Graphical Tools for Rule Development in the Active DBMS SAMOS

Active Database Management Systems (active DBMS) support the definition, management and execution of Event/Condition/Action-rules specifying reactive application behavior. Although the advantages of active mechanisms are nowadays well-known, there is still no wide use in practice. One main problem is that especially for large rule sets, defined by different persons at different points in time, potential conflicts and dependencies between rules are hard to predict and rule behavior is difficult to control. Therefore, tools are needed to assist the development and maintenance of rule bases. These tools should provide for graphical interfaces supporting both, “static“ activities (performed during rule specification) such as rule editing, browsing, design, rule analysis, and “dynamic“ activities (performed at runtime, during the execution of an application) such as testing, debugging and understanding of rule behavior. The aim of this demonstration is to show the use of three of these tools, namely the rule editor, the browser and the termination analyzer in the process of developing applications for the active object-oriented DBMS SAMOS [3]. SAMOS has been build on top of the commercial DBMS ObjectStore. The distinctive feature of the SAMOS rule language is the event algebra for the definition of complex events. Complex events are constructed by applying operators to component events, which can be primitive events (e.g., data modification, transaction and time events) or other complex events. This allows a high expressive power for the specification of active behavior, but at the same time aggravates the problems mentioned above. The concepts underlying these tools are discussed in [4] and are an extension of classical approaches [l] that also considers rules including complex events. The context of the demonstration is a small active financial application FAME [2]. Our current tools are characterized as follows: