The proliferation of open source software (OSS) and different types of reuse has made it incredibly difficult to perform an essential legal and compliance task of accurate license identification within the software supply chain. This study presents a reusable and comprehensive dataset of OSS licenses, created using the World of Code (WoC) infrastructure. By scanning all files containing “license” in their file paths, and applying the approximate matching via winnowing algorithm to identify the most similar license from the SPDX and Open Source list, we found and identified 5.5 million distinct license blobs in OSS projects. The dataset includes a detailed project-to-license (P2L) map with commit timestamps, enabling dynamic analysis of license adoption and changes over time. To verify the accuracy of the dataset we use stratified sampling and manual review, achieving a final accuracy of 92.08%, with precision of 87.14%, recall of 95.45%, and an F1 score of 91.11%. This dataset is intended to support a range of research and practical tasks, including the detection of license noncompliance, the investigations of license changes, study of licensing trends, and the development of compliance tools. The dataset is open, providing a valuable resource for developers, researchers, and legal professionals in the OSS community.

In Open Source Software, the source code and any other resources available in a project can be viewed or reused by anyone subject to often permissive licensing restrictions. In contrast to some studies of dependency-based reuse supported via package managers, no studies of OSS-wide copy-based reuse exist. This dataset seeks to encourage the studies of OSS-wide copy-based reuse by providing copying activity data that captures whole-file reuse in nearly all OSS. To accomplish that, we develop approaches to detect copy-based reuse by developing an efficient algorithm that exploits World of Code infrastructure: a curated and cross referenced collection of nearly all open source repositories. We expect this data will enable future research and tool development that support such reuse and minimize associated risks.

Background: Hackathons have become popular events for teams to collaborate on projects and develop software prototypes. Most existing research focuses on activities during an event with limited attention to the evolution of the code brought to or created during a hackathon. Aim: We aim to understand the evolution of hackathon-related code, specifically, how much hackathon teams rely on pre-existing code or how much new code they develop during a hackathon. Moreover, we aim to understand if and where that code gets reused, and what factors affect reuse. Method: We collected information about 22,183 hackathon projects from Devpost- a hackathon database - and obtained related code (blobs), authors, and project characteristics from the World of Code. We investigated if code blobs in hackathon projects were created before, during, or after an event by identifying the original blob creation date and author, and also checked if the original author was a hackathon project member. We tracked code reuse by first identifying all commits containing blobs created during an event before determining all projects that contain those commits. Result: While only approximately 9.14% of the code blobs are created during hackathons, this amount is still significant considering time and member constraints of such events. Approximately a third of these code blobs get reused in other projects. The number of associated technologies and the number of participants in a project increase reuse probability. Conclusion: Our study demonstrates to what extent pre-existing code is used and new code is created during a hackathon and how much of it is reused elsewhere afterwards. Our findings help to better understand code reuse as a phenomenon and the role of hackathons in this context and can serve as a starting point for further studies in this area.

Background: Some developer activity traditionally performed manually, such as making code commits, opening, managing, or closing issues is increasingly subject to automation in many OSS projects. Specifically, such activity is often performed by tools that react to events or run at specific times. We refer to such automation tools as bots and, in many software mining scenarios related to developer productivity or code quality, it is desirable to identify bots in order to separate their actions from actions of individuals. Aim: Find an automated way of identifying bots and code committed by these bots, and to characterize the types of bots based on their activity patterns. Method and Result: We propose BIMAN, a systematic approach to detect bots using author names, commit messages, files modified by the commit, and projects associated with the commits. For our test data, the value for AUC-ROC was 0.9. We also characterized these bots based on the time patterns of their code commits and the types of files modified, and found that they primarily work with documentation files and web pages, and these files are most prevalent in HTML and JavaScript ecosystems. We have compiled a shareable dataset containing detailed information about 461 bots we found (all of which have more than 1000 commits) and 13,762,430 commits they created.

The data collected from open source projects provide means to model large software ecosystems, but often suffer from data quality issues, specifically, multiple author identification strings in code commits might actually be associated with one developer. While many methods have been proposed for addressing this problem, they are either heuristics requiring manual tweaking, or require too much calculation time to do pairwise comparisons for 38M author IDs in, for example, the World of Code collection. In this paper, we propose a method that finds all author IDs belonging to a single developer in this entire dataset, and share the list of all author IDs that were found to have aliases. To do this, we first create blocks of potentially connected author IDs and then use a machine learning model to predict which of these potentially related IDs belong to the same developer. We processed around 38 million author IDs and found around 14.8 million IDs to have an alias, which belong to 5.4 million different developers, with the median number of aliases being 2 per developer. This dataset can be used to create more accurate models of developer behaviour at the entire OSS ecosystem level and can be used to provide a service to rapidly resolve new author IDs.

In order to understand the state and evolution of the entirety of open source software we need to get a handle on the set of distinct software projects. Most of open source projects presently utilize Git, which is a distributed version control system allowing easy creation of clones and resulting in numerous repositories that are almost entirely based on some parent repository from which they were cloned. Git commits are unlikely to get produce and represent a way to group cloned repositories. We use World of Code infrastructure containing approximately 2B commits and 100M repositories to create and share such a map. We discover that the largest group contains almost 14M repositories most of which are unrelated to each other. As it turns out, the developers can push git object to an arbitrary repository or pull objects from unrelated repositories, thus linking unrelated repositories. To address this, we apply Louvain community detection algorithm to this very large graph consisting of links between commits and projects. The approach successfully reduces the size of the megacluster with the largest group of highly interconnected projects containing under 400K repositories. We expect that the resulting map of related projects as well as tools and methods to handle the very large graph will serve as a reference set for mining software projects and other applications. Further work is needed to determine different types of relationships among projects induced by shared commits and other relationships, for example, by shared source code or similar filenames.

GitHub projects can be easily replicated through the site's fork process or through a Git clone-push sequence. This is a problem for empirical software engineering, because it can lead to skewed results or mistrained machine learning models. We provide a dataset of 10.6 million GitHub projects that are copies of others, and link each record with the project's ultimate parent. The ultimate parents were derived from a ranking along six metrics. The related projects were calculated as the connected components of an 18.2 million node and 12 million edge denoised graph created by directing edges to ultimate parents. The graph was created by filtering out more than 30 hand-picked and 2.3 million pattern-matched clumping projects. Projects that introduced unwanted clumping were identified by repeatedly visualizing shortest path distances between unrelated important projects. Our dataset identified 30 thousand duplicate projects in an existing popular reference dataset of 1.8 million projects. An evaluation of our dataset against another created independently with different methods found a significant overlap, but also differences attributed to the operational definition of what projects are considered as related.

Open source software (OSS) is essential for modern society and, while substantial research has been done on individual (typically central) projects, only a limited understanding of the periphery of the entire OSS ecosystem exists. For example, how are tens of millions of projects in the periphery interconnected through technical dependencies, code sharing, or knowledge flows? To answer such questions we a) create a very large and frequently updated collection of version control data for FLOSS projects named World of Code (WoC) and b) provide basic tools for conducting research that depends on measuring interdependencies among all FLOSS projects. Our current WoC implementation is capable of being updated on a monthly basis and contains over 12B git objects. To evaluate its research potential and to create vignettes for its usage, we employ WoC in conducting several research tasks. In particular, we find that it is capable of supporting trend evaluation, ecosystem measurement, and the determination of package usage. We expect WoC to spur investigation into global properties of OSS development leading to increased resiliency of the entire OSS ecosystem. Our infrastructure facilitates the discovery of key technical dependencies, code flow, and social networks that provide the basis to determine the structure and evolution of the relationships that drive FLOSS activities and innovation.

To predict files with defects, a suitable prediction model must be built for a software project from either itself (within-project) or other projects (cross-project). A universal defect prediction model that is built from the entire set of diverse projects would relieve the need for building models for an individual project. A universal model could also be interpreted as a basic relationship between software metrics and defects. However, the variations in the distribution of predictors pose a formidable obstacle to build a universal model. Such variations exist among projects with different context factors (e.g., size and programming language). To overcome this challenge, we propose context-aware rank transformations for predictors. We cluster projects based on the similarity of the distribution of 26 predictors, and derive the rank transformations using quantiles of predictors for a cluster. We then fit the universal model on the transformed data of 1,398 open source projects hosted on SourceForge and GoogleCode. Adding context factors to the universal model improves the predictive power. The universal model obtains prediction performance comparable to the within-project models and yields similar results when applied on five external projects (one Apache and four Eclipse projects). These results suggest that a universal defect prediction model may be an achievable goal.

Trick question: what is Data Science? The collection and use of low-veracity data in software repositories and other operational support systems is exploding. It is, therefore, imperative to elucidate basic principles of how such data comes into being and what it means. Are there practices of constructing software data analysis tools that could raise the integrity of their results despite the problematic nature of the underlying data? The talk explores the basic nature of data in operational support systems and considers approaches to develop engineering practices for software mining tools.

The source code and its history represent the output and process of software development activities and are an invaluable resource for study and improvement of software development practice. While individual projects and groups of projects have been extensively analyzed, some fundamental questions, such as the spread of innovation or genealogy of the source code, can be answered only by considering the entire universe of publicly available source code and its history. We describe methods we developed over the last six years to gather, index, and update an approximation of such a universal repository for publicly accessible version control systems and for the source code inside a large corporation. While challenging, the task is achievable with limited resources. The bottlenecks in network bandwidth, processing, and disk access can be dealt with using inherent parallelism of the tasks and suitable tradeoffs between the amount of storage and computations, but a completely automated discovery of public version control systems may require enticing participation of the sampled projects. Such universal repository would allow studies of global properties and origins of the source code that are not possible through other means.

Studies have shown that substantial code reuse is common in open source and in commercial projects. However, the precise extent of reuse and its impact on productivity and quality are not well investigated in the open source context. Previously, we have introduced a simple-to-use method that needs only a set of file pathnames to identifies directories that share filenames and partially validated its performance on a set of closed-source projects. To evaluate this method and to improve reuse detection at the file level, we apply it and four additional file copy detection methods that utilize the underlying content of multiple versions of the source code on the FreeBSD project. The evaluation quantified unique advantages of each method and showed that the filename method detected roughly half of all reuse cases. We are still faced with a challenge to scale the content based methods to large repositories containing all versions of open source files.

We consider any quantity which varies as a smooth function of space and time but is measured as the average value over a region in space-time. As a particular example, we consider the incidence rate of the disease mumps; the reported data are given on a state-by-month basis (for the period 1968–1988). By using animation techniques together with various smoothing methods we make a sequence of successively smoother dynamic maps which enable us to see the development of the disease in both space and time dimensions. We find that a smooth function (of the incidence rates) is the best way to convey the behavior of the spread of the disease. We consider various scaling techniques, ways to smooth the data, ways to estimate a smooth function of the incidence rates, and how to choose an appropriate color scale. This article also includes the description of algorithms to produce this kind of animation and a detailed description of the example concerning mumps disease in the United States. © 1994 John Wiley & Sons, Inc.