Understanding some software quality aspects from architecture and design models

Software systems evolve over time and it is often difficult to maintain them. One reason for this is often that it is hard to understand the previous release. Further even if architecture and design models are available and up to date, they primarily represent the functional behaviour of the system. To evaluate whether it is possible to also represent some non-functional aspects, an experiment has been conducted. The objective of the experiment is to evaluate the cognitive suitability of some visual representations that can be used to represent a control relation, software component size and component external and internal complexity. Ten different representations are evaluated in a controlled environment using 35 subjects. The results from the experiment show that it is possible to also represent some non-functional aspects. It is concluded that the incorporation of these representations in architecture and design descriptions is both easy and probably worthwhile. The incorporation of the representations should enhance the understanding of previous releases and hence help software developers in evolving and maintaining complex software systems.