The advent of distributed version control systems has led to the development of a new paradigm for distributed software development; instead of pushing changes to a central repository, developers pull them from other repositories and merge them locally. Various code hosting sites, notably Github, have tapped on the opportunity to facilitate pull-based development by offering workflow support tools, such as code reviewing systems and integrated issue trackers. In this work, we explore how pull-based software development works, first on the GHTorrent corpus and then on a carefully selected sample of 291 projects. We find that the pull request model offers fast turnaround, increased opportunities for community engagement and decreased time to incorporate contributions. We show that a relatively small number of factors affect both the decision to merge a pull request and the time to process it. We also examine the reasons for pull request rejection and find that technical ones are only a small minority.

Abstract-In the pull-based development model, the integrator has the crucial role of managing and integrating contributions. This work focuses on the role of the integrator and investigates working habits and challenges alike. We set up an exploratory qualitative study involving a large-scale survey involving 749 integrators, to which we add quantitative data from the integrator's project. Our results provide insights into the factors they consider in their decision making process to accept or reject a contribution. Our key findings are that integrators struggle to maintain the quality of their projects and have difficulties with prioritizing contributions that are to be merged.

No abstract

Using JavaScript and dynamic DOM manipulation on the client-side of web applications is becoming a widespread approach for achieving rich interactivity and responsiveness in modern web applications. At the same time, such techniques, collectively known as Ajax, shatter the metaphor of web 'pages' with unique URLs, on which traditional web crawlers are based. This paper describes a novel technique for crawling Ajax-based applications through automatic dynamic analysis of user interface state changes in web browsers. Our algorithm scans the DOM-tree, spots candidate elements that are capable of changing the state, fires events on those candidate elements, and incrementally infers a state machine modelling the various navigational paths and states within an Ajax application. This inferred model can be used, for instance, in program comprehension, analysis and testing of dynamic web states, or for generating a static version of the application. In this paper, we discuss our sequential and concurrent Ajax crawling algorithms.We present our open source tool called Crawljax, which implements the concepts and algorithms discussed in this paper. Additionally, we report a number of empirical studies in which we apply our approach to a number of open-source and industrial web applications and elaborate on the obtained results.

The Asf+Sdf Meta-environment is an interactive development environment for the automatic generation of interactive systems for constructing language definitions and generating tools for them. Over the years, this system has been used in a variety of academic and commercial projects ranging from formal program manipulation to conversion of COBOL systems. Since the existing implementation of the Meta-environment started exhibiting more and more characteristics of a legacy system, we decided to build a completely new, component-based, version. We demonstrate this new system and stress its open architecture.