Delivery of XML on web browsers isn't as popular as XML's inventors originally hoped, but it's still useful. It's easy to add a standardized processing instruction to your XML that points at an XSLT stylesheet that converts your XML to HTML, and then when you open the XML file in your browser, you see the result. When you need a rendered version of some XML to review, this can make it happen pretty quickly. (The W3C Recommendation Associating Style Sheets with XML documents is possibly their shortest; its author, James Clark, was always good for a high signal-to-noise ratio.)

I've done this with Firefox very often, and I've set up a system for a client who needed to let users preview XML documents without starting up specialized software by doing the same trick with Internet Explorer. (Their choice of browser, not mine.) Recently, though, I found that this didn't work with Firefox 3.0. The stylesheet was ignored, and the error console told me that there was a "Security Error: Content at file:///c:/my/path/filename.xml may not load data from file:///c:/some/path/stylesheet.xsl". I understand the general idea of not letting a browser allow one file to load another, but when they're both local, I see a baby going out with the bathwater.

I had to look pretty hard to find the solution, and of all places, it turned out to be on a website dedicated to an open source model railroad control system. (It would have been great if a posting in the thread came from Clyde Coil, but none did.) According to to page 3 of a thread on Who can help on XSL-Stylesheets, you need to reset Firefox's security.fileuri.strict_origin_policy setting to "false". This worked for me, and I hope I'm not opening some gaping security hole. I'd hate to have to choose between good security and Firefox rendering of styled XML.

After downloading Google Chrome, this XSLT trick was the first thing I tried, with no luck. When I used chrome to open an XML file with a processing instruction that pointed to an XSLT stylesheet, as described by James' brief W3C Recommendation, it showed nothing—pure blank space, not even the PCDATA from the file. Chrome's clean interface made it difficult to find out how to View Source, but luckily Ctrl+U did it like it does in Firefox. When I tried this, it displayed a color coded version of the XML file, including comments... but with all processing instructions removed, so the standard way to associate stylesheets with arbitrary XML files won't work.

If Chrome is more about being an application development platform than another grab at desktop dominance, then I hope that XSLT is eventually part of that application development picture. Maybe someday.