License Usage and Changes: A Large-Scale Study of Java Projects on GitHub

Abstract

Software licenses determine, from a legal point of view, under which conditions software can be integrated, used, and above all, redistributed. Licenses evolve over time to meet the needs of development communities and to cope with emerging legal issues and new development paradigms. Such evolution of licenses is likely to be accompanied by changes in the way how software uses such licenses, resulting in some licenses being adopted while others are abandoned. This paper reports a large empirical study aimed at quantitatively and qualitatively investigating when and why developer change software licenses. Specifically, we first identify licenses' changes in 1,731,828 commits, representing the entire history of 16,221 Java projects hosted on GitHub. Then, to understand the rationale of license changes, we perform a qualitative analysis-following a grounded theory approach-of commit notes and issue tracker discussions concerning licensing topics and, whenever possible, try to build traceability links between discussions and changes. Our results point out a lack of traceability of when and why licensing changes are made. This can be a major concern, because a change in the license of a system can negatively impact those that reuse it.

On the Detection of Licenses Violations in the Android Ecosystem

“…By tacking licenses changes across releases, we observed that license changes are toward less restrictive licenses, this finding confirms the observation of Vendome et al [20] that open source developers tend to make their projects more open for reuse. However, a deeper look at license changes at file level reveals a strange phenomenon; the licenses of all files are often changed at the same time, and usually after the project has experienced some license inconsistencies.…”

“…In this chapter we conduct a study on licensing evolution, our findings corroborate those obtained by Vendome et al [20] on open-source projects. In the following chapter we will study license violations and their evolution.…”

“…Vendom et al [20] conducted a large study on license usage and changes in a set of 16,221 java projects from Github, analyzing source code files, tracing commit notes and discussions related to license changes and identifying the most common license change patterns. They extracted commit information (e.g.,commit message, file paths, changes applied to files, license changes occurrences, etc...) using The Markos code analyzer [21], which uses Ninka for license identification.…”

When and why developers adopt and change software licenses

“…In our previous work [30], we empirically showed-for software hosted in GitHub-that license changes are common phenomena. Stemming from the results that we previously captured by analyzing licensing and their changes in software repositories [30], the goal of this work is to understand when and why changes in licensing happen.…”

How are Developers Treating License Inconsistency Issues? A Case Study on License Inconsistency Evolution in FOSS Projects

“…Alspaugh et al proposed an approach for calculating conflicts between licenses in terms of their conditions [1]. Vendome et al performed a large empirical study of Java applications and found that changing license is a common event and a lack of traceability between when and why the license of a system changes [9]. In their following research [10], they investigated the reasons on when and why developers adopt and change licenses during evolution of FOSS Java projects on GitHub by conducting a survey with the relevant developers.…”