Refactoring Embedded Software: A Study in Healthcare Domain

Abstract

Context In embedded software industry, stakeholders usually promote run-time properties (e.g., performance, energy efficiency, etc.) as quality drivers, which in many cases leads to a compromise at the levels of design-time qualities (e.g., maintainability, reusability, etc.). Such a compromise does not come without a cost; since embedded systems need heavy maintenance cycles. To assure effective bug-fixing, shorten the time required for releasing updates, a refactoring of the software codebase needs to take place regularly. Objective: This study aims to investigate how refactorings are applied in ES industry; and propose a systematic approach that can guide refactoring through a 3-step process for refactoring: (a) planning; (b) design; and (c) evaluation.

Method The aforementioned goals were achieved by conducting a single case study in a company that develops medical applications for bio-impedance devices; and follows a rather systematic refactoring process in periodic timestamps. Three data collection approaches have been used: surveys, interviews (10 practitioners), and artifact analysis (51 refactoring activities).

Results The results of the study suggest that: (a) maintainability and reusability are the design-time quality attributes that motivate the refactoring of Embedded Software (ES), with 30% of the participants considering them as of “Very High” importance; (b) the refactorings that are most frequently performed are “Extract Method”, “Replace Magic Number with Constant” and “Remove Parameter”. We note that the “Extract Method” refactoring has an applicability of more than over 80%; and (c) to evaluate the refactoring process engineers use tools producing structural metrics, internal standards, and reviews.

Conclusions The outcomes of this study can be useful to both researchers and practitioners, in the sense that the former can focus their efforts on aspects that are meaningful to industry, whereas the latter are provided with a systematic refactoring process.