XQuery from the Experts: A Guide to the W3C XML Query Language

Composition Techniques: Examples

In this section, we consider examples of composition techniques that illustrate the available variety. We divide composition techniques into three fundamental camps: default mappings, extended SQL, and annotated schemas. We illustrate each camp with a specific example—but it should be emphasized that these are just three current examples from a much wider selection, offered by commercial vendors, academic research and freeware.

Default Mapping

In the simplest kind of composition technique, a default mapping,^[1] the structure of the database is exposed directly, as a fixed form of XML document. This is an implicit composition technique, in which the user has little or no control over the generated XML. Listing ...