Requirements Definition of Safe Software Using the Behavioral Patterns Analysis (PBA) Approach: The Railroad Crossing System

This paper is concerned with a new event-oriented approach named the behavioral pattern analysis approach (BPA). In BPA, events are considered the primary objects of the world model. BPA is a more effective alternative to use cases in modeling and understanding the functional requirements. The event defined in BPA is a real-life conceptual entity that is unrelated to any implementation. The BPA behavioral patterns are temporally ordered according to the sequence of the real world events.