Building an Integrated Active OODBMS: Requirements, Architecture, and Design Decisions

Active OODBMSs must provide eecient support for event detection, composition, and rule execution. Previous experience, reported here, building active capabilities on top of existing closed OODBMSs has proven to be ineeective. We propose instead an active OODBMS architecture where event detection and rule support are tightly integrated with the rest of the core OODBMS functionality. After presenting an analysis of the requirements of active OODBMSs, we discuss event set, rule execution modes, and lifespan of events supported in our architecture. We also discuss the coupling of event composition relative to transaction boundaries. Since building an active OODBMS ex nihilo is extremely expensive, we are building the REACH active OODBMS by extending Texas Instru-ment's Open OODB Toolkit. Open OODB is particularly well suited for our purposes because it is the rst DBMS whose architecture closely resembles the active database paradigm. It provides low-level event detection and invokes appropriate DBMS functionality as actions. We describe the architecture of the event detection and composition mechanisms, and the rule ring process of the REACH active OODBMS, and show how these mechanisms interplay with the Open OODB core mechanisms.