XML messaging is at the heart of Web services, providing the flexibility required for their deployment, composition, and maintenance. Yet, current approaches to Web services development hide the messaging layer behind Java or C# APIs, preventing the application to get direct access to the underlying XML information. To address this problem, we advocate the use of a native XML language, namely XQuery, as an integral part of the Web services development infrastructure. The main contribution of the paper is a binding between WSDL, the Web Services Description Language, and XQuery. The approach enables the use of XQuery for both Web services deployment and composition. We present a simple command-line tool that can be used to automatically deploy a Web service from a given XQuery module, and extend the XQuery language itself with a statement for accessing one or more Web services. The binding provides tight-coupling between WSDL and XQuery, yielding additional benefits, notably: the ability to use WSDL as an interface language for XQuery, and the ability to perform static typing on XQuery programs that include Web service calls. Last but not least, the proposal requires only minimal changes to the existing infrastructure. We report on our experience implementing this approach in the Galax XQuery processor.
By: Nicola Onose, Jérôme Siméon
Published in: RC23162 in 2004
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