CIS 28-061 Homework #3: FBN Seat Event / State Diagram

Consider carefully all the possible states of a specific seat on a Flight Instance, from the time the Flight Instance is created to (hopefully!) successful arrival of the Flight Instance at its Destination Gate.
This should include the type of Events that can occur to transition the object between states.
Additional factors for real airlines should be considered. For FBN:
The FBN “Seat” E/S diagram is like the Enrollment System “Section” E/S diagram. It is broken into phases.

CIS 28-061 Homework #3: FBN Seat Event / State Diagram

Ticketing Phase:
• The creation of a Flight Instance 90 days before departure creates all the Seats in the Seat Chart in the “Available” state.
• During this phase, a specific Seat on the Flight Instance (ex: 22B) may be ticketed (for a passenger with a reservation), in which case the Seat becomes “Taken”.
• Reservations can get cancelled, invalidating the Ticket and freeing the Seat.
• If the Flight Instance itself is cancelled, every Taken Seat must notify its Ticket.
Plane Assignment Phase
• A Seat starts out as either Available or Taken.
• The plane assigned to the Flight Instance could have a broken seat, in which case the
corresponding Seat in the Seat Chart for this Flight Instance receives a  YouAreBroken” event.
If the Seat state had been “Taken”, the ticketed Passenger is put at the front of the Flight Instance’s “Wait List”. Regardless of its previous state, the new state of the Seat is then set to “Broken”

CIS 28-061 Homework #3: FBN Seat Event / State Diagram

• If the Flight Instance is cancelled, a Taken Seat must notify its Ticket.
• If the Flight Instance is delayed, a Taken Seat must notify its Ticket.
• Once a Ticket is scanned at the Gate and the Passenger enters the Plane, the corresponding “Taken” Seat is notified that the “Passenger Onboard” event has occurred, and the Seat state is set to “Occupied”.
• The phase ends once the “InitialBoardingComplete” event is received, at which point things get interesting if there is a wait list of Passengers hoping to get on this Plane (including any Passengers holding a Ticket for a broken Seat).