Applications require access to multiple information sources and the data of other applications. WSDL-based web services are becoming a popular way of making information sources available on the web and, hence, to applications that need to consume them -- often via data integration systems that combine the data of multiple sources. We argue that the function signature paradigm that is used today by web services cannot capture the query capabilities provided by structurally rich and functionally powerful information sources, such as relational databases. We propose the Query Set Specification Language (QSSL) that allows the concise description of sets of parameterized XPath queries. A QSS is embedded in a WSDL specification to form a specialized type of web services, called Data Services. Data Services connect the calls that the source accepts with the underlying schema. QSSL will be enhanced to describe subsets of XQuery expressions beyond XPath ones.

Pre-2018 CSE ID: CS2003-0739

Information systems typically support only a limited set of queries over the schema they export. The reason is that the participating information sources contribute limited content and limited access methods. We describe the CLIDE interactive system, which extends the QBE-like query builder of Microsoft's SQL Server with a coloring scheme that guides the user toward formulating feasible queries. We formalize the behavior of the system using an interaction graph. We present a modular architecture consisting of a front-end and a back-end that enables the front-end's behavior by providing answers to particular questions about the interaction graph. We developed a back-end for the case where the content and the access methods are described using parameterized views, a formalism that has been used in integration architectures. In this case the set of feasible queries consists of the queries that have an equivalent rewriting using the views. We present the algorithms, implementation and performance of the back-end, showing that CLIDE is a viable online tool.

Pre-2018 CSE ID: CS2004-0807