Composition Model

• This is a layered model of system construction (design) where a single component references others only through their (public/export) interfaces.
• The horizontal structure relates different components of same realm that can play the same role in the same layer.
• The vertical structure relates the requirements and needs of the different layers.
• 3C model is an example of this structure, though terminology is not common in SE community.
• See Goguen's LIL/OBJ for formal treatment and deChampeaux & Lea for adaptations and extensions for OO systems design.