Functional and Nonfunctional Requirements

Functional Requirements: Requirements include functionalities  and services that are needed by the users to meet their need and to achieve their business objectives.

Typical functional requirements are:

  • Administrative functions
  • Authentication
  • Authorization levels
  • Audit Tracking
  • Business Rules
  • Certification Requirements
  • External Interfaces
  • Historical Data
  • Legal or Regulatory Requirements
  • Transaction correction, adjustments and cancellations.

Non Functional Requirements: Requirements that specifies criteria that can be used to judge the operation of a system, rather than specific behaviors.

Typical non functional requirements are:

  • Availability
  • Capacity
  • Environmental
  • Data integrity
  • Interoperability
  • Maintainability
  • Manageability
  • Performance (for eg. response time, throughput)
  • Reliability
  • Recoverability
  • Regulatory
  • Serviceability
  • Security
  • Scalability
  • Usability