Why it matters

SQS is AWS event-driven default. Understanding shapes decoupled architectures.

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The architecture

Producer sends. Consumer polls. Visibility timeout hides message during processing. Delete when done.

SQS flowProducersendsQueuebuffersConsumerpolls + deletesStandard: at-least-once + unordered. FIFO: exactly-once + ordered, lower throughput
SQS operations.
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How it works end to end

Standard: high throughput, at-least-once delivery, best-effort ordering.

FIFO: exactly-once via deduplication ID; ordered per message group; ~3000 msg/s per group.

Dead-letter queue: messages that fail N times route there.

Long polling: reduces empty poll cost.