PEARD: A Prototype Environment for Active Rule Debugging

This research has investigated dynamic, execution-based rule analysis through the development of a Prototype Environment for Active Rule Debugging, called PEARD. PEARD simulates the execution of active database rules, supporting the Event-Condition-Action rule paradigm. Rule definition is flexible, where changes to rules can be applied immediately during a debugging session without recompiling the system. A breakpoint debugging tool allows breakpoints to be set so that the state of variables may be inspected and changed anytime a breakpoint is reached during rule execution. A rule visualization tool displays the rule triggering process in graph form, supporting different visualization granularities to help the user to understand rule execution. Color coding is also used as part of the visualization tool to help the user see where the different parts of an ECA rule are executed due to deferred coupling modes. Users can examine different parts of the rule graph display to inspect the state of a transaction at different rule execution points. Other debugging features include a means for detecting potential cycles in rule execution and a utility to examine different rule execution paths from the same point in the rule triggering process. Our experience with PEARD has helped to identify some of the useful functional components of an active rule debugging tool and to identify research directions for future active rule development environments.