Querying multiple databases dynamically on the world wide web

The management and retrieval of Web data has recently received significant attention. Among the various approaches, systems have been proposed whose main goal is to provide a framework to integrate different and heterogeneous information sources into a common domain model. The Web-At-A-Glance (WAG) system falls into this category, its key characteristic being that instead of requiring an explicit description of the sources, it attempts to semi-automatically classify the information gathered from various sites based on the conceptual model of the domain of interest. The initial WAG prototype dealt exclusively with "standard" Web pages, which typically are HTML or XML documents and present non- or semi-structured information, and they vary widely in their means of presenting information to the user. In this paper, we present the extension of the WAG system to deal with form pages. In particular, we describe how the system semiautomatically first extracts a conceptual schema for the form page, and then fills and submits the form in consequence of a user query expressed on the domain conceptual schema.