Lets say I want to write an AJAX chat box, just something simple, I write some text, and it gets posted up. Lets not even worry too much about names of users in the box.
First instincts tell me to just write a table and post data into it, and query every few seconds.
Lets pretend this isn’t 2011 and computers a cheap and we’re okay with slow laggy chat boxes that update every 5 seconds, or slow the entire server down with a storm of SQL.
What are some alternatives? Could I do something with XMPP? What if I didn’t have anything other than my favorite server-side language (and some SQL)? Could I use message hashes in some neat way? What can I do to limit the number of requests?
What I’m looking for is a great plan for writing the software behind a web-based chat box, that is very resource efficient, and flexible. I’m sure we’re doing something neat here on SO for the chatrooms we already have.
Your problem is you’re polling every now and then. What you really want is a constant connection to stream data with.
You could try using the Comet method – a streaming connection you can keep open to send chat messages down.
There’s also a trick called long-polling – You keep the connection open until you receive a new message, then close it and start a new one.