Name:
  Mediator

Intent:
  - encapsulates the interaction logic of a set of objects
  - avoid one-to-one communication between a set of objects

Structure:
  - there is a bunch of objects (colleagues) that must interact
    with each other
  - create an object (mediator) the encapsulate the interaction logic
  - each colleagues tells the mediator when something interesting happens
    (interesting is an event)
  - mediator propages the consequences of an event

Note:
  - the colleagues don't need to be homogeneous