Interfaces between solutions, users and networks (p.2)

Question 1

Explain the difference between include and extend in a use case diagram.

Answer 1

«include» represents a mandatory relationship, where one use case always involves another.

«extend» signifies an optional relationship, where a use case can add functionality to another but isn’t always required.

Question 2

Explain the difference between an association and a generalisation in a use case diagram.

Answer 2

Association:
A basic relationship indicating a connection between two elements. It represents a standard relationship without any specific characteristics.

Generalization:
A special type of relationship denoting a parent-child connection between elements, often used for actors. It signifies that one element (child) inherits properties and behaviours from another (parent).

For example, an actor “Manager” (parent) might have two specialized actors:
“Sales Manager” (child)
“Operations Manager.” (child)

Question 3

How does a process differ between context diagrams and data flow diagrams?

Answer 3

Context diagram process:
A process in a context diagram represents the whole system as a generalised concept.

Data flow diagram process:
a process in a data flow diagram represents each of the functions within the system itself.

Question 4

What is an actor in a use case diagram?

Answer 4

An external entity who interacts with the system being modelled. Represented as a stick model.