Callback interface definition.

To be able to register callback object and later do a call, the server need to know the interface of the callback objects. And here we will define it.

• Create new class library in Visual Studio and call it IProgressObserver:

• Put this code into Class1.vb:

Imports System.Runtime.Remoting.Messaging
Public Interface IProgressSubscriber
    <OneWay()> _
    Sub ProgressChanged(ByVal percent As Integer, ByVal message As String)
End Interface

• Save the project and compile the library. You should get IProgressObserver.dll file