public static DateTime?GetLastRecordEnterTimeByPlateNumber(string parkingID, string platenumber, out string ErrorMessage) { if (parkingID.IsEmpty()) { throw new ArgumentNullException("parkingID"); } if (platenumber.IsEmpty()) { throw new ArgumentNullException("platenumber"); } IParkIORecord factory = ParkIORecordFactory.GetFactory(); return(factory.GetLastRecordEnterTimeByPlateNumber(parkingID, platenumber, out ErrorMessage)); }