Reliable software systems using reusable software components

摘要

Summary form only given, as follows. J. Von Neumann (1956) andE.F. Moore and C.F. Shannon (1956) discussed building reliable automataand relay circuits (hardware) using less reliable components. They showthat carefully designed replication of components in a hardware systemcan increase the probability of failure free operation of that system.There is a powerful trend in the industry now to build software systemsusing as many software components as possible. These components might becommercial off the shelf (COTS) or in-house software libraries andmodules; we call all such components reusable software components. Weargue that the reliability of such a software system can be improved notonly by replicating the software components, but also by activemonitoring, checkpointing and rejuvenation, and providing facilities forcold, warm and hot fail over/restart of those components. Thesecapabilities themselves can be built as reusable software modules thatcan be linked to the actual system components. We present thearchitecture of such a software system and a preliminary analysis toshow the feasibility of this approach for building reliable softwaresystems using reusable software components. Research into analyzing thereliability of such systems is gaining attention. These facilitiesprovide diversity in the execution environment of a software componentleading to a higher level of reliability of the software system, much asreplication provides diversity in the physical environment of a hardwarecomponent giving rise to improved reliability of the hardware systemthat Von Neumann and others have pioneered