Rodrigo Morales

Rodrigo Morales, Ruben Saborido, Yann-Gaël Guéhéneuc

The Internet of Things (IoT) is a network of physical, heterogeneous, connected devices providing services through private networks and the Internet. It connects a range of new devices to the Internet so they can communicate with Web servers and other devices around the world. Today's standard platform for communicating Web pages and Web apps is JavaScript (JS) and extending the same standard platform to connect IoT devices seems more than appropriate. However, porting JS applications to the large variety of IoT devices, specifically on System-on-a-Chip (SoCs) devices (\eg~Arduino Uno, Particle \photon), is challenging because these devices are constrained in terms of memory and storage capacity. Running JS applications adds an overhead of resources to deploy a code interpreter on the devices. Also, running JS applications may not be possible ``as is'' on some device missing some hardware/software capabilities. To address this problem, we propose \momit~a multiobjective optimization approach to miniaturize JS applications to run on IoT constrained devices. To validate \momit, we miniaturize a JS interpreter to execute a testbed comprised of 23 applications and measure their performances before and after applying the miniaturization process. We implement \momit~using three different search algorithms and found that it can reduce code size, memory usage, and CPU time by median values of 31\%, 56\%, and 36\% respectively. Finally, MoMIT ported the miniaturized JS interpreters up to to 2 SoCs additional devices, in comparison of using default JS interpreter features.

Rodrigo Morales, Foutse Khomh, Giuliano Antoniol

Refactoring is a maintenance activity that aims to improve design quality while preserving the behavior of a system. Several (semi)automated approaches have been proposed to support developers in this maintenance activity, based on the correction of anti-patterns, which are `poor' solutions to recurring design problems. However, little quantitative evidence exists about the impact of automatically refactored code on program comprehension, and in which context automated refactoring can be as effective as manual refactoring. Leveraging RePOR, an automated refactoring approach based on partial order reduction techniques, we performed an empirical study to investigate whether automated refactoring code structure affects the understandability of systems during comprehension tasks. (1) We surveyed 80 developers, asking them to identify from a set of 20 refactoring changes if they were generated by developers or by a tool, and to rate the refactoring changes according to their design quality; (2) we asked 30 developers to complete code comprehension tasks on 10 systems that were refactored by either a freelancer or an automated refactoring tool. To make comparison fair, for a subset of refactoring actions that introduce new code entities, only synthetic identifiers were presented to practitioners. We measured developers' performance using the NASA task load index for their effort, the time that they spent performing the tasks, and their percentages of correct answers. Our findings, despite current technology limitations, show that it is reasonable to expect a refactoring tools to match developer code.

Rodrigo Morales, Ruben Saborido, Foutse Khomh et al.

The boom in mobile apps has changed the traditional landscape of software development by introducing new challenges due to the limited resources of mobile devices, e.g., memory, CPU, network bandwidth and battery. The energy consumption of mobile apps is nowadays a hot topic and researchers are actively investigating the role of coding practices on energy efficiency. Recent studies suggest that design quality can conflict with energy efficiency. Therefore, it is important to take into account energy efficiency when evolving the design of a mobile app. The research community has proposed approaches to detect and remove anti-patterns (i.e., poor solutions to design and implementation problems) in software systems but, to the best of our knowledge, none of these approaches have included anti-patterns that are specific to mobile apps and--or considered the energy efficiency of apps. In this paper, we fill this gap in the literature by analyzing the impact of eight type of anti-patterns on a testbed of 59 android apps extracted from F-Droid. First, we (1) analyze the impact of anti-patterns in mobile apps with respect to energy efficiency; then (2) we study the impact of different types of anti-patterns on energy efficiency. We found that then energy consumption of apps containing anti-patterns and not (refactored apps) is statistically different. Moreover, we find that the impact of refactoring anti-patterns can be positive (7 type of anti-patterns) or negative (2 type of anti-patterns). Therefore, developers should consider the impact on energy efficiency of refactoring when applying maintenance activities.