Now that we understand the basics behind RabbitMQ, it’s time for us to start working with it. The first step in working with RabbitMQ is to begin sending messages to the exchange so that they can be queued. In RabbitMQ parlance, the “producer” is responsible for “publishing” the messages to the exchange.
He includes the code you'll need to use the AMQP PHP extension to connect with the RabbitMQ server and select a channel. He also shows how to set up an "exchange" and "queue" and bind them to each other. Finally, there's the one line of code that uses the routing key value to push a message into the waiting service.