Saga
A way to manage data consistency across microservices in distributed transaction scenarios. A saga is a sequence of transactions that updates each service and publishes a message or event to trigger the next transaction step. If a step fails, the saga executes compensating transactions that counteract the preceding transactions : https://docs.microsoft.com/en-us/azure/architecture/reference-architectures/saga/saga
Context and problem
Transactions within a single service are ACID (atomic, consistent, isolated, and durable), but cross-service data consistency requires a cross-service transaction management strategy.Solution
Choreography pattern allows a transaction to be executed in parallel steps and/or in sequences.
Features : Orchestration starts with an event and can end with an ending event (event as message, file transfer, entry in table, etc.); coordination is centralized; orchestrator is responsible for the integrity of the transaction.Sage pattern with centralized coordinationChallenges
Hard to debug and complexity will grow the number of participants
Data can’t be rolled back because participants commit changes to their local DB
Very demanding pattern because need to implement countermeasures to reduce anomalies