Question

I am working on a client/server game (C#.NET) where I do not want to trust the client to hold any of my server side application code, but want to share objects.

For example imagine you have a right hand weapon slot and a backpack that can carry additional items. Now there’s a lot of server side code that will control which items can go in which slots and when you swing your right hand what happens. I don’t want to put this code in my client for various reasons, but I am finding often times that if I generate a client side class and server side class for each of these that I see a lot of duplication in data and some duplication in methods. I also have to convert 1 class into the other.

Another example is For Items in the game. Item’s have ‘Use’ abilities (like Use a key, or Use a torch) and properties like Name and Weight. So When I create the Item Class I would prefer to make 1 class like this:

Public Class Item  
{

  int Weight; 

  string Name;

  void Use() { //Do something interesting but not public to the client } 

}

Eventually copies of this object are serialized and sent to the client or server from each other as changes are made. If a Partial Class could span projects that would be very promising (to bad they don’t). I don’t think sub-classing feels right here (like ServerItem : Item) considering Serialization/Deserialization. I will play around some with Extension methods and see what implications there are for sub-classing but if anyone has any ideas or if I’m just missing something obvious please let me know.

Answer 1

You really want to separate Data from Behaviour, and have just lightweight share-able data classes, and then (on the server) have server-centric classes that use data to determine behaviour. (try looking at a few design patters – maybe ‘Decorator’)

One lightweight example of what you may want is:

 // lightweight data class thats shared
public class Item
{
    public int Weight { get; set;  }
    public string Name { get; set; }
}

// decorator pattern class that adds behaviour
public class ServerItem
{
    private Item item;
    public ServerItem(Item item)
    {
        this.item = item;
    }

    public void Use()
    {
        // do something with item;
    }
}

ServerItem currentServerItem = new ServerItem(currentItem);