Evolving Critical Systems

Increasingly software can be considered to be critical, due to the business or other functionality which it supports. Upgrades or changes to such software are expensive and risky, primarily because the software has not been designed and built for ease of change. Expertise, tools and methodologies which support the design and implementation of software systems that evolve without risk (of failure or loss of quality) are essential. We address a research agenda for building software that (a) is highly reliable and (b) retains this reliability as it evolves, either over time or at run-time. We propose Evolving Critical Systems as an area for research to tackle the challenge and outline a number of scenarios to highlight some of the important research questions that should be asked of the community. Given that software evolution can be seen as a compromise between cost and risk, the most pressing question to ask is which processes, techniques and tools are most cost-effective for evolving critical systems?