Evolving Critical Systems

Summary form only given. 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 in computer based systems that (a) is highly reliable and (b) retains this reliability as it evolves, either over time or at run-time and illustrate this with a complex example from the domain of space exploration.