Comments on: On-demand loading of assemblies with Silverlight Navigation – Revisited for Silverlight 4 Beta

By: brennt

brennt — Fri, 29 Jul 2011 10:28:24 +0000

hi, im not using your code, but…

when im trying to go like this:

InternalContentFrame.Navigate(new Uri("P1.xaml", UriKind.RelativeOrAbsolute));[code]
i get an exception:
The type "AssemblyName.Views.P1" specified in the x:Class of "AssemblyName;component/Views/P1.xaml" could not be found in any loaded assembly.
which cant be true coz

1. control containing FRAME is located in the same assembly

2. this works like a charm:
[code]

[ImportMany(AllowRecomposition = true)]

public Page[] MEFPagesList { get; set; }

private void ContentFrame_NavigationFailed(object sender, NavigationFailedEventArgs e) { e.Handled = true; InternalContentFrame.Content = MEFPagesList[0]; }

unfortunately it does not support any of the "navigation" properties e.g. browser navigation support

can anyone help?

By: Hyacinth Broadchest

Hyacinth Broadchest — Mon, 18 Jul 2011 07:59:44 +0000

Hi David,
Worked brilliantly in my Sliverlight Navigation project. Then I tried to apply that to a SL Business Applications WCF RIA project, and can’t really get it to work at all. Symptoms are: It packages all the SLaB dlls into the xap. And attempting to load one of those new xaps throws an error. xaps generated under the SL Nav project and copied into /ClientBin still work fine, but these can’t access the data services…

Many thanks, Hyacinth.

By: Peter

Peter — Sat, 11 Jun 2011 21:42:47 +0000

Hi David
After weighing the pros and cons, I decided to go with storing the xaps in the isolated storage – using it as a cache. I think this gives me more control and allows me to create some sort of versioning as well. Though obviously there are some drawbacks as well…

It could be done with minimal modification to your SLaB code, and a custom ContentLoader…

Thanks
/Peter

By: david.poll

david.poll — Fri, 10 Jun 2011 15:43:13 +0000

Peter,
It’s a bit difficult — Silverlight doesn’t support what you need to do this: multiple AppDomains. This is how you would accomplish this kind of version isolation that you’re describing. The only thing I can think of is to regenerate the assemblies before they’re loaded, changing the names of all of the classes (and updating references within). You might be able to do this with Reflection emit or some other tools along those lines, but it’s likely to be slow and bug-prone (e.g. if you change the name of a class and the class is referenced in XAML, you’d better understand how to change the XAML to get the right result).

-David

By: Peter

Peter — Fri, 10 Jun 2011 13:11:29 +0000

Hi David

I seem to be struggeling a bit with implementing a solution for the “cache loading problem”. I would very much like to reload xap’s that has been modified (a little like what is done with a HttpHandler on this page – http://stackoverflow.com/questions/2281919/expiry-silverlight-xap-file-from-browser-cache-programmatically/4997375#4997375) however I am afraid that I cannot get it to work – not even with inspiration from your XapContentLoader.

Would you consider implementing something that can help with the loading of modified assemblies/xaps. Maybe some kind of versioning. If you do not have the time, do you perhaps have some hints as to how to get it implemented?

Any help would be much appriciated…

Best Regards
Peter

By: Alexander

Alexander — Mon, 06 Jun 2011 10:32:36 +0000

Hi David.

Can you please share the Source of Sample, cant find and download it!

Thanks.

By: david.poll

david.poll — Wed, 04 May 2011 17:05:33 +0000

By default, Silverlight will cache these downloads. More importantly, however, the CLR in Silverlight will only load an assembly once — subsequent attempts to load an assembly with the same name (even if it’s not identical) will continue to reuse the original assembly loaded. With a ContentLoader, however, you could specify a different scheme that uses assemblies with different names each time the URL is requested, and this would help get you around this problem.

By: Kyre

Kyre — Sun, 01 May 2011 23:51:42 +0000

Hello!.

(First of all, excuse my english, is not my first language)

Very interesting job, thanks.

I have read the article, it’s very interesting. I donwloaded and ran the examples, and now I have a question.

When we execute an app and we access to diferents xamls in the same xap, only donwload this xap once. (Ok, that’s expected) But if we run de app few days after and navigate to one of those xamls, the app checks if it must download de xap again or will use the xap downloaded few days ago?

In other words: EVERY time I navigate to a xaml (in independent executions in the same pc) app will download xap?

Thanks again.

By: isheeple

isheeple — Wed, 06 Apr 2011 15:46:52 +0000

Sorry I submitted too soon. I have a case where I need to tell something else to recompose when I am done downloading the request xap + lazy assemblies and I was looking for a hook.

By: isheeple

isheeple — Wed, 06 Apr 2011 15:43:36 +0000

David, nice work. Looking through the code I do not see a way to monitor when downloading is complete – did I miss it or do I need to add that myself?