The IDL level description embodied by the functional description layers of the service description stack is very important, but there is more that should be described about a Web service.
What do we mean by the term nonfunctional description? Basically, these layers can be characterized in contrast to the functional layers. Whereas the functional layers describe where to send the message, what the message syntax needs to look like, and how to use the protocols and encoding schemes, the nonfunctional description addresses why a service requestor should invoke the Web servicefor example, what business function the Web service addresses and how it fits into a broader business process. A nonfunctional description also gives more details about who the service provider is. For example, does the service provider provide auditing and ensure privacy?
The UDDI service registry also has impact on the certain nonfunctional aspects of the service description. In particular, the taxonomy scheme supported by UDDI is another mechanism by which a service provider can describe what kind of service is being provided and what business function it supports.