Asynchronous Messaging
maang.io System Design Series
Asynchronous messaging lets a producer hand off work and move on, decoupling services in time and space so they scale and fail independently. The subject is really about guarantees: point-to-point queues vs pub/sub fan-out, at-most/at-least/exactly-once delivery, ordering, dead-letter queues, and backpressure. It's the backbone of resilient, spike-tolerant systems.
This deep dive comes in three parts:
- Foundations & Core Concepts — queues vs pub/sub, brokers, and decoupling.
- Internals — delivery guarantees, ordering, DLQs, visibility timeouts, and backpressure, with worked examples.
- Interview — Staff/Principal Q&A: exactly-once reality, idempotency, and failure handling.