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New Post: Any MEF books coming?

vandermeulen — Fri, 20 Nov 2009 17:07:14 GMT

Hey Glenn,

A number of potential topics come to mind for me:

1) A discussion of how to build a fully composable application - one with a public, extensible object model (ala Excel or VS) that is independent of and has an extensible user interface (WPF is fine for concrete examples - how to make menus, ribbons, dialogs, etc. runtime composable).

2) A discussion of containment & hierarchy - how to create systems where a given part may need to be non-shared from the point of view of the entire system, but shared from the point of view of its "contained" parts. Think of Excel as a model - a workbook can have many sheets that are created or destroyed based on user requests. These worksheets are non-shared from the workbook point of view, but their contained objects (cells, ranges, etc.) see the sheet as a shared object.

3) A discussion of part lifetime. How do you build a system with a dynamic set of parts (think Excel again) that properly cleans up after itself when a part is no longer needed? Probably such a discussion ties in tightly with #2.

4) A discussion of performance. What are the bottlenecks in MEF (i.e. discovery, composition, etc.)?

5) A discussion of how MEF relates to threads and AppDomains. In particular, how do I build an MEF-based system that allows me to isolate a subset of its parts in a separate AppDomain so I can unload it when I'm done using those parts? What are the implications of creating parts on a different thread, or using a part on a thread other than the one on which it was created?

I too would love to be on the reviewer list for this book...

Ron

New Post: Same Type Exports for Exports

JamesEggers — Fri, 20 Nov 2009 14:32:09 GMT

After starting a new project to simplify things again I discovered that it was working. Looking deeper at the project that I was using when I posted this question, I see that I had an old copy of a DLL in my DirectoryCatalog's path. This old DLL is what was causing my ReflectionTypeLoadException.

Thanks for your help.

New Post: Any MEF books coming?

Ray1984 — Fri, 20 Nov 2009 14:11:05 GMT

Hi Glenn,

I'd like to see the design & architechture of MEF.

Maybe start with something like "implement a MEF yourself step by step", and then introduce how to use MEF and how to extend it.

New Post: Any MEF books coming?

polyGhost — Fri, 20 Nov 2009 11:25:49 GMT

gblock wrote:

Hi polyGhost

Kathleen Dollard, myself and Daniel Plaisted are in the early stages of authoring a MEF book. We're hoping ot have it out some time next year.

What would you want to see in such a book?

Glenn

Hi Glenn,

While I appreciate that MEF has been designed to be lightweight enough (in terms of dependencies) to be domain agnostic, I would love to see a use case in the book that specifically mashed up MEF to enable 3rd party customisation (composition) within a existing UI.

Assuming it's even possible, how would one go about getting on the reviewers list for such a book.

Kind regards,

Tom Kirby-Green

Technical Architect,

SunGard Adaptiv.

New Post: Any MEF books coming?

gblock — Fri, 20 Nov 2009 06:17:37 GMT

Hi polyGhost

Kathleen Dollard, myself and Daniel Plaisted are in the early stages of authoring a MEF book. We're hoping ot have it out some time next year.

What would you want to see in such a book?

Glenn

New Post: Referencing Errors.

slacquer — Fri, 20 Nov 2009 00:17:03 GMT

Ok, probably a nub question but for whatever reason after downloading the MEF preview 6 and the 8, I can not reference the "System.ComponentModel.Composition" from a silverlight 3 project. I then recompiled all source and still same error:

"The given assembly name or codebase was invalid. (Exception from HRESULT: 0x80131047)"

Now this only happens when I try to reference the assembly in a silverlight project, not a console app for ex.

Any thoughts? I Personally haven't seen this error before.

Thanx for your help.

New Post: Same Type Exports for Exports

JamesEggers — Thu, 19 Nov 2009 18:14:26 GMT

Actually, that was an issue with the code paste. I did have IEnumerable<IFoo> but it looks like the text area didn't encoded it. I'll update such.

New Post: Same Type Exports for Exports

weshaggard — Thu, 19 Nov 2009 18:08:03 GMT

What you are doing should work I think the error you are suing is with your ImportMany property type. Try changing it to IEnumerable<IFoo>.

New Post: Silverlight 4 beta and MEF

weshaggard — Thu, 19 Nov 2009 18:04:53 GMT

You could use either, they should basically be the same. The biggest difference is the one in SL4 SDK is signed. It would be nice if you use the one from SL4 SDK to help find any issues with it.

New Post: Silverlight 4 beta and MEF

pekkah — Thu, 19 Nov 2009 16:59:16 GMT

I've been using MEF quite a while now with prototype stuff I'm working on.

I just finished installing the Silverlight 4 beta bits to my machine.

Which version of MEF should I be using with silverlight 4? The version that came with it or the preview 8?

New Post: Same Type Exports for Exports

JamesEggers — Thu, 19 Nov 2009 15:14:01 GMT

I'm looking into a situation where I'd like to provide a recursive model for some Exports on a project. I know that I can create Exports that are also composed of various parts themselves; however, can those "subparts" be of the same type? I tried a quick concept before work this morning and got a Reflection-based error (forgot to note which one).

Ultimately, what I wrote was the below using .net 3.5 and MEF beta 2.

[Export("initialPart", typeof(IFoo))]
public class MyInitialPart : IFoo
{
    // ... IFoo Implementation Code

    [ImportMany("subPart", typeof(IFoo))]
    public IEnumerable SubParts { get; set; }
}

Is it possible to have an Export that also attempts to have Imports of the same type but different contract description/label?

New Post: Make Imports available

weshaggard — Wed, 18 Nov 2009 20:58:50 GMT

ComposablePartCatalog.GetExports is a simply shortcut method to get all the Exports. You can simply traverse ComposablePartCatalog.Parts to get the full list of Exports and Imports.

New Post: Any MEF books coming?

weshaggard — Wed, 18 Nov 2009 20:56:52 GMT

Sorry I'm not aware of any books in the works (of course that doesn't mean there aren't any).

New Post: Loading plugins from UI.

weshaggard — Wed, 18 Nov 2009 20:54:58 GMT

Unfortunately there isn't any built in way to do this but it is certainly possible to build it on top of MEF. I'm not aware of any examples of this yet. It would make for a good sample though if you want to try and tackle it.

New Post: Any MEF books coming?

polyGhost — Wed, 18 Nov 2009 16:48:06 GMT

Just dipping my toes in MEF waters for the first time, and while the blog sphere is providing a lot of useful examples I'm really looking for something far more structured that goes way beyond the MEF whitepaper etc. Does anyone know if any MEF books are coming?

New Post: ModuleName.UserUIExtensions

leblanc — Wed, 18 Nov 2009 07:25:10 GMT

took a look at the ExtensibleGrid.Extensions sample

I have one question around that issue of extentions with UI.
the current implementation:

        void OKButton_Click(object sender, RoutedEventArgs e)
        {
            foreach (var extensionItem in extensionItems)
            {
                if (extensionItem.Enabled == true && extensionItem.Activated == false)
                {
                    var extension = extensionItem.GridExtension.Value;
                    extension.Initialize(this);
                    extensionItem.Activated = true;
                }
            }
            
        }

shouldn't it be:

var extension = extensionItem.GridExtension.Value;
                if (extensionItem.Enabled)
                {
                    extension.Initialize(this);
                }
                else
                {
                    extension.DeInitialize(this);
                }

Internally:
Initialize
DeInitialize

will save this original state before making ui changes
and deinitialize will restore initial ui changes. http://www.dofactory.com/patterns/patternmemento.aspx#_self2
current form is a little cheesy since it doesn't disable effects. : ]


I see this sample as an opportunity to create UserUIExtensions to persist ui positions of windows, loaded modules of a silverlight application... has anyone attempted this?


thumbs up for awesome framework you guys are building!
lm

New Post: Loading plugins from UI.

soldier4faith — Tue, 17 Nov 2009 14:00:56 GMT

Hello,

I've been looking at the Managed Extensibility Framework for about a week now. It has opened up a lot in my applications extensibility and product life. One thing I'm struggling with is how to create a UI and have the catalog know which addons NOT to load out of a directory.

New Post: Make Imports available

alonso — Tue, 17 Nov 2009 13:03:42 GMT

Hi Guys.

I wrote a Custom Catalog to make Exports from an IoC Container available in CompositionContainer.

Now i want to make Imports from IoC Container available in CompositionContainer.

The Question is: How can i make Imports from a IoC Container available in MEF?

For example i have one xml-File which define one component with one export, and a second xml-File which define one component with one import.

Now i want that mef makes the connection between these two components with my CustomCatalog.

Thanks for response

New Post: GetExportedValues very slow

gblock — Fri, 13 Nov 2009 07:00:13 GMT

Cool, glad to help.

New Post: Mono compatibility

gblock — Fri, 13 Nov 2009 06:58:47 GMT

I will be speaking to Miguel de Icaza about this. It should be easy for them to update in their codebase.

Thanks!

Glenn