XML Query is a database query language for manipulating collections of data presented as XML. It is as yet largely untested in the field, although as the specification solidifies and implementations become more common, the first flowers are starting to blossom, and the results are promising for a full harvest. In this paper the author describes a web site back end that uses XML Query to integrate a relational database, RDF image descriptions and a geographical database to support searching of a collection of royalty free images. The web site has a variety of output formats including an SVG graphical mode.

The queries are sored in template files, so that they could be edited easily. A library of XML Query functions is provided for the template writer, both for ease of authoring and for long-tem stability.

Physical properties of the scanned images (file size, width, height and so forth) are stored in a relational database; metadata about what the images depict is stored in RDF; there is also an XML file describing the proximity of geographical regions. This separation was done partly to explore the integration possibilities of XML Query, and partly to help ensure a clean map/terrain separation in the metadata.

The resulting search facility is in use, although currently with only a few hundred images. Three user interfaces are provided, to attempt to address differing user needs. Two of these are in (X)HTML, and one in SVG allowing users to drag thumbnails around and to explore their inter-relationships.

Galax was used as an XML Query engine because of its strong typing via XML Schema, aiding development significantly. Queries are generated on the fly based on the input options and templates, and a results cache helps to reduce load on a busy system.

The paper discusses the architecture used, the development, and the difficulties encountered, ranging from the technical (such as generating random placement of objects using the purely functional XML Query language) to the philosophical (such as separating the description of representations such as actual image scans out from the objects depicted).

The work is unusual because it uses XML Query to tie together a range of data sources all presented as XML, and in this shows how XML is solving problems that a decade ago were major expenses in consulting projects.

The software was quick to develop, and shows clearly the benefits of using XML as a communication format at all points of a system.

Future work may include an exploration of RDF representations of inexact dates and time-lines (e.g., This castle was constructed in approx. 1230 CE), further use of XML Schema to simplify queries and increase robustness, extension of the SVG interface, and the use of full text and updates to improve the searching and metadata.