The State of the XML Standards

January 10, 1998

Seybold Report on Internet Publishing
Vol 2, No 5

On December 8, concurrent with the opening of the Washington conference, the XML 1.0 specification was delivered to the W3C as a "draft recommendation." This is the next-to-last step in the standards-making process. Balloting started immeidately and will continue into January. Assuming the majority of votes favors the specification, it will become a "recommendation," which is (somewhat counterintuitively) the name applied to the final product of the W3C standards-making process. Do not expect an XML 1.1 any time soon. The committee intends to see how well the initial standard works in the market before opening it up for revisions.

Much of the attention that had been focused on standardizing XML now shifts to companion standards: XSL (Extensible Style Language), XLL (Extensible Linking Language), XML-Data and namespaces.

XLL has been through two drafts, and the working group hopes to have a widely endorsed proposal in time for the W3C meeting this April. It has two parts. One part (the "XPointer" specification) deals with the addressing mechanism for identifying the document that is being pointed to. The other part (the "XLink" specification) describes the possible types of links and how they behave. There will be support for storing link information in an external table or database, rather than in the file itself (helpful when large document collections, with lots of links, have to be updated).

The XSL standard got started later (the first draft was released last August), but it has attracted immediate commercial interest, as we saw in demos at the show.

For many, the benefit of SGML and now XML is not only that the tag set is extensible but that the tagged documents can be validated against a known DTD. But DTDs have problems that a new effort, called XML-Data, is designed to address. For example, DTD validation lacks "strong data typing," a technique employed with databases to avoid nonsense entries, such as 99/99/99 in a date field. For developers coming to XML from database backgrounds, the XML DTD syntax seems convoluted. Microsoft, co-author of the proposed XML-Data specification (www.microsoft.com/standards/xml/xmldata.htm), agrees and is leading the charge to develop an alternative.

There also is work going on with regard to "namespaces," which identify the DTD from which a tag is derived. Namespaces will permit the construction of documents from fragments of other documents, each with a different DTD, yet still avoiding problems caused by duplicate tag names in the different DTDs.

Links to current drafts of these, and related, specifications can be found in the XML area of the W3C Website: www.w3.org/xml.

Overall, the outlook for standardization and adoption of XML continues to be very promising. There are lots of big players, with a variety of different motivations, interested in seeing XML succeed. If political in-fighting can be avoided, a strong group of XML standards can be adopted and widely implemented in 1998.