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Functional and Non-Functional Requirements (NON-FUNCTIONAL REQUIREMENT…
Functional and Non-Functional Requirements
NON-FUNCTIONAL REQUIREMENT
TYPE
Product
Usability
Efficiency
Performance
Space
Dependability
Security
Organizational
Enviromental
Operational
Development
External
Regulatory
Ethical
Legistative
Accounting
Safety and Security
DEFINITION
requirements for system properties and constraints
JUSTIFICATION
Be more critical than functional requirements
Affect the overall architecture
Generate a number of related functional requirements
Be very difficult to state precisely and imprecise requirements maybe difficult to verify.
GOALS
= A general intention of the user such as ease of use.
= Helpful to the developer as they convey the intentions of the system users
FUNCTIONAL REQUIREMENT
How it works??
Describe functionality of system services
The user requirement statements may be high-level of what the system should do
System requirements should describe the system in details
Depending on the type of software
Requirements Imprecision
Problem arise when requirements are not stated precisely
Ambiguous requirements may be interpreted in different ways by developers and user
Requirements Completeness and
Consistency
Complete
: To achive complete requirements, the description of all facilities should be included
Consistent
: the description of the system facilities should not have any conflicts of contradictions
DEFINITION
How the system should behave
What the system should not do
Statements of services the system should provide
How the system should react
DOMAIN REQUIREMENT
DEFINITION
could be new functional requirements, constraints on existing requirements or define specific computations
If domain requirements are not satisfied, the system may be
unworkable.
PROBLEM
UNDERSTANDABILITY
= requirements are express in the language of the application domain.
= often not understood by software engineers developing the systems
IMPLICITNESS
= domain specialist understand the are so well that they do not think of making the domain requirements explicits.
