XML tools can tune up e-gov efforts

| SPECIAL TO GCNAs the Web evolves toward greater use of electronic commerce, Extensible Markup Language has emerged as its lingua franca in waiting. XML provides a level of functionality beyond that of Hypertext Markup Language and a common way to identify data in transactional documents.But a greater ease of use doesn't necessarily mean converting to XML is easy. Nor does it mean that HTML will be left behind.The simplest way to understand XML is to understand how it differs from HTML. Both are subsets of Standard Generalized Markup Language, but where HTML concentrates on style, XML focuses on substance.HTML was developed to format documents moving across networks, particularly the Internet, and format paragraphs, headings, lists and simple illustrations for the Web.But HTML is limited in its ability to describe the kind of data displayed. An order form designed in HTML isn't really aware of the data it contains, so the data is difficult to transfer to other applications.XML gets into the content. It is a metalanguage'a language describing how another language is structured'used to define the data structure of documents and make it easier to exchange data between applications.XML lets programmers create documents that describe the various data fields to allow the information to be used by other programs, similar to the way database entries do.In XML, a page developer can define new tags; in HTML, tags are predefined. And in XML, software can easily mine the data over a network'as long as all the programs recognize the same tags.Because of its SGML heritage, XML documents can be parsed and validated the same way any SGML file can. XML is better suited for general use because it discards some of the most complex features of SGML.HTML can do many of the things that proponents tout as XML features but only through a bewildering array of sometimes incompatible plug-ins. As the Web has grown, HTML has been unable to grow with it except through third-party add-on utilities.But HTML won't be riding off into the sunset any time soon. It does some things better than XML'and does some things XML cannot do'so there is no move to replace it.A new World Wide Web Consortium (W3C) standard, XHTML Version 1.0, is a combination of HTML and XML that allows Web sites to add XML to their pages but lets some old browsers continue to view the content.XML promises:' A simple way to exchange data over the World Wide Web' A new beginning for programmers who have pushed HTML to the limit' A new paradigm for querying databases over enterprise or local networks' An easy way to exchange data between various local applications' A solid middleware standard that makes XML distributed computing possible because applications can access distributed objects across the Web.But what XML can do today is wildly different.A lack of standards is one problem. But there is also a fundamental problem with the entire XML concept that must be reconciled before it becomes a transparent data exchange tool.The biggest hurdle to adoption of XML is its most important feature: the ability to create new tags. This ability lets users customize XML documents to exactly fit their needs. But unless you are developing an in-house system, custom tags won't be recognized by other applications, virtually eliminating XML's usefulness.Vendors producing various XML products create Document Type Definitions that describe their product's metadata schema. A validating editor or processor uses the DTDs to determine if a particular document contains valid XML code.Because this is such a flexible process, there is no standard set of definitions and therefore no way to exchange data among different applications unless they share identical DTDs.There are published sets of DTDs but, because there are many different sets, none of them can be described as a standard.If your applications can share data before you incorporate XML, then all probably will be well. But if your data is incompatible now, merely formatting it with XML tags won't magically make it compatible.The best option today is to use mapping tools that can read DTDs from one vendor and translate them into another vendor's DTDs. But is this what you thought XML promised?XML is touted as an easy, seamless way to share data among disparate applications. But when you have incompatible data sets requiring XML coding on both sides, with a layer of translation from mapping tools in between, 'easy' could be a question of degree.In most cases you will have to analyze the two DTD sets and create the mapping. Commercial translation tools don't understand the various DTDs; they just manage the routine translation after you do the work.The W3C XML Schema is intended to define the structure, content and semantics of XML documents, superceding SGML DTDs. The XML Schema reached candidate recommendation status in October, meaning that it now can be implemented on the Web and users can develop feedback on the specification.The XML Schema is necessary to teach XML systems how to parse data to recognize, for example, the difference between a string of text and a Social Security number.Until the XML Schema reaches full recommendation status, which is expected by spring, vendors and industry groups will continue to create their own DTDs.DTDs have become well-entrenched in the user community simply because it has taken more than two years to develop the XML Schema.Microsoft Corp. and other companies have said they will follow any W3C standard once it reaches the recommendation level. The software available for XML ranges from full-blown software development kits to free editors and other tools. IBM's Alphaworks, for instance, publishes a lot of cutting-edge XML products for free download.Editors are simple and valuable tools'they are text editors with XML syntax built in. Software development kits offer the complete set of tools for generating valid XML code, integrating XML into your present operations and even helping to migrate existing data or applications to XML.Although XML is still a few steps away from fulfilling its promise, several agencies are already making use of it.The Patent and Trademark Office, for instance, is using Infrastructures for Information Inc.'s S4/Text to develop an XML system for authoring patent applications that can be filed over the Internet.The Securities and Exchange Commission, the Department of Defense, the IRS and the Government Printing Office also are creating XML documents for such uses as online forms, document exchange and online training.XXXSPLITXXX-