Exception Handling in Object-Oriented Real-Time Distributed Systems

Exception handling in a complex concurrent and distributed system (e.g. one involving cooperating rather than just competing activities) is often a necessary, but a very difficult, task. No widely accepted models or approaches exist in this area. The object-oriented paradigm, for all its structuring benefits, and real-time requirements each add further difficulties to the design and implementation of exception handling in such systems. In this paper, we develop a general structuring framework based on the coordinated atomic (CA) action concept for handling exceptions in an object-oriented distributed system, in which exceptions in both the value and the time domain are taken into account. In particular, we attempt to attack several difficult problems related to real-time system design and error recovery, including action-level timing constraints, time-triggered CA actions, and time-dependent exception handling. The proposed framework is then demonstrated and assessed using an industrial realtime application — the Production Cell III case study.