Event-Driven Architecture Modernization — AWS Solutions Architect Pro (SAP-C02)
SNS for Uniform Fan-Out; EventBridge for Content-Based Routing
'Different services must react to different subsets of events from the same producer' maps to EventBridge, not SNS. SNS fan-out to multiple SQS queues delivers every message to every subscription; filtering is limited to message attribute matching at the subscription level. EventBridge rules filter on event source, detail-type, and specific field values within the event payload itself, routing each event type to the correct downstream target without per-consumer filtering logic inside each service. SNS is simpler and cheaper when all subscribers share a uniform event interest. EventBridge is the answer when routing logic depends on event content and different consumers need different subsets of events from the same source.
What This Pattern Tests
The exam presents a tightly coupled system and asks how to decouple with events. SQS is for point-to-point: one producer, one consumer, messages buffered until processed (order processing, task queues). SNS is for fan-out: one event triggers multiple subscribers in parallel (email + SMS + Lambda). EventBridge is for content-based routing: events from 35+ AWS sources routed to targets based on event content (only route "order.placed" events to the billing service, "order.shipped" to the notification service). The trap is using SQS when multiple consumers need the same event (use SNS+SQS fan-out pattern) or EventBridge for simple point-to-point buffering (SQS is simpler and cheaper).
Decision Axis
Communication pattern determines the service: point-to-point buffering = SQS, parallel fan-out = SNS, content-based routing = EventBridge, fan-out with buffering = SNS+SQS.
Associated Traps
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Decision Rules
Whether to implement multi-attribute content-based event routing using EventBridge event pattern rules with centralized rule management and native archive-and-replay, or to approximate the same topology using SNS fan-out with per-subscription message filter policies or a custom Lambda dispatcher shim—evaluated under a governing constraint of minimal routing-layer operational overhead as consumer count and predicate complexity grow.
Domain Coverage
Difficulty Breakdown