1. type OrderService() =
  2.     let mutable client : option<IDuplexClient> = None
  3.     let mutable orderName : string = null
  4.     let mutable orderQuantity : int = 0
  5.  
  6.     member x.Order (name: string, quantity: int) =
  7.         client <- Some (OperationContext.Current.GetCallbackChannel<IDuplexClient> ())
  8.         orderName <- name
  9.         orderQuantity <- quantity
  10.         use timer = new Timer (new TimerCallback (CallClient), null, 5000, 5000)
  11.         Thread.Sleep 11000