I have a Windows Forms app that's extensible in that it looks for .dlls in a "Plug-In" folder, loads each assembly, iterates through the types, and if a type implements my interface, does stuff. Stuff it does includes grabbing a MenuItem to add to the app's "Plug-In" MenuItem.

This works fine, but it's pretty much a one-way street. That is, the plug-in can't get information from the host. Just for kicks I added a set property to the interface so now the plug-in has a reference to the app's main form - you could do cute things like iterate through the app's MDI children and manipulate which form is activated, or any other public member.

What I really want is to let a plug-in have access to objects in the app. Objects in this case would be data (Mere Mortals business objects) associated with an MDI form.

What I've just started is another interface. I'm thinking my MDI child forms should implement the interface, then when the plug-in has a reference to a child form, could cast it to the new interface, and call, for example, .GetDataSet() or .GetBusinessOjbect().

Is this the right direction to pursue? Any thoughts are appreciated.

Mike