UML Weekend Crash Course™ - To Parent Directory

Answers to Part Reviews 319
20. I assume that the screen design offered by the user has been approved by all the
users who will need to use it. The client assumes that I already know the laws that
govern insurance terms for international shipping.
21. If you replicate the system, you have not fixed the problem that was the justification
for the project.
Saturday Morning Review Answers
1. A person may function in many roles. A person may perform many different functions
and use the system in many different capacities when using a system. There
really is no limitation other than the nature of the problem domain to restrict the
possible number of roles that a person may play. The same person may even use
the same Use Case from different roles.
2. Associations identify interactions between actors and Use Cases. Associations
simply indicate that there is some sort of communication, no matter what that
communication is. To get the details, you need to look at the Use Case narrative or
one of the other models such as the Sequence or Collaboration diagrams. An association
has no way of showing the data flowing between the two elements.
3. The dependency stereotype indicates delegation of part of a task to
another Use Case. “Used” Use Cases are typically autonomous Use Cases that may
also be referenced much like you would seek help from a friend.
4. The dependency stereotype indicates a conditional reference to a Use
Case. During the execution of one Use Case, a condition may be encountered that
requires access to a feature handled by another Use Case. When that condition is
encountered, the extension is invoked. When the condition is not met, the
extending Use Case is not invoked.
5. Generalization may be used to identify an existing actor or Use Case whose definition
forms the basis for a more specialized actor or Use Case.
6. Few, if any, systems function in a void. Other systems, the business itself, and the
people who use the system all influence how we interpret the role of the system
and its value.
7. Identify the actors that interact with the Use Cases. In order to interact, they have
to be aware of one another. An association defines who knows whom.
8. When the first Use Case must always (unconditionally) call on the second Use Case
for help, model the relationship as a dependency with the stereotype.
Draw the dependency arrow from the first Use Case to the second Use Case.
9. When the first Use Case only calls on the second Use Case for help because it
encounters a pre-defined condition, model the relationship as a dependency with
the stereotype. Draw the dependency arrow from the second Use Case
to the first Use Case.
10. When two or more Use Cases share common properties, the common properties can
be defined in a single Use Case. Then the two specialized Use Cases only have to
define what they add to or override from the generalized Use Case. The same concept
may be applied to common properties of actors.