type OrderService() =
    let mutable client : option<IDuplexClient> = None
    let mutable orderName : string = null
    let mutable orderQuantity : int = 0

    member x.Order (name: string, quantity: int) =
        client <- Some (OperationContext.Current.GetCallbackChannel<IDuplexClient> ())
        orderName <- name
        orderQuantity <- quantity
        use timer = new Timer (new TimerCallback (CallClient), null, 5000, 5000)
        Thread.Sleep 11000