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Manifest and the fusion cache

  • Article

When you have an application without a manifest and you try to elevate it with an external manifest, you might get frustrated and get to the conclusion that this external manifest thing is flaky at best. The scenario goes something like this.

You install your legacy application (by which I mean there is no manifest with a requestedExecutionLevel specified) on a Vista machine. You launch the application and you see it is installer detected and for that reason, it prompts for credentials. You know that providing a manifest with that requestedExecutionLevel will make the installer detection go away. Since you don't want to link it in or use the mt.exe tool, you provide an external manifest in the form of myapp.exe.manifest and put that next to your app. Now, whatever you try to do with the requestedExecutionLevel, it just doesn't make a difference. Then you really get frustrated and move the file to another directory. Low and behold, the manifest is picked up. What in the world?

As you might know, the Windows folks have put a tremendous effort in optimizing the performance of the system. Superfetch is a good example. Numbers showed that resolving manifests and SxS probing caused a significant delay in start up time. So they came up with caching of the activation context. Basically, the second time you launch your application we no longer bother to look for a manifest since it wasn't there initially. When you move the executable (or change the time stamp somehow), the entry in the cache is not found and the loader looks for the manifest file again.

Comments

  • Anonymous
    February 04, 2008
    I am getting same frustration with manifest. I am not able to stop prompt for consent while running the VB6 app., which is installed in c:programfiles . Even though I added manifest with Level ="asInvoker". But interestingly if I installed the same modified app in any c: root folder like "c:xyz" , then there is no prompt for consent while running the app. I don't understand why is it happening? What am I suppose to do? or can it be possible to stop prompt for consent for any app which is installed in C: Program Files? How? FYI -  For VB6 app, to add manifest, we need to add a resource file.

  • Anonymous
    May 16, 2009
    After reading the November '06 " Manifest and the fusion cache " blog entry that one my peers wrote,