A comprehensive part model and graphical schema representation for object-oriented databases

Part-whole modeling plays an important role in the development of database schemata in data-intensive application domains such as manufacturing, design, computer graphics. text document processing, and so on. Object-oriented databases (OODBs) have been targeted for use in such areas. Thus, it is essential that OODBs incorporate a part relationship as one of their modeling primitives. In this dissertation, we present a comprehensive OODB part model which expands the boundaries of OODB part-whole modeling along three fronts. First, it identifies and codifies new semantics for the OODB part relationship. Second, it provides two novel realizations for part relationships and their associated modeling constructs in the context of OODB data models. Third. it, provides an extensive graphical notation for the development of OODB schemata. The heart of the part model is a part relationship that imposes part-whole interaction on the instances of an OODB. The part relationship is divided into four characteristic dimensions: (1) exclusive/shared. (2) cardinality/ordinality, (3) dependency. and (A) value propagation. The latter forms the basis for the definition of derived attributes in a part hierarchy. To demonstrate the viability of our part model, we present two novel realizations for it in the context of existing OODBs. The first realizes the part relationship as an object class and utilizes only a basic set of OODB constructs. The second realization, an implementation of which is described in this dissertation, uses the unique metaclass mechanism of the VODAK Model Language (VML). This implementation shows that our part model can be incorporated into an existing OODB without having to rewrite a substantial subsystem of the OODB, and it also shows that the VML metaclass facility can indeed support extensions in terms of new semantic relationships. To facilitate the creation of part-whole schemata, we introduce an extensive graphical notation for the part relationship and its associated constructs. This notation complements our more general OODB graphical schema representation which includes symbols for classes, attributes. methods. and a variety of relationships. OO-dini, a graphical schema editor that employs our notation and supports conversion of the graphical schema into textual formats, is also discussed