Investigating software developers' understanding of open source software licensing

Software provided under open source licenses is widely used, from forming high-profile stand-alone applications (e.g., Mozilla Firefox) to being embedded in commercial offerings (e.g., network routers). Despite the high frequency of use of open source licenses, there has been little work about whether software developers understand the open source licenses they use. To help understand whether or not developers understand the open source licenses they use, I conducted a survey that posed development scenarios involving three popular open source licenses (GNU GPL 3.0, GNU LGPL 3.0 and MPL 2.0) both alone and in combination. The 375 respondents to the survey, who were largely developers, gave answers consistent with those of a legal expert's opinion in 62% of 42 cases. Although developers clearly understood cases involving one license, they struggled when multiple licenses were involved. To understand the context in which licensing issues arise in practice, I analyzed real-world questions posed by developers on online question-and-answer communities. The analysis of these questions indicate that licensing issues can constrain software evolution and technical decisions can have an impact on future licensing issues. Finally, I interviewed software developers in industry to understand how developers reason about and handle license incompatibility in practice. The developers I interviewed are cautious of restrictive licenses. To identify potential licensing issues, these developers rely on licensing guidelines provided by their organization and sometimes use specialized tools to automatically detect licensing issues in their projects. When faced with a situation in which a component that suits their needs is not compatible, developers tend to look for alternative components made available by open source communities. They sometimes leverage the technical architecture of their projects to enable the use of components under restrictive licenses and might rewrite the required functionality if necessary. An analysis of the results indicate a need for tool support to help guide developers in understanding the structure of the code and the technical details of a project while taking into account the exact requirements imposed by the licenses involved.Science, Faculty ofComputer Science, Department ofGraduat