XML Processing and User Interface Generation (Research Seminar, April 25th, 2002) Vasilis Vassalos New York University Abstract I will describe a system for the rapid development of web-based query forms and reports that query and report semistructured data, i.e., data that are characterized by nesting, irregularities and structural variance. The system separates content (what we are asking queries over), query form semantics (which queries are possible through the form, and which are actually asked) and presentation of the form (how the form looks when rendered by a browser). The query semantics of a form are captured by a declarative query set specification, which formally encodes a (possibly infinite) set of queries via a generator of tree-based query conditions. A graphical user interface semi-automates the development of the query set specification and its association with the visual components (i.e., the appearance) of the query form, by translating visual actions into appropriate query set specifications. In the talk we illustrate how the system accommodates the intricacies that the semistructured nature of the underlying databases introduces. We specifically focus on the formal model of the query set specification, its generation via the graphical user interface, and its coupling with the visual components of the Web-based form and report. We also describe how the query set specification used by the system can be adapted for the automated sharing and integration of powerful Web services.