Chapter 6. Transforming XML

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Creating HTML pages for display in browsers used to be frustrating because of the lack of control over how page content was displayed. The arrival of cascading style sheets allowed Web developers to assign new styles to HTML tags and thus provided more control over how the HTML page was rendered. As the XML standard was being formalized , work began on the XML Stylesheet Language (XSL) to provide a facility for controlling the rendering of XML documents in browsers. The developers of XSL quickly worked out that they had two distinct problems to solve: the conversion of XML into a format that would display well in a Web browser and the general conversion of an XML document into another XML dialect (or any other text-based format, such as HTML).

The conversion of a document in one XML dialect to an XML document in another dialect is called transformation . Transformation is usually required in at least one place in an XML-based application because it makes it easier for your application to consume XML documents from external sources. One great advantage of XML is that it is extremely flexible and you can define your own data structures in it. However, one major drawback of XML is that it is extremely flexible and you can define your own data structures in it! In the absence of clearly defined and agreed-upon standards for the representation of a particular type data in XML, this flexibility can lead to XML spawning many different data formats to encode the same information.

This chapter will show how to transform XML data from one format to another and will explain the general support for the Extensible Stylesheet Language Transformations (XSLT) built into Microsoft .NET.

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