' Define a service contract. 
<ServiceContract(Namespace:="http://Microsoft.ServiceModel.Samples")> _
Public Interface IQueueCalculator
    <OperationContract(IsOneWay:=True)> _
    Sub Add(ByVal n1 As Double, ByVal n2 As Double)
    <OperationContract(IsOneWay := True)> _
    Sub Subtract(ByVal n1 As Double, ByVal n2 As Double)
    <OperationContract(IsOneWay := True)> _
    Sub Multiply(ByVal n1 As Double, ByVal n2 As Double)
    <OperationContract(IsOneWay := True)> _
    Sub Divide(ByVal n1 As Double, ByVal n2 As Double)
End Interface

' Service class that implements the service contract.
' Added code to write output to the console window
Public Class CalculatorService
    Implements IQueueCalculator
    <OperationBehavior> _
    Public Sub Add(ByVal n1 As Double, ByVal n2 As Double) Implements IQueueCalculator.Add
        Dim result As Double = n1 + n2
        Console.WriteLine("Received Add({0},{1}) - result: {2}", n1, n2, result)
    End Sub

    <OperationBehavior> _
    Public Sub Subtract(ByVal n1 As Double, ByVal n2 As Double) Implements IQueueCalculator.Subtract
        Dim result As Double = n1 - n2
        Console.WriteLine("Received Subtract({0},{1}) - result: {2}", n1, n2, result)
    End Sub

    <OperationBehavior> _
    Public Sub Multiply(ByVal n1 As Double, ByVal n2 As Double) Implements IQueueCalculator.Multiply
        Dim result As Double = n1 * n2
        Console.WriteLine("Received Multiply({0},{1}) - result: {2}", n1, n2, result)
    End Sub

    <OperationBehavior> _
    Public Sub Divide(ByVal n1 As Double, ByVal n2 As Double) Implements IQueueCalculator.Divide
        Dim result As Double = n1 / n2
        Console.WriteLine("Received Divide({0},{1}) - result: {2}", n1, n2, result)
    End Sub
End Class

' This is the hosting application. This code can appear directly in the service class as well.
Friend Class HostApp
    ' Host the service within this EXE console application.
    Public Shared Sub Main()
        ' Get MSMQ queue name from appsettings in configuration.
        Dim queueName As String = ConfigurationManager.AppSettings("queueName")

        ' Create the transacted MSMQ queue if necessary.
        If (Not MessageQueue.Exists(queueName)) Then
            MessageQueue.Create(queueName, True)
        End If

        ' Get the base address that is used to listen for WS-MetaDataExchange requests.
        ' This is useful to generate a proxy for the client.
        Dim baseAddress As String = ConfigurationManager.AppSettings("baseAddress")

        ' Create a ServiceHost for the CalculatorService type.
        Using serviceHost As New ServiceHost(GetType(CalculatorService), New Uri(baseAddress))
            ' Open the ServiceHostBase to create listeners and start listening for messages.
            serviceHost.Open()

            ' The service can now be accessed.
            Console.WriteLine("The service is ready.")
            Console.WriteLine("Press <ENTER> to terminate service.")
            Console.WriteLine()
            Console.ReadLine()

            ' Close the ServiceHostBase to shutdown the service.
            serviceHost.Close()
        End Using
    End Sub
End Class