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Menu: Extensions: SxS Assemblies

App-V categorizes aspects of an applications installation into a set of "Extensions", each of which require special processing either during app deployment or during the virtual app runtime.

Side-by-Side (SxS) assemblies refers to VC++ redistributable runtimes that are commonly installed with applications.  Some of these extensions, the really old and the fairly new, are perfectly contained and used inside your package. The middle group, however, do not work if they are only inside your package.

Microsoft App-V Sequencer recognizes those versions are creates a SxS Assembly Extension entry for them.  Unless disabled, these will be externally installed (using the system "TrustedInstaller.exe) during publishing time.  No matter how the App-V package is published, this is effectively a global publishing on this extension.

While it is nice that this makes the virtual app work, it comes with issues:

  • Many IT organizations, especially the larger ones using Configuration Manager prefer to control the distribution of runtime dependencies like this globally.
  • Many installers include VC runtimes that have known vulnerabilities.  We want these out of our packages and handle this security patching externally.  We see this in not only larger IT shops, but also those in certain verticals that are more security focussed, like Finance, Health Care, and Government.

More information on the Runtime versions is available in the Visual Studio Runtime Version Chart on the TMurgent Website here.