Microsoft has posted on its Web site a new area devoted to the Extensible Style Language (XSL) that includes a preview of technology for converting XML-tagged data and XSL style sheets to HTML Web pages. The Microsoft XSL Processor is among the first software programs to demonstrate the utility of the new style language for Web publishing.

The preview of the Microsoft XSL processor is available as an ActiveX control or as a DOS command-line utility. Developers can download the software to test it with their own XML documents.

The URL is:

www.microsoft.com/xml/xsl

The product assumes that you have valid XML markup in your documents. One way to validate that assumption is to test your documents with an XML parser. Two that are available off the Web are Norbert Mikula’s NXP (http://www.edu.uni-klu.ac.at/~nmikula/NXP/) and Tim Bray’s Lark (www.textuality.com/Lark).

The Microsoft site also contains one of the first online tutorials on XSL, walking the visitor through 24 lessons that explain how to create XSL style sheets.

An online demo of the Microsoft XSL processor takes restaurant menu data tagged in XML and converts it to HTML. The processor handles a number of interesting XSL features, including reordering elements and inserting generated text without elaborate scripting. Because XSL is being designed for data as well as documents, it has provisions for manipulating elements as they are styled, which CSS lacks. For example, a single stock table could be presented in numerous ways by changing the XSL rules, without affecting the source document.

Commentary. XSL takes Web style sheets a significant step beyond the current CSS1 and CSS2 style specifications. It brings Web style sheets much closer to the level of sophistication to which print publishers have become accustomed. The Web continues to rapidly mature as a rich communication medium, and XSL is an important milestone in that evolution. It sets a foundation that we hope will serve the industry for years to come.

What is especially significant is that XSL has a better chance than DSSSL of developing into the master style sheet language for both print and online. DSSSL proved to be too complex for vendors to implement; XSL is being driven from the bottom up by vendors that are anxious to develop software for it.

Yet, the conceptual approach of XSL owes much to the SGML-related standards that preceded it. The separation of form from content; the adoption of flow models that will handle right-to-left languages; and the openness and vendor neutrality all follow DSSSL. What’s new is the simplicity: XSL styles are simply a set of rules, with each rule consisting of a pattern that identifies the element that you want to style and a corresponding action that defines how you want it to look or where you want to place it in a document.

Browser support for XSL is still many months away. But unlike CSS, which depends on widespread browser support to be practical, XSL—when used in conjunction with a tool such as Microsoft is developing—can be of immediate benefit to developers. Designers can create formatting rules using XSL’s simple declarative style, and let the software take care of generating formatted HTML, without or without the use of CSS styles.

Though Microsoft is out in front in terms of timing, it is clearly aiming for the low end in terms of functionality, affording other vendors ample opportunity to develop other products. With software that is a little more sophisticated, a single XSL style sheet may be used to generate multiple output (RTF or other vendor style sheets, for example).

As we went to press, ArborText was planning to announce the release of its XSL style generator, which we previewed in December (see last month’s issue for details) . Within a year, we hope to see a wide variety of vendors—those with mainstream Web products as well as those from the SGML community—reading and writing XSL style sheets.

In the meantime, Microsoft’s new tool demonstrates how XSL can be used today to effectively style relational data and other information without complex scripting. We recommend that publishers of all types take a look and offer feedback on what the spec and products need to fit your requirements. Microsoft is leading the charge in the right direction; now is the time to help the company steer a course that coincides with your own objectives.