Once you've created a RabbitMQ producer, it's fairly easy to create a consumer. In fact, the only difference is in exactly what commands you're using. The connection, envelope, channel and queue declarations are the same. While in RabbitMQ you publish to the exchange, you actually do consume a specific queue. As a result, the commands for consuming are part of the AMQPQueue class.

He shows you how to set up the code to sit in the background and wait for a queue request and how to fetch them in a non-blocking way. He finishes off the post with a look at handling success and error conditions (based on the status of message consumption, not the result of the processing).

A couple of weeks ago I was thinking about non-blocking I/O in PHP, specifically about how clunky PHP's select implementation is. I say clunky because it's not bad, it's just not as easy to use as it could be.

[...] I have to remember which streams I'm interested in writing to, which streams I'm interested in reading from and when I get to accepting connections, which streams are server sockets that I'm interested in accepting connections on. I'm lazy, I don't want to have to do that , I want a library to handle all that for me. At this point I decided to implement something similar to Java's non-blocking I/O in PHP5. This is now finished and up on sourceforce (under the name of phpmio). In this article I hope to give you enough information to get up and running with the package.

He explains what multiplexed I/O is (including code), what PHP-MIO is (yes, including code), and a more real life example of how to use it - a simple server that accepts connections and spits back a simple response.