Hey,
When you refer to "real time", are you actually meaning in real world example?
I use abstract classes for the Data Provider Model that I use. The Abstract Base classes define what methods need to be overridden by the actual Data Provider.
So, for instance, I have an Abstract Base Class called ArticlesProvider, which has methods such as GetArticles, UpdateArticle etc.
Then I have other classes, namely SqlArticleProvider, and MySqlArticleProvider which inherit from the Abstract Base Class, and implement those methods specifically for SQL Server and MySql Database.
Hope that helps!!
Gary