To use our library we will create another web project in visual studio that will consume our library. In order to use the assembly that contains the code behind code we must add a reference to it in our project.
We can access the assembly as we registered it in the GAC but how can we have access to the .ascx file from our aspx page ? IIS will answer to this question for us. IIS has a neat feature called virtual directories, virtual directories allow us to add to a website root a sub-directory that maps to a different physical path.
We will use this fonctionality to map a new virtual directory called "controls" to the path where our .ascx file reside. We can add a new virtual directory to the root of our web project using the Internet Service Manager.
Note : By default IIS associates an application to the virtual directory, as we don't need it we clicked the "remove" button to remove it.