Event-driven architecture sounds clean in diagrams: one service publishes an event, another service reacts, and the system becomes nicely decoupled. In production it is messier. Events arrive late, arrive twice, arrive out of order, or fail halfway through a workflow. AWS gives you strong building blocks, but the architecture still depends on how you handle those realities. Use EventBridge for Routing, SQS for Work The pattern I like is EventBridge for routing and SQS for durable work queues. EventBridge is good at publishing domain events and letting consumers subscribe without tight coupling. SQS is good at giving workers a queue they can drain, retry, and monitor. { "source": "ads.campaigns", "detail-type": "CampaignBudgetChanged", "detail": { "companyId": 5000, "profileId": 50000100, "campaignId": 123456789, "oldBudget": 50.00, "newBudget": 75.00 } } ...