XML took a basic but crucial step toward maturity today with the World Wide Web Consortium's introduction of XQL, a querying language for XML documents.
Extensible Markup Language, or XML, is a metalanguage that lets developers create tags that make up their own subject- or industry-specific mark-up languages. Part of the promise of XML is to make data contained in Web documents easier to search and mine through the specificity of those tags.
XQL, or XML Query Language, is designed to let XML deliver on that promise.
"XQL allows developers to query XML data the way they would query a SQL database," said David Wasch, a product manager with the marketing group at Microsoft. "It lets you type in requirements for data you want to get out. That's one of the points of XML, but, as of yet, it hasn't been built. This is the kind of thing that's going to make XML super-powerful."
XQL currently is envisioned--and was first proposed in September--as a set of extensions to Extensible Style Language, or XSL. A paper describing XQL has been posted to the Web for consideration at the W3C's Query Languages Workshop, to be held December 3 and 4 in Boston.
Microsoft submitted the paper along with partners webMethods and Texcel. Microsoft supports XQL in the recently released beta version of its Internet Explorer 5.0 browser; webMethods will implement XQL in an upgrade of its B2B Integration Server. Texcel wrote the initial XQL draft.