We require Application Impersonation to make sure that changes made to the meetings from the screen are reflected in the calendars of the meeting's attendees and resources. To do this, the meeting organizer must be the one making the change. Changes are made as follows:
Book meeting from the screen: The meeting is added directly to the meeting room's calendar. If the meeting starts immediately, it is automatically confirmed.
Cancel meeting, either manually before the meeting has begun or automatically if the meeting is not confirmed in time: The meeting room is removed from the meeting's resources/attendees unless the meeting room itself is the organizer, in which case the meeting is cancelled.
Confirm meeting: No changes are made in Exchange.
End meeting: The end time of the organizer's meeting is set to the current time plus 1 or 2 minutes. This is done to prevent Exchange from rejecting the meeting update, which would cause the meeting to be removed from the meeting room calendar.
Extend meeting: The end time of the organizer's meeting is increased by the duration specified.
In all cases, meeting updates are sent to all attendees and resources to ensure that their respective calendars reflect the changes made.