Messages are not published directly to a queue. Instead, the producer sends messages to an exchange. Exchanges are message routing agents, defined by the virtual host within RabbitMQ. An exchange is responsible for routing the messages to different queues with the help of header attributes, bindings, and routing keys.

A binding is a "link" that you set up to bind a queue to an exchange.

The routing key is a message attribute the exchange looks at when deciding how to route the message to queues.

Exchanges, connections, and queues can be configured with parameters such as durable, temporary, and auto delete upon creation. Durable exchanges survive server restarts and last until they are explicitly deleted. Temporary exchanges exist until RabbitMQ is shut down. Auto-deleted exchanges are removed once the last bound object is unbound from the exchange.

Standard RabbitMQ message flow

1. The producer publishes a message to the exchange.
2. The exchange receives the message and is now responsible for the routing of the message.
3. Binding must be set up between the queue and the exchange. In this case, we have bindings to two different queues from the exchange. The exchange routes the message into the queues.
4. The messages stay in the queue until they are handled by a consumer.
5. The consumer handles the message.

Direct Exchange