Saga pattern
A long-running transaction broken into a series of local steps, each with a compensating action if something goes wrong. For distributed systems without two-phase commit.
The concept dates from 1987 (Hector Garcia-Molina, Kenneth Salem). Popular in microservice architectures where an order process spans Order, Payment, Inventory, and Shipping services. Two variants: Orchestration (a central coordinator sends commands, waits for replies), Choreography (each service listens for events and reacts). Tools: Temporal, Camunda, AWS Step Functions, Netflix Conductor.