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XSLT - XSL Transformation

Electronic Medical Records XSLT

XSL Transformations, or XSLT, is an XML-based language used for the transformation of XML documents. The original document is not changed; rather, a new XML document is created based on the content of an existing document. The new document may be serialized (output) by the processor in standard XML syntax or in another format, such as HTML or plain text. XSLT is most often used to convert data between different XML schemas or to convert XML data into web pages or PDF documents.

XSLT was produced as a result of the Extensible Stylesheet Language (XSL) development effort within W3C during 1998–1999, which also produced XSL Formatting Objects (XSL-FO) and the XML Path Language, XPath. The editor of the first version (and in effect the chief designer of the language) was James Clark. The version most widely used today is XSLT 1.0, which was published as a Recommendation by the W3C on 16 November 1999. A greatly expanded version 2.0, under the editorship of Michael Kay, reached the status of a Candidate Recommendation from W3C on 3 November 2005.

The XSLT language is declarative — rather than listing an imperative sequence of actions to perform in a stateful environment, an XSLT stylesheet consists of a template rules collection, each of which specifies what to add to the result tree when the XSLT processor, scanning the source tree, according to a fixed algorithm, finds a node that meets conditions. Instructions within template rules are processed as if they were sequential instructions; but, in fact, they comprise functional expressions, representing their evaluated results - ultimately, nodes to be added to the result tree.

The XSLT specification defines a transformation in terms of source and result trees to avoid locking implementations into system-specific APIs and memory, network and file I/O issues. For example, the specification does not mandate that a source tree always be derived from an XML file, since it may be more efficient for the processor to read from an in-memory DOM object or some other implementation-specific representation. Output may be in a format not envisioned by the XSLT language's designers. However, XSLT processing often begins by reading a serialized XML input document into the source tree and ends by writing the result tree to an output document. The output document may be XML, but can be HTML, RTF, TeX, delimited files, plain text or any other format that the XSLT processor is capable of producing.

XSLT relies upon the W3C's XPath language for identifying subsets of the source document tree, as well as for performing calculations. XPath also provides a range of functions, which XSLT itself further augments. This reliance upon XPath adds a great deal of power and flexibility to XSLT.

Most current operating systems have an XSLT processor installed. For example, Windows XP comes with the MSXML3 library, which includes an XSLT processor. Earlier versions may be upgraded and there are many alternatives, see the External links section.

The W3C finalized the XSLT 1.0 specification in 1999. The XSLT 2.0 specification is currently a Candidate Recommendation.

Source: Wikipedia contributors (2006). XSL Transformations. Wikipedia, The Free Encyclopedia. Retrieved 04:02, January 16, 2006 from http://en.wikipedia.org/w/index.php?title=XSL_Transformations&oldid=35085795.