Native XML Programming: Make Your Tags Active
Résumé
XML engines are usually designed to solve a single class of problems: transformations of XML structures, validations of XML instances, Web publishing, and so forth. As the relevant operations or declarations are described with XML vocabularies, their respective engines have to face similar issues such as unmarshalling, and at runtime data handling. In order to address such issues, the author proposes an innovative and reliable XPath-based framework, active tags, that unifies XML technologies in a coherent system where various XML languages can cooperate. In this chapter's approach, the authors focus on its type system that enhances the XML Data Model, specifically by allowing XPath expressions to be applied on non-XML objects, and on the ability of the engine to mix declarative languages with imperative constructs. This valuable feature is illustrated with the Active Schema Language, which allows the building of dynamic-content models.