Preserving XML Queries During Schema Evolution: A Guide to Writing Queries That Behave Well Across XML Schema Changes

Overview

As XML gains widespread use as an information exchange standard, the ability to persist, validate, and query XML documents becomes increasingly important. Moreover, with the proliferation of Web services and mash-ups, Web application developers increasingly need to query and transform XML messages, where such messages come directly from a Web service or indirectly from a database in which they are persisted. Most commercial database management systems already support XML persistence in some form. For example, IBM's DB2 pureXML provides support for storing XML documents natively in XML typed columns, validating XML documents against XML schemas, and querying XML documents using XQuery and SQL/XML query languages.