SOA Tips-Separation of Concerns03 May 2007
In your Service Description model, your Information model is likely to evolve over time, but at any point in time it is documented by an XML Schema and is referenced from the types section that is part of the Abstract WSDL. The behavioral contract, the message exchange patterns, and the interfaces are defined in the abstract part of the WSDL too. The Abstract WSDL therefore documents business-specific information.
The Concrete WSDL however, is technical in nature and documents information about the protocols, bindings, and transports used to expose and carry the message over the network. The concrete part of the WSDL is also used to document other extensible contracts that are technical in nature and may have nothing to do with business-specific information.
If you are using a UDDI-based registry, the UDDI tModel refers to the abstract WSDL part which is the interface and contains business-specific information. The UDDI binding template refers to the Concrete WSDL.
Refer to an earlier blog entry of mine titled Exploring the Service Description model to learn more about separation of concerns built into the WSDL model.