Extending an Object-Oriented RETE Network with Fine-Grained Reactivity to Property Modifications

Abstract

Managing rule chaining, especially in presence of recursion, is a common difficulty when authoring rule based applications. For this reason, production systems implement strategies such as refraction to control rule activation repeatability. In this paper, we present a related extension for an object-oriented version of the RETE algorithm, called property-based reactivity. This extension provides additional, finer grained control of repeatable rules, at the object property level. Patterns have control over which properties they will react to: by default, this is properties the pattern constrains on, but additional properties may be included or excluded using appropriate annotations in the rule base. The engine enhancement is based on a compile-time analysis of the rule base that minimizes the overhead on the language and the runtime execution. The correlation between the performance impact due to the strategy and the structure of the rules has been analyzed and benchmarked using an implementation based on the open source rule engine Drools.