Chapter 4(requirements)

Question 1

The requirements for a system are …

Answer 1

the descriptions of the services that a system should provide and the constraints on its operation.

Question 2

Types of requirement

Answer 2

User requirements, System requirements

Question 3

User requirements are?

Answer 3

statements, in a natural language plus diagrams, of what services the system is expected to provide to system users and the constraints under which it must operate. The user requirements may vary from broad statements of the system features required to detailed, precise descriptions of the system functionality.

Question 4

System requirements are?

Answer 4

are more detailed descriptions of the software system’s functions, services, and operational constraints. The system requirements document (sometimes called a functional specification) should define exactly what is to be implemented. It may be part of the contract between the system buyer and the software developers.

Question 5

System stakeholders

Answer 5

Any person or organization who is affected by the
system in some way and so who has a legitimate interest

Question 6

Stakeholder types

Answer 6

End users
System managers
System owners
External stakeholders

Question 7

Agile methods requirements are

Answer 7

scenarios/user stories

Question 8

classes of requirements:

Answer 8

Functional, non-functional, domain

Question 9

Functional requirements are?

Answer 9

Statements of services the system should provide, how the system should react to particular inputs and how the system
should behave in particular situations.
May state what the system should not do.

Question 10

Non-functional requirements are?

Answer 10

Constraints on the services or functions offered by the system such as timing constraints, constraints on the development process, standards, etc.
Often apply to the system as a whole rather than individual features or services

Question 11

Domain requirements are?

Answer 11

Constraints on the system from the domain of operation

Question 12

Functional requirements describe and depend on what

Answer 12

Describe functionality or system services, depend on the type of software, expected users and the type of system where the software is used

Question 13

requirements should be both

Answer 13

complete and consistent

Question 14

what class is more important

Answer 14

Non-functional requirements may be more critical than functional requirements. If these are not met, the system may be uselesa

Question 15

Non-functional requirements may affect

Answer 15

the overall architecture of a system rather than the individual components

Question 16

Non-functional classifications

Answer 16

Product requirements, organisational requirements, external requirements

Question 17

Goal

Answer 17

A general intention of the user such as ease of use

Question 18

Verifiable non-functional requirement

Answer 18

A statement using some measure that can be objectively tested

Question 19

Usability requirements

Answer 19

Requirements elicitation & analysis;
Requirements specification
Requirements validation;

Question 20

Requirements elicitation and analysis is also called

Answer 20

requirements elicitation or
requirements discovery.

Question 21

stakeholders are

Answer 21

end-users, managers, engineers involved in maintenance, domain experts, trade unions

Question 22

Requirements elicitation is

Answer 22

Software engineers work with a range of system
stakeholders to find out about the application domain,
the services that the system should provide, the required
system performance, hardware constraints, other
systems, etc.

Question 23

stages of elictation

Answer 23

Requirements discovery,
 Requirements classification and organization,
 Requirements prioritization and negotiation,
 Requirements specification.

Question 24

Problems of requirements elicitation

Answer 24

Stakeholders don’t know what they really want.
 Stakeholders express requirements in their own terms.
 Different stakeholders may have conflicting
requirements.
 Organisational and political factors may influence the
system requirements.
 The requirements change during the analysis process.
New stakeholders may emerge and the business
environment may change.

Question 25

Types of interview and definition

Answer 25

Closed interviews based on pre-determined list of questions
Open interviews where various issues are explored with stakeholders

Question 26

Stories and scenarios

Answer 26

Scenarios and user stories are real-life examples of how a system can be used.

Question 27

Requirements specification

Answer 27

The process of writing down the user and system requirements in a requirements document for users.
System requirements are more detailed requirements and may include more technical information.

Question 28

Why requirements and design are inseparable

Answer 28

requirements should state what the system should do and the design should describe how it does this.

Question 29

Requirements validation

Answer 29

Concerned with demonstrating that the requirements
define the system that the customer really wants.
 Requirements error costs are high so validation is very
important

Question 30

Requirements checking

Answer 30

 Validity. Does the system provide the functions which
best support the customer’s needs?
 Consistency. Are there any requirements conflicts?
 Completeness. Are all functions required by the
customer included?
 Realism. Can the requirements be implemented given
available budget and technology?
 Verifiability. Can the requirements be checked?

Question 31

Requirements validation techniques

Answer 31

Requirements reviews- systematic manual analysis of the requirements.
Prototyping - Using an executable model of the system to check requirements.
Test-case generation - Developing tests for requirements to check testability.