Using XML with Legacy Business Applications

What Is a Namespace?

To begin, every XML instance document has a namespace, whether it is explicitly named or not. So, in the current environment there is no escaping them. You can't run, you can't hide.

A namespace is nothing more than a set of names. Namespaces are themselves identified by a URI, which I'll discuss next. But first let's drill in the concept with an analogy.

Consider a youth soccer league family picnic. The set of everyone attending the picnic forms our universe, or the default, unnamed namespace. Consider two people named Bob who are attending the picnic with their sons and daughters (Figure 4.1).

Figure 4.1. Two Bobs at the Picnic

Suppose that the coach calls out for Bob to help cook the hot dogs. Unless the coach is looking ...