What happens in the Command/Orchestration SAGA pattern?

In the Command/Orchestration SAGA pattern, one API generates events that are passed sequentially to other APIs. This approach effectively orchestrates the coordination of multiple services that each participate in a larger business transaction. By generating an event that triggers the next step in the process, the pattern maintains a clear flow of execution, allowing each service to execute its part of the transaction in a defined order.

This sequential event-passing mechanism is crucial for maintaining data consistency and ensuring that each API can complete its operations before the next API processes its event. Additionally, it allows for handling complex workflows and dependencies between services in a controlled manner, which is a fundamental aspect of the SAGA pattern.

This orchestration enables better visibility of the transaction as a whole and simplifies the error handling process by providing clear checkpoints after each step. Such structured handling is advantageous compared to APIs operating completely independently, which would not ensure coordination among participating services.