The company i work for have been using the described app for the last two years late cancel the T/L simply ticks a couple boxes on a screen on computer it then works out and messages out to available pool of non rostered people with required skillset, first in best dressed for the shift, no obligation to have notifications on, your either available or not. I might add casuals are sent rosters on a Wednesday for following week depending on company requirements and whether you have made yourself unavailable or not.
