Amazon SNS

Compare queues and topics for backend messaging

Compares point-to-point queues with publish-subscribe topics and explains when each model fits.

Design a message envelope with correlation metadata

Explains useful message metadata for tracing, idempotency, ownership, versioning, and support diagnostics.

Design for broker outage and backpressure

Explains how systems behave when the broker is down or slow and how backpressure protects callers and dependencies.

Design safe event replay and backfill

Explains how to reprocess event streams safely for new projections, bug fixes, and data repair.

Distinguish commands and events in message-driven systems

Explains command messages versus event messages and how ownership changes their design.

Explain the exactly-once messaging caveat

Explains why exactly-once claims do not remove the need for idempotent side effects and consistency boundaries.

Message Queues & Events

Queues, events, idempotency, retries, dead letters, ordering, and streaming.

A practical messaging track covering queue-backed workers, publish-subscribe events, retry behavior, idempotent consumers, dead-letter recovery, message ordering, event schemas, consumer lag, replay, and production operations.