On reading a message on the CakePHP mailing list about the web services built into the framework, Chris Hartjes decided to embark on his own look at what functionality the framework offers and how easy it is to use.
Might I add that until I tried this, I had never built a web service with CakePHP before. I found that by turning on the debug mode and actually following the instructions that were in the error messages (best undocumented feature of CakePHP if you ask me) I was able to build.
His code, while it worked, was one-upped by another's submitted to the mailing list (Samuel DeVore) so he's included that code in his example rather than the original. His example makes a TestController, an XmlComponent, and an XmlHelper to vary the output from a normal HTML to an XML format based on if "xml" is included in the path of the location.