Now that we are successfully using XML to mark up our information according to our own vocabularies, we are taking control and responsibility for our information, instead of abdicating such control to product vendors. These vendors would rather lock our information into their proprietary schemes to keep us beholden to their solutions and technology.

But the flexibility inherent in the power given to each of us to develop our own vocabularies, and for industry associations, e-commerce consortia, and the W3C to develop their own vocabularies, presents the need to be able to transform information marked up in XML from one vocabulary to another.

Two W3C Recommendations, XSLT (the Extensible Stylesheet Language Transformations) and XPath (the XML Path Language), meet that need. They provide a powerful implementation of a tree-oriented transformation language for transmuting instances of XML using one vocabulary into either simple text, the legacy HTML vocabulary, or XML instances using any other vocabulary imaginable. We use the XSLT language, which itself uses XPath, to specify how an implementation of an XSLT processor is to create our desired output from our given marked-up input.

XSLT enables and empowers interoperability. This XML.com introduction strives to overview essential aspects of understanding the context in which these languages help us meet our transformation requirements, and to introduce substantive concepts and terminology to bolster the information available in the W3C Recommendation documents themselves.

Since April 1999 Crane Softwrights Ltd. has published commercial training material titled Practical Transformation Using XSLT and XPath, covering the entire scope of the W3C XSLT and XPath through working drafts and the final 1.0 recommendations. This material is delivered by Crane in instructor-led sessions and is licensed to other training organizations around the world needing to teach these exciting technologies.

Crane has rewritten the first two chapters of this material into prose. These prose-oriented chapters are published on XML.com correspondingly as two main sections. The material assumes no prior knowledge of XSLT and XPath and guides the reader through background, context, structure, concepts and introductory terminology.

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