OO jDREW, the Object Oriented Java Deductive Reasoning Engine for the Web is the reference implementation of the (Naf Hornlog) RuleML Web rule language. It is an Object Oriented extension to jDREW. The Object Oriented extensions for RuleML implemented by OO jDREW include:

  • Order Sorted Types
  • Slots
  • Object Identifiers
OO jDREW is written in the Java programming language.


OO jDREW has been moved to GitHub by Markus Zucker and Christian Fabbricatore, where it has been developed from OO jDREW Version 0.961 to OO jDREW Version 1.0 and prepared for further development in a Social Coding community drawing on Web 2.0 methods. Instead of the earlier SourceForge version of OO jDREW, GitHub has thus become the place to get the newest OO jDREW and contribute to it: https://github.com/OOjDREW

Getting OO jDREW

OO jDREW can be run online at this link.

OO jDREW can be downloaded at this link.

Modes of Execution

  • Bottom-Up

    Bottom-up execution is used to infer all derivable knowledge from a set of clauses (forward reasoning).
  • Top-Down

    Top-down execution is used to solve a query on the knowledge base (backward reasoning)

Supported Languages

  • POSL

    POSL is a Positional Slotted Language that implements RuleML shorthand (positional part similar to Prolog).
  • RuleML

    OO jDREW supports the XML syntax of RuleML.


OO jDREW - Copyright (C) 2005 - 2012 Marcel Ball, Ben Craig, and Harold Boley

This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

Last Updated:
   Nov 17, 2012

   Harold Boley