Hook: Change Shutdown Conditions

Requirement

Different or additional conditions have to be imposed on application shutdown.

Method of Adaptation

Augment feature

Level of Support

Parameter Pattern

HotSpot

Shutdown

Hooks used

Incorporate new Shop

Participants

Shop, NewShop

Changes

1. subclass NewShop of Shop.
2. NewShop.canShutDown overrides Shop.canShutDown :
1. Remember shop state at start of method.
2. synchronisation ( Shop.canShutDown , evaluation of additional conditions).
3. if Shop.canShutDown returns false :
1. immediately return false .
4. if shutdown cannot be allowed due to the additional conditions:
1. if shop state at beginning of method was RUNNING :
1. call Shop.resume .
2. return false .
5. return true .
3. Incorporate new Shop [NewShop = NewShop].

Constraints

• Shop.canShutDown will suspend the Shop and all processes running in it before testing any conditions. If any of the standard conditions does not hold (i.e. if there are background processes unwilling to be stopped or any SalesPoints that disagree), the Shop will be resumed again before canShutDown returns. Therefore, if the Shop was running before the method was called and your own conditions did not hold, you must explicitly resume the Shop again, before returning from the method.