Question 360
A high-volume ecommerce platform decouples integration events. The team confirms that a partner requires exactly-once business processing despite at-least-once delivery. Which AWS architecture decision should be prioritized?
Explanation
Correct Answer
The scenario identifies this requirement: A partner requires exactly-once business processing despite at-least-once delivery. Select Make the fulfillment transaction idempotent using a unique order operation key as the specified technical mechanism. Message delivery semantics do not replace business-level deduplication. This response addresses the problem described rather than a different design goal.
Incorrect Answers
The option Buffer fulfillment messages in SQS with consumers that scale on backlog addresses a separate condition: a burst generates more checkout events than fulfillment can immediately process. Durable queues smooth producer-to-consumer rate mismatch. The actual requirement is a partner requires exactly-once business processing despite at-least-once delivery. Recommended corrective action: Make the fulfillment transaction idempotent using a unique order operation key. Message delivery semantics do not replace business-level deduplication.
Publish the domain event to EventBridge with consumer-specific rules would help if multiple services need a consistent customer-changed event. Event-bus routing reduces direct subscriber coupling. That is not the symptom described here: a partner requires exactly-once business processing despite at-least-once delivery. The matching response is Make the fulfillment transaction idempotent using a unique order operation key, because message delivery semantics do not replace business-level deduplication.
Keep payment result in synchronous transaction and queue fulfillment downstream solves a different operational problem where payment authorization must be strongly synchronous but fulfillment can be delayed. Business-critical confirmation can be separated from optional asynchronous steps. It does not directly address a partner requires exactly-once business processing despite at-least-once delivery. The case calls for Make the fulfillment transaction idempotent using a unique order operation key, since message delivery semantics do not replace business-level deduplication.