Making plugin system with shared libraries. Upcast in shared lib

[MrSmith via Digitalmars-d-learn]

I'm using Windows.

I was making some sort of modular system where you can define 
modules that are loaded by host application.
Here is a simple example 
https://gist.github.com/MrSmith33/7692328455a19e820a7c
Now i want to separate these "modules" in separate shared libs 
and link them on the fly.
The issue i have is that some modules can define some useful 
functions and in order to use them you need to upcast to concrete 
type. This is easy in a single application, but i was unable to 
do this through dll boundary.

So basically all dll's have factory function that returns an 
instance of IModule.
Than any module can search for registered modules and try to cast 
them to concrete type (upcast).

in imodule.d

interface IModule
{
        string name();
        void init(ModuleManager modman);
}

in module1.d (dll)

class Module1 : IModule
{
        override string name() {return "Module1";}

        override void init(ModuleManager modman)
        {
                IModule module2 = modman.findModule("Module2");
                if (auto m = cast(Module2)module2)
                {
                        m.someMethod2();
                }
        }
}

in module2.dll (dll)

class Module2 : IModule
{
        override string name() {return "Module2";}
        override void init(ModuleManager modman){}
        void someMethod2(){}
}

And what files should i compile with what packages?
application
        IModule
        main
        other

module1 dll
        IModule
        Module1
        Module2 - should i import it, compile of import .di file?

module2 dll
        IModule
        Module2

Is it possible at all? Or it is an issue with Windows shared lib 
support?