Domain Layer Reference

Package Location

• domain/order for aggregate/value types.
• domain/order/state for state strategy hierarchy.

Aggregate and Value Objects

Order

• Aggregate root that owns lifecycle transitions and cancellation semantics
• Carries ownerSubject (who placed the order; mirrored in persistence as owner_subject) for application-level authorization — the domain does not interpret JWTs itself
• Creation entry points:
  • create(items, idempotencyKey, ownerSubject) for new aggregate construction
  • rehydrate(..., ownerSubject, ...) for persistence reconstruction
• Behavior methods:
  • updateStatus(...)
  • cancel()
  • promotePendingToProcessing()

OrderItem

• Immutable value object (productName, quantity, price)

OrderStatus

• Canonical lifecycle statuses used by state objects and persistence mapping

State Pattern Structure

• OrderState: transition/cancel/promotion contract
• AbstractOrderState: common transition lookup and default conflict behavior
• OrderStateFactory: maps OrderStatus to concrete state implementation
• Concrete states:
  • PendingState
  • ProcessingState
  • ShippedState
  • DeliveredState
  • CancelledState

Transition Rules

• Valid transitions are defined in concrete state maps
• Invalid transitions throw ConflictException
• cancel() is valid only from pending state
• delivered/cancelled are terminal states for further transitions