The Java language liberates software from dependence on a particular operating system. The program you write with the language on a Windows XP box creates class files that can be run on a Linux server or a Mac OS X computer. Extensible Markup Language, better known as XML, achieves a similar liberation for the data produced by software. If XML data follows the simple rules required to make it well-formed, you can read it with any software that parses XML. You don't need to keep the originating program around just to ensure there's always a way to access it. The XML Object Model (XOM) library makes it easy to read and write XML data. When you can grok both Java and XML, you can declare your independence from two of the major obstacles faced by computer programmers for decades—obsolete data and obsolete operating systems.