An Agent-Based Approach to Extending the Native Active Capability of Relational Database Systems

Event-condition-action (or ECA) rules are used to capture active capability. While a number of research prototypes of active database systems have been built, ECA rule capability in Relational DBMSs is still very limited. In this paper, we address the problem of turning a traditional database management system into a full-fledged active database system without changing the underlying system. The advantages of this approach are: transparency; ability to add active capability without changing the client programs; retain relational DBMS's underlying functionality; and persistence of ECA rules using the native database functionality. In this paper we describe how complete active database semantics can be supported on an existing SQL Server (Sybase, in our case) by adding a mediator, termed ECA Agent, between the SQL Server and the clients. ECA rules are fully supported through the ECA Agent without changing applications or the SQL Server. Composite events are detected in the ECA Agent and actions are invoked in the SQL Server. Events are persisted in the native database system. ECA Agent is designed to connect to SQL Server by using Sybase connectivity products. The architecture, design, and implementation details are presented in this paper.