Intrinsic software redundancy for self-healing software systems and automated oracle generation

Abstract: Software systems are intrinsically redundant. We identify the sources of intrinsic software redundancy in good design practices, and suggest how to exploit in-trinsic software redundancy to augment software systems with self-healing capabilities and to automatically generate test oracles. Reliability is becoming a necessity for many software systems used in everyday life, where failures may interrupt important services with severe economical and social consequences. In system and software engineering, reliability is traditionally approached by adding some form of redundancy to overcome the consequences of faults that are unavoidable in human artifacts. RAID (Redundant Array of Independent Disks) [PGK88], HDFS (Hadoop Distributed File Systems) and N-version programming [Avi85] are good examples of the use of redundancy for improving hardware, data and software reliability, respectively. In these approaches, redundancy is added deliberately to the systems to improve reliability, and comes with additional costs that may be acceptable for some systems, like safety critical systems, but may not meet the requirements of other domains, like many software applications used in everyday life. We observe that many software systems are characterize