Software Evolution: An Empirical Study of Mozilla Firefox

The changes to software are inevitable as new requirements emerge with the use of the software. The change is necessary in terms of correcting errors, improving the performance and reliability of the system. The changes corresponding to corrective, preventive, adaptive and perfective maintenance leads to evolution of software. Software product is an evolving entity which starts with an initial implementation of a set of requirements and from then onwards software undergoes frequent modifications generally for the purpose of increasing its functionality, performance or in order to adapt to a changed environment. Software evolution refers to the phenomenon of software change and growth. The environment where software has to operate changes over time and software itself must adapt to this changing environment. The software does not change by itself but changed by the development and maintenance teams. In this study the evolution of Mozilla Firefox Open Source Software (OSS) was analysed empirically on latest fifty versions. The applicability of Lehman’s Law of software evolution was investigated on Mozilla Firefox using different software metrics. The Resource Standard Metrics (RSM) software metrics tool was used to get the values of the size and complexity measures of the software. It is evident from the results of the study that the evolution of the Mozilla Firefox for the latest fifty versions was in accordance with Lehman’s laws of continuing change, increasing complexity, continuing growth and declining quality