RabbitMQ exchanges

Exchanges receive published messages and route them to queues via bindings. Direct exchanges match routing keys exactly; topic exchanges use wildcard patterns; fanout broadcasts to every bound queue; headers exchanges match message attributes. Producers publish to an exchange name and routing key without knowing which queues exist.

Choosing the exchange type is a topology decision: task queues often use direct or topic; event broadcast uses fanout; selective subscriptions use topic with stable key conventions. Decoupling producers from queue layout lets you add consumers without redeploying publishers.

On interviews: name the four exchange types, give one use case each, and explain why producers should not hard-code queue names.

Common pitfalls: using fanout when only a subset should receive messages; topic patterns that are too broad and create surprise deliveries; mixing exchange types without documenting routing contracts.

The trade-off is flexibility versus complexity—know when the simpler path is enough.

Checklist:

• Match exchange type to delivery intent.
• Keep routing keys stable and documented.
• Decouple producers from queue topology.
• Plan how new consumers are added safely.