What is an alternative approach if an API does not support the two-phase commit protocol?

When an API does not support the two-phase commit protocol, using a saga is an effective alternative approach. Sagas provide a mechanism to manage distributed transactions without requiring a global transaction coordination as is the case with two-phase commits.

In a saga, the overall transaction is split into a series of smaller, atomic transactions or operations that can be managed independently. Each operation in the saga performs its task and, if successful, triggers the next operation. If one operation fails, a compensation mechanism is invoked to undo the previously completed operations, thus maintaining the overall consistency of the system.

This model is well-suited for microservices architectures where services operate independently and traditional transaction models might lead to tight coupling or single points of failure. Sagas enhance resilience and eventually achieve a consistent state without relying on the strict locking and coordination that two-phase commit requires. This makes them a popular choice in systems where services need to collaborate while remaining loosely coupled.