Frederico Lopes

An exploratory study of fault-proneness in evolving aspect-oriented programs

This paper presents the results of an exploratory study on the fault-proneness of aspect-oriented programs. We analysed the faults collected from three evolving aspect-oriented systems, all from different application domains. The analysis develops from two different angles. Firstly, we measured the impact of the obliviousness property on the fault-proneness of the evaluated systems. The results show that 40% of reported faults were due to the lack of awareness among base code and aspects. The second analysis regarded the fault-proneness of the main aspect-oriented programming (AOP) mechanisms, namely pointcuts, advices and intertype declarations. The results indicate that these mechanisms present similar fault-proneness when we consider both the overall system and concern-specific implementations. Our findings are reinforced by means of statistical tests. In general, this result contradicts the common intuition stating that the use of pointcut languages is the main source of faults in AOP.

Exploiting software product lines to develop cloud computing applications

With the advance of the Cloud Computing paradigm, new challenges in terms of models, tools, and techniques to support developers to design, build and deploy complex software systems that make full use of the cloud technology arise. In the heterogeneous scenario of this new paradigm, the development of applications using cloud services becomes hard, and the software product lines (SPL) approach is potentially promising for this context since specificities of the cloud platforms, such as services heterogeneity, pricing model, and other aspects can be catered as variabilities to core features. In this perspective, this paper (i) proposes a seamless adaptation of the SPL-based development to include important features of cloud-based applications, and (ii) reports the experience of developing HW-CSPL, a SPL for the Health Watcher (HW) System, which allows citizens to register complaints and consult information regarding the public health system of a city. Several functionalities of this system were implemented using different Cloud Computing platforms, and run time specificities of this application deployed on the cloud were analyzed, as well as other information such as change impact and pricing.

Optimizing services selection in a cloud multiplatform scenario

Services selection is an important challenge for applications that use a composition of services provided by different cloud platforms. This paper presents an optimized cloud services selection approach that evaluates each alternative set of services that composed an execution plan. This approach considers cost and quality parameters for each cloud service in the execution plan, and excludes coincident services in the calculations. Coincident services are those services present in all available execution plans and therefore equally contribute in the calculations encompassing costs and quality parameters regarding these plans. By excluding coincident services, the service selection process by itself should be performed more quickly since it involves a smaller number of services, but with the trade-off of running an additional algorithm for identifying the coincident services among the available ones. In order to evaluate such trade-off and illustrate the proposed approach, we present a case study and an experimental evaluation that compares our new approach with a previous one that considers all services that compose all available execution plans.

Cloud Integrator: Building Value-Added Services on the Cloud

With the advance of the Cloud Computing paradigm, a single service offered by a cloud platform may not be enough to meet all the application requirements. To fulfill such requirements, it may be necessary, instead of a single service, a composition of services that aggregates services provided by different cloud platforms. In this perspective, this work presents Cloud Integrator, a middleware platform for composing services provided by different Cloud Computing platforms. Composition is performed by considering metadata about the services such as QoS, prices etc. By integrating the complementary paradigms of Service-Oriented Computing and Cloud Computing, Cloud Integrator enables the use of services provided by providers in a transparent way for the user, being necessary solutions for publishing, discovering, and composing these services. In terms of cloud infrastructure, Cloud Integrator lies in the PaaS layer, allowing HaaS, SaaS and DaaS resources to be available for the users so that they can build applications consisting of the composition of services provided by these platforms. In this paper, the application of Cloud Integrator is illustrated using a simple cloud-based e-commerce application.

ROTA: A Smart City Platform to Improve Public Safety

This paper describes how the City of Natal in Brazil has been implementing technological systems in the context of public safety to transform itself into a smart city. In particular, this paper presents a smart city platform, named ROTA, that is able to collect, integrate, analyze and share sensitive information regarding citizens and patrol vehicles. A mobile application was developed to assess the feasibility of the proposed platform. Both platform and mobile application have been fully operational since 2014 and added value to the operational policing by providing a technological tool in the hands of patrol supervisors, providing precise and critical information that helps them in their duties.

A smart city initiative: The case of Natal

This paper describes the Natal Smart City initiative, a bottom-up approach to make Natal, a city in Northeastern Brazil, smarter through decentralized initiatives and gradual implementation of successive projects. Such an initiative is hereby described by making use of a well-known problem-oriented roadmap, defining stages and steps to make the city smarter. Some initial results are presented in terms of city connectivity, skill workforce development, innovation network and city resource management. Finally, a set of applications and platforms created by the initiative are described, such as: public safety, non-emergency services, open data, social media and tourism.

Handling Exceptional Conditions in Mobile Collaborative Applications: An Exploratory Case Study

The incorporation of exception handling strategies in mobile collaborative applications bring several challenges to middleware designers due to their intrinsic characteristics of openness, context-awareness, lack of structuring, asynchrony, and increased unpredictability. Publish-subscribe middleware systems are often referred as one of the most common solutions to support the construction of mobile collaborative applications. However, there is no systematic study dedicated to investigate to what extent publish-subscribe mechanisms provide proper support for introducing exception handling strategies into such mobile systems. This paper presents a case study where we have analyzed: (i) the problems emerging from the incorporation of application-specific error handling in a prototype context-aware mobile system from the health care domain, and (ii) the feasibility of a typical publish-subscribe middleware system, called MoCA, to implement the features of an exception handling mechanism tailored to specific requirements of mobile collaborative applications. This paper also discusses the suitability of existing mechanisms recently proposed in the literature to address the identified shortcomings

Context-based heterogeneous middleware integration

The use of context provision middleware is a promising approach to deal with the low-level functions involved in handling contextual events when building ubiquitous applications. Several middleware are currently available that provide support for context handling, each one adopting different models both to interact with applications and to represent contextual data. We present OpenCOPI (Open COntext Platform Integration), a platform that integrates several context provision middleware systems, providing a unified ontology-based context service for ubiquitous applications. OpenCOPI encapsulates the underlying middleware platforms and represents them as services to be provided to client applications thus facilitating the development of ubiquitous applications. This paper presents the OpenCOPI architecture, main implementation issues, and a case study that discusses the use of OpenCOPI in a ubiquitous scenario.

Improving public safety at fingertips: A smart city experience

Nowadays, we are in the century of cities: there are more people living in the cities than in the countryside. In general, overpopulated cities around the world have common problems in several areas, such as city administration, education, health care, public safety, transportation, utilities, etc. In the particular case of Brazil, one of the major problems of cities is the high level of violence. This paper describes how the Brazilian city of Natal is implementing technological systems in the context of public safety to transform itself into a smart city, as a cooperation between university and government secretariat. More specifically, the paper presents ROTA, a smart city platform aiming at contributing to improve public safety. We also hereby describe a robust, scalable mobile application that fulfills the communication gap between control room and field personnel, as well as a Web dashboard intended to support data analysis and statistics about occurrences.

AdaptUbiFlow: Selection and Adaptation in Workflows for Ubiquitous Computing

Ubiquitous environments still suffer from low availability given that any device may fail and it is hard to replace a failed element. In this paper we present AdaptUbiFlow (Adaptive Ubiquitous Workflow), an OpenCOPI´s element that aims to increase the availability of an ubiquitous system. When a device fails, AdaptUbiFlow supports the automatic reconfiguration of the system replacing the failed device (or service) by an equivalent one, this makes the system fault-tolerant without the need of any manual intervention. The replacing of a device/service is chosen taking into account not only the QoS and QoC (Quality of Context) provided but also the applications execution flow to ensure that the best adaptation option will be chosen. AdaptUbiFlow evaluation showed encouraging results.