Raju Halder

A considerable amount of effort in software development is dedicated to the user interaction layer.Given the complexity inherent to the development of this layer, it is important to be able to analyse the concepts and ideas being used in the development of a given user interface. This analysis should be performed as early as possible. Model- based user interface development provides a solution to this problem by providing developers with tools that enable both modeling, and reasoning about, user interfaces at different levels of abstraction. Of particular interest here, is the possibility of animating the models to generate actual user interfaces. This paper describes FlexiXML, a tool that performs the rendering and animation of user interfaces described in the UsiXML modeling language.

The use of a plant model for formal verification of Industrial Automation systems controllers is realistic because all automation systems are composed by a controller and a plant. Therefore, if the plant model is not used, there is a part of the system that is not considered. However, if there are some cases where the use of a plant model makes the formal verification results more realistic and robust, there are other cases where this does not always happen. Moreover, the discussion presented in this paper is related with the need of using a Plant Model considering, not all of the Plant Model, but Partial Plant models in order to facilitate formal verification tasks of Industrial Automation Discrete Event Systems Controllers.

É cada vez mais frequente encontrarem-se investigações sobre a usabilidade dos sistemas de E-learning. Como resultados destas investigações, parece ser claro que grande parte delas aponta para a necessidade de uma discussão crítica acerca de métodos para avaliação de usabilidade específicos para os sistemas educativos, nomeadamente, sobre a importância do foco nos métodos direccionados para os utilizadores principais. Entretanto, parece também ser urgente e fundamental investigar a forma com que as análises ergonómicas tem sido aplicadas, assim como, as adaptações necessárias a tais métodos de usabilidade, de modo a definirem-se avaliações mais coerentes com a natureza do sistema. Sendo assim, com base na observação dos sistemas de E-learning - neste artigo será apresentada uma revisão bibliográfica quanto às principais formas de avaliação de usabilidade em sistemas educativos. Como resultado desta revisão, os estudos de Ergonomia levam-nos a considerar possibilidades de análise da usabilidade através de um ponto de vista mais humano, onde se equaciona a influência que o background do utilizador poderá ter sobre a interacção com o sistema e, consequentemente, que atributos de usabilidade serão mais significativos para aquele determinado perfil de utilizador. Neste sentido, o presente estudo pretende argumentar, através de uma visão geral do estado-da-arte, em prol da necessidade e da importância que o investigador deve ter sobre a noção exacta dos instrumentos de que dispõe, por forma a averiguar os dados que o utilizador poderá fornecer-lhe e qual a relevância dos resultados obtidos para a introdução de melhorias no sistema. Ao longo do artigo é efectuada uma discussão sobre métodos qualitativos de avaliação de usabilidade, baseados em experiências com sistemas de E-learning, académicos e/ou comerciais, ao incluir utilizadores com origens em diversos países e culturas. Dito isto, este artigo pretende retratar uma mudança de paradigma de avaliação que tem sido observada nos últimos anos, tanto na área de ergonomia, como na área do design de sistemas educativos.

New data management systems aimed at huge amounts of data, such as those pioneered by Google, Amazon, and Yahoo, have recently motivated a profound revolution in database management. These systems are characterized by simple data and query models and by their relaxed consistency, that contrasts with the ubiquitous and widely known relational and ACID model. These changes, in combination with the absence of a high level language for query and manipulation, make it harder for developers to port applications or to leverage existing know-how. In fact, the major proponents of such technologies are precisely those companies that can employ highly skilled developers.This paper bridges this gap between the common programmer and the increasingly popular Apache Cassandra distributed database by providing an object mapping for the Java language in the style of object-relational mappers that are commonly used with SQL databases. In detail, we describe how the object-relational paradigm can be mapped to the new data model and experimentally evaluate the result with a combination of the standard TPC-W benchmark and a representative application from the telecom industry.

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 different system assumptions. However, moving from theory to practice imposes compromises and design decisions that may impact the elegance, trade-offs 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 offer a wide range of trade-offs (called mutations) between decision latency and message complexity. The analysis sheds light on the fundamental behavior of the mutations, and leads to the identification of problems related to the real environment. Such problems are addressed without ever affecting the correctness of the theoretical proposal.

This paper presents an equational calculus to reason about bidirectional transformations specified in the point-free style. In particular, it focuses on the so-calledlenses as a bidirectional idiom, and shows that many standard laws characterising point-free combinators and recursion patterns are also valid in that setting. A key result is that uniqueness also holds for bidirectional folds and unfolds, thus unleashing the power of fusion as a program optimisation technique. A rewriting system for automatic lens optimisation is also presented, to prove the usefulness of the proposed calculus.

The Devices Profile for Web Services (DPWS) provides the foundation for seamless deployment, autonomous configuration, and joint operation for various computing de- vices in environments ranging from simple personal multimedia setups and home automation to complex industrial equipment and large data centers. In particular, WS-Discovery provides dynamic rendezvous for clients and services embodied in such devices. Unfortunately, failure detection implicit in this standard is very limited, both by embodying static timing assumptions and by omitting liveness monitoring, leading to undesirable situations in demanding application scenarios. In this paper we identify these undesirable outcomes and propose an extension of WS-Discovery that allows failure detection to achieve eventual leader election, thus preventing them.