This paper describes Collabode, a web-based Java integrated development environment designed to support close, synchronous collaboration between programmers. We examine the problem of collaborative coding in the face of program compilation errors introduced by other users which make collaboration more difficult, and describe an algorithm for errormediated integration of program code. Concurrent editors see the text of changes made by collaborators, but the errors reported in their view are based only on their own changes. Editors may run the program at any time, using only errorfree edits supplied so far, and ignoring incomplete or otherwise error-generating changes. We evaluate this algorithm and interface on recorded data from previous pilot experiments with Collabode, and via a user study with student and professional programmers. We conclude that it offers appreciable benefits over naive continuous synchronization without regard to errors and over manual version control.

Mechanical Turk provides an on-demand source of human computation. This provides a tremendous opportunity to explore algorithms which incorporate human computation as a function call. However, various systems challenges make this difficult in practice, and most uses of Mechanical Turk post large numbers of independent tasks. TurKit is a toolkit for prototyping and exploring truly algorithmic human computation, while maintaining a straight-forward imperative programming style. We present the crash-andrerun programming model that makes TurKit possible, along with a variety of applications for human computation algorithms. We also present a couple case studies of TurKit used for real experiments outside our lab.

When faced with the need for documentation, examples, bug fixes, error descriptions, code snippets, workarounds, templates, patterns, or advice, software developers frequently turn to their web browser. Web resources both organized and authoritative as well as informal and community-driven are heavily used by developers. The time and attention devoted to finding (or re-finding) and navigating these sites is significant. We present Codetrail, a system that demonstrates how the developer's use of web resources can be improved by connecting the Eclipse integrated development environment (IDE) and the Firefox web browser. Codetrail uses a communication channel and shared data model between these applications to implement a variety of integrative tools. By combining information previously available only to the IDE or the web browser alone (such as editing history, code contents, and recent browsing), Codetrail can automate previously manual tasks and enable new interactions that exploit the marriage of data and functionality from Firefox and Eclipse. Just as the IDE will change the contents of peripheral views to focus on the particular code or task with which the developer is engaged, so, too, the web browser can be focused on the developer's current context and task.2

Aspects are program modules that include descriptions of key events (called joinpoints) and code segments (called advice) to be executed at those key events when the aspect is bound (woven) to an underlying system. The MAVEN tool verifies the correctness of an aspect relative to its specification, independently of any specific underlying system to which it may be woven, and also allows establishing noninterference among aspects, or detecting potential interference. The specification includes assumptions about properties of the underlying system, and guaranteed properties of any system after the aspect is woven into it. The approach is based on model checking of a state machine constructed using the linear temporal logic (LTL) description of the assumptions, a description of the join-points, and the state machine of the aspect advice. The tableau of the LTL assumption is used in a unique way, as a representative of any underlying system satisfying the assumptions. This is the first technique for once-and-for-all verification of an aspect relative to its specification, thereby increasing the modularity of proofs for systems with aspects. The individual correctness proofs along with proofs of interference freedom are appropriate for a library of reusable aspects, when multiple aspects are to be woven to a system.

Abstract. Aspects are program modules that include descriptions of key events (called joinpoints) and code segments (called advice) to be executed at those key events when the aspect is bound (woven) to an underlying system. The MAVEN tool verifies the correctness of an aspect relative to its specification, independently of any specific underlying system to which it may be woven. The specification includes assumptions about properties of the underlying system, and guaranteed properties of any system after the aspect is woven into it. The approach is based on model checking of a single state machine constructed using the linear temporal logic (LTL) description of the assumptions, a description of the joinpoints, and the state machine of the aspect advice. The tableau of the LTL assumption is used in a unique way, as a representative of any underlying system satisfying the assumptions. This is the first technique for once-and-for-all verification of an aspect relative to its specification, thereby increasing the modularity of proofs for systems with aspects.