Imports System.ServiceModel

<ServiceContract()> _
<ServiceKnownType(GetType(class2))> _
Public Interface IInterface

    <OperationContract()> _
    Function GetDate() As class2

    <OperationContract()> _
    Sub MB(ByVal Text As String)

End Interface

Public Class Class1
    Implements IInterface

    Public Function GetDate() As class2 Implements IInterface.GetDate
        Return New class2(Date.Now.ToString)
    End Function

    Public Sub MB(ByVal Text As String) Implements IInterface.MB
        Form1.txt_Mesage.Text &= "Пришло сообщение:" & vbNewLine & Text & vbNewLine
    End Sub

End Class

Public Class class2

    Public Value As String

    Public Sub New(ByVal Value As String)
        Me.Value = Value
    End Sub

End Class

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <system.serviceModel>
    <behaviors>
      <serviceBehaviors>
        <behavior name="mexEnabled">
          <serviceMetadata
            httpGetEnabled="true"
            httpGetUrl="http://localhost:8081/HelloService" />
        </behavior>
      </serviceBehaviors>
    </behaviors>
    <services>
      <service
        behaviorConfiguration="mexEnabled"
        name="ConsoleApplication1.Class1">
        <endpoint
          address="http://localhost:8081/HelloService"
          binding="basicHttpBinding"
          contract="ConsoleApplication1.IInterface" />
      </service>
    </services>
  </system.serviceModel>
</configuration>