Archived: 21 January 2009
University of Adelaide Masters by coursework thesis, June 2007.
Supervisors: Andrew Wendelborn, Paul Coddington
Web services are one of the standardized ways of web-based communication over internet protocols. Passing messages by using Extensible Markup Language (XML) enables multi-platform communication. For instance, a service implemented by Java language is capable of exchanging data with the one implemented by C++ via web services.
In order to support web services interoperability, each language requires a web services engine as a middleware to facilitate the transformation of its native input and output object into the standard XML format and vice versa. Nevertheless, most existing engines process service calls across a network which is a non-trivial task. Complicated processes are required for generating proxy objects and Web Services Definition Language (WSDL) documents. However, most engines still have some problems with incompatible object types occurring when the data objects are converted into XML format, especially in object oriented languages.
This project aims to reduce the complexity of exposing and requesting services via web services standards by developing a new model of web services engine based on Extensible Style sheet Language Transformations (XSLT). XSLT is a programming language whose native input is in XML format. As a result of using XML as native input, XSLT web service engine would not only reduce the complexity processes for data type conversion, but also avoid the incompatible object type problem.
XSLT is a commonly used language for XML data processing. However current implementations provide no support for exposing XSLT programs as web services, or enabling XSLT programs to invoke web services. Thus, we are providing extra mechanisms to XSLT to support web services functionalities and make them easy to use
This project was undertaken in three major stages. First stage involves an attempt to publish XSLT source programs as web services. The second stage was to enhance ability of XSLT language to invoke services from other web services providers. This stage built upon one of the most widely used XSLT processor named Saxon which has been devised by saxonica.com. The final stage was to test functionalities of the developed XSLT web services engine in term of general use cases with realistic scenario.