XML to power smart Web pages

Web-based scripting language standard promises smarter, more efficient applications

By Joe Paone

Despite developer fears that it will be co-opted with proprietary extensions, a new World Wide Web-based scripting language standard is rapidly gathering industry support and could drastically change the face of Web applications as early as the end of this year.

Released as a proposed recommendation by the World Wide Web Consortium (W3C) last month, eXtensible Markup Language (XML) 1.0 is entering the final membership review and voting process. If it passes early next month as expected, XML will become an official W3C recommendation.

Already endorsed by Microsoft Corp., Netscape Communications Corp., and Sun Microsystems Inc., XML will split off the chores of data handling from HTML (HyperText Markup Language), letting developers build sophisticated Web pages without Sun Microsystems Java or Microsoft ActiveX programming.

However, many developers and industry watchers are concerned that, despite assurances to the contrary, browser makers will adopt proprietary enhancements to the language, forcing them to write more than one version of their applications.

"There will be proprietary extensions, but we went through the same thing with HTML," said Ron Rappaport, an analyst at Zona Research Inc. in Redwood City, Calif. "Vendors add extensions, and some of the extensions are standardized in the next version. It goes back and forth."

But even with proprietary extensions, the overall benefit of XML will make it difficult for developers to ignore. Recent newsgroup postings indicate that, although many programmers continue to be frustrated by the nonstandard HTML implementations from Microsoft and Netscape, they are resigned to the fact that they will be forced to write two sets of applications.

XML is a simplified derivative of the highly complex Standard Generalized Markup Language (SGML) used for international text processing, and it is complementary to HTML.

Best described as an electronic publishing and data interchange format, XML represents an effort to standardize the delivery and categorization of data over the Web, a task that observers say HTML, which is best suited for display, handles clumsily.

"The support for XML represents a desire on the part of the Internet community to embrace one standard for structuring Web pages," said Rappaport. "XML is one key prong in the effort to unify Web development into a common environment."

Rappaport likens XML to "the difference between a library and a mass of books on the floor. XML acts as a card catalog," he said. He expects XML to become the document format of choice in the future.

"There is currently no Dewey Decimal System on the Internet, no method of categorization," said Dave Pool, president and CEO of DataChannel Inc., a vendor in Bellevue, Wash., that has developed Web-channel and database-engine software based on XML. "XML could provide the method."

XML can specifically categorize data within Web pages as well as other sources, such as Microsoft Word documents, databases, and E-mail messages, using defined dictionaries of specialized grammar called Document Type Definitions (DTD).

Such an approach would, among other things, let Web-based applications behave more like traditional client-based apps.

For example, instead of entering credit-card data on one HTML page, sending the whole form and receiving a second page with a confirmation, the entire transaction could occur on a single page--the verification or rejection would be received without any additional Web-page downloads.

"It will result in more intelligent, more real-world-like applications than what we have now," said Pool. "You'll only pass the data that needs to be executed. XML will break out application transfers from display transfers."

Examples of DTDs include Microsoft Channel Definition Format (CDF), which describes active channel content, and push vendor Marimba Inc.'s Open Software Description (OSD), which describes software components.

XML-aware browsers and other user interfaces will be able to specify exactly what data they want or require through negotiations with the server.

Observers expect industry-specific DTDs to emerge, for example, a specific DTD for the legal industry or for beverage makers, to be defined by relevant vertical industry groups.

Application-specific XML work is already under way at the XML/EDI Group in Washington. David Webber, a consultant with the group, said XML will bring Electronic Data Interchange (EDI), a cornerstone in business-to-business electronic commerce among large companies, "global reach, to smaller companies. XML is going to be pervasive."

Webber said HTML simply isn't able to address the needs of trading partners for transactions.

"You can't describe a purchase order in HTML," explained Steve Sklepowich, product manager, platform marketing team at Microsoft. "In XML, you can define descriptions for price, order, quantity, and so on. There are going to be hundreds of vocabularies, or DTDs, popping up in the next few months."

Sklepowich predicts numerous related products will turn up from a variety of sources, including XML utilities based on particular DTDs, and tools for converting mainframe and database data to XML.

Given its broad support, the hype is compelling for XML; however, most in the industry do not expect it to take off until later this year when vendors and developers begin using the language in earnest.

One potential use for XML will be the creation of customized channels of data that can be viewed, stored, and manipulated by users in any format they desire.

Likewise, once most standard intranet applications and suites support XML, updates will be much easier. Instead of updating a phone list, for example, by handing changes to a Webmaster, a user will simply be able to save an XML-formatted file on the Web server, resulting in a nearly instantaneous update.

Completion of the XML standard by the end of February is uncertain, but much of the Internet industry has already rallied behind XML as a facilitator for a whole new generation of Web applications and for its ease of use.

XML scripting and management tools have already begun to emerge, both as Internet freeware and in offerings from software vendors. And more support is emerging.

Numerous vendors are members of the W3C XML Working Group, including both Microsoft and Netscape, Adobe Systems Inc., ArborText Inc., DataChannel Inc., Fuji Xerox, Grif S.A., Hewlett-Packard Co., Inso Corp., Isogen International Corp., SoftQuad Inc., and Sun Microsystems Inc., as well as experts in structured documents and electronic publishing. All are expected to support XML in their products.

For example, Microsoft followed on the heels of the W3C announcement by proclaiming its own plans to use HTML as a companion file format in the next version of Microsoft Office with a similar plan to support XML file formats. The company did not reveal a time frame for this integration.

In the meantime, the industry appears short on posturing and griping about the possibly less-than-standard rollout of XML and more abuzz over the proposed standard's potential.

"This will be an evolution, not a revolution," said Microsoft's Sklepowich. "XML won't replace HTML, they'll work together to open up a whole new generation of Web applications."