SQS

• Decouple application tiers with SQS
• Standard queue performs best effort ordering. Ordering is not guaranteed. Unlimited Throughput
• FIFO Queue: Ordering is guaranteed. 300 messages per second. With 10 messages batched per operation (maximum), 3000 messages per second
• Standard: At-least once delivery. FIFO: Exactly once processing.

FIFO Queues

• FIFO Queue requires Message Group ID and Message Deduplication ID

Delay Queue

• Set a delay time before a message is seen.

Long Polling

• Long polling can reduce costs. Waits for messages to arrive.
• SQS Long polling can be enabled either at the Queue level or API level using WaitTimeSeconds.
• Receive Message Wait Time can be set up to 20 seconds.