composition is a containment relationship of physical type where the content entity is a part of a container entity
This relationship is also known as:
- a whole/part relationship (ie whole/component)
composition is also known as physical containment because when the container is destroyed, the content entity is supposed to be destroyed (whereas in a aggregation containment it is not)
The container is said to be a composite type.
Composition aims to tackle the specialization of some entity.
It's a binary association (link between only two element).
A composition introduce a dependency relationship.
composition: same as wrapper + injection through parameters set. ?
- an engine is part of a car
- a windows is composed of a slider, an header, a panel
- a parent child relationship
Example in an class diagram