Communicating between two users/sessions

As a learning device, I want to create a tiny game which two players will play in real time. Both players will plot their action at the same time and submit their action. There doesn't seem to be a handy way to communicate the moves/results to each player.

I guess using javascript to poll for changes every few seconds would be doable but it would be nice to have a cleaner way to propogate changes. Any suggestions would be welcome. I don't want to run applets or flash. Consider PHP, javascript, mysql, html+ as my options.

MySQL for sure.

You can create a temporary table.
Use it during the game, and delete it afterwards.

Normally, I think of events. Change is made and a signal is made from the server to the client. In this case, there isn't a way that I am aware of to signal the client end. Therefore polling is require from the client to the server.

I guess the bottom line question in all of this. Do I have any options to signal to the client such changes?

If you used a Windows Server with ASP.net, you could probably have each
player load and run some sort of Visual BASIC exe file. It would pretty much
connect them together online. That's a bit out of my area of expertise though.