In everyday conversation, people greet each other, exchange banter, and then eventually end the conversation and continue on their way. Low-level TCP connections function in the same way over lightweight channels in RabbitMQ. Applications that are going to exchange messages over RabbitMQ need to establish a permanent connection to the message broker. When this connection is established, a channel needs to be created so that message-oriented interactions, such as publishing and consuming messages, can be performed.

After demonstrating these fundamentals, this chapter will cover how a broker uses exchanges to determine where each message should be delivered. An exchange is like a mailman: it delivers messages to their proper queues (mailboxes) for consumers to find at a later time.

The basic RabbitMQ concepts are shown in the following diagram:

By the end of this chapter, you will have a solid understanding of the application architecture behind the Complete Car (CC) platform and how they sent the first message through RabbitMQ. This requires an introduction to two different types of exchanges: direct exchange, which delivers messages to a single queue, and topic exchange, which delivers messages to multiple queues based on pattern-matching routing keys.

• The application architecture behind CC
• Establishing a connection to RabbitMQ
• Sending the first messages
• Adding topic messages

Let's get started!