Comment by jwarden

Another architecture might be that the service responsible for Seat Selection emits a `SeatSelected` event, and another service responsible for updating bookings emits a `BookingUpdated(Reason: SeatSelected)` "fat" event. Same for `PaymentReceived` and `TicketIssued`.

Both events would "describe a space of things that occurred" as @bob1029 suggests.

The seat selection process for an actual airline probably needs to be more involved. @withinboredom recommends:

  - SeatTimeLimitedReserved {41A, 15m}
  - SeatAssignedTo {UserA}
  - SeatBooked {41A}

In which case, only SeatBooked would trigger a BookingUpdated event.