Interconnection schemes for RTO.k objects in loosely coupled real-time distributed computer systems

A highly desired property in complex real time distributed computer systems (DCS's) is the high degree of autonomy of the various subsystems that compose the DCS. In recent years, we have formulated two system structuring techniques which could be used as basic tools for enhancing the subsystem autonomy: (1) the RTO.k object structuring scheme, and (2) the Hitachi-UCI (HU) Data Field (DF) interprocess group communication scheme. The RTO.k object structuring scheme has been devised to enable the realization of real time computing in the form of a generalization of non real time computing and yet allow system engineers to confidently produce certifiable real time DCS's. The HU-DF scheme enables the enhancement of the object autonomy, especially the relocation autonomy and the data acceptance autonomy. Schemes for interconnecting RTO.k objects using the HU-DF scheme with the aim for maximizing the subsystem autonomy and easing the design time guarantee of timely service capabilities of the objects are the main theme of the paper. A new approach for interconnecting RTO.k objects is presented. This and the earlier established basic interconnection approach are qualitatively analyzed mainly with respect to their contribution to autonomy and service timing predictability of the subsystems. Both of these approaches have been incorporated into an operating system kernel model named the DREAM kernel and its prototype implementation supporting both conventional real time processes and RTO.k objects with guaranteed timely kernel services.