A modular implementation model of the Primary-Shadow TMO replication scheme and a testing approach using a real-time environment simulator

An extension of the conventional object structuring approach, called the TMO structuring scheme, has been formulated as a unified scheme for object oriented structuring of both real time and non real time applications while enabling the system designer to provide design time guarantees of timely service capabilities of the objects designed. In another area, the DRB/PSP scheme has been established as a concrete scheme for achieving scalable time bounded fault tolerance for both software and hardware faults in distributed and parallel computer systems. A recent integration of the TMO structuring scheme and the basic principle of the DRB/PSP scheme is the primary shadow TMO replication (PSTR) scheme. The TMO scheme and the PSTR scheme present good potentials for realizing a quantum jump in design productivity and system reliability in the real time distributed computing application field. We first present a modular implementation model of the PSTR scheme that can be incorporated into most commercial real time operating systems. This modular implementation model is amenable to a rigorous analysis of the recovery time bounds, a measure of great importance in complex systems. In addition, a new style of testing both control algorithms and time bounded fault tolerance protocols by use of real time simulation components is presented. The implementation model and the testing approach have been validated by a non trivial experiment