I've been reading up on message queueing lately, and I'd like to implement a simple, extendable, system for my app. While there's a lot of good information on the subject of setting up a MQ system out there, I can't find a lot about the actual implementation.

I'm looking for patterns and best practices on how to properly format messages for a queue, and ways to execute the jobs in PHP. Should I use JSON, serialized objects, text, URLs or XML? What information should I send? Is a worker with a switch($job['command']) {} (or something like that) the way to go, or are there any established patterns out there to implement a worker?

Help greatly appreciated!