An Evolutionary Analysis of Software-Architecture Smells

If software quality assurance is postponed or even abandoned for a software system, maintenance and evolution become harder or even impossible. One widely known symptom for the degradation of system quality are Architecture Smells (ASs), which violate fundamental principles of software design. In this paper, we present a study on the evolution of ASs as well as on how and when they foster system degradation. Thus, we provide valuable insights regarding what ASs are meaningful to assure system quality. To this end, we analyzed the evolution of three types of ASs in 14 open-source systems with a total of 485 versions. We adapted indicators used in previous studies to assess the severity of ASs (e.g., growth, lifetime), and relate ASs to technical debt as another established indicator. Our results indicate that 1) ASs remain mostly stable compared to the code size of a system, 2) certain types of ASs, such as cyclic dependencies, have a greater impact on system degradation, and 3) certain properties determine how much an AS contributes to software degradation. These findings are valuable for practitioners to identify and tackle system degeneration, as well as for researchers to scope new research on managing ASs and technical debt.