ROAFTS: A Middleware Architecture for Real-Time Object-Oriented Adaptive Fault Tolerance Support

A middleware architecture named ROAFTS (Real-time Object-oriented Adaptive Fault Tolerance Support) is presented. ROAFTS is designed to support adaptive fault-tolerant execution of not only conventional process-structured distributed RT application software but also new-style object-structured distributed RT application software. While ROAFTS contains fault tolerance schemes devised for quantitatively guaranteed real-time fault tolerance, it is also designed to relax that characteristics while the application is in a soft real-time phase in order to reduce resource use. Through three different prototype implementation experiences using both commercial OS kernels and home-grown real-time kernels, the middleware architecture has been refined and its basic capabilities and effectiveness have been validated. The fault tolerance schemes supported and the integrating architecture are discussed in this paper. Implementation experiences and some future tasks are also discussed.