An OODB \Part" Relationship Model

The whole-part organizational method is one which pervades human thinking, and as such plays an important role in data modeling. This is especially true in manufacturing, design, graphics, multi-media, and document processing|areas targeted by object-oriented databases (OODBs). In this paper, we formally deene OODB relationships which provide constraints and functionalities that enforce real-world, whole-part interactions between objects of the database. These OODB \part" relationships capture a variety of semantics including exclusiveness/sharing, single-/multi-valuedness, cardinality range-restriction, ordering of deenite or indeenite number, essentiality, dependency, and value propagation. For each kind of relationship, we present a graphical symbol which enhances an OODB graphical schema representation that we have previously developed. Among the part relationships presented, two of them, the global exclusive and the class exclusive, reene the notion of exclusiveness between wholes and parts. Two others allow dependency to be directed from the part to the whole, or vice versa. Similarly, data values may be propagated either upward or downward along the part relationship. A basis for the realization of the part relationships in the context of an existing OODB data model is discussed.