Ownership as a conceptual modeling construct

Ownership is a relationship that pervades many aspects of our lives, from the personal to the economic, and is particularly important in the realm of the emerging electronic economy. As it is understood on an intuitive level, ownership exhibits a great deal of complexity and carries a rich semantics with respect both to the owner and the possession. A formal model of an ownership relationship that inherently captures varied ownership semantics is presented. This ownership relationship expands the repertoire of available conceptual data modeling primitives. It is built up from a set of characteristic dimensions, namely, exclusiveness, dependency, documentation, transferability, and inheritance, each of which focuses on a specific aspect of ownership semantics. The data modeler has the ability to make a variety of choices along these five dimensions, and thus has access to a wide range of available ownership features in a declarative fashion. These choices ultimately impose various constraints (specified in OCL) on the states of data objects and their respective ownership activities, including transactions such as acquiring and relinquishing ownership. To complement the formal aspects of the ownership model and enhance its usability, we present a graphical ownership notation that augments the Unified Modeling Language (UML) class diagram formalism. An implementation of the ownership relationship in a commercial object-oriented database system is discussed.