Assessing Software Maintainability Based on Class Diagram Design: A Preliminary Case Study

—Can software maintainability be assessed at the early design stage? For a preliminary answer, we conducted a case study. The study adopts a set of metrics for class diagram measurement, and defines three indices for maintainability assessment from the defect-correction perspectives. The dataset under investigation includes the defect repository and corrective maintenance history of Apache Tomcat (maintained from 2006 to 2014). Statistical findings show that some class diagram metrics (such as the number of class association across packages, the number of classes, the inheritance depth for a class et al.) are significantly correlated with the maintainability assessment in this software. The result can guide maintenance-oriented software design, and also motivates us to do a stronger empirical evaluation.