Principles of constructing a timeliness-guaranteed kernel and time-triggered message-triggered object support mechanisms

One of the major components required for the construction of future complex real-time computer systems (RTCS) needed in safety-critical applications is a timeliness-guaranteed operating system. A model of an operating system kernel called the DREAM kernel that can support both conventional real-time processes and new-style real-time objects has been formulated. The key emphasis in formulating the DREAM kernel was in the realization of guaranteed timely responses to the service requests from supported client programs. This paper presents a summary of the main structuring principles that were exploited to realize guaranteed timely service capabilities while maintaining the modular and easily expandable structure in the DREAM kernel. Implementation of real-time processes and real-time objects involves designing various calls to DREAM kernel services. A library of functions, called the DREAM library and providing user-friendly interfaces to the DREAM kernel, has been developed in the authors' laboratory. This library consists of a collection of specific C++ classes. A 32-bit prototype version of the DREAM kernel, version D3.0, encapsulated by the DREAM library that supports well-structured real-time application programming in C++ has been implemented. This prototype version has been used in efficient development of several real-time object structured applications including a non-trivial defense C/sup 3/ system, a steel factory control system, and an advanced traffic management system.