A New Perspective on Rule Support for Object-Oriented Databases

Abstract

This paper proposes a new approach for supporting reactive capability in an object-oriented database. We introduce an event interface, which extends the conventional object semantics to include the role of an event generator. This interface provides a basis for the specification of events spanning sets of objects, possibly from different classes, and detection of primitive and complex events. This approach clearly separated event detection from rules. New rules can be added and use existing objects, enabling objects to react to their own changes as well as to the changes of other objects. We use a runtime subscription mechanism, between rules and objects to selectively monitor particular objects dynamically. This elegantly supports class level as well as instance level rules. Both events and rules are treated as first class objects. © 1993, ACM. All rights reserved.