Chapter 5: Use Case Diagrams

Question 1

What is: Use Case Diagram

Answer 1

This Diagram lets you display various kinds of elements and relationships to express information about the services your system provides and the stakeholders who require those services.

Conveys a set of use cases—the externally visible services that a system provides—as well as the actors that invoke and participate in those use cases. This Diagram is a black-box view of the system; it is therefore well suited to serve as a system context diagram.

Question 2

T/F: A Use Case Diagram is generally created later in the system life cycle

Answer 2

F, A use case diagram is an analysis tool and is generally created early in the system life cycle. System analysts may enumerate use cases and create use case diagrams during the development of the system concept of operations (ConOps).

Question 3

What is: Primary Actor

Answer 3

The actors that invoke a use case

Question 4

What is: Secondary Actor

Answer 4

The actors that participate in the use case

Question 5

T/F: A primary actor can also be a secondary actor

Answer 5

T

Question 6

What is: Use Case Specification

Answer 6

The use case specification conveys the narrative that unfolds when a primary actor invokes the use case.

Question 7

T/F: Use Case & Scenario are synonyms

Answer 7

F, Use case and scenario are not synonyms. Each path of execution through a use case from beginning to end is a distinct scenario.

A use case therefore consists of one or more scenarios. At a minimum, a use case consists of a main success scenario—the nominal path of execution.

Question 8

List the allowable model element types of a Use Case Diagram

Answer 8

The model element type that the diagram frame represents can be any of the following:
- package
- model
- modelLibrary
- view

Question 9

How: is a use case displayed

Answer 9

The notation for a use case is an ellipse (oval). You can display the name of a use case—generally, a verb phrase—either inside or beneath the ellipse. (Putting the name inside the ellipse is much more common.)

Question 10

What is: System Boundary

Answer 10

The system boundary (also called the subject) represents the system that owns and performs the use cases on the diagram.

Question 11

How: is a system boundary displayed

Answer 11

The notation for the system boundary is a rectangle that encloses the use cases (not to be confused with the diagram frame). The name of the subject—shown at the top inside the rectangle—must always be a noun phrase.

Question 12

T/F: You can create an association between two actors

Answer 12

F

Question 13

T/F: You cannot create an association between two use cases

Answer 13

T

Question 14

T/G You cannot create a composite association between an actor and a use case

Answer 14

T

Question 15

What is: Base Use Case

Answer 15

A base use case is any use case that is connected to a primary actor via an association relationship. This means that a base use case is one that represents a primary actor’s goal.

Question 16

What is: Included Use Case

Answer 16

An included use case is any use case that is the target—the element at the arrowhead end—of an include relationship. The notation for an include relationship is a dashed line with an open arrowhead and the keyword «include» floating next to it.

Question 17

What is: Extending Use Case

Answer 17

An extending use case is any use case that is the source—the element at the tail end—of an extend relationship. The notation for an extend relationship is a dashed line with an open arrowhead and the keyword «extend» floating next to it.