Andrew Wils

Agility in the avionics software world

This paper takes a look at how XP and other agile practices can improve a software process for the development of avionics software. Developers of mission critical airborne software are heavily constrained by the RTCA DO-178B regulations [8]. These regulations impose strict rules regarding traceability and documentation that make it extremely hard to employ an iterative software development process. In particular, the extra validation overhead increases the time spent on small iteration cycles (for example, a bug-fix) to several weeks. Currently, this sector is also pressed to switch to a more agile, customer driven approach. In this paper we investigate how to speed up development and cope with changing requirements using agile techniques. The research was carried out in cooperation with Barco, a major Belgian avionics equipment supplier. We explain why certain agile techniques have less effect as the project progresses. We point out the stadia in which each XP practice is beneficial and where XP practices might cause a slowdown.

Timing driven architectural adaptation

Self-adaptation is currently addressed in general frameworks and reference architectures but not in the application architecture. This paper defines concrete concepts to specify timing driven self-adaptation in the software architecture. This self-adaptation is aimed at high-end embedded component based applications. We create an architectural view of a music application describing this kind of adaptation and discuss its implementation. The novelty of our approach is the definition of separate constructs for the monitoring, the adaptation decision logic and the adaptation itself. This allows independent specification of policy and mechanisms and the possibility to adapt other applications in order to satisfy important constraints. The implementation itself consists of reusable run-time counterparts of the constructs. These counterparts are managed by the component middleware and configured by the architectural specification. This way one does not need to write additional self-adaptation code.