A controlled experiment to evaluate the understandability of KAOS and i* for modeling Teleo-Reactive systems

• A novel method to model software requirements for Teleo-Reactive systems using i*.
• A novel method to model software requirements for Teleo-Reactive systems using KAOS.
• i* notation has higher understandability level for modeling Teleo-Reactive systems than KAOS.

ContextTeleo-Reactive (TR) specifications allow engineers to define the behavior of reactive systems while taking into account goals and changes in the state of the environment.ObjectiveThis article evaluates two different Goal Oriented Requirements Engineering notations, i* and KAOS, to determine their understandability level for specifying TR systems.MethodA controlled experiment was performed by two groups of Bachelor students. Each group first analyzed a requirements model of a mobile robotic system, specified using one of the evaluated languages, and then they filled in a questionnaire to evaluate its understandability. Afterwards, each group proceeded similarly with the model of another system specified with the second language.ResultsThe statistical analysis of the data obtained by means of the experiment showed that the understandability of i* is higher than that of KAOS when modeling TR systems.ConclusionBoth languages are suitable for specifying TR systems although their notations should be specialized to maximize the understandability attribute. i* surpasses KAOS due to two main reasons: i* models represent dependencies between agents and goals or tasks; and notational differences between tasks and goals in i* are more evident than those between goals and requirements in KAOS.

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