The SetProperties (ControlAppPool) method allows you to control
the running status of an application pool. The status of the site
is available in AppPoolState. The AppPoolState is primarily under
control of a sophisticated scheduling and error detection
mechanism, and thus is not a good subject for rollback. Rollback is
therefore not implemented for changes in AppPoolState.
Although this call does make direct control of AppPoolState
possible, it is preferred to use the rich set of AppPool properties
to configure automatic state control as appropriate, rather than
performing manual control operations.