Architecture design decision maps for software sustainability

In software engineering, sustainability can be defined as the "capacity to endure" and to "preserve the function of a system over an extended period of time". These definitions mainly point towards technical sustainability over time. Sustainability, however, may entail a much broader scope including economic, social and environmental sustainability as well. In spite of the exciting hype around sustainability, we are very much lacking suitable instruments to design software-intensive systems that are sustainable and enable sustainability goals. To fill this gap, we advocate the treatment of sustainability as a software quality property and define a software sustainability assessment method that helps make sustainability-driven design decisions. The method essentially relies on the definition of so-called "decision maps", i.e. views aimed at framing the architecture design concerns around the four sustainability dimensions mentioned above - technical, economic, social and environmental sustainability. This paper presents the notion of decision map. We use two illustrative examples extracted from industrial projects, to summarize our lessons learned and reflections