Actors
pop out use cases fora each actor
Identifying the events that you need to react to will help you identify the use cases.
Use Case Relationships
Apply the following rules
Use include when you are repeating yourself in two or more separate use cases and you want to avoid repetition.
Use generalization when you are describing a variation on normal behavior and you wish to describe it casually.
Use extend when you are describing a variation on normal behavior and you wish to use the more controlled form, declaring your extension points in your base use case.
System、Business use cases
a system use case is an interaction with the software, whereas a business use case discusses how a business responds to a customer or an event.
I focus on business use cases first, and then I come up with system use cases to satisfy them. By the end of the elaboration period, I expect to have at least one set of system use cases for each business use case I have identified-at minimum
When to Use Use Cases
requirements capture and in planning and controlling an iterative project. Capturing use cases is one of the primary tasks of the elaboration phase.
I've also found that conceptual modeling with users helps uncover use cases. So I tend to do use cases and conceptual modeling at the same time.
use cases represent an external view of the system. As such, don't expect any correlations between use cases and the classes inside the system.
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