Why and How Java Developers Break APIs

Modern software development depends on APIs to reuse code and increase productivity. As most software systems, these libraries and frameworks also evolve, which may break existing clients. However, the main reasons to introduce breaking changes in APIs are unclear. Therefore, in this paper, we report the results of an almost 4-month long field study with the developers of 400 popular Java libraries and frameworks. We configured an infrastructure to observe all changes in these libraries and to detect breaking changes shortly after their introduction in the code. After identifying breaking changes, we asked the developers to explain the reasons behind their decision to change the APIs. During the study, we identified 59 breaking changes, confirmed by the developers of 19 projects. By analyzing the developers' answers, we report that breaking changes are mostly motivated by the need to implement new features, by the desire to make the APIs simpler and with fewer elements, and to improve maintainability. We conclude by providing suggestions to language designers, tool builders, software engineering researchers and API developers.Comment: Accepted at International Conference on Software Analysis, Evolution and Reengineering, SANER 2018; 11 page

How Do Developers React to API Evolution? The Pharo Ecosystem Case

International audienceSoftware engineering research now considers that no system is an island, but it is part of an ecosystem involving other systems, developers, users, hardware,. .. When one system (e.g., a framework) evolves, its clients often need to adapt. Client developers might need to adapt to functionalities, client systems might need to be adapted to a new API, client users might need to adapt to a new User Interface. The consequences of such changes are yet unclear, what proportion of the ecosystem might be expected to react, how long might it take for a change to diffuse in the ecosystem, do all clients react in the same way? This paper reports on an exploratory study aimed at observing API evolution and its impact on a large-scale software ecosystem, Pharo, which has about 3,600 distinct systems, more than 2,800 contributors, and six years of evolution. We analyze 118 API changes and answer research questions regarding the magnitude, duration, extension, and consistency of such changes in the ecosystem. The results of this study help to characterize the impact of API evolution in large software ecosystems, and provide the basis to better understand how such impact can be alleviated

HALO : a multi-feature two-pass analysis to identify framework API evolution

Software frameworks and libraries are indispensable to today’s software systems. Because of the fast development of open-source software in recent years, frameworks and libraries have became much versatile as any open-source system or part thereof can be used as a framework (or a library). Developer can reuse frameworks in innovative ways that are not expected by the providers of frameworks. Many frameworks are not well documented and very few owners provide specific documents to describe the changes between different releases of their frameworks. When they evolve, it is often time-consuming for developers to keep their dependent code up-to-date. Approaches have been proposed to lessen the impact of framework evolution on developers by identifying API evolution or change rules between two releases of a framework. However, the precision and recall of the change rules generated by these approaches depend on the features that they use, such as call-dependency relations or text similarity. If these features do not provide enough information, the approaches can miss correct change rules and compromise the precision and recall. For example, if a method in the old release of a framework is not called by other methods, we cannot find its change rule using call-dependency relations alone. Considering more features can overcome this limitation. Yet, because many features may also give contradictory information, integrating them is not straightforward. We thus introduce Halo, a novel hybrid approach that uses multiple features, including call dependency relations, method documentations, inheritance relations, and text similarity. Halo implements a two-pass analysis inspired by pattern classification problem. We implement Halo in Java and compare it with four state-of-the-art approaches. The comparison shows that, on average, the recall and the precision of Halo are 43% and 5% higher than that of other approaches

Actes des Sixièmes journées nationales du Groupement De Recherche CNRS du Génie de la Programmation et du Logiciel

National audienceCe document contient les actes des Sixièmes journées nationales du Groupement De Recherche CNRS du Génie de la Programmation et du Logiciel (GDR GPL) s'étant déroulées au CNAM à Paris du 11 au 13 juin 2014. Les contributions présentées dans ce document ont été sélectionnées par les différents groupes de travail du GDR. Il s'agit de résumés, de nouvelles versions, de posters et de démonstrations qui correspondent à des travaux qui ont déjà été validés par les comités de programmes d'autres conférences et revues et dont les droits appartiennent exclusivement à leurs auteurs

Mining framework usage changes from instantiation code

Framework evolution may break existing users, which need to be migrated to the new framework version. This is a tedious and error-prone process that benefits from automation. Existing approaches compare two versions of the framework code in order to find changes caused by refactorings. However, other kinds of changes exist, which are relevant for the migration. In this paper, we propose to mine framework usage change rules from already ported instantiations, the latter being applications build on top of the framework, or test cases maintained by the framework developers. Our evaluation shows that our approach finds usage changes not only caused by refactorings, but also by conceptual changes within the framework. Further, it copes well with some issues that plague tools focusing on finding refactorings such as deprecated program elements or multiple changes applied to a single program element