Technology
• WebSockets
• Java Applet / Flash WebSockets / SilverLight?
• Server-sent Events and EventSource
• HTTP server push

The Push technology article on wikipedia is a good read.

The Transports at socket.io should give you examples of how to implement these technologies.