Data Consistency in Microservices: The Saga Pattern in Node.js

The Saga pattern manages distributed transactions by executing a sequence of local transactions, each with a corresponding 'compensating' action to roll back changes if a later step fails.

Node.js services often cannot use traditional ACID transactions across different databases. The Saga pattern solves this using either Choreography (services exchange events) or Orchestration (a central service directs the flow). If the 'Payment Service' fails after the 'Order Service' succeeded, the 'Order Service' must receive a 'RevertOrder' event to mark the order as cancelled.