●●● ●●●●● ●●●● 系统事件 ●●●● ●●●● ●●0● makeNewSale, etc, are the system operations from the SSD each major interaction diagram starts with a system operation going into a domain layer controller object, such as Register makeNewSale Register ??? Window objects GUI widget objects enterltem Registe 1:??? Web control objects endSale -+ Register 1:??? makePayment Register 1:??? UI LAYER DOMAIN LAYER系统事件 :Register enterItem :Register endSale :Register makePayment 1: ??? 1: ??? 1: ??? :Register makeNewSale 1: ??? makeNewSale, etc., are the system operations from the SSD each major interaction diagram starts with a system operation going into a domain layer controller object, such as Register UI LAYER DOMAIN LAYER Window objects or GUI widget objects or Web control objects . .