Use System.Net.HttpContinueDelegate to specify the callback method to be called when an HTTP 100-continue response is received from the server. When set, the delegate is called whenever the first protocol response of type HttpStatusCode.Continue is received. This is a change from the behavior of the version 1.1 Framework.
Your event handler must declare the same parameters as the System.Net.HttpContinueDelegate.
StatusCode is always HttpStatusCode.Continue.
This is useful when the client wants to display the status of data being received from the server.