On using UML class diagrams for object-oriented database design specification of integrity constraints

Abstract

In the course of object-oriented software engineering, the UML class diagrams are used to specify the static structure of the system under study, such as classes, types and various kinds of static relationships among them. Objects of the persistent classes can be stored in object-oriented databases or in relational databases. In the former case, the UML class diagrams are actually used for conceptual object-oriented database designs. However, the standard UML class diagram lacks the ability to specify some inherent integrity constraints, such as keys and uniqueness, for object-oriented databases. This paper proposes an extension to the UML metamodel, i.e., the introduction of two new model elements (key and IConstraint) and some new attributes to the existing meta model, to accommodate further, additional features for constraint specification. On the model level, a compartment CONSTRAINT of the class notation and some property strings for displaying the integrity constraints are added. The database design is then mapped to the extended ODMG-ODL schema definition.