messaging

AWS event-driven architecture selection depends on communication patterns: SQS provides queue-based load leveling, SNS enables fan-out pub/sub delivery, and EventBridge offers content-based event routing for complex asynchronous workflows.

Configure dead-letter queues and retries by setting visibility timeouts on SQS queues, defining retry policies for failed message delivery, and implementing idempotency strategies to handle duplicate messages during failure recovery in production workloads.

Design an SNS and SQS fan-out pattern by subscribing multiple SQS queues to a single SNS topic, allowing messages to be delivered asynchronously to competing consumers for scalable parallel processing and reliable distributed workloads.

Use EventBridge event routing instead of SNS when your event-driven systems require content-based filtering, schema validation, or complex saga orchestration, whereas SNS is better suited for simple high-throughput fan-out messaging without conditional routing.

You can implement CQRS and event sourcing using EventBridge to route domain events and SQS to separate command and query workloads, enabling scalable distributed systems with asynchronous processing and reliable state reconstruction.

Duplicate processing in competing consumer architectures occurs when SQS visibility timeouts are too short, causing messages to become visible again before processing completes; adjusting timeout values and implementing idempotency strategies resolves this failure scenario.