My PHP framework I'm developing for Orbited (called "Callisto") is a
generalized pub/sub framework. This means it allows any kind of data
to be published and users to subscribe as they wish accordingly.
The basic idea is: Each user subscribes to a channel (identified by a
string) and opens up a single HTTP polling connection. Then your PHP
application publishes data to all the users of a particular channel
(again identifying it with the same string). The subscription is
passed through the PHP script, so it can handle authentication and
other issues. Data is stored in MySQL using a table for all
subscriptions (but not for channels).
I hope I can publish the source code of the framework as I'm done with
this, hopefully you'll be able to use it as a base for your chatting
system as well, it sounds a very fitting application.
Dionysis.
Sounds neat! keep us posted as you make progress. :)
-Jacob