how to know application is for web or windows

I developed my own framework like Entity framework (simple one). It's a small dll and you can add your web or windows application. But it has a connection class and it reads connectionstring from web.config. But as you know there is no web.config file in windows application. So i will get the connection string from application config file in windows form application. In my connection class i want to check the application is for web or windows. How can i do that? I don't want to use try catch for this. Is there anu way? Thanks.