reference DLL from app across .NET versions... possible?

Question

Our organization's software is compiled for the .NET 3.5 Framework. We have some customers who wish to plug into our libraries, but insist on using older versions of Visual Studio (that preceded .NET 3.5), such as VS 2003. Is there a way for those customers to plug into our application, despite the fact that they're using older versions of Visual Studio (and therefore, older versions of .NET)? Currently, when they try to reference our assemblies, they get an error (which they didn't care to specify, unfortunately).

Is this possible? Any experience with this?

Answer 1

So far, you could only have a single CLR version loaded in a process. It's not possible to run CLR 1.0 and 2.0 in a single process. This is going to change in .NET 4.0 (you'll be able to load .NET 2.0 CLR and 4.0 side by side). You can reference the DLL as long as you load the whole thing in the newer version of the runtime (which might cause some compatibility problems for older apps). If they don't want to install the new .NET framework at all, it won't be possible to do it.

Answer 2

You can reference and use libraries written using previous versions of the .NET framework, but not the other way around. So a .NET 3.5 project can use a library written using .NET 1.1. But a .NET 1.1 project can not use a library written using .NET 3.5.