UML use case diagram (1)

Use Case Diagrams are used to determine the scope of requirements. These requirements are the basis for design and development. The use case diagram treats the system as a black box and understands the system from the perspective of external executors. As shown in Figure 12.2, the use case in the figure is a typical scenario between the user and the computer.

Figure 12.2 use case diagram of the announcement Management System

Interaction. In UML, the use case is represented as an elliptic.

Performer refers to the role played by the user in the system. Its graphical representation is a villain. It should be noted that the performer is represented in a person-like figure in the use case diagram, but the performer is not necessarily
Person. For example, an executor can be an external system, which may need to obtain information from the current system and interact with the current system. The Use Case of the announcement management system is shown in Figure 12.2.