Conceptual Design of Active Object-Oriented Databases

By Peter Lang .
Advised by Gerti Kappel

This work has been finished in September 1997.

Business rules are statements about business policies and can be formulated according to the event-condition-action structure of rules provided by active database systems, which allow to react to predefined situations by performing an operation if a certain condition is satisfied when the event occurs.

The conceptual design of active object-oriented databases includes modeling the structure of objects, their passive behavior (the operations that can be peformed on objects), and their active behavior (rules that allow objects to react autonomously to predefined situations by performing an operation). Modeling business rules at the conceptual level by means of the active behavior of objects requires different concepts than currently provided by active object-oriented database systems and by recent approaches to active object-oriented database design.

This thesis presents a high-level graphical language called Active Object/Behavior Diagrams, which meets the requirements identified for modeling business rules at the conceptual level. Active Object/Behavior Diagrams extend the already introduced Object/Behavior Diagrams with Situation/Activation Diagrams, a graphical rule and event language.

In order to cope with the complex domain of business applications, concepts for specializing the object structure and the passive behavior have been elaborated and presented in the diverse literature. Specializing active behavior (business rules) has received little attention so far. This thesis extends the specialization concepts already defined for Object/Behavior Diagrams with the concepts for specializing Situation/Activation Diagrams.

The usage of modeling concepts is constrained by a set of consistency rules. They have the designer stick to a correct usage of the modeling concepts in order to achieve a consistent database schema. Even if all consistency rules are obeyed, different designers may yield different consistent database schemata, which may differ in their quality. This thesis presents guidelines for the conceptual design of active behavior in active object-oriented databases. These design guidelines should help the designer to achieve a consistent as well as a high-quality database schema, i.e., a comprehensible and maintainable database schema.