public static MovieRentalDatabase getInstance()
        {
            if (instance == null)
            {
                instance = new MovieRentalDatabase();
            }

            return(instance);
        }
    private UserConnection()
    {
        channel = new TcpClientChannel();

        channel = new TcpClientChannel();
        ChannelServices.RegisterChannel(channel);
        mrd = (MovieRentalDatabase.MovieRentalDatabase)
              Activator.GetObject(typeof(MovieRentalDatabase.MovieRentalDatabase),
                                  "tcp://localhost:9999/Rental");
    }