Teaching Web services using WSExplorer

It is important for Web services developers to know "under the hood" aspects of Web services technology for both creating and consuming them. To fulfill this need, we have developed WSExplorer, a tool for teaching Web services concepts and its building blocks. It facilitates hands-on experimentation with the inquiry aspect of UDDI registries, obtaining and analyzing WSDL documents, invoking Web service operations, and examining SOAP requests and responses. This paper begins with a brief introduction to Web services so that the paper is self-contained. Next, we describe how WSExplorer can be used in distributed computing and related courses to learn the underlying technical aspects of Web services. We discuss motivation, rationale, and approach for the exercises that we have designed for use in these courses. More specifically, the exercises explore: discovering Web services using UDDI registry; understanding the structure of a WSDL document; understanding how XML schemas are written by examining the WSDL schema; verifying that a retrieved WSDL document is valid against its schema; identifying operations and I/O message formats supported by a Web service; locating the operations identified by the WSDL analyzer in the corresponding WSDL document; examining SOAP requests/responses and validating them against the corresponding WSDL; and interacting with Web services developed by other students in the class.