Jaime Navon

Identifying Relevant Messages in a Twitter-based Citizen Channel for Natural Disaster Situations

During recent years the online social networks (in particular Twitter) have become an important alternative information channel to traditional media during natural disasters, but the amount and diversity of messages poses the challenge of information overload to end users. The goal of our research is to develop an automatic classifier of tweets to feed a mobile application that reduces the difficulties that citizens face to get relevant information during natural disasters. In this paper, we present in detail the process to build a classifier that filters tweets relevant and non-relevant to an earthquake. By using a dataset from the Chilean earthquake of 2010, we first build and validate a ground truth, and then we contribute by presenting in detail the effect of class imbalance and dimensionality reduction over 5 classifiers. We show how the performance of these models is affected by these variables, providing important considerations at the moment of building these systems.

Towards a practical model to facilitate reasoning about REST extensions and reuse

We believe that there is a need for a practical model to visualize the structure and design rationale of REST, so researchers can study more easily the reutilization of this architectural style or parts of it, to the design of software solutions with different requirements than those of the early WWW. In this work we propose the utilization of extended influence diagrams to represent the structure and design rationale of an architectural style. The model is evaluated qualitatively by showing how a diagram of REST, populated with information extracted from the doctoral dissertation that introduced the term, is helpful to gain a better understanding of the properties and limitations of this style, and to reason about potential modifications for applications with different goals than those of the early WWW.

MobiCOP: A Scalable and Reliable Mobile Code Offloading Solution

Code offloading is a popular technique for extending the natural capabilities of mobile devices by migrating processor-intensive tasks to resource-rich surrogates. Despite multiple platforms for offloading being available in academia, these frameworks have yet to permeate the industry. One of the primary reasons for this is limited experimentation in practical settings and lack of reliability, scalability, and options for distribution. This paper introduces MobiCOP, a new code offloading framework designed from the ground up with these requirements in mind. It features a novel design fully self-contained in a library and offers compatibility with most stock Android devices available today. Compared to local task executions, MobiCOP offers performance improvements of up to 17x and increased battery efficiency of up to 25x, shows minimum performance degradation in environments with unstable networks, and features an autoscaling module that allows its server counterpart to scale to an arbitrary number of offloading requests. It is compatible with the most relevant Android technologies optimized for heavy computation (NDK and Renderscript) and has so far been well received by fellow mobile developers. We hope MobiCOP will help bring mobile code offloading closer to the industry realm.

Rethinking the mobile code offloading paradigm: from concept to practice

Mobile code offloading is a relatively well known proposal for enhancing the capabilities of mobile platforms by migrating resource intensive tasks to resource rich surrogates hosted in the cloud. Yet, most of the research in the area has been focused on theoretical gains achieved through custom OS versions in ideal scenarios. This paper presents MobiCOP, a new code offloading platform that seeks to address the reproducibility issues of other offloading solutions by encapsulating all offloading logic in a library and offering compatibility with major IaaS providers. MobiCOP achieves comparable performance and battery improvements with gains of up to a factor of 11 in both areas. Moreover, MobiCOP has also been tested in scenarios with unreliable connectivity, as is usually the case in actual mobile networks, where it has shown that it still manages to outperform local task executions by a fair margin.

Understanding Student Interactions in Capstone Courses to Improve Learning Experiences

Project-based courses can provide valuable learning experiences for computing majors as well as for faculty and community partners. However, proper coordination between students, stakeholders and the academic team is very difficult to achieve. We present an integral study consisting of a twofold approach. First, we propose a proven capstone course framework implementation in conjunction with an educational software tool to support and ensure proper fulfillment of most academic and engineering needs. Second, we propose an approach for mining process data from the information generated by this tool as a way of understanding these courses and improving software engineering education. Moreover, we propose visualizations, metrics and algorithms using Process Mining to provide an insight into practices and procedures followed during various phases of a software development life cycle. We mine the event logs produced by the educational software tool and derive aspects such as cooperative behaviors in a team, component and student entropy, process compliance and verification. The proposed visualizations and metrics (learning analytics) provide a multi-faceted view to the academic team serving as a tool for feedback on development process and quality by students

Towards native code offloading platforms for image processing in mobile applications: a case study

In this paper, we present a real-life case study to show the advantages of a new code offloading solution focused on improving both performance and energy consumption for image processing mobile applications. From our experiments, we found that offloading an image processing task would allow up to 5.7x speedup and 85% of reduction in energy consumption for low-end devices, and 1.7x speedup and 64.3% of reduction in energy consumption for high-end devices.

The Essence of REST Architectural Style

There is an increasing interest in understanding and using REST architectural style. Many books and tools have been created but there is still a general lack of understanding its fundamentals as an architecture style. The reason perhaps could be found in the fact that REST was presented in a doctoral dissertation, with relatively high entry barriers for its understanding, or because the description used models that were more oriented towards documentation than to working practitioners.

Web application development: java, .net and lamp at the same time

Web applications are usually built starting from incomplete design documents and proceeding directly to implementation for some specific software platform. The resulting application is usually difficult to change or extend. Although several methodologies have been proposed in the last few years, most of them use a concrete approach that leverages the features of a specific software platform or concrete Web elements. Model-driven development proposals, on the other hand, are difficult to adopt. This paper discusses a successful intermediate approach that allows the designer to work with abstract artifacts that can be readily mapped into any MVC-based (application) framework, independently of which software platform is used. This methodology is simple and easy to learn, even by those who are not platform experts. We present it in terms of a real-life running application for use by local governments in Chile.

Web applications: a simple pluggable architecture for business rich clients

During the past decade we have been witnesses of the rise of the Web Application with a browser based client. This brought us ubiquitous access and centralized administration and deployment, but the inherent limitations of the approach however, and the availability of new technologies like XML and Web Services has made people start building rich clients as business applications front ends. But very often these applications are tied to the development tools and very hard to extend. We propose a clean and elegant architecture which considers a plugin based approach as a general solution to the extensibility problem. The approach is demonstrated by refactoring a simple application taken from a public forum into the proposed architecture including two new extensions that are implemented as plugins.

Code offloading solutions for audio processing in mobile healthcare applications: a case study

In this paper, we present a real-life case study of a mobile healthcare application that leverages code offloading techniques to accelerate the execution of a complex deep neural network algorithm for analyzing audio samples. Resource-intensive machine learning tasks take a significant time to complete on high-end devices, while lower-end devices may outright crash when attempting to run them. In our experiments, offloading granted the former a 3.6x performance improvement, and up to 80% reduction in energy consumption; while the latter gained the capability of running a process they originally could not.