XML: Introduction to Xquery

by Srinivas Pandrangi and Alex Cheng

When my team at a healthcare software company was developing internet distributed workflow systems a few years ago we had to write a homegrown query language for examining XML process definitions. The W3C XML Query Working Group has finally delivered a working draft of a general solution, XQuery 1.0: An XML Query Language. Pandrangi and Cheng have published the first of four articles on Introduction to Xquery:

"Over the past few years, XML has rapidly gained popularity as a formatting language for information, finding constituencies in both the document-centric and data-centric worlds. The explosive growth of XML-based standards bears testimony to XML's interest to many different technical communities. Applications now use XML for both transient messages, such as SOAP or XML-RPC messages, and as persistent storage, such as in XML databases or content management systems. An XML-based web, as opposed to an HTML-based web, no longer sounds like fantasy.

"As the volume of information stored in XML grows, it becomes correspondingly more important to be able to access information in XML documents efficiently and effectively. To do that, you need an expressive query language so you can specify precisely what information you want to retrieve or update in an XML data source. XQuery intends to be that language."