There are various other concepts regarding objects and classes that are not discussed above. Return to Contents Links and Associations Links and associations abstract relationships among entities. Links are representational constructs of entities that relate other entities. Links are instances of associations. Fundamentally, links are abstracted relationships among objects.
Associations are descriptions of links with a common implementation.
Aggregations are associations that specify a whole-part relationship among an aggregate and component parts. Compositions are aggregations with strong ownership and coincident lifetime constraints among a composite and component parts. Generalizations are associations specifying a taxonomic relationships that relate more general representational constructs and more specific representational constructs. The more specific representational constructs are derived from existing more general representational constructs and acquire the characteristics of the more general representational constructs via inheritance. The more specific representational constructs may override characteristics received via inheritance and introduce new characteristics.