How do I handle partial failure across services?

Definition:

A cross-service workflow can partly succeed because each service commits independently. A saga coordinates local steps and compensating actions to recover when a later step fails. Compensation is a business recovery action, such as refunding a payment, and may not exactly erase every observable effect of the original action.

Key points:

• Use local transactions and durable workflow state.

• A saga uses compensating actions when later steps fail; compensation is not always an exact undo.

• Reconcile uncertain external results before repeating actions such as payments or notifications.

• Persist workflow progress and support reconciliation when a timeout leaves a step's outcome uncertain.

Interview point:

• Describe both the success sequence and the failure after a particular committed step; “use transactions” is insufficient across arbitrary external APIs.