As XML becomes deeply embedded in the Internets infrastructure, three particular implementations — ebXML, SOAP and XHTML — have emerged as technologies likely to provide the foundations for future Web services.
The downturn in the economy hasnt slowed XML development as much as it has consolidated support behind the most durable XML technologies, says Ronald Schmelzer, senior analyst of ZapThink, an XML market research firm in Waltham, Mass.
"Companies have been forced to focus on the technologies that have been determined to be most valuable," he says. "Theyre no longer willing to invest in three competing standards efforts."
One of those leading XML-based technologies is the Simple Object Access Protocol, though the growing support behind it has been surprising. Initially, there was widespread opposition to a specification that originated from Microsoft, which introduced the first version of SOAP in the fall of 1999. But last year, Hewlett-Packard, IBM and several others joined Microsoft in sponsoring SOAP to the World Wide Web Consortium, and last month the W3C issued its working draft of SOAP 1.2. SOAP now underlies many of the exchanges of simple XML messages between dissimilar systems.
In another example of SOAPs industry momentum, the Organization for the Advancement of Structured Information Standards has adopted the technology. OASIS was a rival to Microsoft when OASIS launched XML.org, a registry of XML definitions, in mid-1999. "Some fear being locked into vendor-specific implementations," OASIS executive director Laura Walker said at the time. Now, OASIS is a sponsor of Electronic Business XML, an effort to create international XML standards for e-commerce. It is using SOAP as its primary means for encapsulating ebXML messages.
SOAP has also given rise to other XML standards, industry observers point out. One outgrowth is the Universal Description, Discovery and Integration standard, sponsored by Ariba, IBM and Microsoft. UDDI sits on top of SOAP and provides a registry of services automatically available over the Web. One day, its supporters say, UDDI servers may be as common on the Internet as Domain Name System servers.
UDDI is a "big Yellow Pages in the sky," says Mark Herring, director of marketing of Sun Microsystems Forte development tools. "Its one big XML document." Inside the UDDI directory, services will be listed in Web Services Description Language, another SOAP derivative.
The W3Cs XML Protocol Working Group is continuing the development of SOAP, and the committee is now working on SOAP 2.0, which will extend SOAPs message-passing capabilities across systems.
"With XML, the intercompany and intracompany boundaries are vanishing," says John Streiff, senior marketing manager of Software AG, which produces the Tamino XML Database system and is involved in the development of SOAP. He says XML specifications are succeeding where earlier attempts failed.
Meanwhile, the backers of ebXML are trying to set simple XML formats that allow one business to exchange the data necessary for e-commerce with another, regardless of location.
EbXML is viewed as beyond the influence of any one U.S. company or industry group, so it has a good chance of being adopted internationally, ZapThinks Schmelzer says. In addition, ebXML is serving as a starting point for specific, vertical industry dialects, such as the travel industrys OpenTravel Alliance language, the health care industrys Health Level Seven and the financial industrys eXtensible Business Reporting Language, he says.
Another little-noticed — but potentially far-reaching — XML technology is eXtensible HTML, which is the combination of XML 1.0 and HTML 4.0, the latest version of the language created by the Webs original architect, Tim Berners-Lee. By meshing HTML with XML, the W3C has given site builders the chance to create Web pages in a more structured format, Streiff says.
But not many site builders have seized on the opportunity to use XHTML, which has been under development for almost three years, Schmelzer says. Why not? For one thing, XHTML requires more programming-style discipline than is often associated with Web site designers and HTML writers. For another, it requires a large investment in an existing Web site to convert it to XHTML, he says.
IBM is one of the few companies that have converted their Web sites to XHTML. In April, Big Blue launched the 11th redesign of its site, entirely formatted in XHTML. IBM wouldnt disclose how much the conversion cost, but David Leip, IBMs corporate Webmaster, says the switch to XHMTL was relatively inexpensive because it took place concurrently with a major redesign. XHTML, he says, makes it easier to tag and define the content on IBM.coms 4.5 million Web pages, which means the pages can be more easily indexed by search engines.
"The issue we had with HTML is that its fairly free-flowing, so that makes it difficult to do things with it in an automated fashion," Leip says. "XHTML has a very strict grammar, and that helps us ensure weve got Web pages that are compliant to certain standards, like accessibility and privacy standards."
And once a site converts its content to XHTML, Leip says, it can then distribute HTML pages in multiple formats, regardless of the receiving device — and that opens the door to mass distribution of pages or services to personal digital assistants and future portable devices. "Because XHTML is so structured, were in a much better position to deliver content to non-PC devices," he says.