As I familiarize myself with Asp.Net MVC, I am using MVC 2, I have noticed the use of a BaseViewData class in the Kigg project which I am unsure how to implement.

I want each of my ViewModels to have certain values available. Using an iterface comes to mind but I am wondering what the best practice is and how does Kigg do it?

Kigg

public abstract class BaseViewData 
{ 
  public string SiteTitle { get; set; }
  // ...other properties
}
public class UserListViewData : BaseViewData
{
   public string Title { get; set; }
   // .. other stuff
}

In my WebForms application I use a BasePage that inherits from System.Web.UI.Page.
So, in my MVC project, I have this:

public abstract class BaseViewModel
{
    public int SiteId { get; set; }
}
public class UserViewModel : BaseViewModel
{
  // Some arbitrary ViewModel
}

Referencing the Kigg methodology, how do I make sure that each of my ViewModel that inherits from the BaseViewModel have the SiteId property?

What is the best practice, samples or patterns I should be using?