Giuseppe Valetto

Design Rule Hierarchies and Parallelism in Software Development Tasks

As software projects continue to grow in scale, being able to maximize the work that developers can carry out in parallel as a set of concurrent development tasks, without incurring excessive coordination overhead, becomes increasingly important. Prevailing design models, however, are not explicitly conceived to suggest how development tasks on the software modules they describe can be effectively parallelized. In this paper, we present a design rule hierarchy based on the assumption relations among design decisions. Software modules located within the same layer of the hierarchy suggest independent, hence parallelizable, tasks. Dependencies between layers or within a module suggest the need for coordination during concurrent work. We evaluate our approach by investigating the source code and mailing list of Apache Ant. We observe that technical communication between developers working on different modules within the same hierarchy layer, as predicted, is significantly less than communication between developers working across layers.

Group Informatics: A Methodological Approach and Ontology for Sociotechnical Group Research

We present a methodological approach, called Group Informatics, for understanding the social connections that are created between members of technologically mediated groups. Our methodological approach supports focused thinking about how online groups differ from each other, and diverge from their face-to-face counterparts. Group Informatics is grounded in 5 years of empirical studies of technologically mediated groups in online learning, software engineering, online political discourse, crisis informatics, and other domains. We describe the Group Informatics model and the related, 2-phase methodological approach in detail. Phase one of the methodological approach centers on a set of guiding research questions aimed at directing the application of Group Informatics to new corpora of integrated electronic trace data and qualitative research data. Phase 2 of the methodological approach is a systematic set of steps for transforming electronic trace data into weighted social networks.

Elicitation and utilization of application-level utility functions

We present a non-analytic approach to self-assessment for Autonomic Computing. Our approach leverages utility functions, at the level of an autonomic application, or even a single task or feature being exercised within that application. This paper describes the fundamental steps of our approach: instrumentation of the application; collection of exhaustive samples of runtime data about relevant quality attributes of the application, as well as characteristics of its runtime environment; elicitation of a utility function through statistical correlation over the collected data points; and embedding of code corresponding to the equation of the elicited utility function within the runtime of the application, which enables online evaluation of utility values. To illustrate our elicitation method, as well as our framework for instrumentation, monitoring, and utility function embedding/evaluation, we discuss our experience with two different case studies, with their results and implications.

Using gamification to incentivize sustainable urban mobility

Sustainable urban mobility is an important dimension in a Smart City, and one of the key issues for city sustainability. However, innovative and often costly mobility policies and solutions introduced by cities are liable to fail, if not combined with initiatives aimed at increasing the awareness of citizens, and promoting their behavioural change. This paper explores the potential of gamification mechanisms to incentivize voluntary behavioural changes towards sustainable mobility solutions. We present a service-based gamification framework, developed within the STREETLIFE EU Project, which can be used to develop games on top of existing services and systems within a Smart City, and discuss the empirical findings of an experiment conducted in the city of Rovereto on the effectiveness of gamification to promote sustainable urban mobility.

ProxiScientia: toward real-time visualization of task and developer dependencies in collaborating software development teams

This paper introduces ProxiScientia, a visualization tool that provides awareness support to developers, as they engage in collaborative software development activities. ProxiScientia leverages streams of fine-grained events that are generated by team members as they interact with software artifacts in their development environments. The main goal of the tool is to make each developer aware of coordination needs and opportunities as they arise, by depicting ego-centered views of the developers and tasks that most closely impact their work, and showing how they change in real time. In this paper, we illustrate the conceptualization of ProxiScientia and discuss its initial evaluation.

Do all task dependencies require coordination? the role of task properties in identifying critical coordination needs in software projects

Several methods exist to detect the coordination needs within software teams. Evidence exists that developers’ awareness about coordination needs improves work performance. Distinguishing with certainty between critical and trivial coordination needs and identifying and prioritizing which specific tasks a pair of developers should coordinate about remains an open problem. We investigate what work dependencies should be considered when establishing coordination needs within a development team. We use our conceptualization of work dependencies named Proximity and leverage machine learning techniques to analyze what additional task properties are indicative of coordination needs. In a case study of the Mylyn project, we were able to identify from all potential coordination requirements a subset of 17% that are most critical. We define critical coordination requirements as those that can cause the most disruption to task duration when left unmanaged. These results imply that coordination awareness tools could be enhanced to make developers aware of only the coordination needs that can bring about the highest performance benefit.

Creating a model of the dynamics of socio-technical groups

Individuals participating in technologically mediated forms of organization often have difficulty recognizing when groups emerge, and how the groups they take part in evolve. This paper contributes an analytical framework that improves awareness of these virtual group dynamics through analysis of electronic trace data from tasks and interactions carried out by individuals in systems not explicitly designed for context adaptivity, user modeling or user personalization. We discuss two distinct cases to which we have applied our analytical framework. These two cases provide a useful contrast of two prevalent ways for analyzing social relations starting from electronic trace data: either artifact-mediated or direct person-to-person interactions. Our case study integrates electronic trace data analysis with analysis of other, triangulating data specific to each application. We show how our techniques fit in a general model of group informatics, which can serve to construct group context, and be leveraged by future tool development aimed at augmenting context adaptivity with group context and a social dimension. We describe our methods, data management strategies and technical architecture to support the analysis of individual user task context, increased awareness of group membership, and an integrated view of social, information and coordination contexts.

Mycocloud: Elasticity through Self-Organized Service Placement in Decentralized Clouds

We present Mycocloud, a fully self-organized approach to service placement. Mycocloud supports service elasticity within a network of hosts with heterogeneous computational capacity. Mycocloud proposes a completely decentralized algorithm that continuously calculates the dynamic placement of different services on the host nodes, in response to the varying demand for each service, the churn and dynamism of the node set contributing resources to the system, and the changes in the overlay topology. Our simulation results show how Mycocloud provides good performance in terms of convergence rate, response time, system load and network traffic overhead.

Collective Adaptation in Process-Based Systems

A collective adaptive system is composed of a set of heterogeneous, autonomous and self-adaptive entities that come into a collaboration with one another in order to improve the effectiveness with which they can accomplish their individual goals. In this paper, we offer a characterization of ensembles, as the main concept around which systems that exhibit collective adaptability can be built. Our conceptualization of ensembles enables to define a collective adaptive system as an emergent aggregation of autonomous and self-adaptive process-based elements. To elucidate our approach to ensembles and collective adaptation, we draw an example from a scenario in the urban mobility domain, we describe an architecture that enables that approach, and we show how our approach can address the problems posed by the motivating scenario.

Facilitating Coordination between Software Developers: A Study and Techniques for Timely and Efficient Recommendations

When software developers fail to coordinate, build failures, duplication of work, schedule slips and software defects can result. However, developers are often unaware of when they need to coordinate, and existing methods and tools that help make developers aware of their coordination needs do not provide timely or efficient recommendations. We describe our techniques to identify timely and efficient coordination recommendations, which we developed and evaluated in a study of coordination needs in the Mylyn software project. We describe how data obtained from tools that capture developer actions within their Integrated Development Environment (IDE) as they occur can be used to timely identify coordination needs; we also describe how properties of tasks coupled with machine learning can focus coordination recommendations to those that are more critical to the developers to reduce information overload and provide more efficient recommendations. We motivate our techniques through developer interviews and report on our quantitative analysis of coordination needs in the Mylyn project. Our results suggest that by leveraging IDE logging facilities, properties of tasks and machine learning techniques awareness tools could make developers aware of critical coordination needs in a timely way. We conclude by discussing implications for software engineering research and tool design.