@article {1847,
	title = {License usage and changes: a large-scale study on gitHub},
	journal = {Empirical Software Engineering},
	year = {2016},
	abstract = {Open source software licenses determine, from a legal point of view, under which conditions software can be integrated and redistributed. The reason why developers of a project adopt (or change) a license may depend on various factors, e.g., the need for ensuring compatibility with certain third-party components, the perspective towards redistribution or commercialization of the software, or the need for protecting against somebody else{\textquoteright}s commercial usage of the software. This paper reports a large empirical study aimed at quantitatively and qualitatively investigating when and why developers adopt or change software licenses. Specifically, we first identify license 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 on 1,160 projects written in seven different programming languages, namely C, C++, C$\#$, Java, Javascript, Python, and Ruby{\textemdash}following an open coding approach inspired by grounded theory{\textemdash}on commit messages and issue tracker discussions concerning licensing topics, and whenever possible, try to build traceability links between discussions and changes. On one hand, our results highlight how, in different contexts, license adoption or changes can be triggered by various reasons. On the other hand, the results also highlight 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. In conclusion, results of the study trigger the need for better tool support in guiding developers in choosing/changing licenses and in keeping track of the rationale of license changes.},
	issn = {1573-7616},
	doi = {10.1007/s10664-016-9438-4},
	author = {Vendome, Christopher and Bavota, Gabriele and Di Penta, Massimiliano and Linares-V{\'a}squez, Mario and German, Daniel and Poshyvanyk, Denys}
}
@proceedings {1726,
	title = {Open Source-Style Collaborative Development Practices in Commercial Projects Using GitHub},
	volume = {1},
	year = {2015},
	month = {05/2015},
	pages = {574-585},
	publisher = {ACM/IEEE},
	abstract = {Researchers are currently drawn to study projects
hosted on GitHub due to its popularity, ease of obtaining data,
and its distinctive built-in social features. GitHub has been found
to create a transparent development environment, which together
with a pull request-based workflow, provides a lightweight mechanism
for committing, reviewing and managing code changes.
These features impact how GitHub is used and the benefits it
provides to teams{\textquoteright} development and collaboration. While most of
the evidence we have is from GitHub{\textquoteright}s use in open source software
(OSS) projects, GitHub is also used in an increasing number of
commercial projects. It is unknown how GitHub supports these
projects given that GitHub{\textquoteright}s workflow model does not intuitively
fit the commercial development way of working. In this paper, we
report findings from an online survey and interviews with GitHub
users on how GitHub is used for collaboration in commercial
projects. We found that many commercial projects adopted
practices that are more typical of OSS projects including reduced
communication, more independent work, and self-organization.
We discuss how GitHub{\textquoteright}s transparency and popular workflow can
promote open collaboration, allowing organizations to increase
code reuse and promote knowledge sharing across their teams.},
	keywords = {github},
	doi = {10.1109/ICSE.2015.74},
	attachments = {https://flosshub.org/sites/flosshub.org/files/icse-camera.pdf},
	author = {Kalliamvakou, E and Damian, Daniela and Blincoe, Kelly and Singer, L. and German, Daniel}
}
@proceedings {1775,
	title = {What is the Gist? Understanding the Use of Public Gists on GitHub},
	year = {2015},
	month = {05/2015},
	publisher = {IEEE},
	keywords = {gist, github},
	author = {Weiliang Wang and Poo-Caama{\~n}o, Germ{\'a}n and Evan Wilde and German, Daniel}
}
@article {springerlink:10.1007/s10664-012-9199-7,
	title = {Software Bertillonage},
	journal = {Empirical Software Engineering},
	year = {2012},
	note = {10.1007/s10664-012-9199-7},
	pages = {1-43},
	publisher = {Springer Netherlands},
	abstract = {Deployed software systems are typically composed of many pieces, not all of which may have been created by the main development team. Often, the provenance of included components{\textemdash}such as external libraries or cloned source code{\textemdash}is not clearly stated, and this uncertainty can introduce technical and ethical concerns that make it difficult for system owners and other stakeholders to manage their software assets. In this work, we motivate the need for the recovery of the provenance of software entities by a broad set of techniques that could include signature matching, source code fact extraction, software clone detection, call flow graph matching, string matching, historical analyses, and other techniques. We liken our provenance goals to that of Bertillonage, a simple and approximate forensic analysis technique based on bio-metrics that was developed in 19th century France before the advent of fingerprints. As an example, we have developed a fast, simple, and approximate technique called anchored signature matching for identifying the source origin of binary libraries within a given Java application. This technique involves a type of structured signature matching performed against a database of candidates drawn from the Maven2 repository, a 275 GB collection of open source Java libraries. To show the approach is both valid and effective, we conducted an empirical study on 945 jars from the Debian GNU/Linux distribution, as well as an industrial case study on 81 jars from an e-commerce application. },
	issn = {1382-3256},
	doi = {10.1007/s10664-012-9199-7},
	url = {http://dx.doi.org/10.1007/s10664-012-9199-7},
	author = {Davies, Julius and German, Daniel and Michael Godfrey and Hindle, Abram}
}
@conference {585,
	title = {An Empirical Study of the Reuse of Software Licensed under the GNU General Public License},
	booktitle = {OSS2009: Open Source Ecosystems: Diverse Communities Interacting (IFIP 2.13)},
	series = {IFIP Advances in Information and Communication Technology },
	volume = {299/2009},
	year = {2009},
	month = {2009///},
	pages = {185 - 198},
	publisher = {Springer},
	organization = {Springer},
	chapter = {17},
	abstract = {Software licensing is a complex issue in free and open source software (FOSS), specially when it involves the redistribution of derived works. The creation of derivative works created from components with different FOSS licenses poses complex challenges, particularly when one of the components is licensed under the terms of one of the versions of the GNU General Public License (GPL). This paper describes an empirical study of the manner in which GPLed licensed software is combined with components under different FOSS licenses. We have discovered that FOSS software developers have found interesting methods to create derivative works with GPLed software that legally circumvent the apparent restrictions of the GPL. In this paper we document these methods and show that FOSS licenses interact in complex and unexpected ways. In most of these cases the goal of the developers (both licensors and licensees) is to further increase the commons of FOSS.
},
	issn = {978-3-642-02031-5},
	doi = {http://dx.doi.org/10.1007/978-3-642-02032-2_17},
	attachments = {https://flosshub.org/sites/flosshub.org/files/Empirical\%20Study\%20of\%20the\%20Reuse\%20of\%20Software.pdf},
	author = {German, Daniel and Gonz{\'a}lez-Barahona, Jes{\'u}s}
}
@conference {Germ04b,
	title = {Mining CVS repositories, the softChange experience},
	booktitle = {Proc. Int{\textquoteright}l Workshop on Mining Software Repositories ({MSR})},
	year = {2004},
	note = {"Mailing lists. Mailing lists are an important source of information about the evolution of the project. We currently correlate MRs [modification requests] to mail messages by using the author and the date attributes of both the MR and the message."},
	pages = {17{\textendash}21},
	abstract = {CVS logs are a rich source of software trails (information left behind by the contributors to the development process, usually in the forms of logs). This paper describes how softChange extracts these trails, and enhances them. This paper also addresses some challenges that CVS fact extraction poses to researchers.},
	keywords = {bugzilla, cvs, email archives, log files, logs, softchange},
	attachments = {https://flosshub.org/sites/flosshub.org/files/17MiningCVS.pdf},
	author = {German, Daniel}
}
@conference {German03automatingthe,
	title = {Automating the measurement of open source projects},
	booktitle = {Proceedings of the 3rd Workshop on Open Source Software Engineering},
	year = {2003},
	note = {"We have chosen to use Evolution to illustrate some of the capabilities of SoftChange. We focus on the data provided by CVS logs and the CVS commit mailing list. Our data includes changes to the CVS repository from April 1998 to January 2003."},
	pages = {63{\textendash}67},
	abstract = {The proliferation of open source projects raises a number of vital economic, social, and software engineering questions that are subject of intense research. Based on experience analyzing numerous open source and commercial projects we propose a set of tools to support extraction and validation of software project data. Such tools would streamline empirical investigation of open source projects and make it possible to test existing and new theories about the nature of open source projects. Our soft- ware includes tools to extract and summarize information from mailing lists, CVS logs, ChangeLog files, and defect tracking databases. More importantly, it cross-links records from various data sources and identifies all contributors for a software change. We illustrate some of the capabilities by analyzing data from Ximian Evolution project.},
	keywords = {bug reports, bug tracking, changelog, cvs, defects, evolution, log files, logs, mailing list, scm, softchange, source code, ximian, ximian evolution},
	attachments = {https://flosshub.org/sites/flosshub.org/files/germanMockus2003.pdf},
	author = {German, Daniel and Audris Mockus}
}
