HASLab - Indexed Articles in Conferences

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  • Item
    Worldwide Consensus
    ( 2011) José Orlando Pereira ; Francisco Almeida Maia ; Miguel Marques Matos ; Rui Carlos Oliveira
    Consensus is an abstraction of a variety of important challenges in dependable distributed systems. Thus a large body of theoretical knowledge is focused on modeling and solving consensus within diff erent system assumptions. However, moving from theory to practice imposes compromises and design decisions that may impact the elegance, trade-o ffs and correctness of theoretical appealing consensus protocols. In this paper we present the implementation and detailed analysis, in a real environment with a large number of nodes, of mutable consensus, a theoretical appealing protocol able to o ffer a wide range of trade-o ffs (called mutations) between decision latency and message complexity. The analysis sheds light on the fundamental behavior of the mutations, and leads to the identi cation of problems related to the real environment. Such problems are addressed without ever a ffecting the correctness of the theoretical proposal.
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    Time Series Motifs Statistical Signi cance
    ( 2011) Paulo Jorge Azevedo ; Nuno Constantino Castro
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    Online Spectrum-based Fault Localization for Health Monitoring and Fault Recovery of Self-Adaptive Systems
    ( 2012) Alberto Gonzalez-Sanchez ; Éric Piel ; Rui Maranhão ; Arjan J. C. van Gemund ; Hans-Gerhard Gross
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    A Patterns Based Reverse Engineering Approach for Java Source Code
    ( 2012) José Creissac Campos ; Rui Miguel Couto ; António Nestor Ribeiro
    The ever increasing number of platforms and languages available to software developers means that the software industry is reaching high levels of complexity. Model Driven Architecture (MDA) presents a solution to the problem of improving software development processes in this changing and complex environment. MDA driven development is based on models definition and transformation. Design patterns provide a means to reuse proven solutions during development. Identifying design patterns in the models of a MDA approach helps their understanding, but also the identification of good practices during analysis. However, when analyzing or maintaining code that has not been developed according to MDA principles, or that has been changed independently from the models, the need arises to reverse engineer the models from the code prior to patterns' identification. The approach presented herein consists in transforming source code into models, and infer design patterns from these models. Erich Gamma's cataloged patterns provide us a starting point for the pattern inference process. MapIt, the tool which implements these functionalities is described.
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    Relations as executable specifications: taming partiality and non-determinism using invariants
    ( 2012) Alcino Cunha ; Nuno Moreira Macedo ; Hugo Pereira Pacheco
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    Analysis of FLOSS communities as learning contexts
    ( 2012) Luís Soares Barbosa ; António Cerone ; Sara Santos Fernandes
    It can be argued that participating in Free/Libre Open Source Software (FLOSS) projects can have a positive effect in the contributor's learning process. The need to collaborate with other contributors and to contribute to a project can motivate and implicitly foster learning. In order to validate such statements, it is necessary to (1) study the interactions between FLOSS projects' participants, and (2) explore the didactical value of participating in FLOSS projects, designing an appropriate questionnaire asking FLOSS contributors about their experience in FLOSS projects. In this paper, we illustrate how this questionnaire was designed and disseminated. We conclude the paper with results from 27 FLOSS projects contributors, determining that, not only they contribute and collaborate to the project and its community, but also that FLOSS contributors see that this type of activity can be regarded as a complement to formal education.
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    Serious Game in Security: A Solution for Security Trainees
    ( 2012) Rui Guimarães ; Olga Pacheco ; António Coelho ; Carlos Rebelo
    Serious games have been used with success for training field operatives in tasks where there is a danger of injury or life threatening situations. This paper presents the development of a serious game aimed at the areas of security and safety, supporting the training of specialists through supervised situational scenarios. DDThe training plans involve security against third parties, focusing on social level security at a corporate level, and also safety actions on events such as floods and fires in buildings/facilities. The game provides a 3D virtual environment of the real location/facility to be secured and a multiplayer platform to allow collaborative training and supervising.DD.
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    BRISA: Combining Efficiency and Reliability in Epidemic Data Dissemination
    ( 2012) Valerio Schiavoni ; Rui Carlos Oliveira ; Etienne Riviere ; Miguel Marques Matos ; Pascal Felber
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    MapIt: A Model Based Pattern Recovery Tool
    ( 2012) José Creissac Campos ; António Nestor Ribeiro ; Rui Miguel Couto
    Design patterns provide a means to reuse proven solutions during development, but also to identify good practices during analysis. These are particularly relevant in complex and critical software, such as is the case of ubiquitous and pervasive systems. Model Driven Engineering (MDE) presents a solution for this problem, with the usage of high level models. As part of an effort to develop approaches to the migration of applications to mobile contexts, this paper reports on a tool that identifies design patterns in source code. Code is transformed into both platform specific and independent models, and from these design patterns are inferred. MapIt, the tool which implements these functionalities is described.
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    Hybridisation at work
    ( 2013) Renato Jorge Neves ; Alexandre Castro Madeira ; Martins,MA ; Luís Soares Barbosa
    This paper presents the encoding of the hybridisation method proposed in [MMDB11, DM13] into the Hets platform. © 2013 Springer-Verlag Berlin Heidelberg.
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    Integrating formal and informal learning through a FLOSS-based innovative approach
    ( 2013) Fernandes,S ; Martinho,MH ; Cerone,A ; Luís Soares Barbosa
    It is said that due to the peculiar dynamics of FLOSS communities, effective participation in their projects is a privileged way to acquire the relevant skills and expertise in software development. Such is probably the reason for a number of higher education institutions to include in their Software Engineering curricula some form of contact with the FLOSS reality. This paper explores such a perspective through an on-going case study on university students' collaboration in FLOSS projects. The aim of this research is to 1) identify what should be learnt about software development through regular participation in a FLOSS project/community, and 2) assess the didactic potential of this kind of non-standard learning experiences. To this aim we resorted to a participatory research action approach and qualitative methods, namely case studies combining direct observation and interviews. © Springer-Verlag 2013.
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    Cues for Scent Intensification in Debugging
    ( 2013) Alexandre Campos Perez ; Rui Maranhão
    Information foraging is a theory to understand how people search for information. In this theory, information scent is the perceived likelihood by the "predator" that a cue will lead to a "prey". The better the cues, the better the information scent. In automatic debugging, it is the perceived likelihood that the diagnostic report leads to the cause of failures. In this paper, we detail a visualization, offered by the GZOLTAR toolset, that has the potential to provide better cues. With better we mean providing more information that leads to the fault than, e. g., the source code and code coverage information. The toolset provides a graphical display of the diagnostic reports yielded by well-known debugging techniques. From an information foraging point of view, we argue that the visualization is of added value while debugging. Finally, we report a user study to confirm that GZOLTAR's visualization provides better cues for pinpointing faults.
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    An empirical study on immersive prototyping dimensions
    ( 2013) Moreira,S ; Rui Peixoto José ; José Creissac Campos
    Many aspects of the human experience of ubiquitous computing in built environments must be explored in the context of the target environment. However, delaying evaluation until a version of the system can be deployed can make redesign too costly. Prototypes have the potential to solve this problem by enabling evaluation before actual deployment. This paper presents a study of the design space of immersive prototyping for ubiquitous computing. It provides a framework to guide the alignment between specific evaluation goals and specific prototype properties. The goal is to understand the potential added-value of 3D simulation as a prototyping tool in the development process of ubiquitous computing environments. © 2013 Springer-Verlag.
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    Bisimilarity and refinement for hybrid(ised) logics
    ( 2013) Alexandre Castro Madeira ; Martins,MA ; Luís Soares Barbosa
    The complexity of modern software systems entails the need for reconfiguration mechanisms governing the dynamic evolution of their execution configurations in response to both external stimulus or internal performance measures. Formally, such systems may be represented by transition systems whose nodes correspond to the different configurations they may assume. Therefore, each node is endowed with, for example, an algebra, or a first-order structure, to precisely characterise the semantics of the services provided in the corresponding configuration. Hybrid logics, which add to the modal description of transition structures the ability to refer to specific states, offer a generic framework to approach the specification and design of this sort of systems. Therefore, the quest for suitable notions of equivalence and refinement between models of hybrid logic specifications becomes fundamental to any design discipline adopting this perspective. This paper contributes to this effort from a distinctive point of view: instead of focussing on a specific hybrid logic, the paper introduces notions of bisimilarity and refinement for hybridised logics, i.e. standard specification logics (e.g. propositional, equational, fuzzy, etc) to which modal and hybrid features were added in a systematic way. © A. Madeira, M.A. Martins & L.S. Barbosa.
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    When even the interface evolves ...
    ( 2013) Alexandre Castro Madeira ; Renato Jorge Neves ; Martins,MA ; Luís Soares Barbosa
    This paper extends the authors' previous work on a formal approach to the specification of reconfigurable systems, introduced in [7], in which configurations are taken as local states in a suitable transition structure. The novelty is the explicit consideration that not only the realisation of a service may change from a configuration to another, but also the set of services provided and even their functionality, may themselves vary. In other words, interfaces may evolve, as well.
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    Boilerplates for Reconfigurable Systems: A Language and Its Semantics
    ( 2013) Alexandre Castro Madeira ; Martins,MA ; Luís Soares Barbosa
    Boilerplates are simplified, normative English texts, intended to capture software requirements in a controlled way. This paper proposes a pallet of boilerplates as a requirements modelling language for reconfigurable systems, i.e., systems structured in different modes of execution among which they can dynamically commute. The language semantics is given as an hybrid logic, in an institutional setting. The mild use made of the theory of institutions, which, to a large extent, may be hidden from the working software engineer, not only provides a rigorous and generic semantics, but also paves the way to tool-supported validation.
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    The mobile context framework: Providing context to mobile applications
    ( 2013) Oliveira,L ; António Nestor Ribeiro ; José Creissac Campos
    The spread of mobile devices in modern societies has forced the industry to create software paradigms to meet the new challenges it faces. Some of these challenges are the huge heterogeneity of devices or the quick changes of users' context. In this scenario, context becomes a key element, enabling mobile applications to be user centric and adapt to user requirements. The Mobile Context Framework, proposed in this paper, is a contribution to solve some of these challenges. Using Web servers running on the devices, context data can be provided to web applications. Besides the framework's architecture, a prototype is presented as proof of concept of the platform's potential. © 2013 Springer-Verlag Berlin Heidelberg.
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    Development challenges in web apps for public displays
    ( 2013) Taivan,C ; Andrade,JM ; Jose,R ; Silva,B ; Pinto,H ; António Nestor Ribeiro
    Digital public displays can have a key role in urban ubiquitous computing infrastructures, but they have not yet managed to fill this role. A key step in that direction would be the emergence of an application model for open display networks that would enable anyone to create applications for display infrastructures. In this work, we study the development of web-based applications for public displays. We report on our experience of application development for real world public deployment and also on an experiment with external web developers to assess their ability to create such applications using our own development tools. The results show that the web-based app model can effectively be used in the context of public displays and that web developers are able to leverage upon their expertise to create this type of applications. © Springer International Publishing 2013.
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    MeT: Workload aware elasticity for NoSQL
    ( 2013) Francisco Miguel Cruz ; Francisco Almeida Maia ; Miguel Marques Matos ; Rui Carlos Oliveira ; João Tiago Paulo ; José Orlando Pereira ; Ricardo Pereira Vilaça
    NoSQL databases manage the bulk of data produced by modern Web applications such as social networks. This stems from their ability to partition and spread data to all available nodes, allowing NoSQL systems to scale. Unfortunately, current solutions' scale out is oblivious to the underlying data access patterns, resulting in both highly skewed load across nodes and suboptimal node configurations. In this paper, we first show that judicious placement of HBase partitions taking into account data access patterns can improve overall throughput by 35%. Next, we go beyond current state of the art elastic systems limited to uninformed replica addition and removal by: i) reconfiguring existing replicas according to access patterns and ii) adding replicas specifically configured to the expected access pattern. MeT is a prototype for a Cloud-enabled framework that can be used alone or in conjunction with OpenStack for the automatic and heterogeneous reconfiguration of a HBase deployment. Our evaluation, conducted using the YCSB workload generator and a TPC-C workload, shows that MeT is able to i) autonomously achieve the performance of a manual configured cluster and ii) quickly reconfigure the cluster according to unpredicted workload changes. © 2013 ACM.
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    MapIt: A model based pattern recovery tool
    ( 2013) Rui Miguel Couto ; António Nestor Ribeiro ; José Creissac Campos
    Design patterns provide a means to reuse proven solutions during development, but also to identify good practices during analysis. These are particularly relevant in complex and critical software, such as is the case of ubiquitous and pervasive systems. Model Driven Engineering (MDE) presents a solution for this problem, with the usage of high level models. As part of an effort to develop approaches to the migration of applications to mobile contexts, this paper reports on a tool that identifies design patterns in source code. Code is transformed into both platform specific and independent models, and from these design patterns are inferred. MapIt, the tool which implements these functionalities is described. © 2013 Springer-Verlag.