Requirements

Question 1

List the 3 sources of software unreliability

Answer 1

1. Failure in design and development
   - failing to meet requirements
   - inadequate specification
2. Failure during operation
   - bugs
3. Failure in maintenance
   - platform upgrade incompatibilities
   - poor documentation

Question 2

Define user requirements and give an example

Answer 2

Statements in natural language or diagrams of the service. This is written for customers, not developers.
Example: We need to be able to spell check documents.

Question 3

Define system requirements and give an example

Answer 3

A structured document setting out detailed descriptions of the system services - this serves as a contract between client and customer
Example: The system needs to be able to spell check documents and provide autocorrect facilities. There will be the support for the following languages: English, French and German

Question 4

Define software specifications and give an example

Answer 4

A detailed description which can serve as a basis for a design/implementation. This is written for developers.
Example:
CheckResult function:
- Word is defined in UNICODE string
- spellCheck will use hashing to improve efficiency

Question 5

Define SRS

Answer 5

Software Requirements Specification - a description of a software system to be developed - lays out a set of requirements and use cases that the software must provide.

Question 6

What are some common problems in the requirements phase?

Answer 6

• Requirements do not accurately account for the user’s real problems
• Requirements are not properly prioritized
• Requirements are stated at an inappropriate level of specification

Question 7

List the four steps of the Requirements Engineering Process

Answer 7

1. Feasibility Study
2. Requirement Gathering
3. Software Requirement Specification
4. Software Requirement Validation

Question 8

Describe the process of the feasibility study

Answer 8

The analysts do a detailed study about whether the rough idea of the customer is feasible to develop. The output of this phase is a feasibility study that should contain comments/recommendations about whether the project should be undertaken

Question 9

Describe the process of requirement gathering

Answer 9

Once the feasibility report is finished, the next phase is gathering requirements from the user. Analysts/engineers communicate with the user and discuss their ideas of what the software should do.

Question 10

Describe the process of software requirement specification (SRS)

Answer 10

A document is written after the requirements are collected from various stakeholders. SRS defines how intended software will interact with hardware, external interfaces, speed of operation, etc.
The requirements received from the client are written in natural language.

Question 11

Describe the process of software requirement validation

Answer 11

The requirements are validated against some conditions, including
- if they are practical
- if they are valid as per functionality
- if there are any ambiguities
- if they are complete
- if they can be demostrated
- if they are ethical/legal

Question 12

Why can agile methodologies lead to issues with requirements?

Answer 12

Agile methods argue that producing detailed system requirements is a waste of time - therefore the requirements document is almost always out of date.

Question 13

Define ‘functional requirement’

Answer 13

A requirement that specifies what the system should do
Examples:
- All users will access the system using an ID and password
- Every order shall be allocated using a unique identifier (ORDER_ID)

Question 14

Define ‘non functional requirement’

Answer 14

Specifies how the system should perform certain functions

Question 15

Explain the difference between a “goal” and a “requirement”

Answer 15

A goal is a general intention of the user while a requirement is a statement that can be measured and objectively tested

Question 16

Describe the process of requirements elicitation

Answer 16

SW engineers work with a range of stakeholders to find out about the system requirements

Question 17

List the 4 steps of requirements elicitation

Answer 17

1. Requirements discovery
2. Requirements classification and organization
3. Requirements prioritization and negotiation
4. Requirements specification

Question 18

Describe what happens during requirements discovery

Answer 18

Information is gathered about the required and existing systems
This happens between system stakeholders and developers

Question 19

Describe the difference between open and closed interviews

Answer 19

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

Question 20

What is ethnography in SWE?

Answer 20

A social scientist spends time observing how people work in the workplace - people do not explain or articulate their work. Then requirements are derived from these observations and discussed with stakeholders

Question 21

Describe what a ‘scenario’ is in the context of requirements engineering

Answer 21

A scenario is a structured form of a user story, with specific details including:
- A description of the starting situation
- A description of the normal flow of events
- A description of what can go wrong
- A description of the state when the scenario is finished

Question 22

Describe what happens during requirements specification

Answer 22

Requirements specification is he process of writing system requirements in a requirements document. User requirements have to be understandable by end-users and customers. System requirements are more detailed and more technical for the developers.

Question 23

What are some problems with natural language in the context of requirements engineering?

Answer 23

There is often a lack of clarity and precision in natural language that can lead to confusion and unclear requirements if written only in natural language.

Question 24

Define form-based specifications

Answer 24

A definition of the function or entity - a description of inputs, where they come from, and where the outputs should go.

Question 25

Define tabular specification

Answer 25

Used to supplement natural language wit ha more rigid and precise definition - shows exactly what computations should happen in what functions

Question 26

Define Use Case

Answer 26

Use cases identify actors in an interaction and describe the interaction itself. Use cases can be represented with stick diagrams in UML or with words.

Question 27

List the two components of the software requirements document

Answer 27

• A definition of user requirements
• A specification of the system requirements

Question 28

Describe the requirements validation phase

Answer 28

The process of demonstrating the requirements define the system that the customer wants

Question 29

Name some techniques of requirement validation

Answer 29

1. Requirements reviews - systematic analysis
2. Prototyping - use an executable version of the model to check requirements
3. Test-case generation

Question 30

Name some checks during requirements validation

Answer 30

1. Verifiability - is the requirement testable?
2. Comprehensibility - is the requirement properly understood?
3. Traceability - is the origin of the requirement clearly stated?
4. Adaptability - can the requirement be changed w/o a large impact on other requirements?

Question 31

Define requirements management

Answer 31

The process of managing changing requirements during the requirements engineering process and system development