The XML typechecking problem

• Authors: Dan Suciu
• Venue: ACM SIGMOD Record
• Year: 2002

When an XML document conforms to a given type (e.g. a DTD or an XML Schema type) it is called a valid document. Checking if a given XML document is valid is called the validation problem, and is typically performed by a parser (hence, validating parser), more precisely it is performed right after parsing, by the same program module. In practice however XML documents are often generated dynamically, by some program: checking whether all XML documents generated by the program are valid w.r.t. a given type is called the typechecking problem. While a validation analyzes an XML document, a type checker analyzes a program, and the problem's difficulty is a function of the language in which that program is expressed. The XML typechecking problem has been investigated recently in [MSV00, HP00, HVP00, AMN+01a, AMN+01b] and the XQuery Working Group adopted some of these techniques for typechecking XQuery [FFM+01]). All these techniques, however, have limitations which need to be understood and further explored and investigated. In this paper we define the XML typechecking problem, and present current approaches to typechecking, discussing their limitations.