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November 1, 1999

XML: The Language Of Integration
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The value of XML, Lamoureux discovered, "is that it lets us focus at a higher level." Before XML, his team spent a considerable amount of effort developing the low-level infrastructure required to support the FIX protocol. This meant building a parser to read the data and a service engine to extract it from the message correctly. "This should all be a commodity item," he says. With XML, the low-level architecture has indeed become a commodity. XML provides the infrastructure.

What XML doesn't provide is the mechanism to process the data once you have it. When the data arrives, some application needs to do something with it. Companies can use Java or any number of scripting languages or high-level programming tools such as Forté to provide the instructions to process XML data.

For example, the FIX protocol relies on Tcl scripts to take the XML data and process it in various ways. "We can write Tcl scripts and attach them to parts of an XML document to redefine things at runtime if we need to," Lamoureux says.

Many companies will rely on Java to provide the processing to complement the XML because of its widespread acceptance and wide availability. "XML is a perfect fit with Java," says Bob Bickel, senior VP of Bluestone Software Inc. in Mount Laurel, N.J. Bluestone provides an XML server built using Java that includes a Java-based parser. Developers can write Java programs to process the XML data however they see fit.

Java preserves XML's portability, a key strength, Bickel says. With Java, not only is the XML data portable across every platform that offers an XML parser--which is little more than a simple text parser--but the processing is portable too, at least to the extent that Java is portable.

The independent software vendor community has been quick to jump on XML, building it into a wide range of products. For example, Documentum Inc. in Pleasanton, Calif., incorporated XML into its Web content-management portal product. "We use XML to exchange data between our own components and for transmitting data to a browser for client-side manipulation, such as sorts," says Lalith Subramanian, Documentum's director of engineering for E-business. The company also uses XML for customizing screens and for repurposing XML data received from other systems.

Similarly, Art Technology Group Inc. in Cambridge Mass., uses XML in its suite of customer-relationship management personalization products. An early adopter, the company has been actively using XML for a year. Before it adopted XML, ATG developers had to deal with a variety of individual integration mechanisms for each system they needed to integrate. These included vendor APIs or specialized connectors. Often, the company found itself building custom connectors. "This created serious maintenance issues," says VP Ken Volpe.

Fortpoint Partners Inc., a San Francisco E-commerce system integrator, was an early pioneer of XML, using the technology for the past two years in its E-commerce assignments for companies such as Egghead.com Inc. "XML makes it easier to integrate with legacy systems," says company president Matthew Roche.

It's not just the ease with which Fortpoint developers can forge the initial integration, but the flexibility XML allows. "In the past, we had to define fixed fields for integration. If something changed--even one character--then it didn't work," Roche says. With XML, the developers define fields for, say, customer, price, and product, and can fit in any assortment of data that carries the appropriate XML tags. If a trading partner uses a different number of characters in its product ID or price format, it doesn't matter.

Despite its enthusiastic reception, XML is not a complete integration vehicle in itself. Developers are finding that they must use XML in conjunction with Extensible Style Sheet Language. XSL, a related standard from the World Wide Web Consortium, is a language for creating style sheets that describe how XML data is to be presented to the user through HTML. XSL, an extension of the Document Style Semantics and Specification Language and the Cascading Style Sheet standards, lets developers tell a browser how to display particular pieces of XML data based on how that data is tagged. With XSL, developers can identify which XML data to display and where and how to display it.

Larry Chen
Photo by Alan Blaustein
XSL can be used to compensate for some of the current shortcomings of XML. For example, because XML is not yet universally supported in browsers, companies are restricting it to servers, where developers have more control. "We don't send XML to the browser, because we can't be sure the browser will support it," Volpe says. Instead, the company uses XSL to reformat XML into HTML, which it passes along to the client. The HTML can be viewed with any browser.

Bidcom Inc., a San Francisco construction-industry collaboration portal that coordinates the efforts of multiple parties working a construction project, uses XML and XSL in its workflow- process engine. It creates a form in XML that is mapped to its Oracle database schema. It then uses XSL to customize the form when it's presented to various users. Depending on the user's role in the project, for example, the user will see different fields, says Larry Chen, Bidcom's CTO.

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