4 - Software Requirements

Question 1

What is requirements engineering ?

Answer 1

A process that establishes the services and constraints of a system and under which is operates.

Question 2

Give the 3 types of requirements?

Answer 2

• User
• System
• Software specification

requirements

Question 3

What are functional requirements?

Answer 3

Statements of services the system should provide.

Describe functionality or system services.

eg:

Adjustments and cancellations
Administrative functions
Authentication
Authorisation levels

Describe system services in detail

Question 4

What are non-functional requirements?

Answer 4

Constraints on the services offered by the system.

Define system properties and constraints.

eg:

Performance
Scalability
Capacity
Availability
Reliability
Response time

Usually more critical than functional reqs. If not met, system could be useless (e.g. key length for encrypting secure email must be >=256 bits).

Question 5

Give non-functional classifications?

Answer 5

• Product requirements
• Organisational requirements
• External requirements

Question 6

What are domain requirements ?

Answer 6

Requirements that come from the application domain of the system reflect its characteristics.

Question 7

What is a verifiable non-functional requirement ?

Answer 7

A statement that can be objectively tested.

Question 8

Difference between shall and should in writing reqs?

Answer 8

• Shall > Mandatory

- Should > Desirable