Quality Attribute Trade-Offs in Industrial Software Systems

The main challenge of architecting modern industrial control and automation systems (ICASs) is that they need to fulfill quality attributes (QAs) traditional to real-time systems - such as timeliness and predictability - and modern software engineering - such as modularity or reusability. QAs often are conflicting, which entails difficult trade-offs. As a consequence, even the architecture of closely related ICAS products can differ substantially due to their different priorities on QAs. This article presents six essential, but partially conflicting quality attributes for ICAS and shows how the shift in priority of these QAs impacts the architecture of three functionally very similar ICAS platforms.