The REWERSE Working Group I1 on Rule Markup Languages has completed its work in February 2008. Its objectives are summarized in the following statement:

Facilitate the use of rule formalisms and technologies for inference-enabled Web applications by developing an integrated rule modelling, visualization, verbalization and markup framework that is supported by tools.

Work performed towards objectives

The work performed towards the objectives of WG I1 has focused on rule modelling and rule markup, but it has also been concerned with rule visualization and rule verbalization. In addition, WG I1 has adopted the objective to develop a Web rule formalism based on RDF.

In the area of rule markup and rule interchange, a markup language for different kinds of rules (R2ML) has been defined in the form of a MOF/UML model and an XML schema, and a set of experimental translators for rule interchange have been developed and deployed on the Web.

In the area of rule modelling, a UML-based rule modelling language (URML) has been defined (in the form of a MOF/UML model) and implemented in the graphical rule modelling tool Strelka, which allows to capture rules in the semi-graphical syntax of URML and to serialize the URML rule expressions in the R2ML format with the option to generate specific rule code from the R2ML representation for one of the target platforms Jena Rules, JBoss Rules and FLogic.

Concerning the objective to develop a Web rule formalism based on RDF, WG I1 has developed Extended RDF (ERDF) by extending the triple and XML syntax of RDF, and by conservatively extending its model-theoretic semantics on the basis of partial logic. Unlike RDF and OWL, ERDF supports two kinds of negation, open and closed predicates, as well as default rules for expressing heuristics. A prototype implementation of ERDF has been built on top of the Jena Semantic Web framework.

End results/durable impact

The main results are

• the UML-based rule modelling language URML and its implementation in the Eclipse-based visual rule modelling tool Strelka
• the rule markup language R2ML and the experimental rule interchange toolset based on it
• the Web rule formalism ERDF

Main Results: Reasoning Languages and Advanced Web Applications

• the reasoning language ERDF
• The R2ML-based rule interchange Web service

Main results: Use-case suites, datasets, user studies

A rule-based implementation of the UServ use case for computing the fee of vehicle insurance policies using URML and R2ML

Main results: Publication/exploitation of demonstrators and prototypes

The group has published its demonstrators and prototypes on the project Web site:

• The world’s first public Web service for interchanging rules on the Web
• The Eclipse-based rule modelling tool Strelka
• ERDF inference engine ("reasoner") prototype