Victor Guana

Do the stars align?: multidimensional analysis of Android's layered architecture

In this paper we mine the Android bug tracker repository and study the characteristics of the architectural layers of the Android system. We have identified the locality of the Android bugs in the architectural layers of the its infrastructure, and analysed the bug lifetime patterns in each one of them. Additionally, we mined the bug tracker reporters and classified them according to its social centrality in the Android bug tracker community. We report three interesting findings, firstly while some architectural layers have a diverse interaction of people, attracting not only non-central reporters but highly important ones, other layers are mostly captivating for peripheral actors. Second, we exposed that even the bug lifetime is similar across the architectural layers, some of them have higher bug density and differential percentages of unsolved bugs. Finally, comparing the popularity distribution between layers, we have identified one particular layer that is more important to developers and users alike.

SociQL: A Query Language for the SocialWeb

Social-networking sites are becoming increasingly popular with users of all ages. With much of our social activity happening online, these sites are now becoming the subject of scholarly study and research. Unfortunately, despite the fact that they collect similar content and support similar relations and activities, the current generation of these sites are hard to query programmatically, offering limited views of their data, effectively becoming disconnected islands of information. We describe SociQL, a high-level query language, and a corresponding service, to which social-networking sites can subscribe, that supports the integrated representation, querying and exploration of disparate social networks. Unlike generic web query languages, SociQL is designed specifically to support the integration of networks through a common information model for the purpose of examining sociological questions, motivated by social theories. The paper discusses the design and rationale for the SociQL language elements and syntax, as well as our experience using the SociQL service to query a variety of social-network sites.

Building a game engine: a tale of modern model-driven engineering

Game engines enable developers to reuse assets from previously developed games, thus easing the software-engineering challenges around the video-game development experience and making the implementation of games less expensive, less technologically brittle, and more efficient. However, the construction of game engines is challenging in itself, it involves the specification of well defined architectures and typical game play behaviors, flexible enough to enable game designers to implement their vision, while, at the same time, simplifying the implementation through asset and code reuse. In this paper we present a set of lessons learned through the design and construction PhyDSL-2, a game engine for 2D physics-based games. Our experience involves the active use of modern model-driven engineering technologies, to overcome the complexity of the engine design and to systematize its maintenance and evolution.

ChainTracker, a Model-Transformation Trace Analysis Tool for Code-Generation Environments

Model-driven engineering is advocated as an effective method for developing families of software systems that systematically differ across well defined dimensions. Yet, this software construction paradigm is rather brittle at the face of evolution. Particularly, when building code-generation environments, platform evolution scenarios force developers to modify the generated code of individual generation instances in an ad-hoc manner. Thus violating the systematicity of the original construction process. In order to maintain the code-generation environment synchronized, code refinements have to be traced and backwardly propagated to generation infrastructure, so as to make these changes systematically possible for all systems that can be generated. This paper presents ChainTracker, a general conceptual framework, and model-transformation composition analysis tool, that supports developers when maintaining and synchronizing evolving code-generation environments. ChainTracker gathers and visualizes model-to-model, and model-to-text traceability information for ATL and Acceleo model-transformation compositions.

Improving software product line configuration: A quality attribute-driven approach

Context: During the definition of software product lines (SPLs) it is necessary to choose the components that appropriately fulfil a products intended functionalities, including its quality requirements (i.e., security, performance, scalability). The selection of the appropriate set of assets from many possible combinations is usually done manually, turning this process into a complex, time-consuming, and error-prone task. Objective: Our main objective is to determine whether, with the use of modeling tools, we can simplify and automate the definition process of a SPL, improving the selection process of reusable assets. Method: We developed a model-driven strategy based on the identification of critical points (sensitivity points) inside the SPL architecture. This strategy automatically selects the components that appropriately match the products functional and quality requirements. We validated our approach experimenting with different real configuration and derivation scenarios in a mobile healthcare SPL where we have worked during the last three years. Results: Through our SPL experiment, we established that our approach improved in nearly 98% the selection of reusable assets when compared with the unassisted analysis selection. However, using our approach there is an increment in the time required for the configuration corresponding to the learning curve of the proposed tools. Conclusion: We can conclude that our domain-specific modeling approach significantly improves the software architects decision making when selecting the most suitable combinations of reusable components in the context of a SPL.

ChainTracker: Towards a Comprehensive Tool for Building Code-Generation Environments

Code-generation environments have emerged as a new mechanism for building software systems in a systematic manner. At their core, model-driven engineering technologies such as model-to-model and model-to-text transformations are effectively used to build generation engines. However, due to the complexity of model-to-model and model-to-text transformation scripts, which is exacerbated as they are composed in complex transformation chains, developers face technical and cognitive challenges when architecting, implementing, and maintaining code-generation environments. In this paper we present Chain Tracker, a visualization and trace analysis tool for model-to-model and model-to-text transformation compositions. Chain Tracker aims to support developers of code-generation environments by making the usage of model-driven engineering technologies more efficient, less error prone, and less cognitively challenging.

Supporting maintenance tasks on transformational code generation environments

At the core of model-driven software development, model-transformation compositions enable automatic generation of executable artifacts from models. Although the advantages of transformational software development have been explored by numerous academics and industry practitioners, adoption of the paradigm continues to be slow, and limited to specific domains. The main challenge to adoption is the fact that maintenance tasks, such as analysis and management of model-transformation compositions and reflecting code changes to model transformations, are still largely unsupported by tools. My dissertation aims at enhancing the fields understanding around the maintenance issues in transformational software development, and at supporting the tasks involved in the synchronization of evolving system features with their generation environments. This paper discusses the three main aspects of the envisioned thesis: (a) complexity analysis of model-transformation compositions, (b) system feature localization and tracking in model-transformation compositions, and (c) refactoring of transformation compositions to improve their qualities.

Backward propagation of code refinements on transformational code generation environments

Transformational code generation is at the core of generative software development. It advocates the modeling of common and variable features in software-system families with domain-specific languages, and the specification of transformation compositions for successively refining the abstract domain models towards eventually enriching them with execution semantics. Thus, using code-generation environments, families of software systems can be generated, based on models specified in high-level domain languages. The major advantage of this software-construction methodology stems from the fact that it enables the reuse of verified execution semantics, derived from domain models. However, like all software, once an implementation is generated, it is bound to evolve and manually refined to introduce features that were not captured by its original generation environment. This paper describes a conceptual framework for identifying features that have to be propagated backwards to generation engines, from refined generated references. Our conceptual framework is based on static and symbolic execution analysis, and aims to contribute to the maintenance and evolution challenges of model-driven development.

UnderControl an educational serious-game for reproductive health

Educational serious games are effective tools to communicate topics of interest to diverse audiences through well defined gameplay designs. In recent years, reproductive health has become an area of special interest for government and health organizations when designing educational programs for teens and young adults. In this paper we present UnderControl, a multi-level mobile serious game that educates players about contraception and STI prevention in an elegant, yet straightforward fashion.

Detecting Cognitive Ability Changes in Patients With Moderate Dementia Using a Modified “Whack-a-Mole” Game

This paper presents the results from a one-year study of 12 patients with moderate dementia in an adult day program who played a novel whack-a-mole game-based measurement instrument for cognitive behavior and performance. The ongoing measurement of cognition and changes associated with dementia is a challenge for healthcare providers. Measurement methods based on a tablet-based instrument are proposed. Partnership with the adult day program greatly eased recruitment: all but 1 eligible participant joined our study, compared to one in five, or lower, for previous studies with similar populations. There are three unique aspects to the design of our game: first, it has two distinct targets requiring different actions, which increases the cognitive processing for the users; second, each level is systematically more difficult; third, it records and analyzes player performance. The results show that the patients’ game performance improves over the first few weeks; this indicates that they are learning the game and retaining ability gains from week-to-week, suggesting some procedural learning is still intact. Over the year, 4 participants showed cognitive decline, 4 were stable and 3 improved based on their Minimental State Exam (MMSE) score. Two measures are proposed based on level progression within the sessions and mole hit performance. The level progression measure identifies declining participants with one false negative (FN) and one false positive error. The mole hit performance measure identifies declining participants with one FN error. These results demonstrate the potential for the proposed instrument to provide an ongoing measurement as an alternative for the repeated application of the MMSE.