5.3 系统顺序图

Posted 2021-02-13 mayzhou

系统顺序图 System Sequence Diagram

　　? 把待建系统看成一个黑盒子，研究参与者与系统边界的交互
　　? SSD

　　　　? System Sequence Diagram

　　? What is SSD

　　　　? A SSD is a picture that shows, for one particular scenario of a use case, the events that external actors generate, inter-system events , and their order

　　　　? All systems are treated as a black box

　　　　? the emphasis of the diagram is events that cross the system boundary from actors to systems

　　? System Event

　　　　? external input events

　　　　　　? actor generates events to a system

　　? system operation

　　　　? to handle the system event , for example

　　　　　　? when a cashier enters an item‘s ID, the cashier is requesting the POS system to record that item‘s sale (the enterItem event). That event initiates an operation upon the system