Watchdog an application from a service

How can I make a service to be a watchdog for a desktop application knowing that Services cannot/shouldn't interact with Des开发者_运维问答ktop applications.

Or is it only working assuming there is only one user?

Service can not have a UI but they can run executables. It is just that for windows vista, windows 7 and on, the service need to find out under which user/session to run the executable.

Here is a blog post explaining how to do [that].1