How to cite this paper

Brüggemann-Klein, Anne, Mustapha Maalej and Marouane Sayih. “Identity constraints for XML.” Presented at Balisage: The Markup Conference 2014, Washington, DC, August 5 - 8, 2014. In Proceedings of Balisage: The Markup Conference 2014. Balisage Series on Markup Technologies, vol. 13 (2014).

Balisage: The Markup Conference 2014
August 5 - 8, 2014

Balisage Paper: Identity constraints for XML

Anne Brüggemann-Klein

Technische Universität München

Mustapha Maalej

Technische Universität München

Marouane Sayih

Technische Universität München

Copyright © 2014 by the authors. Used with permission.


Identity constraints, a fundamental database concept, are built in to XML Schema. In this paper, we attempt to explain clearly our reading of XML Schema's identify constraint concepts. We illustrate our reading with examples, in the style of a tutorial. We also illustrate usage styles and limitations of identity constraints in XML Schema. Finally, we demonstrate how a more general notion of identity constrains that is adapted to the hierarchical nature of XML documents can be expressed with XPath 2.0. Hence, the limitations that we have identified can be by-passed with assertions as introduced by XML Schema 1.1.