Architecting Fault Tolerant Systems

As building trustworthy (dependable) systems is one of the major challenges faced by software developers, dealing with various threats (such as errors, faults and failures) is becoming one of the main foci of software and system research and development. In the core of ensuring system dependability is acceptance of the fact that errors always happen in spite of all the efforts to eliminate faults in the system, its components and its environment. To this end, various fault tolerance mechanisms have been developed by researchers and used in industry. Unfortunately, more often than not these solutions ignore earlier development phases- most importantly, the architecture design- exclusively focusing on the implementation instead. This creates a dangerous gap between the requirement to build dependable (and fault tolerant) systems and the failure to deal with these issues until the implementation step. Software Architecture (SA) has been widely accepted as a way to achieve a better software quality while reducing the time and cost of production. It provides both