Requirements Engineering with Tropos
The most important contribution of Tropos is in the area of Requirements Engineering. Tropos adopts the Eric Yu's i* modeling framework, which offers the notions of actor, goal and (actor) dependency, and uses these as a foundation to model early and late requirements. Tropos proposes goal-oriented modeling techniques to capture and analyze both business and system requirements, risk and security, and (social and geographic) location requirements.
Requirements modeling is divided into two sub-phases: early requirements and late requirements. The former activity is intended to depict the scenario as-is, whereas the latter introduces the system to-be and shows how the social relationships between actors do change.
The two pictures above represent early and late requirements, respectively, for a case study describing an e-culture system for the province of Trento (PAT). The picture on the left partially shows the scenario as-is, where citizens, visitors and PAT are connected by a number of social relations (dependencies). On the right side, the eCulture system has been introduced and the PAT delegates some responsibilities to this software system.