The Managed Extensibility Framework (MEF) CTP Released (Not to be confused with the Managed Addin Framework [MAF] which became System.Addin)

Mircea Trofin's blog - The Managed Extensibility Framework (MEF) CTP is out!

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For those that are not familiar with the topic, MEF "provides developers with a tool to easily add extensibility to their applications and with minimal impact on existing code. The application developer can define extension points according to the functionality required of an extension, while the extension developer uses those points to interact with the application.

MEF enables this extensibility to take place without creating a hard dependency in either direction. Applications can be extended at run time without recompilation, and extensions can be used by multiple applications sharing the same extension requirements. MEF also allows an application to delay the loading of an extension while still examining its metadata, enabling efficient traversal of large catalogs of extensions”

Krzysztof Cwalina - Managed Extensibility Framework

“Several months ago we formed what we call Application Framework Core team. The charter of the team is to play the same role in the application frameworks space (WinForms, ASP.NET, WPF, Silverlight) as the Base Class Libraries (BCL) team plays at the bottom of the platform stack.

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One of the first concrete projects that we are working on and are ready to slowly talk about is what we call the Managed Extensibility Framework (MEF). We observed that there are more and more places in the .NET Framework itself and increasingly managed applications (like Visual Studio) where we want to provide, or already provide, hooks for 3^rd party extensions. Think about TraceListener plugins for the TraceSource APIs, pluggable rules for Visual Studio Code Analysis (and the standalone FxCop), etc. In the absence of a built-in extensibility framework (like MEF), our developers who want to enable such extensions often are forced to create custom mechanisms, thus duplication. We hope that MEF will both stop such duplication and encourage/enable more extensibility in the Framework and applications built on top of it.

We will blog more details about MEF in the upcoming months, but here are some early details (subject to changes, of course): MEF is a set of features referred in the academic community and in the industry as a Naming and Activation Service (returns an object given a “name”), Dependency Injection (DI) framework, and a Structural Type System (duck typing). These technologies (and other like System.AddIn) together are intended to enable the world of what we call Open and Dynamic Applications, i.e. make it easier and cheaper to build extensible applications and extensions.…”

I like System.Addin, and understand why it needs its complexity, but that doesn’t mean I can’t hope for something that’s easier… ;)