Design patterns·Who calls whom, and when
the six components stopped calling each other and all called one object in the middle instead.
Mediator pattern
Also calledmediator, hub, coordinator
Replacing many-to-many references between colleagues with a single object that coordinates them. It turns a tangle into a hub, which is a genuine improvement in the tangle and a genuine risk in the hub — the mediator is the class most likely to grow into a god object. It differs from an observer in direction: an observer broadcasts a change outward, a mediator receives events and decides what everyone should do.