Use Case Model

Question 1

What is a Use Case Model?

Answer 1

to show how users interact with the system in order to solve a problem. As such, the use case model defines the user’s objective, the interactions between the system and the user, and the system’s behavior required to meet these objectives.

nb//use case model is NOT the diagram, it involves the diagram and the specifications that accompany it
nb//users are always external

Question 2

What is the purpose of use case modelling?

Answer 2

To illustrate the user’s goals and give the stakeholders an idea of how the system will operate.

Question 3

What are the best practices in regards to naming use cases.

Answer 3

• use case should start with a strong verb
• use case should be named using domain specific language
• use case names should not be greater than 3 words

-Actors should be singular entity
-Actors should be named based on their role in the system and not their job titles.
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Question 3

Distinguish between the nature and value of the use case

relationships: include, extend and inheritance (specialization/generalization)

Answer 3

INCLUDE:
Include is used to indicate that one use case is going to use all the steps of the use case that it is pointing to.

EXAMPLE:
a —-> b
whenever we use , use case a, we will use all the steps of use case b.
nb// this helps to remove redundancy

EXTEND:
extend is used to indicate that the extended use case will only be used when an optional condition is met.
a —–> b
a extends b .
use case a will only be invoked sometimes( optional cases)

SPECIFICATION
use to indicate more specific versions of the main use case

Question 4

Describe the fields in use case specification

Answer 4

Trigger- an event that starts the use case
Main Flow - A series of steps in the use case to a path of a successful use case
Precondition - a precondition is something that has to be true before the use case can be executed
extension :
failed condition: the state of the system at the end of the exception path
successful condition: a condition that has to be met at the end of successful execution of the normal flow of a use case
primary actor: actors that initiate a use case
secondary primary: facillitates succesful commpletion of a use case