I haven&#39;t found a really comprehensive page, but there are a few:

[Microsoft Docs][1]

[Simple Example from a msdn blog][2]

[Code Project&#39;s Introduction to MEF (part 1)][3]

[MEF 101 part A from Geek with Blogs][4]

[MEF 101 part B][5]

[Another MSDN blog, a little more history than tutorial][6]


  [1]: https://docs.microsoft.com/en-us/dotnet/framework/mef/
  [2]: http://blogs.msdn.com/brada/archive/2009/07/20/simple-example-using-managed-extensibility-framework-in-silverlight.aspx
  [3]: http://www.codeproject.com/KB/library/mefpart1.aspx
  [4]: http://geekswithblogs.net/malisancube/archive/2009/05/26/managed-extensibility-framework-101---a.aspx
  [5]: http://geekswithblogs.net/malisancube/archive/2009/06/09/managed-extensibility-framework-101-b.aspx
  [6]: http://blogs.msdn.com/kcwalina/archive/2008/04/25/MEF.aspx

Mike Taulty recently did a set of [screencasts][1] on using MEF in Silverlight, which should be a good introduction to MEF.

  [1]: http://mtaulty.com/CommunityServer/blogs/mike_taultys_blog/archive/2009/12/31/silverlight-4-screencasts-the-managed-extensibility-framework-mef.aspx

I&#39;ve done an ever growing series on MEF from the very basics into more advanced stuff planned in the near future.

[http://randomactsofcoding.blogspot.com/2009/11/working-with-managed-extensibility.html][1]


  [1]: http://randomactsofcoding.blogspot.com/2009/11/working-with-managed-extensibility.html

I wrote [this MEF demo article](http://www.codeproject.com/KB/WPF/SoapBoxCorePinBallDemo.aspx) on CodeProject, and all the code is open sourced.

[Microsoft Docs][1] is a good start

[Kathleen Dollard][2] has some good materials as well 


  [1]: https://docs.microsoft.com/en-us/dotnet/framework/mef/
  [2]: http://msmvps.com/blogs/kathleen/

If you&#39;re looking for information on the latest version of MEF that is shipping with the next .NET Framework, the definitive source of information is the [BCL Team Blog][1] on MSDN.

(MEF is part of the .NET Base Class Libraries.)

  [1]: http://blogs.msdn.com/b/bclteam/archive/tags/mef/

Dependency Injection in .NET by Mark Seemann has a section on MEF, as well as Castle Windsor, StructureMap, Spring.NET, Autofac, and Unity.

I just saw some code in bash that I didn&#39;t quite understand.  Being the newbie bash scripter, I&#39;m not sure what&#39;s going on.  

    echo ${0##/*}
    echo ${0}

I don&#39;t really see a difference in output in these two commands (prints the script name).  Is that `#` just a comment?  And what&#39;s with the `/*`.  If it is a comment, how come it doesn&#39;t interfere with the closing `}` brace?  

Can anyone give me some insight into this syntax?


What is the meaning of the ${0##...} syntax with variable, braces and hash character in bash?

One of the extension methods on ``IEnumerable&lt;T&gt;`` is ``.AsEnumerable()``. This method converts the enumerable object it was called on into an instance of ``IEnumerable&lt;T&gt;``. However, since an object must implement ``IEnumerable&lt;T&gt;`` in order to apply to this extension method, converting to ``IEnumerable&lt;T&gt;`` is a simple matter of casting to ``IEnumerable&lt;T&gt;``. My question is why does this method exist at all?

Example:

    List&lt;string&gt; strings = new List&lt;string&gt;() { &quot;test&quot;, &quot;test2&quot;, &quot;test3&quot; };
    IEnumerable&lt;string&gt; stringsEnum1 = strings.AsEnumerable();
    IEnumerable&lt;string&gt; stringsEnum2 = (IEnumerable&lt;string&gt;)strings;

In the example above, ``stringsEnum1`` and ``stringsEnum2`` are equivalent. What&#39;s the point of the extension method?

**Edit**: As a corollary, why is there an ``.AsQueryable()`` method when casting to ``IQueryable&lt;T&gt;`` is equivalent?

Why use .AsEnumerable() rather than casting to IEnumerable&lt;T&gt;?

I watched the DNR TV episode with Glenn Block and it looks like MEF would be useful for my company.  I am trying to find out more information on it&#39;s strengths and weaknesses and some sample projects that use it.  Are there any good blogs/tutorials on using MEF?

Note: I use C#, so if the examples are in C#, that would be awesome.

Where can I learn about MEF?

<p>I watched the DNR TV episode with Glenn Block and it looks like MEF would be useful for my company.  I am trying to find out more information on it's strengths and weaknesses and some sample projects that use it.  Are there any good blogs/tutorials on using MEF?</p>
<p>Note: I use C#, so if the examples are in C#, that would be awesome.</p>


Why is [`ReadOnlyObservableCollection.CollectionChanged`][1] protected and not public (as the corresponding [`ObservableCollection.CollectionChanged`][2] is)?

What is the use of a collection implementing `INotifyCollectionChanged` if I can&#39;t access the `CollectionChanged` event?

  [1]: http://msdn.microsoft.com/en-us/library/ms653378.aspx
  [2]: http://msdn.microsoft.com/en-us/library/ms653375.aspx

Why is ReadOnlyObservableCollection.CollectionChanged not public?

I am using Entity Framework in my C# based code.  I am running into an unexpected weirdness and am looking for suggestions.

Case 1, 2, 3, 4...
Projects:  
RivWorks.dll  
RivWorks.Service.dll  
RivWorks.Alpha.dll  

Samples (all of these work):&lt;br/&gt;
**RivWorks.Alpha.dll:**

    public static bool EndNegotitation(long ProductID)
    {
        var product = (from a in _dbFeed.AutoWithImage 
                       where a.AutoID == ProductID select a).FirstOrDefault();
    ...
    }

**RivWorks.Service.dll**

    public static RivWorks.Model.NegotiationAutos.AutoWithImage 
        GetProductById(long productId)
    {
        var myProduct = from a in _dbFeed.AutoWithImage 
                        where a.AutoID == productId select a;

        return myProduct.FirstOrDefault();
    }
    public static List&lt;RivWorks.Model.NegotiationAutos.AutoWithImage&gt; 
        GetProductByCompany(Guid companyId)
    {
        var myProduct = from a in _dbFeed.AutoWithImage 
                        where a.CompanyID == companyId select a;

        return myProduct.ToList();
    }

etc

Case &quot;weirdness&quot;:  
RivWorks.Web.Service.dll (WCF project)  
Contains the same references as the other projects.

    public NegotiateSetup GetSetup(string method, string jsonInput)
    {
        ...
        long.TryParse(ProductID, out result);
        var product = (from a in _dbFeed.AutoWithImage 
                       where a.AutoID == result select a).FirstOrDefault();
        ...
    }

I am getting this compile time error (the word &quot;where&quot; is highlighted in my editor):&lt;br/&gt;
*Cannot convert lambda expression to type &#39;string&#39; because it is not a delegate type*&lt;br/&gt;

Any ideas what would cause this?


Entity Framework - Cannot convert lambda expression to type &#39;string&#39; because it is not a delegate type

Sometimes it&#39;s handy to have access to your language to do quick things without starting Visual Studio and creating a new console app. 

Is there something like Python&#39;s interactive mode or groovy shell, except for C#? 


Is there an interactive interpreter for C#?

I want to know if a class can inherit from a class and an interface. 
The example code below doesn&#39;t work but I think it conveys what I want to do.
The reason that I want to do this is because at my company we make USB, serial, Ethernet, etc device. I am trying to develop a generic component/interface that I can use to write programs for all our devices that will help keep the common things (like connecting, disconnecting, getting firmware) the same for all of our applications.

To add to this question:  If GenericDevice is in different project, can I put the IOurDevices interface in that project then then make the USBDevice class implement the interface if I add a reference to the first project? Because would like to just reference one project and then implement different interfaces depending on what the device is.

    class GenericDevice
    {
       private string _connectionState;
       public connectionState
       {
          get{return _connectionState; }
          set{ _connectionState = value;}
       }
    }
    
    interface IOurDevices
    {
       void connectToDevice();
       void DisconnectDevice();
       void GetFirmwareVersion();
    }
    
    class USBDevice : IOurDevices : GenericDevice
    {
       //here I would define the methods in the interface
       //like this...
       void connectToDevice()
       {
           connectionState = &quot;connected&quot;;
       }
    }
    
    //so that in my main program I can do this...
    
    class myProgram
    {
       main()
       {
          USBDevice myUSB = new USBDevice();
          myUSB.ConnectToDevice;
       }
    }


In C#, can a class inherit from another class and an interface?

I know it is pretty simple to add a certificate to a HttpWebRequest. However, I have not found a way to do the equivalent using WebClient. Basically, I want to send out a POST with a specific certificate using WebClient.

How would you accomplish this exact code using WebClient:

```
var request = (HttpWebRequest) WebRequest.Create(&quot;my-url&quot;);
request.Method = &quot;POST&quot;;
request.ClientCertificates.Add(new X509Certificate()); //add cert
```

How can you add a Certificate to WebClient (C#)?

I have two ASP.NET Web projects (ProjectA and ProjectB). When class in ProjectA is instantiating a class of ProjectB which uses a resource file Blah.resx, I get this error:   

&gt; An exception of type &#39;System.Resources.MissingManifestResourceException&#39; occurred in mscorlib.dll but was not handled in user code.
&gt; 
&gt; Could not find any resources appropriate for the specified culture or the neutral culture.  Make sure &quot;Resources.Blah.resources&quot; was correctly embedded or linked into assembly &quot;App_GlobalResources.sn_flri6&quot; at compile time, or that all the satellite assemblies required are loadable and fully signed.

Whats causing this? 

There is an article on Microsoft&#39;s site about this http://support.microsoft.com/kb/318603  which suggests: 

&gt; To resolve this problem, move all of the other class definitions so that they appear after the form&#39;s class definition.

This is a solution for Windows Forms project, I&#39;m not sure if that also applies to Web projects. 





Could not find any resources appropriate for the specified culture or the neutral culture

I&#39;m writing some super simple async code. Just saving a file off-thread.

I&#39;d like to test this code using the MSTest unit test framework in Microsoft Visual Studio Team System 2008.

How do I do this?

I&#39;d like to simple block the test method until the method returns. I can imagine some ways to do this, but I&#39;m blown away there aren&#39;t any best practices or helper classes around this.

I see *a lot* for Silverlight, but nothing generic.

How does one test async code using MSTest

I would like to use WebSockets in my Windows Forms or WPF-application. Is there a .NET-control that is supporting WebSockets implemented yet? Or is there any open source project started about it?

An open source solution for a Java Client supporting WebSockets could also help me.

Is there a WebSocket client implemented for .NET?

I am looking for a simple and secure way to access plugins from a .NET application. Although I imagine that this is a very common requirement, I am struggling to find anything that meets all my needs:

 - The host application will discover and load its plugin assemblies at runtime
 - Plugins will be created by unknown 3rd parties, so they must be sandboxed to prevent them from executing malicious code
 - A common interop assembly will contain types that are referenced by both the host and its plugins
 - Each plugin assembly will contain one or more classes that implement a common plugin interface
 - When initializing a plugin instance, the host will pass it a reference to itself in the form of a host interface
 - The host will call into the plugin via its common interface and the plugins may call into the host likewise
 - The host and the plugins will exchange data in the form of the types defined in the interop assembly (including generic types)

I have investigated both MEF and MAF, but I am struggling to see how either of them can be made to fit the bill.

Assuming my understanding is correct, MAF is unable to support the passing of generic types across its isolation boundary, which is essential to my application. (MAF is also very complex to implement, but I would be prepared to work with this if I could solve the generic type problem).

MEF is almost a perfect solution, but appears to fall short on the security requirement, as it loads its extension assemblies in the same AppDomain as the host, and thus apparently prevents sandboxing.

I have seen &lt;a href=&quot;https://stackoverflow.com/questions/3402109&quot;&gt;this question&lt;/a&gt;, which talks of running MEF in a sandboxed mode, but doesn&#39;t describe how. &lt;a href=&quot;http://visualstudiomagazine.com/articles/2009/04/01/working-with-mef.aspx&quot;&gt;This post&lt;/a&gt; states that &quot;when using MEF you must trust extensions not to run malicious code, or offer protection via Code Access Security&quot; but, again, it doesn&#39;t describe how. Finally, there is &lt;a href=&quot;http://blogs.microsoft.co.il/blogs/bnaya/archive/2010/01/01/securing-the-mef-directory-catalog.aspx&quot;&gt;this post&lt;/a&gt;, which describes how to prevent unknown plugins from being loaded, but this is not appropriate to my situation, as even legitimate plugins will be unknown.

I have succeeded in applying .NET 4.0 security attributes to my assemblies and they are correctly respected by MEF, but I don&#39;t see how this helps me to lock out malicous code, as many of the framework methods that might be a security threat (such as methods of &lt;code&gt;System.IO.File&lt;/code&gt;) are marked as &lt;code&gt;SecuritySafeCritical&lt;/code&gt;, which means that they are accessible from &lt;code&gt;SecurityTransparent&lt;/code&gt; assemblies. Am I missing something here? Is there some additonal step I can take to to tell MEF that it should provide internet privileges to plugin assemblies?

Finally, I have also looked at creating my own simple sandboxed plugin architecture, using a separate AppDomain, as described &lt;a href=&quot;http://msdn.microsoft.com/en-us/library/bb763046.aspx&quot;&gt;here&lt;/a&gt;. However, as far as I can see, this technique only allows me to use late binding to invoke static methods on classes in an untrusted assembly. When I try to extend this approach to create an instance of one of my plugin classes, the returned instance cannot be cast to the common plugin interface, which means that it is impossible for the host application to call into it. Is there some technique I can use to get strongly-typed proxy access across the AppDomain boundary?

I apologize for the length of this question; the reason was to show all the avenues that I have already investigated, in the hope that somebody can suggest something new to try.

Many thanks for your ideas,
Tim

Looking for a practical approach to sandboxing .NET plugins

I just start study DI (I&#39;m working on WPF/Silverlight but I have a plan to move to ASP.NET). After I read some DI articles from internet there are two Frameworks that I&#39;m interested in, MEF and Unity. I want to know what is the real-world different between them and which one is good to go.

What is different between and purpose of MEF and Unity?

I wish to test the core class of a plugin by directly referencing the plugin project and instantiating the plugin class. When I create a test Console App project and add a project reference to the plugin project, I get a warning icon (yellow triangle with exclamation mark) next to the reference in the References list. 

When I instead add a reference to the dll, the assembly build output of the plugin, I get no such warning. What could this warning be trying to tell me?

Why do I get a warning icon when I add a reference to an MEF plugin project?

I am trying to build a MVC4/MVC5 application with a pluggable architecture like Orchard CMS. So I have a MVC application which will be the startup project and take care of auth, navigation etc. Then there will be multiple modules built separately as asp.net class libraries or stripped down mvc projects and have controllers, views, data repos etc.

I have spent all day going through tutorials on the web and downloading samples etc and found that Kenny has the best example around - http://kennytordeur.blogspot.in/2012/08/mef-in-aspnet-mvc-4-and-webapi.html

I am able to import the controllers from the modules(separate DLLs) if I add reference to those DLLs. But the reason behind using MEF is being able to add modules at runtime. I want the DLLs along with views to be copied to a ~/Modules/&lt;module 1&gt;/ directory in the startup project (I have managed to do this) and MEF would just pick them up. Struggling to make MEF load these libraries.

There is also MefContrib as explained in this answer https://stackoverflow.com/questions/17579232/asp-net-mvc-4-0-controllers-and-mef-how-to-bring-these-two-together which is the next thing I am about to try. But I&#39;m surprised that MEF doesnt work out of the box with MVC. 

Has anyone got a similar architecture working (with or without MefContrib)? Initially I even thought of stripping Orchard CMS and using it as a framework but it is too complex. Also would be nice to develop the app in MVC5 to take advantage of WebAPI2.



Content Type	Original Author	Original Content on Stackoverflow
Question	Jeffrey Lott	View Question on Stackoverflow
Solution 1 - C#	Francisco Noriega	View Answer on Stackoverflow
Solution 2 - C#	Daniel Plaisted	View Answer on Stackoverflow
Solution 3 - C#	JamesEggers	View Answer on Stackoverflow
Solution 4 - C#	Scott Whitlock	View Answer on Stackoverflow
Solution 5 - C#	kenwarner	View Answer on Stackoverflow
Solution 6 - C#	Nicholas Blumhardt	View Answer on Stackoverflow
Solution 7 - C#	Contango	View Answer on Stackoverflow

Where can I learn about MEF?

C# Problem Overview

C# Solutions

Solution 1 - C#

Solution 2 - C#

Solution 3 - C#

Solution 4 - C#

Solution 5 - C#

Solution 6 - C#

Solution 7 - C#

Why use .AsEnumerable() rather than casting to IEnumerable<T>?

What is the meaning of the ${0##...} syntax with variable, braces and hash character in bash?

Attributions