XML Schema Complete Reference, The

1.4. Object-oriented Concepts

One of the foundations of this book is object-oriented technology. Specifically, the foundation of XML schemas is extensional object-oriented technology; the foundation of more “conventional” languages such as C++ or Java is intensional object-oriented technology. In fact, software that processes XML documents must often process both intensional and extensional objects.

The poignant distinction between intensional and extensional objects is that in an intensional language, an instance exists because of instantiation. For example, you might use ‘instance = new(class)’ or some other similar syntax. Extensionally, however, an object simply is or is not an instance of a particular class according to whether or not it ...