Rules have been proposed for providing active behaviour in DBMS. Previous attempts to add rules to Object Oriented DBs have often resulted in a dichotomy between rules and other kind of objects. Bere a uniform approach is presented, in which rules are described and handled in the same way as any other object in the system, without any additional mechanisms being introduced. Thus rules can be related to other objects or arranged in hierarchies, and rules can even be defined which are triggered by methods attached to rules themselves. Since rules and classes are both objects, a relationship between these two kinds of objects can be used to provide a class-based index for rules. In this way, the search for applicable rules is considerably reduced. An early implementation and several examples are shown in ADAM, an Object Oriented DB in PROLOG.
Oscar Díaz, Norman W. Paton, Peter M. D. Gr