using System;

using System.ComponentModel;

public class Program

{

    public static void Main()

    {

        try

        {

            Item _Item = new Item();

            _Item.ItemId = 10256;

            _Item.Name = "SilverRing";

            _Item.Price = 205.00;

            _Item.StockInHand = 10;

            int i = 25;

            while(_Item.StockInHand > 0)

            {

                Console.WriteLine("Remaining Stock On Item {0} => {1}", _Item.ItemId, _Item.StockInHand);

                _Item.StockInHand--;

                if(i-- < 0)

                    break;

            }

        }

        catch(Exception ex)

        {

            Console.WriteLine("Error : {0}", ex.Message);

        }

    }   

}

​

public class Item : INotifyPropertyChanged

{

    public int ItemId { get; set; }

    public string Name { get; set; }

    public double Price { get; set; }

    private int _StockInHand;

    public int StockInHand { 

        get { return _StockInHand; } 

        set { 

            _StockInHand = value; 

            OnPropertyChanged("StockInHand");

        }

    }

    public event PropertyChangedEventHandler PropertyChanged;

    public Item()

    {

        PropertyChanged += Item_PropertyChanged;

    }

    public void OnPropertyChanged(string PropertyName)

    {

        if(PropertyChanged != null)

            PropertyChanged(this, new PropertyChangedEventArgs(PropertyName));

    }

    public void Item_PropertyChanged(object sender, PropertyChangedEventArgs e)

    {

        switch(e.PropertyName)

        {

            case "StockInHand":

            Item _Item = (Item)sender;

            if(_Item._StockInHand < 5)

            {

                Order _Order = new Order();

                _Item._StockInHand = _Order.RefillRequest(_Item.ItemId);

            }

            break;

        }

    }

}

​

public class Order

{

    public int RefillRequest(int ItemId)

    {

        try

        {

            Console.WriteLine("Refill request rised for item {0}", ItemId);

            return 12;

        }

        catch(Exception ex)

        {

            throw ex;

        }

    }

}