Friend Class SampleService
    Implements ISampleService
#Region "ISampleService Members"

  Public Sub Push(ByVal msg As String) Implements ISampleService.Push
       Console.WriteLine("Proxy: " & msg)
    Me.WriteHeaders(OperationContext.Current.IncomingMessageHeaders)
    Dim outBoundHeader As MessageHeader = MessageHeader.CreateHeader("Client-Bound-One-Way-Header", "http://Microsoft.WCF.Documentation", "Custom Outbound Header")
    OperationContext.Current.OutgoingMessageHeaders.Add(outBoundHeader)
    Console.ForegroundColor = ConsoleColor.Red
    Console.WriteLine("OutgoingHeader:")
    Console.Write(vbTab)
    Console.ForegroundColor = ConsoleColor.Blue
    Console.WriteLine(outBoundHeader.ToString())
    Console.ResetColor()
    OperationContext.Current.GetCallbackChannel(Of IClientCallbackContract)().PushBack("Here's something to examine in response.")
  End Sub

  Private Sub WriteHeaders(ByVal headers As MessageHeaders)
    Console.ForegroundColor = ConsoleColor.Red
    Console.WriteLine("IncomingHeader:")
    Console.ForegroundColor = ConsoleColor.Blue
          For Each h In headers
              If Not h.Actor.Equals(String.Empty) Then
                  Console.WriteLine(vbTab & h.Actor)
              End If
              Console.ForegroundColor = ConsoleColor.White
              Console.WriteLine(vbTab & h.Name)
              Console.ForegroundColor = ConsoleColor.Blue
              Console.WriteLine(vbTab & h.Namespace)
              Console.WriteLine(vbTab & h.Relay)
              If h.IsReferenceParameter = True Then
                  Console.WriteLine("IsReferenceParameter header detected: " & h.ToString())
              End If
          Next h
    Console.ResetColor()
  End Sub