We describe an extensible constructor tool that helps information experts (e.g., librarians) create specialized query synthesizers for heterogeneous digital-library environments. A query synthesizer produces a graphical user interface in which a digital-library patron can specify a high-level, fielded, multi-source query. Furthermore, a query synthesizer interacts with a query translator and an attribute translator to transform high-level queries into sets of sourcespecific queries. In this paper, we discuss how our tool for constructing synthesizers can facilitate the discovery of available attributes (e.g., `title'), the collation of schemas from different sources, the selection of input widgets for a synthesizer (e.g., a drop-down list widget to support input of controlled vocabulary), and other design aspects. We also describe the user interface of our prototype constructor, which is implemented based on the Stanford InfoBus and metadata architecture.
Michelle Q. Wang Baldonado, Seth Katz, Andreas Pae