If you are building an XML Web service client, then a proxy class that derives indirectly or directly from WebClientProtocol must be created for the XML Web service. When the XML Web service client calls using SOAP, the proxy class must derive from SoapHttpClientProtocol, which derives from HttpWebClientProtocol. HttpWebClientProtocol, in turn, derives from WebClientProtocol.
To communicate with an XML Web service, create a proxy class that derives indirectly or directly from WebClientProtocol for the XML Web service you want to call. Instead of creating the proxy class manually, use the Web Services Description Language tool (Wsdl.exe) to create a proxy class for a given XML Web service's service description. When a proxy class is generated for the SOAP protocol, synchronous calls to XML Web service methods are made via the Invoke method, whereas asynchronous calls are made using the BeginInvoke method and the EndInvoke method.
Notes to Inheritors:
When you override this class, you can introduce methods in the derived class which are specific to a particular type of XML Web service. The methods capture the parameters and call the base class to do the work of communicating with the XML Web service. If the introduced methods are asynchronous, call the BeginInvoke method and the EndInvoke method. If the introduced methods are synchronous, call the Invoke method. The overridden constructor typically sets the Url property to the URL of the XML Web service method.