What happens behind the scenes
When Business Data Catalog clients, such as Business Data Web Parts and custom solutions, use the Business Data Catalog to execute back-end Web methods, the Business Data Catalog does the following:
Queries the Web service URL (the WsdlFetchUrl property on the LobSystem element) for discovery information.
Extracts a WSDL-based Web service description.
Dynamically generates the code for a Microsoft Visual C# proxy in memory.
Compiles the Visual C# proxy code to an in-memory assembly.
Assigns a namespace with the user-specified name (the ProxyNamespace property on the LobSystem element) to the proxy class and method parameter types, and saves the namespace to the Shared Services database for future use.
When requested, creates the required SOAP requests, plugs in any filter values, and sends the request to the Web server.