●●● 什么是用例实现 ●●●●● ●●●● ●●●●● ●●●● ●●0● 用例如何在设计模型中实现 ystem as black box the name could be "NextGenPOS"but"System"keeps it the":and underline imply an instance, and are explained in a ater chapter on sequence diagram notation in the UML Process sale Scenario Cashier makeNewsale a UML loop oop丿 more items interaction enterltem (itemID, quantity) a boolean guard expression description, total end sale ssociated with the it is an abstraction previous message representing the an abstraction that ystem event of make Payment(amount). some mechanism the return line is change due, receipt not returned什么是用例实现 ⚫ 用例如何在设计模型中实现 enterItem(itemID, quantity) : Cashier :System endSale makePayment(amount) a UML loop interaction frame, with a boolean guard expression external actor to system Process Sale Scenario system as black box the name could be "NextGenPOS" but "System" keeps it simple the ":" and underline imply an instance, and are explained in a later chapter on sequence diagram notation in the UML a message with parameters it is an abstraction representing the system event of entering the payment data by some mechanism description, total return value(s) associated with the previous message an abstraction that ignores presentation and medium the return line is optional if nothing is returned total with taxes change due, receipt makeNewSale loop [ more items ]