Using design patterns to support migration between different system architectures

Complex software is a key part of many safety-critical embedded systems. Changes to such software over the system lifetime or to support product upgrades - particularly in applications which require realtime behaviour - can be a costly, time consuming, and risky process, requiring detailed re-testing and even recertification. This paper begins to explore ways in which techniques known as “design patterns” can be used to support the required migration processes. The particular focus of the work described in this paper is on migration between “event triggered” and “time triggered” software architectures.