XML is here to stay: Page 3

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These dictionaries are springing up everywhere. They cover practically every subject imaginable, from mathematics to music, and from astronomy to air traffic control. As an example of why XML is useful, consider this: HTML offers no way to mark up mathematical equations. So scientists and mathematicians have resorted to inserting images of equations into documents. The proposed XML standard MathML will allow XML-capable Web browsers to display equations directly.

 LESSONS LEARNED ABOUT XML
Keep an eye on the standards, and bet on one that's going to win. XML vocabularies that have the backing of major competitors stand the best chance of emerging as accepted standards.
Get involved. XML vocabularies for many industries are currently being hammered out, so now is the time to make sure that they represent the data in your organization.
XML may not always be the answer.For OLTP/ high-transaction type systems, XML is not necessarily your best choice.

But one risk is that different groups will produce multiple dictionaries, leading to a balkanization of XML, warns a recent report published by Zona Research Inc. of Redwood City, Calif. In key fields such as e-commerce, for example, there are already several competing dictionaries, including the Internet Open Trading Protocol (IOTP, http://www.iotp.org) and Open Buying on the Internet (OBI, http://www.openbuy.org).

Efforts at standardization are already being made in some industries. For example, RosettaNet (http://www.rosettanet.org) is an initiative by a consortium of 34 companies in the PC industry, ranging from manufacturers such as Compaq Computer Corp., Hewlett-Packard Co., and Intel Corp. to resellers like Arrow Electronics and CompUSA. The group has hammered out an XML dictionary that defines all the properties of a personal computer--everything from modems and monitors to the amount of RAM on the motherboard. The goal is a common business language that will link the entire PC industry's supply chain.

THE ABCs OF XML
BizTalk:Microsoft's XML initiative, including BizTalk.org, a Web portal for XML information and DTDs.

CSS: Cascading Style Sheet. The style sheet for displaying HTML, and now XML, documents.

DCD:Document Content Description. A proposed XML schema that includes features such as datatypes, aimed at making XML better at handling data from relational databases.

DDML:Document Definition Markup Language. A proposed XML schema modeled on XML syntax itself.

DTD:Document Type Definition. A file that defines the tags or vocabulary of XML documents for a specific industry or area of knowledge. There are already DTDs for e-commerce, mathematics, air traffic control, and a whole host of other fields.

SGML:Standard Generalized Markup Language. The mother of all markup languages, SGML began life in the 1970s and has since spawned HTML and XML.

SOX:Schema for object-oriented XML. A proposed XML schema to make XML easier to use by allowing the reuse of sections of code and other object-oriented techniques.

Xlink:XML Linking Language. A proposed standard that would allow multiple options when clicking on a hypertext link in an XML Web page.

XML.com:XML portal site run by Seybold Publications.

XML.org:Web portal for XML backed by Sun, Oracle, IBM, and others, and serving as a clearinghouse for XML information and DTDs.

XML Data:An approach to defining the content of an XML document that uses XML itself to store the document meta data.

XML Schema:General term for a file that defines the structure and content of XML documents. Although DTDs currently serve this purpose, other approaches have been proposed, including XML Data, DCD, SOX, and DDML. Also called XML vocabularies or XML dictionaries.

XSL:Extensible Stylesheet Language. An XML style sheet tells a Web browser exactly how to display the data in an XML document. XSL complements, but doesn't necessarily replace, Cascading Style Sheets (CSS).

There's also the question of who will manage the data dictionaries for particular industries or areas. IT standards bodies such as the W3C may seem like a reasonable choice. However, these groups do not necessarily have the same influence in specific vertical markets as they have in the technology vendor community, according to Zona. Trade associations may be more effective; they could be responsible for storing XML vocabularies for their particular industry. Such industry-specific clearinghouses already exist for other standards, including http://www.fixprotocol.org for the stock brokerage industry.

As might be expected, industry vendors are also jockeying for position as gatekeepers of the dictionaries. Microsoft, for example, plans to make DTDs available on the Web as part of its BizTalk initiative (http://www.biztalk.org). Not willing to stand idly by, IBM, Sun Microsystems Inc., and others have launched XML.org as a central repository of XML dictionaries.

Tag, you're it

So how do you decide when and where to use XML in your organization? "Pay attention to the standards," advises Forrester's Walker, "and bet on a horse that's going to win." VoxML, for example--which aims to standardize the way Web content is accessed by voice recognition software--has the backing of three major competitors: Motorola Inc., Lucent Technologies Inc., and AT&T Corp. With such heavy hitters behind it, "Guess what?" says Walker. "It will last." Similarly, on Wall Street, FIXML has garnered support from more than 40 companies, including such industry heavyweights as Solomon Smith Barney, Morgan Stanley Dean Witter & Co., and PaineWebber, and seems well on its way to widespread adoption.

Since XML dictionaries for many industries are still being defined, Walker and others suggest now is a good time to find the standards bodies in charge of the XML vocabularies for your industry. Getting involved in the process will help ensure that the tags defined for each industry as a whole will match the data in your particular organization.

Following the standards is also important because XML is still evolving. The W3C is considering new proposals, for example, that could challenge the role of DTDs in storing XML data. One popular candidate, called XML data, is XML itself: simply storing XML descriptions in XML. And Darmstadt, Germany-based Software AG earlier this year announced a native-XML database called Tamino, which stores XML information without converting it into other data structures. That offers a performance advantage, according to company officials. Oracle's version 8i and object-oriented databases from companies like POET Software Corp., in San Mateo, Calif., and Object Design Inc., in Burlington, Mass., also offer XML storage capabilities.

And what do you do if you're like GM, and you have lots of data that's not in XML format? "For data in a relational database, it's easy," says Goulde of the Patricia Seybold Group. "You can use the existing meta data from the database schema to wrap XML tags around the data. Where it gets trickier is when you have huge piles of unstructured data, like repair manuals or other documents, that you want to tag with XML." Admittedly, XML won't be the easy solution for all your problems. Says Microsoft's Schmidt, "It's not quite the holy grail."

For example, XML may not be optimal for high-volume transaction systems, says Forrester's Walker. "For applications that run something like CICS (a transaction monitor)," he says, "which are all about how many bits you can run through the system rapidly, XML is just not optimal. XML is text based, and sometimes, bits are better than letters. So if you don't need to use it, don't use it."

But Walker, Schmidt, and most other observers agree that XML is here to stay. It has something rare in the computing industry, observes Walker: unanimous support of Internet standards bodies, software vendors, and industry trade groups. //

Dan Orzech is a Philadelphia-based writer specializing in technology. His work has appeared in the Los Angeles Times, The Philadelphia Inquirer, and many computer industry publications. He can be reached at orzech@well.com.



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