MEF & Silverlight 4 Beta - Part 5, the PackageCatalog

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Description

Part 5 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 an additional catalog in the Silverlight Toolkit Preview for Silverlight Beta 4, the PackageCatalog. This catalog adds the key ability of being able to download XAPs dynamically at runtime and ask MEF to discover and compose the types contained within those XAPs into a pluggable application.

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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    The Discussion

    • User profile image
      Yazid

      Excellent screencasts,

       

      Half way through the screencast I get a failure. Is it possible to fix this?

       

      Is there some code we could download?

       

      I am a newbie uisng MEF, what can we do with MEF that we cannot do with PRISM?

       

       

      TIA

      Yaz

       

       

    • User profile image
      mliebster

      Wonderful series of screencasts. Immensely informative for me.

      At approx 10:06 & 18:30 the video stops and there's a "Media Failure" notification. I just refreshed the page and dragged the time slider to past that and it resumes.

       

       

    • User profile image
      mtaulty

      Hi,

       

      I've just played the video and, like you, I got a media failure at about 10 mins. I'm not sure what's causing this but, in the meantime I'd suggest a workaround using the "Downloads" drop down menu to download the HIGH WMV version, save it to your disk and watch it from there.

       

      Ironically, that should be the same file that's appearing in the video player so I'm not sure how it works in one place and not the other but I'll see if I can get it resolved and will post here as/when that's done.

       

      Thanks & sorry for the file problem,

       

      Mike.

    • User profile image
      philcockfie​ld

      Hi Mike.  Thanks so much for these videos.  You're a gifted communicator.
      I had a question about the PackageCatlog video (part 5).
      The way you structured the application was to divide it up into the various class libraries AND create corresponding Package (SL Apps) which were really just there to tie various configurations of DLL's together.
      I was wondering if that was a hard-n-fast best practice?  Would it also be sensible that if your application logic did cleave fairly readily around the XAP files, that you just create a set of SL-Apps (XAPs) and put the module's logic straight into that project (rather than seperate ClassLibrary assemblies)?
      Many thanks.

      [I posted this question to your blog - but it didn't show up, so I'm not sure if it went into a moderator inbox, or the blog was broken.  So, apologies if it got posted multiple times.  Not *trying* to spam you].

       

      Hi Mike.  Thanks so much for these videos.  You're a gifted communicator.

       

      I had a question about this PackageCatlog video.

       

      The way you structured the application was to divide it up into the various class libraries AND create corresponding Package (SL Apps) which were really just there to tie various configurations of DLL's together.

       

      I was wondering if that was a hard-n-fast best practice?  Would it also be sensible that if your application logic did cleave fairly readily around the XAP files, that you just create a set of SL-Apps (XAPs) and put the module's logic straight into that project (rather than seperate ClassLibrary assemblies)?

       

      Many thanks!

    • User profile image
      philcockfie​ld
    • User profile image
      cesnek

      Why is better download XAP package ?

      It is possible download single DLL files from web site, not XAP file ?

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