Providing Safety-Critical and Real-Time Services for Mobile Devices in Uncertain Environment

Executing critical services through small, portable devices in harsh environment with uncontrolled system boundaries requires resilient and self-adaptive services and networks, which are able to track the current status of the system, to estimate its uncertainties and to react accordingly. Achieving the required dependability, timeliness and security levels is an architectural challenge due to the intrinsic asynchrony of the system and the complexity of its fault model. In this paper we present the design of a resilient middleware and architecture for real-time, safety-critical and distributed mobile devices which operates in an uncertain environment. Such mobile devices, called Mobile Terminals (MTs), are developed as part of the ALARP (A railway automatic track warning system based on distributed personal mobile terminals) project which aims to design and develop a safety-critical Automatic Track Warning System (ATWS) for railway trackside workers. The MTs are wearable devices which operate in a railway worksite, to execute the real-time and safety critical service of notifying to the railway worker a train approaching the worksite or the occurrence of hazardous situation (e.g., workers missing or not responding).