EMERALD is an implementation framework for interoperable reasoning among agents in the Semantic Web, by using third-party trusted reasoning services. The advantage is that every agent can exchange its position justification arguments with any other agent, without the need for all agents to conform to the same kind of rule paradigm or logic; the receiving agent can use an external reasoning service to grasp the semantics of the rule set, namely the set of the results of the rule set. EMERALD is built on-top of the JADE multi-agent system. In EMERALD, reasoning services are “wrapped” by an agent interface, called the Reasoner, allowing other Ias to contact them via ACL messages. The Reasoner can launch an associated reasoning engine, in order to perform inference and provide results.