Working with Use Cases
CS 3371 - Feb. 21

1. What is the difference between an actor and an individual user?

2. Complete this analogy.
      class : object :: use case : _________

3. Draw a UML use case diagram representing the following use cases cases from the point of sale system we've been discussing in class. Indicate the system boundary and, for each use case, the actor serving as the initiator.
    
   The customer checks out and returns items with the assistance of the cashier, who has previously logged in to the system.

4. Describe two possible scenarios for the "return copy of book" use case illustrated in figure 7.1 on page 94 of Using UML.

5. What is the role of use cases and scenarios (a) in design validation and (b) in system testing?

6. Why might some actors be added to a use case diagram during the design phase that were not included during requirements development?

7. Classify each of these relationships between or among use cases from the point of sale system as an example of "includes," "extends," or "generalization":

1. "Check out" and "Check out with manufacturers' discounts."
2. "Check out," "Return items," and "Update inventory."
3. "Check out" and "Check out VIP customer."

8. Explain two dangers arising from the use of the includes, extends, and generalization relationships between use cases. When might we avoid using them to help lessen these risks?