Tarcisio da Rocha

Bio: Tarcisio da Rocha is an academic researcher from State University of Campinas. The author has contributed to research in topics: Database transaction & Adaptation (computer science). The author has an hindex of 2, co-authored 5 publications receiving 13 citations.

Promoting levels of openness on component-based adaptable middleware

Abstract: It is widely accepted that middleware is an important architectural element which facilitates the development of software systems. In this paper we propose a novel approach for designing middleware. It is based on hardware motherboards and two distinct views with a clear separation of concerns. The view for middleware designer (MD-view) is concerned with all complex details of middleware structure and the view for middleware users (MU-view) is only concerned with an abstract set of open architectural elements that can be used to customize the middleware.

Um sistema de transações adaptavel para o ambiente de comunicação sem fio

Abstract: Recentes avancos nas tecnologias de telecomunicacao e de dispositivos de computacao portateis possibilitaram o surgimento da Computacao Movel. Assim, dispositivos como laptops e PDA?s equipados com interfaces de comunicacao sem fio ganharam a capacidade de participar de computacoes distribuidas mesmo estando em movimento ou desconectados. Apesar da computacao movel ser muito atraente, ela impoe uma serie de obstaculos aos sistemas distribuidos. Dentre estes obstaculos esta a baixa largura de banda das redes de comunicacao sem fio, desconexoes inesperadas e escassez de recursos do dispositivo de computacao movel (como energia e espaco em disco). Diante deste contexto, esta dissertacao apresenta um sistema de transacoes que possui a capacidade de adaptacao diante dos obstaculos impostos pelo ambiente de comunicacao sem fio. Esta adaptacao e obtida atraves da colaboracao entre as transacoes e um sistema de apoio. O sistema de apoio e responsavel pelo monitoramento dos recursos do ambiente, por notificar as transacoes sobre as mudancas ocorridas no ambiente e por prover mecanismos de adaptacao as transacoes. Cada transacao pode reagir as mudancas ocorridas no ambiente de acordo com a sua politica de adaptacao. Basicamente, os mecanismos de adaptacao providos pelo sistema sao os modos de operacao e os niveis de isolamento. Para a validacao do modelo proposto, esta dissertacao apresenta tambem um prototipo que foi implementado usando as tecnologias Java e CORBA Abstract

Serviços de transação abertos para ambientes dinamicos

Abstract: Tecnicas de processamento de transacoes tem sido de grande importancia no que diz respeito a preservacao da correcao em diversas areas da computacao. Devido a funcoes como, garantir a consistencia de dados, a recuperacao de falhas e o controle de concorrencia, transacoes sao consideradas blocos de construcao apropriados para a estruturacao de sistemas confiaveis. Contudo, desenvolver tecnicas de apoio a transacoes para ambientes dinamicos pode ser uma tarefa complexa. O primeiro obstaculo esta no proprio dinamismo - a disponibilidade de recursos pode variar inesperadamente. Isso pode causar dois efeitos diretos: altas taxas de cancelamento de transacoes e grandes atrasos na execucao das tarefas transacionais. O segundo obstaculo esta na crescente flexibilizacao do conceito de transacao. Isso ocorre porque os requisitos transacionais exigidos pelas aplicacoes atuais estao se tornando mais variados, indo al´em das propriedades tradicionalmente definidas para uma transacao. Nesse contexto, esta tese aborda a viabilizacao de servicos de transacoes abertos, ou seja, capazes de terem sua estrutura e comportamento configurados pelos programadores de aplicacoes como um meio de atender a requisitos especificos do dominio de suas aplicacoes. Como parte desse estudo foi proposto um modelo que abstrai alguns elementos arquiteturais como jumpers, slots e demultiplexadores que podem ser usados na especificacao de pontos de configuracao em servicos de transacao. Esse modelo e implementado como uma camada acima de um modelo de componentes existente. Com isso, desenvolvedores de servicos de transacao passam a contar com esses elementos abertos alem daqueles disponibilizados por abordagens tradicionais baseadas em componentes. Para confirmar os beneficios em usabilidade, flexibilidade e extensao, esta tese apresenta dois servicos de transacao abertos que foram especificados com base no modelo proposto. O primeiro servico faz parte de uma plataforma de transacoes adaptavel para ambientes de computacao movel. O segundo servico faz parte de um sistema que prove adaptacao dinamica de protocolos de efetivacao (commit) de transacoes. Segundo os testes realizados, a abordagem apresentada nesta tese trouxe a esses servicos a capacidade de atender requisitos de aplicacoes de diferentes dominios. Abstract

Adaptation Mechanisms for Transactions in Mobile Computing Environments

Abstract: Advances in wireless communication technologies and portable computers have turned mobile computing into a reality. These environments are characterized by a high dynamism that can hamper the execution of applications. This paper presents a set of adaptation mechanisms that can be used within a transaction context to overcome the high dynamism and resource restrictions of the mobile environment. Three adaptation mechanisms were proposed: isolation level, operation mode and transaction mobility.

A CORBA-Based Transaction System for the Wireless Communication Environment

Abstract: This paper introduces a transaction system for the wireless communication environment. Its main feature is providing flexibility and collaborative adaptation. In this type of adaptation the underlying system and applications have different responsibilities. The system is responsible for monitoring resources and notifying transactions about changes in the environment. Transactions can then react properly to these changes. Two aspects are considered: isolation level and operation mode. Moreover, the paper describes the architecture and a prototype based on CORBA.

Modèles de conception et d'exécution pour la médiation et l'intégration de services

Abstract: Les systemes logiciels s'orientent vers des environnements de plus en plus heterogenes et dynamiques. Cette evolution est induite par differents facteurs : explosion des dispositifs embarques avec de fortes capacites de calcul, adoption rapide des services distants fournis par des tiers, mobilite des usagers et evolution du contexte associe, etc. Ces facteurs ouvrent de grandes possibilites pour la construction de nouveaux services numeriques dans des domaines aussi divers que la sante, le divertissement, la domotique, ou encore le transport. Ces nouveaux domaines d'applications demandent la mise en œuvre des operations d'integration dans des contextes dynamiques et heterogenes. Il est aujourd'hui admis que les approches a services facilitent l'integration logicielle par la definition de protocoles standard de decouverte et de liaison. La problematique d'integration, au sens mediation, reste neanmoins entiere. Le probleme principal aborde par cette these est l'integration de services dans des contextes heterogenes et dynamiques. Plus precisement, nous avons concu un modele a composant specifique a l'integration logicielle, nomme CILIA. Ce modele repose sur des composants, appeles mediateurs, et sur un langage d'assemblage de ces mediateurs. CILIA reprend les grands principes du Genie Logiciel tels que l'abstraction, la separation de preoccupations et la modularite, et s'appuie sur des patrons d'integration bien connus (Enterprise Integration Patterns). CILIA est implante sous la forme d'un framework dynamique qui permet la mise a jour a l'execution des solutions d'integration. Ce framework CILIA est pleinement operationnel et disponible en open source. Il est utilise dans plusieurs projets collaboratifs.

A reflective framework for mediation applications

Abstract: The highly evolutionary aspect of new application domains, such as pervasive computing, demands new and more adaptable integration solutions. Those solutions should be flexible enough to be modified at runtime and should provide information about its structure and behavior. This paper presents additions made to the Cilia mediation framework[9] in order to built adaptable mediation applications. More precisely, we add reflection capabilities to obtain information about the architectural structure, and the system behavior at runtime. The presented approach shows how it is possible to built such adaptable applications and, in particular, analyze the impact of introspect application behavior and architecture reconfigurations on-the-fly.

Atomic commit protocols, their integration, and their optimisations in distributed database systems

Abstract: Advanced software application systems commonly execute atop multiple interconnected computing platforms. Regardless of whether the underlying platforms being homogeneous or heterogeneous, such systems require basic reliability guarantees to ensure deterministic outcomes in the presence of faults. Similar guarantees are provided by database systems through the 'atomicity' property of transactions. In distributed database systems, this property is ensured, across different database sites, by means of 'atomic commit protocols' (ACPs). An ACP guarantees, in spite of possible failures, that each transaction has a deterministic final outcome. This outcome represents either the execution of the transaction as a whole, across all participating sites, or none at all. Thus, it is imperative to trace the problem of atomic commitment in distributed database systems and to highlight its current dimensions as well as its proposed solutions. Such an effort establishes a foundational stage for investigating and developing more elaborate and novel solutions to the problem. These solutions are likely to satisfy the reliability needs of future generations' application systems in a cost-effective manner.

HighFrame: An integrated solution for developing component-based distributed systems

Abstract: The development of distributed systems has become a complex task. An approach that has become widely accepted in this context is the component-based development. However, the effort aimed at developing technical code for component models and remote communications is yet a discouraging obstacle. In this paper we present HighFrame, a framework that provides to developers a high level development solution for component-based distributed systems. The framework is designed to provide automatic generation of components based on code annotations and a graphical planner. This proposal abstracts from developer the complexity of component models, methods of distributed communication and interoperability among different models.