Debsources: Live and historical views on macro-level software evolution

Context. Software evolution has been an active field of research in recent years, but studies on macro-level software evolution-i.e., on the evolution of large software collections over many years-are scarce, despite the increasing popularity of intermediate vendors as a way to deliver software to final users. Goal. We want to ease the study of both day-by-day and long-term Free and Open Source Software (FOSS) evolution trends at the macro-level, focusing on the Debian distribution as a proxy of relevant FOSS projects. Method. We have built Debsources, a software platform to gather, search, and publish on the Web all the source code of Debian and measures about it. We have set up a public Debsources instance at http://sources.debian.net, integrated it into the Debian infrastructure to receive live updates of new package releases, and written plugins to compute popular source code metrics. We have injected all current and historical Debian releases into it. Results. The obtained dataset and Web portal provide both long term-views over the past 20 years of FOSS evolution and live insights on what is happening at sub-day granularity. By writing simple plugins (~100 lines of Python each) and adding them to our Debsources instance we have been able to easily replicate and extend past empirical analyses on metrics as diverse as lines of code, number of packages, and rate of change-and make them perennial. We have obtained slightly different results than our reference study, but confirmed the general trends and updated them in light of 7 extra years of evolution history. Conclusions. Debsources is a flexible platform to monitor large FOSS collections over long periods of time. Its main instance and dataset are valuable resources for scholars interested in macro-level software evolution.