Building Reliable Distributed Systems with AWS Serverless

Full resolution diagram: Microservices Diagram Introduction Most microservices architectures share similar trade-offs. Two of the most common challenges are transactional consistency and keeping services synchronized with data changes. As a result, distributed systems often deal with duplicate events, lost messages, and partial failures. This is where idempotency becomes essential. In simple terms, idempotency means an operation can be executed multiple times without changing the final result . That property makes it especially valuable in transactional domains like retail, finance, or travel. Another key piece of the puzzle is the Outbox Pattern . Instead of notifying external systems directly—which risks message loss if the network or broker fails—the service persists both the data change and the event message in a single atomic transaction. This guarantees reliable event delivery. In this demo, we’ll explore a retail scenario that combines idempotency , the Outbox Pattern , and a si