domain-command-outcomes.keiro

language keiro-dsl 5
context domain-outcomes

enum ReservationRejection { AlreadyCancelled=already-cancelled CapacityUnavailable=capacity-unavailable }
enum ReservationNoOp { DuplicateRequest=duplicate-request }

aggregate Reservation
  domain-outcomes rejection=ReservationRejection no-op=ReservationNoOp
  regs
    lastRequestId Text = "none"
  states Eligible CancelledState

  command Cancel { requestId:Text }

  event Cancelled = fields(Cancel)

  Eligible -- Cancel -->
    write lastRequestId := cmd.requestId
    outcome accepted
    emit Cancelled
    goto CancelledState

  CancelledState -- Cancel -->
    guard cmd.requestId != reg.lastRequestId
    outcome rejected ReservationRejection.AlreadyCancelled
    goto CancelledState

  CancelledState -- Cancel -->
    guard cmd.requestId == reg.lastRequestId
    outcome no-op ReservationNoOp.DuplicateRequest
    goto CancelledState