Sitting in a small room with about 20 other folks, I’m hoping to learn something about XSL and XSLT. Our instructor for this half-day tutorial is Mike Fitzgerald of Wy’east Communications (whose website appears to be unavailable right now).
XSLT has been around for 3 or 4 years now, but this is the first time I’ve had an opportunity to look at it in any detail.
We started simple, with a basic transformation:
<!-- msg.xml --> <msg/> <!-- msg.xsl --> <stylesheet version="1.0" xmlns="http://www.w3.org/1999/XSL/Transform"> <output method="text"/> <template match="msg">Found it!</template> </stylesheet>
On the surface, XSLT looks simple and elegant. But things get complicated very quickly. Over the course of the next 3 hours, Mike built upon the basics, teaching us the syntax and concepts involved.
XSLT uses a language called XPath to access or refer to parts of an XML document. I quickly grew tired of all the magic characters that XPath uses: /, //, @, {}, *, ::, [], |, etc. It seems to me that the designers of XPath had love affair with braces, brackets, and other operators. Instead of doing some sort of human-readable query language, you end up with stuff that looks like id("foo")/child::para[position()=5]. Haven’t these folks ever heard of something called whitespace?
Even though I tend to think of things procedurally, I really do like the idea of using a declarative language to describe a way of transforming data into presentation. I guess when you’re coding XPath every day, the idea is to keep things as terse as possible; XPath excels at that.
However, when you start using XSLT Functions and Variables, things start to look more & more like a scripting language like PHP or Perl. Apparently you can’t do everything with the declarative approach.
XSLT also seems very well integrated with other XML-related concepts. You’ve gotta be namespace-savvy to get things right in XSLT.
Overall, it was a very good session. The pace was a little slow for me, but he did a couple of things really well:
- Almost every single slide was accompanied by an example. Mike stepped through the source code line-by-line, and then ran the examples live to show us how it all worked.
- He handed out CD-ROMs of all of the examples (and 3 or 4 XSLT processors) at the beginning of the talk so we could try the examples right then & there on our laptops.