Excellent Decision Table based Rules Engine implementation in Java
DT4J is a Java implementation of Decision Table based rules engine. It supports excel based and an editor based Decision Table authoring. It integrates with Spring expressions (SpEL) to express conditions and actions. Put together it's a power rules engine.
jSemanticService is a lightweight framework that allows to use Rules and Semantics in Services or Applications using Annotations. Features: jBoss Rules (Drools 4.0) as Business Rules Engine provider. Full support of Annotations, Spring, Flex/Blaze DS.