OWL-S Plugin

What is the OWL-S Plugin?

Axis OWLS plugin is a suggestion for service provdiers to how to provide service description using OWL Services (OWL-S). For demonstration we have extended the Axis Implementation from the Apache Web Services Project. We believe, that obtaining OWLS description about a Web service should work the same way as today WSDL descriptions are requested. For further information about Apache's Axis please visit the Axis Homepage.

What is OWL-S

In short, OWL-S is a set of markup language constructs for describing the properties and capabilities of web services in a machine interpretable form. More details can be found at the DAML Services Homepage.

How will it work?

Axis OWL-S Plugin uses the Axis Servlet Query String Plugin Mechanism. By evaluating query strings like ?wsdl or ?owls certain actions can be invoked. This is done by defining a Query String Plugin Handler. The idea is, that such a Query string handler processes requests for OWL-S description for each Web service.

How to create OWL-S description?

Currently it is planned to use the OWL-S API from the Mindswap project to generate descriptions in OWLS dynamically. Details about Mindswap and their OWL-S API can be found at the Mindswap OWL-S API Site.

What's ready?

Currently the OWLS plugin is realised on a basic level. OWL-S Descriptions are not created, but available in the file system. To manage the description files a simple Web interface is provided. It is possible to upload and name a OWLS file and to view all stored files. If an OWLS description is requested by the query string ?owls the handler looks for the appropriate file and returns it.

Open Issues

At the moment there is a problem with the Axis plugin mechanism. Although it is documented we didn't succeed to deploy our plugin in the descripted way. Axis (1.2 alpha, Java) doesn't seem to consider the server-config.wsdd. As a temporary workaround we decided to define our Query String Handler as a default handler by editing the source of org.apache.axis.transport.http.AxisServlet and rebuilding Axis. Following there are two ways to integrate the OWL-S Plugin:

What is used to develop the OWL-S Plugin?

This product includes software developed by the Apache Software Foundation (http://www.apache.org/).
The software is licensed under the LGPL.