Effort estimation for architectural refactoring to introduce module isolation

Abstract

The decomposition of software architecture into modular units is driven by both functional and quality concerns. Dependability and security are among quality concerns that require a software to be decomposed into separate units isolated from each other. However, it appears that this decomposition is usually not aligned with the decomposition based on functional concerns. As a result, introducing module isolation forced by quality attributes, while preserving the existing decomposition, is not trivial and requires a substantial refactoring effort. In this work, we introduce an approach and a toolset to predict this effort prior to refactoring activities. As such, a selection can be made among potential decomposition alternatives based on quantitative estimations. These estimations are obtained from scalable analysis of module dependencies based on a graph database and reusable query templates. We discuss our experiences and evaluate our approach on a code base used in a commercial Digital TV and Set-top Box software.