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25 August 1997|
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Shawn P. McCarthy|
Can anything topple the Hypertext Markup Language as the universal language of the World Wide Web? Don't bet your career on it, but don't ignore the rumblings about the Extensible Markup Language.
XML holds great promise for the Web's future because HTML--even Version 4.0--isn't extensible. It's just not easy enough to integrate straight HTML documents into other programs and information systems.
Managers of government Web sites should consider XML as a standard way to create new data tags. These embedded tags make it much easier to search documents by content fields and to extract or update information.
The military could use XML to define tags for parts and equipment. The tags would allow specific content in, say, a Web-based user manual to be reused in catalogs, reports or order forms.
Tags would look fairly familiar: <partnumber> </partnumber>. Tags such as <report> </report> would make it possible to reference other documents or parts of them, so a chunk of one document could appear as part of a document.
As more and more intelligent software agents roam Web sites, managers could tag information that is updated daily, making it easier for the agents to find pointers to what's truly news.
XML's champion, the World Wide Web Consortium of Cambridge, Mass., sees it as a logical way to integrate Web data into multiple applications. The recently finalized standard got a huge boost when Microsoft Corp. used it to develop the Channel Definition Format for its new push technology.
For more information on XML, visit the consortium's site at http://www.w3.org and look for the XML pointer. Or visit http://www.w3.org/pub/WWW/MarkUp/SGML/Activity for details on structured document interchange.
You probably know that HTML is a subset of the Standardized General Markup Language, or SGML. SGML's Document Type Descriptions automate information retrieval in a standard way.
XML is a subset of SGML, too. It's designed to be broad enough for anticipated Web needs without encompassing everything in the farther-reaching SGML set. XML could push SGML out of the picture for complex Internet systems.
So what's not to like about XML?
Well, it's not easy to incorporate into graphical Web authoring tools, which are used by most Web page creators who don't have programming experience.
And conventional Web browsers can't do much with custom-tagged content. Netscape Communications Corp. has reluctantly agreed to support XML, but it's not clear what, if anything, Netscape browsers will do with it. Then there's the possibility of over-customizing XML. In theory, users could even define a common tag to mean anything.
But in my book, the pluses outweigh the minuses. XML has the potential to support cross-platform data exchange between office applications such as calendars.
It could become the cornerstone of electronic commerce, tracking prices and exchanging secure payment information. Mixed with Java, it could become the perfect funnel for channeling information into custom Web applications.
There's a lot of XML talk now, but you won't find much support for it in Internet application development kits.
That will change next year, so get ready to decide whether XML is going in your site's future.
The French company Grif SA has an online demo about authoring and formatting XML documents that highlights how SGML authoring technology can be used to create and publish XML documents. Check it out at http://www.grif.fr/newsref/xmldemo.html.
ArborText Inc. of Ann Arbor, Mich., a publisher of SGML tools, maintains a list of SGML and XML resources. Visit it at http://www.arbortext.com/linksgml.html.
Shawn P. McCarthy is a computer journalist, webmaster and Internet programmer for GCN's parent, Cahners Publishing Co. E-mail him at email@example.com.