Exporting and interactively querying Web service-accessed sources: The CLIDE System

The CLIDE System assists the owners of sources that participate in Web service-based data publishing systems to publish a restricted set of parameterized queries over the schema of their sources and package them as WSDL services. The sources may be relational databases, which naturally have a schema, or ad hoc information/application systems whereas the owner publishes a virtual schema. CLIDE allows information clients to pose queries over the published schema and utilizes prior work on answering queries using views to answer queries that can be processed by combining and processing the results of one or more Web service calls. These queries are called feasible. Contrary to prior work, where infeasible queries are rejected without an explanatory feedback, leading the user into a frustrating trial-and-error cycle, CLIDE features a query formulation interface, which extends the QBE-like query builder of Microsoft's SQL Server with a color scheme that guides the user toward formulating feasible queries. CLIDE guarantees that the suggested query edit actions are complete (i.e., each feasible query can be built by following only suggestions), rapidly convergent (the suggestions are tuned to lead to the closest feasible completions of the query), and suitably summarized (at each interaction step, only a minimal number of actions needed to preserve completeness are suggested). We present the algorithms, implementation, and performance evaluation showing that CLIDE is a viable on-line tool.