One of the challenges of designing distributed systems is balancing the local and global complexity. In some cases, we might want to reduce the local complexity (and cognitive load) by splitting a single system into multiple smaller ones, that are going to be loosely coupled.

That often brings a problem of managing the specification of behaviours of the subsystems in the context of the whole system. Usually, we want to have the specification consistent between the subsystems, but at the same time keep them loosely coupled and independent.