Application Integration
Amazon SQS
Managed message queues for decoupling
Amazon SQS is a fully managed message queue that decouples producers and consumers. Standard queues maximize throughput with at-least-once delivery; FIFO queues preserve order with exactly-once processing. Dead-letter queues isolate failing messages.
When to use it
- Buffering work between a fast producer and slower/failable consumer
- Absorbing traffic spikes without losing requests
- Enabling independent scaling of producers and consumers
- Retry handling via visibility timeouts and DLQs
When NOT to use it
- Fan-out to many consumers (use SNS, or SNS→SQS fan-out)
- Real-time request/response where the caller must block on the result
Key exam points
- Visibility timeout hides a message while a consumer processes it
- Standard = at-least-once, best-effort order; FIFO = ordered, exactly-once
- DLQ + redrive policy isolates poison messages after maxReceiveCount
- Long polling reduces empty receives and cost
Compared with
- Amazon SNS — SNS is pub/sub fan-out to many subscribers; SQS is a queue where one consumer processes each message.