Implementing RPC (Remote Procedure Call) with RabbitMQ

Things to Note

• Correlation ID: Needed to match the response to the request.
• Reply-to queue: Often a temporary, exclusive queue just for that client.
• Blocking: RPC makes the client wait, so it loses some benefits of async messaging.
• Timeouts: Always set timeouts on the client side to avoid waiting forever.
• Idempotency: Make sure the server function is safe if retried.

Best Practices

• Use RPC only when you must get a direct reply.
• For most workflows, prefer async events (publish/subscribe).
• Add timeouts and retries to make it reliable.
• Monitor request and response queues for performance.

Conclusion

RabbitMQ can be used not only for async messaging but also for RPC-like request/response patterns. By using reply_to and correlation_id, we can build a simple RPC mechanism.

However, RPC over RabbitMQ should be used with care. If your system can be event-driven, prefer async messaging. Use RPC only for cases where a service must return a value immediately.