Package drools2: Information

Drools is a Rules Engine implementation based on Charles
Forgy's Rete algorithm tailored for the Java language.
Adapting Rete to an object-oriented interface allows for
more natural expression of business rules with regards to
business objects. Drools is written in Java, but able to run
on Java and .Net.
Drools is designed to allow pluggeable language
implementations. Currently rules can be written in Java,
Python and Groovy. More importantly, Drools provides for
Declarative Programming and is flexible enough to match the
semantics of your problem domain with Domain Specific
Languages (DSL) via XML using a Schema defined for your
problem domain. DSLs consist of XML elements and attributes
that represent the problem domain.

Drools is now a JBoss JEMS product.