Which best describes the 'Event' pattern in the SAGA pattern?

The 'Event' pattern within the SAGA design pattern is characterized by each API independently generating an event after completing its process or transaction and sending it to a subsequent API that needs to perform its own processing based on that event. This approach emphasizes the asynchronous nature of communication between services, where APIs do not need to directly invoke each other. Instead, they rely on events to trigger subsequent actions, promoting loose coupling and enhancing scalability within a distributed architecture.

The essence of the Event pattern is its ability to facilitate a reactive programming model where components react to changes in state or information communicated through events. This allows for greater flexibility and adaptability in a microservices architecture, preserving the independence of each service while still enabling complex workflows to take place across the system.

In contrast, the other descriptions do not accurately capture the nature of the Event pattern. For instance, the notion that APIs generate a result and send it back depicts a synchronous request-response interaction rather than an event-driven architecture. Similarly, using shared storage suggests a coupling between services that contradicts the decoupled event-driven approach. Finally, stating that one API manages all transactions suggests a centralized control that opposes the decentralized nature of Saga patterns, where each service must manage its own transactions and state changes through events.