The nature of non-functional requirements

The nature of non-functional requirements pic

Non-functional requirements describe important aspects:

  • performance
  • robustness
  • scalability
  • usability
  • technical and compliance requirements

They influence:

  • The design of the user interface
  • The architecture
  • The choice of technology

The description of non-functional requirements:

  • Non-functional requirements can be expressed in general terms, or as a separately defined constraint for an item, independent of the strategic level
  • User experience requirements are best outlined in the form of sketches, storyboards, navigation diagrams and prototypes.

The management of non-functional requirements:

  • A distinction shall be made between global and local requirements

Global non-functional requirements:

  • They are linked to all non-functional requirements
  • They are detailed at the beginning – when the product vision is created
  • Too late detailing and refinement can lead to wrong decisions and have a negative impact on the success of the product
  • It can be kept separately in the product backlog
  • It is useful to build them into the Definition of Done
  • During demos, it shall be credibly proven, on a case-by-case basis, that they have been taken into account and fulfilled

Local non-functional requirements:

  • They apply only to a specific functional requirement
  • They can be treated as a restriction attached to stories

ATTENTION! If non-functional requirements are not dealt with, whether consciously or not, they can easily turn into Technological Debt.

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