In this paper we present BBQ (Blended Browsing and Querying), a graphic user interface for seamlessly browsing and querying XML data sources. BBQ displays the structure of multiple data sources using a paradigm that resembles drilling-down in Windows' directory structures. BBQ allows queries incorporating one or more of the sources. Queries are constructed in a query-by-example (QBE) manner, where DTDs play the role of schema. The queries are arbitrary conjunctive queries with GROUPBY, and their results can be subsequently used and refined. To support query refinement, BBQ introduces virtual result views: standalone virtual data sources that (i) are constructed by user queries, from elements in other data sources, and (ii) can be used in subsequent queries as first-class data sources themselves. Furthermore, BBQ allows users to query data sources with loose or incomplete schema, and can augment such schema with a DTD inference mechanism.
Kevin D. Munroe, Yannis Papakonstantinou