public interface IPlugin { void Execute(); } [Export(typeof(IPlugin))] public class MyPlugin : IPlugin { public void Execute() => Console.WriteLine("Hello from plugin"); } If you meant a (like Entity Framework 4, Spring Framework 4, etc.), please clarify and I’ll produce the correct feature.

Here’s one major feature: Built into .NET Framework 4 (in System.ComponentModel.Composition ).

It looks like you're referring to (or a specific "Framework v4" in another context, like Java, Qt, or a game engine).