MEF & Silverlight 4 Beta - Part 4, Recomposition | mtaulty

Part 4 of a series of screencasts looking at the new Managed Extensibility Framework (MEF) in the Silverlight 4 beta.

MEF is a framework that simplifies the design of extensible applications and components. It can flexibly and dynamically discover a set of loosely coupled components and analyse their dependencies in order to compose them together at run time.

In this screencast, we look at how composition of component parts in MEF is not necessarily a static or "one-time" process and that as changes are made to MEF's CompositionContainer it can re-compose components to take account of those changes.

Tips for viewing:

Each video in this series has a 3.5 minute standard introductory "header" on it so once you have seen that header you may like to skip it on subsequent videos
For the time pressured - I find that I speak so slowly that you can speed me up to approximately 1.5-2.0 times normal speed and still listen comfortably.

I'm working to get together a Live Meeting in early 2010 with people from the MEF team in order that people can chat more about MEF in Silverlight. Stay tuned.

The next screencast in this series is here.

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gpatnew

Dec 31, 2009 at 1:46 PM

Very powerful
bigbag

Jan 06, 2010 at 7:20 PM

Where is part 5?

Shouldn't this be already an inherent design attribute of the Silverlight platform? ...The intrinsic ability to handle bulky application parts with heuristic algorithms to prioritise which parts get loaded first?

I must say this all seems very frustrating... to sit and waste so much time learning these "brilliant" ideas, designed to mitigate Silverlight flaws.
mtaulty Mike Taulty

Jan 08, 2010 at 4:16 AM

Hi,

Part 5 is here - it's hyperlinked from the text above as well so not sure whether you're having some problem with that link or not?

There are capabilities within Silverlight today to download XAPs dynamically and to also package up sets of functionality into related ZIP files to avoid downloading them more than once across common uses in multiple apps.

So, it is possible to build a partitioned and extensible app with Silverlight today if you need this kind of functionality but MEF is coming along and trying to offer a pre-built, flexible, extensible, supported Microsoft framework for doing that kind of thing so you don't have to burn time/money on it.

It's also not just a Silverlight thing - it'll be part of .NET Framework 4 for the desktop/server as well.

For me, that's not mitigation of a flaw in either Silverlight 3 or .NET Framework 3.5 Sp1. It's a welcome addition to both platforms that takes away a bunch of "plumbing" code that a lot of application builders don't want to write so, personally, I welcome it along with other Silverlight 4 additions that broaden out the platform.

Thanks,

Mike.
Thundar Viking

Jul 10, 2010 at 6:42 PM

A very good video and good basic example on adding typecatalogs and the automatic discovery by MEF of classes implementing requested interfaces through export-import functionality of MEF. The video explains how to apply [Import(AllowRecomposition=true)]

or [ImportMany(AllowRecomposition=true)] - the AllowRecomposition setting of an import to specify that an import might change during execution time and making it possible to satisfy an import at a later stage when the program is running.

I followed along the video in Visual Studio ("coding along") and everything in this video worked great on my setup also. Another pedagogical masterpiece of Mike Taulty explaining the wonders of MEF.

-= The somewhat civilized barbarian =-