World Wide Web Journal - Special issue on XML: principles, tools, and techniques
Dependent types in practical programming
Proceedings of the 26th ACM SIGPLAN-SIGACT symposium on Principles of programming languages
ACM Computing Surveys (CSUR)
DSD: A schema language for XML
FMSP '00 Proceedings of the third workshop on Formal methods in software practice
xlinkit: a consistency checking and smart link generation service
ACM Transactions on Internet Technology (TOIT)
POPL '03 Proceedings of the 30th ACM SIGPLAN-SIGACT symposium on Principles of programming languages
Expressiveness of XSDs: from practice to theory, there and back again
WWW '05 Proceedings of the 14th international conference on World Wide Web
Expressiveness and complexity of XML Schema
ACM Transactions on Database Systems (TODS)
Simple off the shelf abstractions for XML schema
ACM SIGMOD Record
Improving self-interpretation of XML-based business documents by introducing derived elements
Electronic Commerce Research and Applications
Using semantics for XPath query transformation
International Journal of Web and Grid Services
Validation of XML documents: from UML models to XML schemas and XSLT stylesheets
ADVIS'06 Proceedings of the 4th international conference on Advances in Information Systems
Complete and reusable description of message structural constraints in web service interfaces
Computer Standards & Interfaces
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In the past few years, a number of constraint languages for XML documents has been proposed. They are cumulatively called schema languages or validation languages and they comprise, among others, DTD, XML Schema, RELAX NG, Schematron, DSD, xlinkit. One major point of discrimination among schema languages is the support of co-constraints, or co-occurrence constraints, e.g., requiring that attribute A is present if and only if attribute B is (or is not) presentin the same element. Although there is no way in XML Schema to express these requirements, they are in fact frequently used in many XML document types, usually only expressed in plain human-readable text, and validated by means of special code modules by the relevant applications. In this paper we propose SchemaPath, a light extension of XML Schema to handle conditional constraints on XML documents. Two new constructs have been added to XML Schema: conditions -- based on XPath patterns -- on type assignments for elements and attributes; and a new simple type, xsd:error, for the direct expression of negative constraints (e.g. it is prohibited for attribute A to be present if attribute B is also present). A proof-of-concept implementation is provided. A Web interface is publicly accessible for experiments and assessments of the real expressiveness of the proposed extension.