JavaZone 2007: Real-time web
Jonas Jacobi, a Swede with background from Oracle, has a new company called Kaazing which focuses on real-time solutions for the web.
Comet is a software concept that enables web servers to send data to the client program (normally a web browser) without having any need for the client to request it (quoting Wikipedia).
Polling vs streaming: Polling means more control for the client, but also a lot of load on the server. Streaming (long-timed requests)
Traditional AJAX apps means polling. The server has no way to notify the client if the client doesn't poll.
Jonas compared polling to a child asking "Are we there yet?" a gazillion times :)
Firewalls mean client-server breaks. AJAX and Comet works.
Comet means instant response. That's why traders normally use desktop solutions.
Most browsers (including IE and Firefox) will only open two connections to a server, which is a challenge for Comet. This means we need common request handling.
Both Jetty and Glassfish support the Bayeux protocol. Tomcat 6 will support Comet.
They are trying to get support for Comet in the servlet 3.0 spec. Comet is not currently a standard.
Jonas showed a nice online poker demo in Firefox with Comet on the server.
The main benefit of Comet is the ability to scale (unlike traditional approaches to push).
They are considering open source (discussing with Terracotta and their experiences), but they have to please their investors. They don't necessarily want to make money on the Project Chai engine, but whatever they could build on top.