Amazon Simple Queue Service (SQS)
- What it is
- Simple Queue Service — fully managed message queue for decoupling components.
- A producer puts a message on the queue; a consumer pulls it, processes it, and deletes it.
- Model: one-to-one, pull-based
- Each message is processed by exactly one consumer.
- Messages persist (up to 14 days) until consumed — the consumer can be offline and catch up later.
- Queue types
- Standard — nearly unlimited throughput, at-least-once delivery, best-effort ordering.
- FIFO — strict ordering and exactly-once processing, lower throughput.
- Related concepts
- Visibility timeout — how long a message is hidden while being processed.
- Dead-letter queue — where messages go after repeated processing failures.
- Not to be confused with
- Amazon Simple Notification Service (SNS) — push-based pub/sub, one message fans out to many subscribers, no persistence for the consumer to catch up on.
- Amazon EventBridge — event routing with content-based filtering across many AWS services and SaaS partners.
- Exam signal
- “Decouple”, “buffer”, “handle traffic spikes”, “process later” → SQS.