Presenting Data Records Using XSLT Expressions
By Michael Floyd
Last month, I mentioned that just as I was placing the final touches on my column, the W3C's XSL Working Group quietly released an update to the XSL Working Draft Specification. Showing just how in flux the standard is, the new XSL draft specification dumps virtually every feature (with the exception of formatting objects) into a new working draft called XSL Transformations, or simply XSLT. XSL now refers specifically to XSL formatting objects, which are to XML what Cascading Style Sheets are to HTML.
By and large, XSLT contains all of the features I've covered over the past few columns including tree processing, patterns, and templates. However, XSLT adds a plethora of new features. The pattern syntax I described in June has been expanded and a new syntax called location paths has been introduced. Possibly the most dramatic change, however, is the addition of a complete expression language, which looks much like a small programming language. This month, I'll examine the salient points of XSLT expressions and give you an idea of how you can use them. I'll also deliver on a past promise to talk about iteration and conditional processing in XSL (now XSLT). Finally, I'll show how you can take any number of database records in XML format, sort them in either ascending or descending order, and transform them to HTML for presentation.
Expressions
As you'll recall from past columns, an XML document can be broken down into a collection of objects that are ordered in a hierarchical fashion.
