The XSLT language is a subdivision of the Extensible Stylesheet Language which is responsible for the transformation of XML documents. The need for these transformations is important because unless you are a developer, these XML documents make absolutely no sense at all. By transforming them into something that is more readily understood by the average person, one can make their website development more accessible to all those who choose to visit it. In other words, the XSLT allows for an XML file to be read as a plain text document or even in PDF format. It can also be used to convert an XML document into an HTML one which can be readily displayed in any type of browser. In all simplicity, the XSLT is the template engine for the formatting of XML documents and the XSL language is the means in which the XSLT language can operate on a server.
This technology is a development of the World Wide Web Consortium and is currently available as XSLT 2.0. This version became a recommendation of the W3C in the beginning of 2007 so it is still relatively new. For this reason, as of the time of writing this, most developments using XSLT are still based on the older 1.0 version.
When originally developed it was considered to be an actual part of the Extensible Stylesheet Language, however after the development of XSL, it was deemed that the XSLT should be made as a separate sub family of the XSL language instead. It was also during this time period that it was determined that the XSL Formatting Objects or XSL-FO should also be made as a sub-family of the language. All in all, there are a total of three sub families in XSL; with the third being that of XPath.
When ran, the XSLT processes one or many different XML documents as the sources for the transformations. It will then look at the stylesheet modules used in the development followed by the processing engine. Once these steps have been completed, then XSLT can output one or even many different documents. The source and the stylesheet documents are required for this process to occur as it is like trying to start a fire without any fuel. You have to have the source document; the one which is intended to be transformed, as well as the stylesheet data so that the process knows how to transform the original source into the human legible output.
Of course while this may seem to be very simple, it is important to remember that the W3C workgroup which developed XSL, XSLT, XSL-FO and XPath knew that the language would be expansive and complex; which is why the determination to subdivide XSL into 3 sub families of languages became important. Of course with that said, you still cannot use the XSLT language without the necessary knowledge of the remaining groups as they will be required for the completion of the steps followed in the transformation of the XML documents.
Original Authors: Nick
Edit Update Authors: M.A.Harris
Updated On: 04/03/2009