Legacy Software Restructuring: Analyzing a Concrete Case

TL;DR

This paper investigates the effectiveness of common cohesion and coupling metrics in a real-world software restructuring case on the Eclipse platform, finding they did not assist engineers as expected.

Contribution

It provides an empirical analysis of the relevance of traditional metrics in practical software restructuring, challenging their assumed usefulness.

Findings

Metrics did not behave as expected during restructuring

Traditional metrics likely do not aid maintainers in restructuring tasks

Reducing cyclic dependencies did not meet expected outcomes

Abstract

Software re-modularization is an old preoccupation of reverse engineering research. The advantages of a well structured or modularized system are well known. Yet after so much time and efforts, the field seems unable to come up with solutions that make a clear difference in practice. Recently, some researchers started to question whether some basic assumptions of the field were not overrated. The main one consists in evaluating the high-cohesion/low-coupling dogma with metrics of unknown relevance. In this paper, we study a real structuring case (on the Eclipse platform) to try to better understand if (some) existing metrics would have helped the software engineers in the task. Results show that the cohesion and coupling metrics used in the experiment did not behave as expected and would probably not have helped the maintainers reach there goal. We also measured another possible restructuring which is to decrease the number of cyclic dependencies between modules. Again, the results did not meet expectations.