In case you're not convinced that both XML and Java enjoy cross-platform portability, look over these facts about the two technologies.

• In its brief lifetime, XML has become the worldwide standard for representing structured, self-describing data.

The XML registry lists over one hundred XML data formats. They include formats for financial data, healthcare, arts and entertainment, human resources, multimedia, and many other domains. The XML standard encapsulates almost any kind of data in a way that's flexible, extensible, and easy to maintain.

• Java runs as bytecode on a virtual machine.

A "compiled" Java class file that runs on Windows will run the same way on Linux, on Windows, or on whatever platform supports the Java Virtual Machine.

With Java, there's no such thing as platform-specific code. When you go from a .java source file to a .class bytecode file, you don't lose portability. To run the .class file, all you need is an operating system that can support a Java Virtual Machine. And versions of the Java Virtual Machine are available for at least twenty different operating systems.

• Java is based on object-oriented programming technology.

Java code is reusable. You can call methods from existing classes, extend classes, or stretch and bend classes to meet your specialized needs. If someone writes a wonderful XML-handling package in Java, and the package has bits and pieces that you can use in your own work, you can import the package and extend the classes to solve exactly the problems that you need to solve.

This cooperative model works both ways. When you create a package for your own anticipated needs, other developers can adopt your package, enhance your package, and spread the good word about your code.

Taken together, these factors eventually ensure that software written in one environment can run in all other environments. Instead of reinventing the wheel, programmers reuse the wheel. This ideal — the seamless integration of parts from many sources to build large, reliable software systems — has been the Holy Grail of computing for the past several decades. Now portable code and portable data put the ideal within reach.