Using XML with Legacy Business Applications

Derivation of Complex Types by Restriction

We talked earlier about deriving simple types from built-in types by restriction and about deriving complex types by extension. We didn't talk about deriving complex types by restriction. There are several reasons for this. One reason is the general mechanism by which this restriction is performed. For example, if you want to remove Elements from a sequence content model, you have to restate the sequence, listing only those Elements you want to use. This is a bit more awkward than just listing those you want to remove. In addition, most people designing hierarchies of complex types tend to follow an object-oriented approach. This generally involves defining base classes with a few common properties, ...