The Managed Extensibility Framework (MEF) has been getting a lot of interest lately and it’s something that’s out on CodePlex and it’s also part of .NET Framework 4.0.

It’s also part of Silverlight 4.

The name’s a good one – it’s a framework for building an application that is made up of a bunch of loosely coupled components with a lot of flexibility around component discovery, registration, lookup and lifetime management. If I had to sum it up in my own words I’d say something like;

MEF composes an application by extensibly discovering a set of components which offer exported functionality and ( possibly ) rely on imported functionality. The link between the two is a simple string name ( a MEF “contract name” ) which is usually represented by a .NET type name and MEF has the capability to plug things together where it finds ( possibly further constrained ) matches.

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As Silverlight increases its Out of Browser features it will become more important to detect if the application is running in or out of the browser.  This is the check:

if (Application.Current.IsRunningOutOfBrowser)
{
       // Out of Browser 

}
else

{
      //   in the browser

}

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3. Data Sources Window
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