EMERALD – Rule Responder Gateway

Funding/Industry: RuleML Inc.

Category: International Projects

Project's URL: Website


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 (i.e. rule set) 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 (Agent Communication Language) messages. The Reasoner can launch an associated reasoning engine, in order to perform inference and provide results. Notice that the Reasoner is actually a service and not a fully autonomous agent. The only reason that we have provided an agent interface is to be able to integrate into the JADE MAS environment.

Rule Responder

Rule Responder is a tool for creating virtual organizations as multi-agent systems that support collaborative teams on the Semantic Web. It provides the infrastructure for rule-based collaboration between the distributed members of such a virtual organization. Human members of an organization are assisted by semi-autonomous rule-based agents, which use Semantic Web rules to describe aspects of their owners’ derivation and reaction logic.

Each Rule Responder instantiation employs three classes of agents, an Organizational Agent (OA), Personal Agents (PAs), and External Agents (EAs). The OA represents goals and strategies shared by its virtual organization as a whole, using a global rule base that describes its policies, regulations, opportunities, etc. Each PA assists a single person of the organization, (semi-autonomously) acting on his/her behalf by using a local knowledge base of derivation rules defined by the person. Each EA uses a Web (HTTP) interface, accepting queries from users and passing them to the OA.


  • Emerald – Intelligent Systems group, Dept. of Informatics, Aristotle University of Thessaloniki, Greece
    • Kalliopi Kravari
    • Nick Bassiliades
  • Rule Responder – RuleML Inc., 34 Reading Street, Fredericton, NB, E3B 6B9, Canada
    • Prof. Dr. Yevgen Biletskiy (treasurer)
    • Prof. Dr. Harold Boley (co-chair)