This separation provides a number of benefits; to start, keeping your business logic completely separate from your control and view logic makes it very easy to add new views to your application.

In a typical Service-Oriented Architecture (SOA) deployment, a number of layers are introduced to facilitate the separation of concerns and to assist in loose coupling.

Besides the separation of concerns, that separation of WSDL port type from the WSDL binding in two documents allows for any number of bindings for a given port type.