DTDs versus XML Schema: A Practical Study

Among the various proposals answering the shortcomings of Document Type Definitions (DTDs), XML Schema is the most widely used. Although DTDs and XML Schema Defintions (XSDs) differ syntactically, they are still quite related stract level. Indeed, freed from all syntactic sugar, XML Schemas can be seen as an extension of DTDs with a restricted form of specialization. In the present paper, we inspect a number of DTDs and XSDs harvested from the web and try to answer the following questions: (1) which of the extra features/expressiveness of XML Schema not allowed by DTDs are effectively used in practice; and, (2) how sophisticated are the structural properties (i.e. the nature of regular expressions) of the two formalisms. It turns out that at present real-world XSDs only sparingly use the new features introduced by XML Schema: on a structural level the vast majority of them can already be defined by DTDs. Further, we introduce a class of simple regular expressions and obtain that ...

• Type: Conference
• Year: 2004
• Where: WEBDB
• Authors: Geert Jan Bex, Frank Neven, Jan Van den Bussche
• Keywords: Internet Technology, Regular Expressions, WEBDB 2004, Xml Schema, XML Schema Defintions