I understand that SA describes the customer expectations on the system, the expected services that have to be delivered in different usage contexts. The SA exhibits system need functions and external exchanges through the identification of the main interactions/collaborations of the actors with the system.
What needs to be clarified for me is the signification of the internal exchanges between those functions in terms of system needs, especially when internal functions are created to link transversal paths. Establishing communications between paths to mutualize need functions may help simplifying the system needs description. But then two questions come to mind:
- what is the meaning of the internal functional exchanges in terms of system needs (would they relate to system requirements)?
- Regarding internal functions with no external changes with actors, how should they be dealt with in terms of system requirements? What do they mean in terms of system needs? (They seem to be instrumental).
Thank you in advance for your inputs on this topic.