When Windows 8 installs automatic updates?

Is it possibile that windows 8, contrary to win 7, immediately installs updates after download and doesn't wait the user shutdown request?

I'm using win 8 in a POS application and yesterday (after many many days without any problem) this application has stopped (precisely fails the the link between application and its smartcard, seems that the smartcard service, or something like this, was stopped). I solved simply restarting windows. During restart I saw that windows was updating something and I related the application fault with windows update. Restarting windows everything was back to work.
I obviously disabled automatic updates, but with the same application in a win 7 enviroment it never suffered about this trobules with windows autoupdates on.

Answer

Windows Updates are generally installed in three stages:

1. After downloading (if the recommended setting is activated), or when a user clicks "Install"


2. During shutdown


3. During the next boot

I'm not sure exactly what changes are made during the first stage and whether or not they can affect running applications and drivers, but it's possible that that's what caused your POS application to stop working (e.g. if one of the updates was a driver update for your smart card reader, or otherwise related to smart card functionality).

If you want to make sure updates cannot interfere with user sessions, you can configure Windows Update to only check for and download updates, but not install them, or disable automatic updates altogether. This way any and all actual installation of updates will have to be done manually, at whatever time you choose.