Metrics and Evolution in Open Source Software

This paper presents an analysis of the evolution of an open source software system, JFreeChart, which is an open source charting library [1], based on its size, fan-in/out coupling, and cohesion metrics. We developed JamTool, a Java automated measurement tool [4] to obtain the metrics and to observe the quality change along the evolution of the twenty-two released versions of JFreeChart. The empirical study clearly indicates that there are positive relations between the number of classes and the fan-in/out coupling, and the added class group has better software quality than the removed class group. Moreover, the experimental results follow Lehman´s 1^st, 2^nd, 6^th laws 6^th but against 7^th law of software evolution.