I dont think COMET is the best solution for using push technology in ajax. It seems that Adobe and ICE Technology Corp. both think so. Ive got something interesting about this topic, and Id like to share with you.

Pjax Push Technology in an Ajax-like paradigm

The conecpt of Pjax is similar with that of Fjax. Fjax is a lightweight, cross-browser, rapid-development methodology for Ajax-style web 2.0 development that puts an invisible Flash engine under the hood to take the role of XMLHttpRequest in Ajax. Of course, you may develop an invisible Java applet to do the same thing as the flash engine does. In Pjax, we call the engine as flush engine. A flush engine is able to connect and bi-directionally communicate with iPush Server, and communicate with browser using javascript , and updates the changed data on the screen without reloads.

ICE Technology Corp. has launched iPush Java and Flash APIs, and developers can use them to develop their own flush engines (Flash .swf or applet) to take the role of XMLHttpRequest. After you have implemented a flush engine and relative javascript library (.js), it is very easy to develop your own Ajax-like rich internet application equipped with server push functionality.

-- Quotes from "Push Technology in RIA", by ICE Technology Corp.

What do you think about the new paradigms?

Reference:Fjax http://www.fjax.net/