Amazon SQS

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 at-least-once delivery with idempotent handlers

Explains why message handlers must tolerate duplicate delivery and how idempotency protects side effects.

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 retry, backoff, and poison message policy

Explains retry strategy for transient failures and poison-message handling for permanent failures.

Distinguish commands and events in message-driven systems

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

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.