(9) Use-Cases

Question 1

Software Requirements Specification - why important?

Answer 1

Is both the starting point and end point for a software development project and should describe requirements that the system must fulfil in a way that is clear, concise, consistent, complete, verifiable, …

Question 2

Which kinds of software requirements exist?

Answer 2

Functional Requirements:

• Capture statements of services the system should provide
• Depend on the type of software, users and the environment in which the software is used
• Example: User shall be able to search

Non-functional Requirements:

• Constraints on the services or functions offered by the system
• Example: The system shall conform to certain requirements defined in XYZ (e.g. privacy or efficiency requirements)

Question 3

What is the traditional requirement approach?

Answer 3

• Typically result in detailed, low-level feature lists

- Problems: no cohesive requirement description and unstructured

Question 4

What is the modern requirement approach?

Answer 4

• Use Cases and User Stories
• Both focus on the interaction between user and software
• Virtues: Simplicity and utility

Question 5

What is the Use Case Modeling Approach?

Answer 5

The system is perceived as a black box with which the users interact via well-defined interfaces.

Question 6

Use Case Modeling Approach

Actor - Definition

Answer 6

Entity with behaviour outside the system under discussion

Question 7

Use Case Modeling Approach

use case instance - Definition

Answer 7

Specific sequence of actions and interactions between actors and the system under discussion

Question 8

Use Case Modeling Approach

Use Case - Definition

Answer 8

Collection of related success and failure scenarios that describe actors using s system to support a goal

Question 9

Use Case Modeling Approach

Use Case Model - Definition

Answer 9

Set of all use cases

Question 10

Which elements does the use case model comprise?

Answer 10

• Use Case Texts: Requirements are captured as text
• System Sequence Diagrams
• Use Case Diagrams: Graphical overview of use cases

Question 11

How can use cases be discovered?

Answer 11

• Tasks can be grouped at many levels of granularity from individual small steps to enterprise level activities
• Focus on elementary business processes

Question 12

Elementary Business Process - Definition

Answer 12

• Task performed by one person in one place at one time in response to a business event, which adds measurable business value and leaves data in a consistent state
• Often useful to create sub-use cases