The advanced development of embedded computing devices, accessible networks, and sensor devices has triggered the emergence of complex cyber-physical systems (CPS). A cyber-physical system continuously monitors and affects the physical environment which also interactively imposes the feedback to the information processing system. The applications of CPS include healthcare, automotive systems, aerospace, power grids, water distribution, disaster recovery, etc. Due to their intensive interaction with the physical world, in which time naturally progresses, timeliness is an essential requirement of correctness. Communication and computation of safety-critical tasks should be finished within a specified amount of time, called deadline. Otherwise, even if the results are correctly delivered from the functional perspective, the reaction of the CPS may be too late and results in a catastrophe.
One example is the release of an airbag in a vehicle, which only functions properly if the bag is filled with the correct amount of air in the correct time interval after a collision, even in the worst-case timing scenario. While in an entertainment gadget a delayed computation result is inconvenient, in the control of a vehicle it can be fatal. A modern society cannot adopt a technological advance when it is not safe.
To design a timing predictable and rigorous cyber-physical real-time system, two separate but co-related problems have to be considered:
1. how to design scheduling policies to feasibly schedule the tasks on the platform and system model, referred to as the scheduler design problem, and
2. how to validate the schedulability of a task system under a scheduling algorithm, referred to as the schedulability test problem, to ensure deterministic and/or probabilistic timing guarantees.
The goal of PropRT is to provide formal properties that can be used modularly to compose safe and tight analysis and optimization for the scheduler design and schedulability test problems. In fact, some properties already exist, but they were not properly stated in the literature due to historical reasons. One main reason is that these properties were not formulated with the goal of general applicability but for a specific problem. To successfully tackle complex cyber-physical real-time systems that
involve computation, parallelization, communication, and synchronization, new, mathematical, modulable, and fundamental properties for property-based (schedulability) timing analyses and scheduling optimizations are strongly needed. They should capture the pivotal properties of cyber-physical real-time systems, and thus enable mathematical and algorithmic research on the topic.
