An Extensible Approach to Realizing Advanced Transaction Models

Abstract

Use of databases for non-traditional applications has prompted the development of an array of new transaction models whose semantics vary from the traditional model as well as from each other. The implementation details of most of the proposed models have been sketchy at best. Furthermore, current architectures of most DBMSs do not lend themselves to supporting more than one built-in transaction model. As a result, despite the presence of rich transaction models, applications cannot realize semantics other than that provided by the traditional transaction model. In this dissertation, we propose a framework for supporting various transaction models in an extensible manner. We demonstrate how ECA (event-condition-action) rules, defined at the system level on significant operations of a transaction and/or data structures such as a lock table, allow the database implementor/customizer to support: (i) currently proposed extended transaction models, and (ii) newer transaction models as they become available. Most importantly, this framework allows one to customize transaction (or application) semantics in arbitrary ways using the same underlying mechanism. Sentinel, an active object-oriented database system developed at UF, is used for demonstrating our approach for implementing extended transaction models.