Abstract. Rule Responder is an intelligent multi-agent system for collaborative teams and virtual communities that uses RuleML as its rule interchange format. The system allows these virtual organizations to collaborate in an effective semi-automatic manner, and is implemented as a Web-based application on top of the Enterprise Service Bus Mule. It supports rule execution environments (rule/inference engines) such as the Prova distributed Semantic Web rule engine and OO jDREW (Object Oriented java Deductive Reasoning Engine for the Web). The paper describes the role of OO jDREW for answering queries against rule bases in the Naf Hornlog RuleML sublanguage for the real-world use case of a symposium organization.