Domain 2 of 4 · Chapter 1 of 2

Scalable and Loosely Coupled Architectures

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Included in this chapter:

  • SQS Standard vs FIFO: throughput, ordering, deduplication windows
  • EventBridge rule syntax + content-based filtering patterns
  • Step Functions Standard vs Express: choosing by execution duration + cost
  • Lambda-SQS pairing: visibility timeout, batch size, partial-batch failure
  • Kinesis Data Streams: shard math, enhanced fan-out vs polling
  • Dead-letter queues: alarms, redrive policies, message inspection

Messaging primitives compared

ServicePatternOrderingRetentionConsumersBest for
SQS StandardQueueBest-effort14 days max1+ workersDecoupled async work items, max throughput
SQS FIFOQueueStrict per MessageGroupId14 days max1+ workers (per group)Order-critical work; 300 msg/s default (3 000 w/batching)
SNSPub/sub topicN/ANot retained (in-memory delivery)Many subscribersFan-out to email, SMS, HTTP, Lambda, SQS
EventBridgeEvent busN/AUp to 24h archive (replayable)Many rules + targetsSchema-routed events; SaaS integrations; cross-account
Kinesis Data StreamsStreamPer shardUp to 365 daysMany parallel consumers (KCL)Ordered events with replay; real-time analytics
Step FunctionsWorkflowLinear (or parallel branches)Up to 1 year history (Standard)Service integrations + LambdasMulti-step orchestration with retries

Decision tree

Consumer pattern?Work queueFanoutEventsWorkflowStrict order required?SNS(pub/sub fanout)Need replay?Step Functions(orchestrate Lambdas)YesNoYesNoSQS FIFO(300 msg/s default)SQS Standard(unlimited TPS)Kinesis(replay 24h-365d)EventBridge(schema routing)Always: DLQ + alarm on depth; SQS visibility timeout ≥ 6× Lambda timeout
Cheat sheet

Cheat sheet

  • Pick integration primitive by consumer model
  • Always pair queues with DLQs + retry policies
  • SQS visibility timeout ≥ 6× Lambda timeout
  • SQS FIFO throughput: 300 / 3 000 / high-throughput mode
  • SNS doesn't retain — SQS does
  • EventBridge archive + replay
  • Step Functions Standard vs Express
  • EventBridge Pipes: SQS / Kinesis / DDB stream → target (no Lambda glue)
  • SQS long polling reduces empty receives + cost
  • API Gateway throttling: account, stage, method levels
  • Target tracking with ALBRequestCountPerTarget scales by request rate
  • Step Functions Distributed Map for large-scale S3 parallel processing
  • Step Functions .waitForTaskToken pauses workflow for external callbacks
  • Step Functions Retry with exponential backoff + Catch for fallback
  • Parallel state Catch intercepts any branch failure
  • SQS + Lambda partial batch response via ReportBatchItemFailures
  • SQS DLQ retention period must exceed source queue retention
  • EventBridge global endpoints for automatic multi-region failover
  • EventBridge DLQ per rule target captures undeliverable events

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Also tested in

References

  1. Amazon SQS Developer Guide
  2. Amazon SNS Developer Guide
  3. What is Amazon EventBridge
  4. Amazon Kinesis Data Streams
  5. AWS Step Functions Developer Guide
  6. Amazon SQS FIFO queues
  7. EventBridge rules
  8. Amazon SQS dead-letter queues
  9. Lambda asynchronous invocation (DLQ)
  10. Amazon SQS visibility timeout
  11. Using Lambda with Amazon SQS
  12. Lambda quotas
  13. High throughput for FIFO queues
  14. Amazon SQS quotas
  15. EventBridge archive and replay
  16. Step Functions Standard vs Express
  17. Amazon EventBridge Pipes
  18. Amazon SQS short and long polling
  19. Amazon API Gateway throttling and quotas