A company accepts payment requests 24/7.

To fulfill the SLA of ensuring every payment is processed while simultaneously resolving the issue of intermittent update errors, the architect must introduce an orchestration layer capable of managing state and concurrency. In a high-volume payment environment, "Fire and Forget" messages (as seen in the provided diagram) can lead to race conditions if multiple threads attempt to update a single record simultaneously—a common challenge when scaling payment systems.

The recommendation to have Middleware coordinate request delivery and payment processing (Option C) transforms the architecture into a managed queueing system. By coordinating delivery, the middleware can act as a traffic controller, ensuring that requests are delivered sequentially or that appropriate locks are respected before an update is attempted. This orchestration allows the system to meet its SLA by implementing a "guaranteed delivery" pattern, where the middleware tracks the status of each payment and only "forgets" the message once the Payment System confirms successful processing.

Furthermore, the architect should emphasize idempotency by leveraging the globally unique identifier created at the Data Entry Point. The Payment System should be designed to use this identifier to check if a specific transaction has already been processed before attempting an update. This prevents duplicate entries and conflicting updates, even if the middleware retries a message due to a network timeout. While retries (Options A and B) are part of a resilient system, they do not solve the root cause of record contention; only the coordination and sequencing provided by the middleware can ensure a stable, conflict-free integration flow.78