Graphical query interfaces for semistructured data: the QURSED system

We describe the QURSED system for the declarative specification and automatic generation of Web-based query forms and reports (QFRs) for semistructured XML data. In QURSED, a QFR is formally described by its query set specification (QSS) which captures the complex query and reporting capabilities of the QFR and the associations of the query set specification with visual elements that implement these capabilities on a Web page. The design-time component of QURSED, called QURSED Editor, semi-automates the development of the query set specification and its association with visual elements by translating intuitive visual actions taken by a developer into appropriate specification fragments. The run-time component of QURSED produces XQuery statements by synthesizing fragments from the query set specification that have been activated during the interaction of the end-user with the QFR and renders the query results in interactive reports as specified by the QSS. We describe the techniques and algorithms employed by QURSED with emphasis on how it accommodates the intricacies introduced by the semistructured nature of the underlying data. We present the formal model of the query set specification, as well as its generation via the QURSED Editor, and focus on the techniques and heuristics the Editor employs for translating visual designer input into meaningful specifications. We also present the algorithms QURSED employs for query generation and report generation. An online demonstration of the system is available at http://www.db.ucsd.edu/qursed/.