Managed Extensibility Framework (MEF, MEF2)
The Managed Extensibility Framework (MEF) is a composition layer for .NET that improves the flexibility, maintainability and testability of large applications. MEF can be used for third-party plugin extensibility, or it can bring the benefits of a loosely-coupled plugin-like architecture to regular applications. MEF is a part of the Microsoft .NET Framework, with types primarily under the System.ComponentModel.Composition.* namespaces.