Buyer beware: XML and eForms come in various flavors - Internet - Buyers Guide

Computer Technology Review, Oct, 2002 by Micah Dubinko

Schemas--Present and Future

The fact remains that since it is extensible, XML comes in many flavors, often differentiated from another by document type definitions, also called DTDs. These allow for formal description of a specific flavor of XML in a machine-readable format. However, DTD syntax differs from standard XML and is limited in expressiveness. Because of inherent limitations of DTDs, there is great interest in a more effective technique called "XML Schemas", another W3C standard, which defines the specific markup that is valid within an XML document. Additionally, Schemas provide rules to ensure that the internal structure of the XML to which they apply remains predictable and consistent. For instance, the contents of an "" element should only be numeric. Instead of the awkward DTD syntax, XML Schemas use actual XML to represent their contents. In this way, one XML document describes another. Schemas are a powerful tool for vendors and developers alike, and can be used to ensure the integrity of XML data, perhaps eventual ly replacing DTDs. Since XForms can directly apply Schema constraints directly to form data, system integrators have a powerful tool to catch "bad data" at the source, before it spreads to other systems.XML and related specifications from the W3C are still evolving. Today, XML offers a valuable technology for collecting data and sharing it with other applications. By choosing XML as the foundation for all data exchange, enterprises gain access to a growing repository of tools and functionality.

The standards for designing forms and Web pages are still in flux, however. Eventually this work will culminate in the publication of a "Recommendation"--a finalized, stable reference for XML technology on the Web. The progress of W3C drafts in various states of completions can be tracked at website http://www.w3.org/TR/.> Until then, present XML-based form solutions are proprietary in nature, and organizations must be aware of this when selecting an XML/eForms product.

www.cardiff.com

Micah Dubinko is chief XML architect for Cardiff Software (San Diego, Calif.), and represents the company as an editor with the World Wide Web Consortium (W3C).