Implementations

From its inception, DSML has had an impressive list of vendors lined up behind it. The initial work was done under the auspices of DSML.org, a group of vendors including IBM, Microsoft, Netscape, Novell, Oracle and Sun, as well as Bowstreet and a number of smaller vendors. The initiative is now being coordinated by the Organization for the Advancement of Structured Information Standards (OASIS), with all the original DSML.org vendors and more on the roster.

However, Microsoft is also developing an alternative approach to accessing directories, which may turn out to be more important in Windows environments. In addition, Novell, despite statements of support, appears to have no immediate plans involving DSML.

Microsoft

Microsoft was an active participant in the creation of DSML 1.0. They will preview DSML 1.0 support for Active Directory within the next three to six months, says Peter Houston, group program manager for Active Directory. Microsoft is also supportive of the work on DSML 2.0.

At the same time, Microsoft is working on an alternative approach to directory access based on XPath and the Document Object Model (DOM). DOM is a standard specification for representing objects in a Web page (e.g. text, images, links). It supports queries and updates. The DOM provides a general-purpose programming interface to XML documents.

XPath is the result of an effort to provide a common syntax and semantics for functionality shared between XSL (Extensible Stylesheet Language) Transformations and XPointer. XPath defines syntax for addressing particular objects and attributes within an XML document. XPath is read-only. It allows you to be more productive by providing a much easier and more flexible way of navigating XML documents than is provided by the DOM.

Microsoft will map directory data into a DOM structure that can be accessed via XPath.

The DOM/XPath approach leaves Microsoft plenty of room for developing directory access interfaces and structures that are substantially different from anyone else’s. In particular, Microsoft can define its own document structure, fulfilling much the same function as the XML schema defined by DSML, but optimized for Active Directory, and with Microsoft development tools and applications representing the first-to-market, most widely used, and safest path to compatibility.

Microsoft can also use the DOM to push developers and users towards Microsoft tools and applications. The DOM has already been a significant battlefield in the browser wars. For instance, differences in the Netscape and Microsoft DOMs can cause Dynamic HTML (DHMTL) to display differently in the two browsers, since DHTML relies on the DOM when it needs to dynamically change the appearance of a Web page. There is an emerging W3C DOM standard that attempts to accommodate both Netscape and Microsoft. However, it would presumably take some time to harmonize Microsoft’s emerging DOM-based directory access with the W3C standard, and there is no guarantee that it will ever happen.

David Strom, an independent networking consultant based in Port Washington, NY, argues that it is not in Microsoft’s best interest to put their competitors on an equal footing when it comes to directory access.

“Microsoft wants to use XML as a leverage point,” says Strom, “the same way they have used Word, Excel and PowerPoint [formats] as leverage points to get you to use their products.”

Strom predicts that once people create content using Microsoft schemas, they will find it easiest to continue to manipulate that content using Microsoft products.

“People think XML is like the Good Housekeeping seal of approval,” says Strom. “But if you have a lot of tags and a hierarchical structure you’re not sure of, searching through all those tags and making sure how they relate to each other is a mammoth undertaking. You can be lured into a false sense of compatibility.”

As a portent of things to come, Strom points to XML files created by Word 2000. “It is supposedly standard XML, and if you bring it up in a browser, it looks like any other document - as long as the browser is Internet Explorer, of course.” But if you bring up Visual Interdev Lite, which ships with Windows 2000, and examine the XML source, it’s harder to decode than the underlying format of an ordinary Word file, says Strom.

Today, Microsoft Word is often used as a de facto standard for exchanging formatted documents. Microsoft will attempt to get its XML schemas used in the same way, says Strom.

Much of this effort may take place in the context of Microsoft’s BizTalk initiative. BizTalk, launched in March, 1999, has been slower in emerging than initially promised, but it remains the centerpiece of Microsoft's e-commerce strategy. The BizTalk Server facilitates integrating computer systems for B2B e-commerce, and coordinates business processes without requiring modifications to underlying applications. Server-based tools build XML schemas, transform data into XML from various protocols such as EDI, and track data.

The BizTalk Framework, which provides the infrastructure for the server, defines XML-based methods for transporting data and getting applications to work together. Microsoft wants companies to adopt the XML used in the BizTalk Framework as a standard for B2B e-commerce. The likes of SAP, Commerce One and Boeing, all of whom helped develop the framework, are behind them.

Clearly, Active Directory will play an important role in BizTalk by providing an information store accessible across companies and applications. Directory-related XML schemas will be necessary to facilitate that role.

Houston notes that Microsoft intends, assuming that the ongoing work bears fruit, to submit the results to appropriate standards committees. However, that would merely allow Microsoft’s competitors to play catch-up, and give official status to the Microsoft standard, while still allowing Microsoft to stay as many steps ahead of the market as they wish.

Introduction to Directory Services Markup Language (DSML)
Introduction to Directory Services Markup Language (DSML)
Other Directory Vendors