Welp I figure now that I have some time to update this thing I might as well do it! As most of you may know Vista is DONE!! after 5+ years of waiting, it's DONE!! It's game time now people and a lot of you have been responding to the call of getting your apps Vista compatibile. I have been seeing a lot of questions on Vista's new Virtualization feature, so much so that even I'm getting confused as to some of the details so I will be writing it out here for some clarity .

• C:\WINDOWS
• C:\Program Files
• C:\Program Data
• HKLM in the registry

These files and keys get virtualized into these locations:

• C:\Users\%username%\AppData\Local\VirtualStore\WINDOWS
• C:\Users\%username%\AppData\Local\VirtualStore\Program Files
• C:\Users\%username%\AppData\Local\VirutaliStore\ProgramData
• HKCU\Software\Classes\VirtualStore\MACHINE

When does Virtualization occur?:

        Virtualization occurs whenever an appliation attempts to write a file to the directories or registry keys noted above and the application is running in a context that does not have permissions to access the resource. So if an application that is running under a standard user context writes a file to C:\Program Files, the write will succeed, however the file will be placed into the users virtual store: (C:\Users\%username\AppData\Local\VirtualStore\Program Files). If the same application, even while still running in the standard user context reads from C:\Program Files looking for a specified file, the read will FAIL because that file was not written to C:\Program Files but instead written to the users virtual store.

Where in my application do I need to correct this?:

        This depends on your application, however a general place to start would be anywhere your application reads/writes to any of the above specified directories. To correct any potential issues, you should first look at the data your application is writing out and determine if this data is global to your application for all users and whether or not the users will need write access to it. Also, you should determine if the data being written is per user. Here are a couple of these scenarios and the steps you could take to fix them:

Data being written is application global and users need write access to it:

        This data could be placed in C:\Program Data\<AppName> directory

Data being written is application global and users do not need write access to it:

        This data could be placed in the C:\Program Files\<AppName> directory and if an update is needed should be done through an application updater that has been appropriately configured to elevate.

Data being written is user specific

        This data could be placed in C:\Users\%username%\AppData\Local\<AppName> directory

Why did Microsoft impliment this feature into Vista?:

        I have seen a lot of complaints about the UAC Virtualization feature. While I do agree some pain does slip through the cracks with it in place but Virtualization was implimented to buy developers some time to update their applications. If it weren't for Virtualization, things would be a lot worse.

 Here are some links to some resources regarding Virtualization:

http://msdn.microsoft.com/windowsvista/reference/default.aspx?pull=/library/en-us/dnlong/html/AccProtVista.asp#accprotvista_topic4 

http://msdn.microsoft.com/windowsvista/reference/default.aspx?pull=/library/en-us/dnlong/html/AppComp.asp#appcomp_topic4

http://msdn.microsoft.com/windowsvista/reference/appcompat/default.aspx

Also if you have any questions feel free to post a question in the App Compat MSDN Forums:

http://forums.microsoft.com/MSDN/ShowForum.aspx?ForumID=904&SiteID=1

Let’s get it done! Make your applications Clear, Confident, Connected!!!