Schema extraction from XML collections

Abstract

XML Schema language has been proposed to replace Document Type Definitions (DTDs) as schema mechanism for XML data. This language consistently extends grammar-based constructions with constraint- and pattern-based ones and have a higher expressive power than DTDs. As schemas remain optional for XML, we address the problem of XML Schema extraction. We model the XML schema as extended context-free grammars and develop a novel extraction algorithm inspired by methods of grammatical inference. The algorithm copes also with the schema determinism requirement imposed by XML DTDs and XML Schema languages.