[Serializable]
    public class Order 
	{
        .........................
        public virtual void BeginEdit()
        {
                BinaryFormatter formatter = new BinaryFormatter();

                using (MemoryStream stream = new MemoryStream())
                {
                    formatter.Serialize(stream, this.OrderItems);
                    stream.Position = 0;
                    originalState = new byte[stream.Length];
                    stream.Read(originalState, 0, (int)stream.Length);
                }
        }

        public virtual void CancelEdit()
        {
                if (originalState != null)
                {
                        BinaryFormatter formatter = new BinaryFormatter();

                        using (MemoryStream stream = new MemoryStream())
                        {
                            stream.Write(originalState, 0, originalState.Length);
                            stream.Position = 0;
                            this.OrderItems = (IList<OrderItem>)formatter.Deserialize(stream);

                            originalState = null;
                        }
                    
                }
        }
................