[04] use case

Use Cases are a way to capture the needs of the real world.

A use case is a set of activities that interact with participants and provide them with Observability and meaningful results.

1. Features of use cases (1) Use Cases are relatively independent

It does not need to interact with other use cases to accomplish the goal of the participants alone. A use case cannot fully fulfill the desire of the participants.

The withdrawal ticket is not a use case, because it is not a participant's purpose, and his purpose is to get money.

(2) The execution results of use cases are Observability and meaningful to participants.

For the participants, it is unnoticeable and meaningless. It is not a use case and must be a background monitoring program.

(3) Use cases must be initiated by participants

There are no use cases without participants, and the use case should not start another one.

(4) use cases must appear in the form of Dynamic Object phrases

(5) A use case is a requirement, analysis, design, development, and test unit.

2. Use Case Granularity

(3) Use Cases