InformationWeek
Defining The Business Value Of Technology
June 28, 1999
 Print this story |
continued...page 3 of 5
XML is being adopted for all these standards because it's a structured, easily understood way of describing data.
XML Vocabularies
Now that it's clear that XML is tailor-made for defining standards for data interchange, it's no longer a stretch to see uses for XML in a systems architecture. After all, what is the interaction between the components of a three-tiered architecture if not data interchange? While one would hope that members of a development team are communicating more efficiently than large, monolithic companies, they still need to agree upon an interface between the components they're developing.
This interface can be efficiently described using XML. The process involves defining an XML vocabulary for a specific piece of application functionality (a use case in UML parlance). This XML vocabulary is nothing more than the XML document that one software component should expect to receive from another.
Now, if I'm developing the business tier, for example, I no longer have to define and exhaustively test the whole suite of API calls that the user interface might possibly make. I know that all I will ever receive from the user-interface tier is the XML document whose structure has been agreed upon in advance. Encoded within that document will be all the information I need about what action to perform and what data to return. When I'm done processing, I pass back to the user-interface tier another XML document that contains the results that were requested, and I let the user interface worry about how to present the results.
A sample application that uses XML buffers to communicate between software layers can be found at www.kpmgconsulting.com/fs.html?url=industry/fs/dnafs/dnafs_home.html.
This application implements several use cases from the retail-banking industry and was developed as part of KPMG's work with Microsoft on the Distributed interNet Applications for Financial Services specification. DNAfs is an architectural framework that utilizes XML to integrate financial-services applications and software components, including legacy systems and emerging technologies.
An architecture that utilizes XML vocabularies, which efficiently describe data but make no assumptions about presentation, allows for the efficient delivery of the same application via different delivery channels.
A company often wants to give its customers the ability to perform the same transaction in a variety of ways. Take for instance a funds transfer that can be made via a bank teller, an automated teller machine, an Interactive Voice Response system, and the Web.
Once business components are built, having those components return an XML document allows the power of XML's styling counterpart, the Extensible Style Sheet Language, to be utilized to take care of presentation issues. XSL is a W3C draft specification that defines a styling language used for creating style sheets that operate on XML documents.
continued...page 4, 5
return to page 1, 2
Back to This Week's Issue
Send Us Your Feedback
Top of the Page
