2014
Autores
Campos, F; Matos, M; Pereira, J; Rua, D;
Publicação
14-TH IEEE INTERNATIONAL CONFERENCE ON PEER-TO-PEER COMPUTING (P2P)
Abstract
Important challenges in interoperability, reliability, and scalability need to be addressed before the Smart Grid vision can be fulfilled. The sheer scale of the electric grid and the criticality of the communication among its subsystems for proper management, demands a scalable and reliable communication framework able to work in an heterogeneous and dynamic environment. Moreover, the need to provide full interoperability between diverse current and future energy and non-energy systems, along with seamless discovery and configuration of a large variety of networked devices, ranging from the resource constrained sensing devices to servers in data centers, requires an implementation-agnostic Service Oriented Architecture. In this position paper we propose that this challenge can be addressed with a generic framework that reconciles the reliability and scalability of Peer-to-Peer systems, with the industrial standard interoperability of Web Services. We illustrate the flexibility of the proposed framework by showing how it can be used in two specific scenarios.
2014
Autores
Paulo, J; Pereira, J;
Publicação
ACM COMPUTING SURVEYS
Abstract
The automatic elimination of duplicate data in a storage system, commonly known as deduplication, is increasingly accepted as an effective technique to reduce storage costs. Thus, it has been applied to different storage types, including archives and backups, primary storage, within solid-state drives, and even to random access memory. Although the general approach to deduplication is shared by all storage types, each poses specific challenges and leads to different trade-offs and solutions. This diversity is often misunderstood, thus underestimating the relevance of new research and development. The first contribution of this article is a classification of deduplication systems according to six criteria that correspond to key design decisions: granularity, locality, timing, indexing, technique, and scope. This classification identifies and describes the different approaches used for each of them. As a second contribution, we describe which combinations of these design decisions have been proposed and found more useful for challenges in each storage type. Finally, outstanding research challenges and unexplored design points are identified and discussed.
2014
Autores
Campos, F; Pereira, J;
Publicação
CoRR
Abstract
2014
Autores
Martins, MA; Madeira, A; Barbosa, LS; Neves, R;
Publicação
2014 IEEE 15TH INTERNATIONAL CONFERENCE ON INFORMATION REUSE AND INTEGRATION (IRI)
Abstract
As a complex artefact, software has to meet requirements formulated and verified at different levels of abstraction. A basic distinction is drawn between behavioural (dynamic) and data (static) aspects. From an educational point of view, although disguised under a number of different designations, both issues are usually present, but kept separated, in typical Computer Science undergraduate curricula. It is often argued that they tackle orthogonal problems through essentially different methods. This paper explores an alternative path in which students progress from equational to hybrid specifications in a uniform setting, integrating paradigms, combining data and behaviour, and dealing appropriately with systems evolution and reconfiguration.
2014
Autores
Oliveira, N; Silva, A; Barbosa, LS;
Publicação
SAC
Abstract
2014
Autores
Martins, MA; Madeira, A; Barbosa, LS;
Publicação
LOGICAL METHODS IN COMPUTER SCIENCE
Abstract
Stepwise refinement of algebraic specifications is a well known formal methodology for program development. However, traditional notions of refinement based on signature morphisms are often too rigid to capture a number of relevant transformations in the context,at of software design, reuse, and adaptation. This paper proposes a new approach to refinement in which signature morphisms are replaced by logical interpretations as a means to witness refinements. The approach is first presented in the context of equational logic, and later generalised to deductive systems of arbitrary dimension. This allows, for example, relining sentential into equational specifications and the latter into modal ones.
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