Compensation is an interesting form of loose coupling. It has to do with the question of transaction safety. If you have to update two different backends to be consistent, how can you avoid problems that occur when only one update is successful, resulting in an inconsistency? The usual approach to solving this problem is to create a common transaction context using a technique such as two-phase commit (2PC). With this approach, you first perform all the modifications on both backends, except for the final "switch to the updated data"; then, if no system signals a problem, the final commit performs the update on both systems.