Common DLL referencing throughout Silverlight project

I have a common silverlight project. This project project, among other things, includes constants and static classes.

The silverlight App i have references this common library. In addition, i have a handful of external modules that are loaded on-demand (via Prism). Each module is its own .Xap file and they too reference the common library.

So now each Xap in my silverlight application has a reference to the Common.dll. Does this mean the common.dll is loaded every time a xap is loaded, or does it essentially mean only the main App's common.dll is 开发者_StackOverflowever loaded?

The ultimate question im getting at is this: If i make a code change (bug fix) in the common.dll, do i have to release ALL Xap files or just the main App xap?

Thanks.

If you use Assembly Caching in all projects that reference the common dll then you'll just get one copy downloaded as it's own zip file. This way all the different XAP files will reference the same dll. Otherwise common.dll will be included in each XAP file that references.

You'll need to create a common.extmap.xml file for your common.dll which needs to be in the same folder from where the dll is referenced.

By default DLLs are loaded on demand. This means that you can't really guarantee which directory they will load from. This is a common issue among modular applications and one that there isn't a ready prescription for. It depends on requirements, essentially.

Some things you can do:

1. GAC the Common.dll in the target environment. This will allow you to control the versioning of that DLL centrally.
2. Release everything every time Common.dll changes (as you mentioned).

We have opted for number 2 (we treat our "Common.dll" as a contract assembly that changes rarely) in order to keep our xcopy deployments intact.

Number 1 might make more sense if you anticipate that code churn on Common.dll will be high or you want to keep your deployment schedules for modules completely autonomous (like if the modules were being developed and deployed by seperate teams with seperate build and source respositories, for example).

Edit: It looks like Silverlight has something to provide an xcopy variant of the GAC approach. ChrisF's answer is probably the way I would go with Silverlight (we do WPF, so that's a bit different). I'll leave this here for posterity.