ASP.NET and VB.NET config files
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I am trying to share a DLL between an ASP.NET application and a VB.NET (Forms) application.  The client application uses a configuration file to store settings e.g. connection strings and so does the ASP.NET application.

The ASP.NET application uses the System.Web.Configuration namespace whilst the VB.NET application uses the System.Configuration namespace.  I notice that they inherit from the Object class.  I was expecting them both to inherit from a common class so that I could perhaps use Polymorphism to create an instance of the appropriate type in the DLL.

What is the best practice for using config files for DLLs that are shared across ASP.NET and VB.NET applications.  I have researched this and I read somewhere that you should use System.Configuration in the ASP.NET application and I read somewhere else that you should not do this because you cannot write to the web.config if you use System.Configuration in the ASP.NET application.  I do not need to write to the web.config; I need to read it.  What is the best practice?