Evolving dependable real-time systems

To keep systems affordable, there is a trend towards using open standard and commercial off the shelf (COTS) components in the development of dependable real-time systems. However, the use of COTS also introduces the vendor-driven upgrade problem that is relatively new to the dependable real-time computing community. If we refuse to accept the “new and improved” hardware and software components provided by vendors, then the hope that using COTS components will help keep the system modern via market forces will be dashed. If we decide to keep our systems modern, then we have to develop approaches that can introduce new hardware and software components into deployed systems safely, reliably and easily, in spite of the inevitable bugs in some of the new COTS components. In this paper, we give an informal review of the Simplex Architecture, which has been developed to support safe and reliable online upgrade of dependable computing systems. This paper is a revision of the SEI technical report: A Software Architecture for Dependable and Evolvable Industrial Computing Systems. CMU/SEI-95-TR-005