Andrzej Jodłowski, Piotr Habela, Jacek Płodzień, Kazimierz Subieta

Dynamic Object Roles in Conceptual Modeling and Databases

932

Abstract

The paper discusses the concept of dynamic object roles as a facility for conceptual modeling and as a data structure to be implemented in object-oriented database management systems. Emphasis is put on implications of this concept for an object model and a corresponding query language. We discuss advantages of the concept and known approaches to implement it. A new approach is proposed, which assumes that a role is a distinguished subobject of an object. A role inherits dynamically attribute values and methods of its parent object. Objects can be accessed by their names, as well as by the names of their roles. The role concept essentially changes the semantics of other notions of object-oriented models, such as classes, inheritance and substitutability. In the paper we discuss how dynamic roles could be involved into an object store, an object definition language and a query language built in the spirit of the ODMG standard.

Keywords : dynamic object role, object-oriented, conceptual modeling, query language, database metamodel, database schema, ODMG standard.