The Evolving Nature of Developers' Contributions in Open Source Projects.

Code ownership refers to the knowledge and responsibility a developer has about a given software code. Previous studies have shown a significant relationship between software quality and human factors, reporting that one of the main causes of software quality degradation is the lack of developers' knowledge of the source code. This study aims to understand how the knowledge on the code is distributed among developers throughout the life cycle of open source projects. We carried out five case studies. The results show that a large part of the knowledge is concentrated in a restricted set of authors, called heroes. The results also brings the following new insights on code ownership: the main contributors at the beginning of the project did not remain in this position throughout its evolution; there is an alternation of developers as heroes in the projects; the knowledge on the project becomes more distributed among developers as the project evolves.