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< Contents ERCIM News No. 58, July 2004

Towards a Library of Problem-Solving Methods on the Internet

by Alvaro Arenas and Brian Matthews

Modern knowledge-engineering frameworks include problem-solving methods. They are reusable software components that incorporate domain knowledge to solve users' tasks. Researchers at CCLRC are developing a library of problem-solving methods implemented as web services available on the Internet.

Problem-Solving Methods (PSMs) are software components that can be assembled with domain knowledge bases to create application systems. The knowledge-engineering community has identified and developed PSMs for specific high-level tasks such as diagnosis, assessment, planning, etc, and develop systems using them as components which are combined and instantiated into complete systems.
Researchers at CCLRC are developing a PSMs library, where each method is expressed as a web service described in the OWL-S language. The library is part of a wider research objective that is applying knowledge-based methodologies for developing intelligent systems for the Web; indeed this research objective was identified in the well-known EU-NSF report on Research Challenges and Perspectives of the Semantic Web in 2002 (

In particular, we are utilising the library with the CommonKADS methodology. By contrast to traditional web services discovery, tasks can be determined when modelling a system based on the involved knowledge as well as associated to particular PSMs.

The aim of method is to produce an application which can be deployed on the Web using the emerging web technologies of the Semantic Web and Web Services. Thus the knowledge model in CommonKADS is transformed into an OWL Ontology. The PSM which corresponds to a design pattern is transformed into a class of Web Service. This Web service is represented via a Web service description in the proposed Web Service Description language OWL-S, which uses Semantic Web ontologies to describe the functionality of a web service. When a PSM is invoked to provide a particular instance of the PSM for a particular implementation, a particular instance of the OWL-S class is derived.

Future developments would be using existing OWL-S features to derive a WSDL description of the service. Also, a mechanism of deriving combinations of web-services is required to deliver complete systems deployed across the Web. Further, there is a clear need to be able to express logical rules in the PSMs which is beyond the scope of the current version of OWL-S.

Thus we can use good software and knowledge engineering principles to develop web-based applications. One further advantage of this method is that existing verification methods can be used to develop web applications, leading to more reliable web applications. Consequently, we propose to explore methods such as the B model-based formal method to similarly develop web-based applications. In this case, we use formal verification tools to ensure the correctness of the web application.

The project is developed within the framework of the Semantic Web Advance Development for Europe initiative (SWAD-E).


Please contact:
Alvaro Arenas, CCLRC, UK
Tel: +44 1235 44 6423

Brian Matthews, CCLRC, UK
Tel: +44 1235 44 6684