Christoph Hannebauer

Patterns for tearing down contribution barriers to FLOSS projects

The success of a “Free, Libre and Open Source Software” (FLOSS) project depends on its ability to attract new developers. However, before prospective developers can contribute their first patch, they have to overcome the contribution barriers of the FLOSS project. This paper presents two patterns. Each pattern identifies a possible problem in the contribution processes of FLOSS projects and shows a practice to alleviate this problem. The first pattern helps prospective developers compile the FLOSS projects source code and build an executable application. The second pattern encourages prospective developers to submit their modifications back to the FLOSS project and at the same time fosters integration of these modifications into the main development branch of the FLOSS project.

An exploratory study of contribution barriers experienced by newcomers to open source software projects

Contributing to a Free, Libre and Open Source Software (FLOSS) project is not a trivial task even for experienced developers: Beyond the effort required for understanding and editing a projects source code for ones own purposes, submitting the changes back to the community requires additional motivation, time, and social and technical effort. Although several surveys have examined the dynamics driving FLOSS contributors, most focus either on the motivations of core developers or indicators of potential long-term commitment, i.e. the small but quite involved and visible minority at the core of a project. Our survey in contrast examines the experiences of the much larger, but nearly invisible group of developers who are just making and submitting their first patch, and identifies barriers that hinder or even prevent them from making a valuable contribution.

Security of public continuous integration services

Continuous Integration (CI) and Free, Libre and Open Source Software (FLOSS) are both associated with agile software development. Contradictingly, FLOSS projects have difficulties to use CI and software forges still lack support for CI. Two factors hamper widespread use of CI in FLOSS development: Cost of the computational resources and security risks of public CI services. Through security analysis of public CI services, this paper identifies possible attack vectors. To eliminate one class of attack vectors, the paper describes a concept that encapsulates a part of the CI system via virtualization. The concept is implemented as a proof of concept.

Automatically recommending code reviewers based on their expertise: an empirical comparison

Code reviews are an essential part of quality assurance in Free, Libre, and Open Source Software (FLOSS) projects. However, finding a suitable reviewer can be difficult, and delayed or forgotten reviews are the consequence. Automating reviewer selection with suitable algorithms can mitigate this problem. We compare empirically six algorithms based on modification expertise and two algorithms based on review expertise on four major FLOSS projects. Our results indicate that the algorithms based on review expertise yield better recommendations than those based on modification expertise. The algorithm Weighted Review Count (WRC) recommends at least one out of five reviewers correctly in 69 % to 75 % of all cases, which is one of the best results achieved in the comparison.

Motivation of Newcomers to FLOSS Projects

While the motivations of Free/Libre and Open Source Software (FLOSS) developers have been the subject of extensive research, the motivations for their initial contribution to a FLOSS project has received only little attention. This survey of 94 newcomers to the FLOSS projects Mozilla and GNOME identifies the motivations for the modification of the FLOSS components and for the submission of these modifications back to the FLOSS project. With the responses, we test a hypothesis based on the previous qualitative research on newcomer motivations: Most newcomers modify a component because they need the modification for themselves. Surprisingly, this is not the case for our respondents, who have a variety of primary modification motivations. Newcomer occupation is discussed as a reason for this difference to previous results.

Algorithmic Complexity of the Truck Factor Calculation

Software development projects differ in their sensitivity to losing developers. Some projects must stop already if they lose a few developers, while other projects can continue if the same number of developers leave the project. The TF quantifies these differences: It is the number of developers that would stop the project if they left the project. Multiple specific variants of the TF have been suggested in literature. This paper proves that some of these implementations are actually NP-hard to compute, including the promising worst-case metric TF min ,c . NP-hardness prevents their use for large software development projects. For the TF variants not proved to be NP-hard, this paper provides efficient algorithms. However, this paper argues that these TF variants have less explanatory power.

Quality attestation: an open source pattern

A number of small Open Source projects let independent providers measure different aspects of their quality that would otherwise be hard to see. This paper describes this observation as the pattern Quality Attestation. Quality Attestation belongs to a family of Open Source patterns written by various authors.

Wiki development environments

The doctoral thesis Wiki Development Environments analyzes contribution barriers to Free, Libre and Open Source Software (FLOSS) projects. Contribution barriers exist between particular subgroups within the community around a FLOSS project. Contribution barriers include social and technical factors. The hurdles that constitute the contribution barrier to become a co-developer receives special emphasis. The doctoral thesis also describes a pattern language for maintainers of FLOSS projects. The patterns in this pattern language describe practices that lower the contribution barriers in FLOSS projects that employ the patterns. The doctoral thesis includes a novel approach that minimizes contribution barriers. This approach comprises the combination of a wiki system and an Integrated Development Environment (IDE) into a Wiki Development Environment (WikiDE). A WikiDE is a web-based code editor that allows anonymous users to edit source code and contribute it to a FLOSS project. From the pattern language perspective, a WikiDE helps to realize some of the patterns described earlier and amplifies their effect. Editing source code of software differs from editing text in a natural language. WikiDE realizations must take these differences into account. This imposes challenges for WikiDEs realization that exceed the requirements of IDEs and wiki systems for natural language text.