Characterizing essential and incidental complexity in software architectures

This paper reports results from an experimental case study that seeks to characterize essential and incidental complexity in the design of a complex software product using design structure matrices (DSMs). A DSM captures structural dependencies among the modules and can be used to identify parts of a system that lack cohesion and/ or are highly coupled. We consider such parts as excessively complex. In the case study, we capture the complexity of an Internet-based collaborative system as it was originally designed and after it was redesigned using an architecture-centric development methodology. We find significant reduction in excessive complexity of the redesigned system suggesting that excessive complexity can be an incidental byproduct of a development methodology that lacks focus on the systemic properties of a system that strongly influence its architecture.