[Silverlight] What is a .xap File?

So in my travels I bumped into a screencast, and in it, the presenter appended the .zip extension to the end of the .xap file and was able to open up a collection of files by unzipping it! I was like... woooooooah, that's something I didn't know.

What is an .xap file?

The .XAP file is a .zip compressed file that contains the client DLL for the Silverlight application as extra DLLs of assemblies that you are using in your application. This can be your own assemblies of user controls or assemblies that are not part of the Silverlight runtime by default that gets installed on the client.(2)

For more information regarding the files contained in the xap, most notably the AppManifest.xml file, please see the following blogs:
(1)http://pietschsoft.com/post/2008/03/Silverlight-Anatomy-of-an-XAP-file.aspx
(2)http://blogs.msdn.com/katriend/archive/2008/03/16/silverlight-2-structure-of-the-new-xap-file-silverlight-packaged-application.aspx


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