Advantage of COMET over long request polling?

Question

I've been wondering if there is a real advantage to using COMET / push-technologies over the much simpler polling with long requests where the server will wait a certain maximum time for new events to happen before telling the clients that nothing happened.

Both technologies have similar client latencies and while common wisdom is that long requests are worse because they need to establish a new connection, there's also the fact that there is HTTP keep-alive -- so in the end, both seem to produce a very similar amount of traffic / load.

So is there some clear advantage to using COMET?

Answer 1

Some advantages I can think of:

• Makes client programming easier.
• Minimum latency between the real event and the notification reaching the client. With polling this has a mean time of [POLL TIME]/2 and a worst case of [POLL TIME].
• Can minimize the resources needed in the server. See this article for example. New server technologies need to be used for this to happen.

Answer 2

AFAIK polling with long requests pretty much IS comet. Polling with short requests is not.