Chat Application

I wish to develop a mobile chat application...
Well Quick overview is here:

1) Their will be n number of mobile phone users chatting with each other, and a single web server which coordinates chatting.

2) All interactions between mobile phone & web server will be through HTTP protocol.

3) A mobile phone can talk to another mobile phone only through web server in between.

As we all know HTTP is a request response protocol.
Assume that user1 sends a chat message to user2, Now How should web server forward that message to user2(When user2 has not requested anything)?

One solution I can think of is: Send request to web server from all the mobile phones periodically(say once every minute), then web server can find if their is any message for that user and respond accordingly.

How feasible is my solution?
If you have an other solution please do suggest?

Thanks..

Have you perhaps considered the Jabber protocol? It might be easier than trying to code something from the ground-up, especially since I do believe there are Jabber-protocol chat clients out there for Java ME...

Just a thought.