Chapter 4 - Use Case Analysis

Question 1

What is a use case?

Answer 1

A use case is a document that depicts a set of activities that, when performed, produce a result. It shows how a system interacts with its environment by illustrating the activities that are performed by the users, and then the system’s response to those activities.
Use cases help us better understand how a process works, and how the user interacts with that process.

Question 2

In what phase are use cases used?

Answer 2

Use cases are used in the analysis phase.

Question 3

What is event-driven modeling?

Answer 3

Event-driven modeling is a modelling principle where everything in a system operates as a response to some triggering event. When there are no events, the system is at rest. Use cases operate on this principle.

Question 4

What are the basic elements of a use case?

Answer 4

There are numerous elements in a use case:

• Basic Information
• • Use Case Name
• • Use Case Number
• • Priority
• • Trigger (The event that causes the use case to happen)

Question 5

In a use case, what are preconditions?

Answer 5

Preconditions in a use case define what state the system must be in before the use case can begin.

Question 6

In a use case, what is the actor?

Answer 6

In a use case, the actor is the person or thing that interacts with the system.

Question 7

In a use case, what is the normal course?

Answer 7

The normal course in a use case is where the major steps are listed. These steps are listed with their inputs or outputs in a column to the right, with arrows indicating whether they are inputs out outputs.

Question 8

In a use case, what are alternative courses?

Answer 8

In a use case, alternative courses are depictions of alternate paths that could be taken from the steps in the normal course that would still end in a successful completion of the use case.

Question 9

In a use case, what are postconditions?

Answer 9

In a use case, postconditions are how the system environment should be after a successful completion of the use case. It defines the “product” of the use case, to a degree.

Question 10

In a use case, what are exceptions?

Answer 10

Exceptions in a use case are error conditions that may occur as the use case steps are performed. They would prevent the successful completion of the use case.

Question 11

What should be the final section of a use case?

Answer 11

The final section of a use case should be the inputs and outputs.

Question 12

What are some examples of additional sections that might be added to use cases?

Answer 12

Some additional sections that can be added to use cases are:

• Frequency of Use
• Business Rules
• Special Requirements
• Assumptions
• Notes and Issues

Question 13

What is a “fully-dressed” use case?

Answer 13

A fully-dressed use case is one that is exceptionally thorough, detailed, and highly structured.

Question 14

What is the difference between a use case and a functional requirement?

Answer 14

Use cases are only able to convey the user’s point of view, whereas a functional requirement looks at the system through the developer’s eyes, giving more detail as to what the system should do.

Question 15

How do use cases and testing mesh?

Answer 15

Use cases and testing mesh easily. Use cases can be studied early on to determine and create tests for the system later on.

Question 16

What are the steps to building a use case?

Answer 16

There are four steps needed to create a use case:

1. Identify the use cases needed.
2. Identify the major steps within each use case.
3. Identify the elements within each step (triggers, inputs, etc).
4. Confirm the use case.