Saga Pattern

The Saga pattern manages data consistency across microservices in distributed transaction scenarios. A Saga is a sequence of local transactions. Each local transaction updates the database and publishes a message or event to trigger the next local transaction in the saga.

When to Use

• Distributed Transactions: e.g., "Book Flight" + "Book Hotel" + "Charge Card".
• Long-running processes where you can't hold a DB lock.
• Ensuring eventual consistency across Services A, B, and C.

Core Concepts

Compensating Transactions

If a step fails (e.g., Card Declined), the Saga must execute compensating transactions to undo the changes made by the preceding steps (e.g., "Cancel Hotel", "Cancel Flight").

Choreography

Each service listens to events and decides what to do.