Understanding Use Case Diagrams

What is an actor in a use case diagram?

• A person who designs the system

• An external entity that interacts with the system

• A software component within the system

• A database used by the system

Answer explanation

An actor in a use case diagram represents an external entity that interacts with the system, such as users or other systems, highlighting their role in the system's functionality.

Which of the following is NOT a type of use case relationship?

• Include

• Extend

• Generalisation

• Aggregation

Answer explanation

The correct answer is Aggregation, as it is not a recognized type of use case relationship. The valid relationships are Include, Extend, and Generalisation.

What does the system boundary in a use case diagram represent?

• The limits of the system's functionality

• The physical location of the system

• The time constraints of the system

• The financial budget of the system

Answer explanation

The system boundary in a use case diagram represents the limits of the system's functionality, indicating what is included within the system and what is outside of it. This helps clarify the scope of the system.

Which of the following best describes a functional requirement?

• A description of the system's performance

• A specification of what the system should do

• A constraint on the system's design

• A measure of the system's reliability

Answer explanation

A functional requirement specifies what the system should do, detailing its behaviors and functionalities. This distinguishes it from performance, design constraints, or reliability measures.

In a use case diagram, which relationship is used to show that one use case is a part of another?

• Include

• Extend

• Generalisation

• Association

Answer explanation

In a use case diagram, the 'Include' relationship indicates that one use case is a part of another, allowing for shared functionality. This distinguishes it from 'Extend', which adds optional behavior.

What is the purpose of an "extend" relationship in a use case diagram?

• To show optional behaviour that can be added to a use case

• To indicate a mandatory sequence of actions

• To define the main flow of events

• To connect actors to use cases

Answer explanation

An 'extend' relationship in a use case diagram indicates optional behavior that can enhance a use case. It allows for additional functionality to be included without altering the core use case, making it flexible and adaptable.

Which of the following is an example of an actor in a use case diagram?

• A user interface

• A customer

• A database

• A software module

Answer explanation

In a use case diagram, an actor represents a user or entity that interacts with the system. A customer is a clear example of an actor, as they engage with the system to achieve specific goals, unlike the other options.

How is a system boundary typically represented in a use case diagram?

• A dashed line

• A solid rectangle

• A circle

• A dotted arrow

Answer explanation

In a use case diagram, a system boundary is typically represented by a solid rectangle. This rectangle encloses the use cases and actors, clearly defining the scope of the system.

What does a use case diagram primarily focus on?

• The internal structure of the system

• The interactions between the system and its environment

• The data flow within the system

• The hardware components of the system

Answer explanation

A use case diagram primarily focuses on the interactions between the system and its environment, illustrating how users and other systems interact with the system being designed.

Which of the following is NOT typically considered a functional requirement?

• The system must send an email notification

• The system must be available 24/7

• The system must allow users to reset their passwords

• The system must generate monthly reports

Answer explanation

The system must be available 24/7 is a non-functional requirement, focusing on system performance and reliability, while the others specify specific functionalities the system must provide.