From User Requirements to Tasks Descriptions in Real-Time Systems

Real-time scheduling theory has made a great progress in the last decades. From small devices to enormous satellites or industrial plants take advantage of this ongoing research. However, to the authors belief, there is still a gap to fully exploit the benefits of the theory. The cornerstone of real-time scheduling theory is the concept of task. Nevertheless, very little is mentioned about how to discover such tasks. Thus, the objective of this paper is to propose a systematic way of describing real-time tasks by means of requirements elicitation. The process begins with the gathering of user requirements through Use Case Diagrams. Then, those use cases are refined to turn them into tasks descriptions. Lastly, tasks descriptions are further refined and brought to a detailed characterization of individual execution flows. This final tasks characterization is made with Activity Diagrams. Finally, a Line-Follower System is used to exemplify the proposed approach.