If Web services live up to their potential, a once obscure technology known as Extensible Markup Language may become an instant success story as the linchpin that holds the concept together.
Star: XML could become new lingua franca
By Mike Ricciuti
In a few short years, a once obscure technology bearing the unremarkable name of Extensible Markup Language has gone from a dry-as-dust specification to the center of the newest Web revolution.
Like the title character in Woody Allen's movie "Zelig," whenever industry luminaries--Microsoft's Bill Gates, Oracle's Larry Ellison, Sun Microsystems' Scott McNealy--take the stage to tout their companies' Web services strategies, XML is right there. Although it predates the Web services stampede, the technology seems almost custom-made for development of the trend.
"The main problem is the very buzz about XML as the solution for all needs," said John E. Simpson, an XML specialist who has been a programmer for more than 20 years.
Classified as a "page description language," it is something closer to Hypertext Markup Language (HTML)--the current lingua franca of the Web--than to true programming languages such as Java or Visual Basic. Just as HTML helped fuel the first great wave of the Web's popularity, XML is poised to spur a new world of Web-based services that promise to make technology more usable.
The language provides terms used to define a Web document's tags--that is, the elements of the document that describe its various pieces--and the relationships between them. Developers at either end of a data exchange then agree to use a common set of tags. In this way, XML is uniquely flexible and versatile: It can be used to describe tennis balls or tires, employment contracts or engine parts.
That flexibility, however, can also present a problem. Because each XML transfer includes a large amount of information describing the data contained in it, file sizes can quickly mushroom.
Some companies have found XML files too big, especially when the transmission already carries large amounts of primary data. Humana, a regional health insurance company based in Louisville, Ky., uses XML to transmit some of its claims information to health care providers and other partners but relies on decades-old electronic data interchange systems for the bulk of its transfer needs.
"XML is much more flexible," he said. "But it's not a well-standardized world yet, so when people talk about XML they are still trying to evolve standards around how data will be defined, and so on."
XML's creators at the World Wide Web Consortium don't see the language's propensity for weight gain as an obstacle. In fact, a document describing XML and posted to the W3C's Web site states that XML is "verbose, but that is not a problem. That was a conscious decision by the XML developers. The advantages of a text format are evident...and the disadvantages can usually be compensated."
Those advantages are apparently clear to Microsoft, which has in large part defined Web services through a high-pitched marketing campaign for its .Net strategy. XML is the technological linchpin of the .Net services plan.
"XML is the next revolution on the horizon," Microsoft CEO Steve Ballmer said at an industry conference earlier this year.
Sun, Oracle and IBM have also lauded XML and its central role in the Web services world, as have other major players. "XML has many really strong, positive characteristics, and that is why we have chosen it for more or less the foundation of everything we do," said Ray Ozzie, founder of Groove Networks and creator of Lotus Notes.
Going beyond Web pages
One of XML's key strengths is its application beyond Web pages. For example, the language can be used to exchange vital information for business transactions--such as shoe sizes, shipping crate numbers or the vintage of a case of wine--between different computing systems that would otherwise be unable to communicate.
In this way, XML is unparalleled for broadcasting data between servers and to Web pages as part of a Web services architecture. Many of the first uses of XML-based Web services are for unglamorous yet essential data-exchange applications.
XML, by contrast, describes the language used to define documents. That is, it's used when no preset vocabulary exists.
"In XML, you are defining the data, the names you call the data, and the relationship of all data to one another," Humana's LeClaire said.
While Web services pioneers find ways to adapt XML, the W3C is tackling new parts of the language that could play a key role in advancing the trend, such as technologies involving multimedia and security. Last month, the organization posted a draft specification for VoiceXML 2.0, which is designed to bring synthesized speech, spoken and touch-tone commands, digitized audio, and computer-human conversations to the Web.
The W3C also is soliciting comment from programmers on how best to encrypt data transmitted using XML. A draft of a specification has been posted, and final debate is slated for this month.
As with all other evolving technologies, the progress of Web services will mean that other areas will be more fully defined either through standards or through accepted workarounds.
Dan Bricklin is confident that it will be only a matter of time before Web services take off. As the co-inventor of the first PC spreadsheet, VisiCalc, and one of those who helped start the personal computer revolution two decades ago, he has seen other major technologies go through similar growing pains.
"A lot of what we are building today we are building for the first time," Bricklin said. "And we don't fully understand it."
News.com's Sandeep Junnarkar contributed to this report.
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