Building an integrated active OODBMS: requirements, architecture, and design decisions

Active OODBMSs must provide efficient support for event detection, composition and rule execution. Previous experience of building active capabilities on top of existing closed OODBMSs has proven to be ineffective. 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 the event set, rule execution modes and lifespan of the events supported in our architecture. We also discuss event composition coupling relative to transaction boundaries. Since building an active OODBMS ex nihilo is extremely expensive, we are building the REACH (REal-time ACtive Heterogeneous) OODBMS by extending Texas Instruments' Open OODB toolkit. Open OODB is particularly well-suited for our purposes because it is the first 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-firing process of the REACH active OODBMS, and show how these mechanisms interplay with the Open OODB core mechanisms.<>