Requirements Analysis and Modeling with Problem Frames and SysML: A Case Study

Requirements analysis and modeling based on Problem Frames is getting an increasing attention in the academic community. This paper reports on an experience in analyzing and specifying the requirements of a controller for traffic lights of an intersection using Problem Frames and the SysML notation. The problem has been decomposed into simpler sub-problems that fit the definition of basic frames. All the sub-problems have been individually analyzed by identifying their requirements and defining a machine specification. The re-composition of the sub-problems has been carried out by merging the requirements of the sub-problems, defining new requirements that solve the conflicts among the sub-problems, and specifying a new machine that, in combination with the problem domains, satisfies the requirements. This case study allowed us to identify two decomposition and re-composition patterns.