"If there is coherence to the subsystem, it is probably possible to describe it as a set of SERVICES." #readingToday

_The team may be doing the same thing again and again. If there is any coherence to the subsystem, it is probably possible to describe it as a set of SERVICES that cover the common needs of other subsystems. It is a lot harder to design a protocol clean enough to be understood and used by multiple teams, so it pays off only when the subsystem's resources can be described as a cohesive set of SERVICES and when there are a significant number of integrations. Under those circumstances, it can make the difference between maintenance mode and continuing development.

Domain-Driven Design, Eric Evans