CORBA vem se tornando o middleware padrão no desenvolvimento de aplicações distribuídas, tornando-as independentes de plataforma e linguagem. Ele tem sido utilizado também em aplicações de tempo real através de sua extensão para tempo real, o RT-CORBA. Apesar desta extensão ter conseguido reduzir vários dos problemas do CORBA no que se refere ao não-determinismo e falta de garantias temporais, ainda há muito estudo na área de mecanismos de escalonamento utilizados. Assim, este trabalho tem por objetivo apresentar uma proposta de escalonamento adaptativo no ambiente Real-Time CORBA. Nesta proposta o período das tarefas é controlado, variando dentro de uma faixa pré-estabelecida com o propósito de reduzir o atraso médio das tarefas da aplicação.

Orientador : Maria Beatriz Felgar de Toledo / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Matematica, Estatistica e Computação Cientifica / Made available in DSpace on 2018-08-03T07:39:05Z (GMT). No. of bitstreams: 1 Hervella_Alvaro_M.pdf: 3926402 bytes, checksum: 06b360ca5dd522549bde3f1ceed97800 (MD5) Previous issue date: 2002 / Resumo: O Serviço de Transações Cooperativas desenvolvido nessa tese visa atender os requisitos de aplicações cooperativas. Para isso, oferece novos modos de tranca mais flexíveis que melhoram a visibilidade entre usuários que trabalham em colaboração, permite a estruturação de aplicações em uma hierarquia de transações que modelam a hierarquia de grupos de trabalho e relaxa a propriedade de atomicidade salvando de forma persistente estados das transações. Esse Serviço é oferecido através de objetos CORBA e foi implementado na linguagem Java utilizando OrbixWeb 3.1 como a plataforma de comunicação / Abstract: The Cooperative Transaction Service developed in this thesis aims at meeting the requirements of cooperative applications. For that, it provides new lock modes to increase the visibility between users that work in collaboration; it allows application structuring as a hierarchy of transactions which models the hierarchy of work groups; and finally it relaxes the atomicity property saving transaction state persistently. This Service is provided by CORBA objects and was implemented in Java using OrbixWeb 3.1 as the underlying communication platform / Mestrado / Mestre em Ciência da Computação

Orientador: Edmundo Roberto Mauro Madeira / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Computação / Made available in DSpace on 2018-08-03T17:46:42Z (GMT). No. of bitstreams: 1 Barros_MariaClaudiaBorges_M.pdf: 784009 bytes, checksum: d002e78a701c5dbdec8f79ba3161d649 (MD5) Previous issue date: 2003 / Mestrado

Orientador: Eleri Cardozo / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-03T18:38:05Z (GMT). No. of bitstreams: 1 Miglinski_CarlosAlexandre_M.pdf: 818232 bytes, checksum: f5bed20dcfe6418c2f06820453b48809 (MD5) Previous issue date: 2003 / Mestrado

Orientadores: Alfredo Goldman vel Lejbman, Islene Calciolari Garcia / Dissertação (mestrado profissional) - Universidade Estadual de Campinas, Instituto de Computação / Made available in DSpace on 2018-08-04T11:56:37Z (GMT). No. of bitstreams: 1 Calabrez_CarlosEduardo_M.pdf: 2809639 bytes, checksum: 25f27e0fd288194f67d158f07bb12e62 (MD5) Previous issue date: 2004 / Resumo: Este trabalho apresenta diversas tecnologias de comunicação entre objetos distribuídos em Java: RMI, RMI-IIOP, CORBA (JavaIDL e JacORB) e JAX-RPC (SOAP). Suas arquiteturas e suas principais características são descritas, assim como exemplos contendo os passos principais para a sua utilização. Em seguida são apresentadas comparações detalhadas do desempenho dessas tecnologias em cenários distintos. Estudos similares demonstraram que RMI obtém um bom desempenho em muitos casos. Este trabalho confirma essa tendência e verifica a diferença de desempenho ao se utilizar as demais tecnologias / Abstract: This work presents several communication technologies for distributed objects in Java: RMI, RMI-IIOP (JavaIDL and JacORB) and JAX-RPC (SOAP). We describe their architectures and main characteristics, and we also present practical examples of their usage. We complete the work with detailed comparisons among these technologies on different scenarios. From previous works we already know that RMI generally outperforms the other technologies, but we also want to verify the performance ratio of the other technologies / Mestrado / Engenharia de Computação / Mestre em Computação

The Swedish field of digital X-ray imaging has since several years relied heavily on distributed information systems and digital storage containers. To ensure accurate and safe radiological reporting, Swedish software-firm eCare AB delivers a system called Feedback—the first and only quality assurance IT support product of its kind. This thesis covers several aspects of the design and implementation of future versions of this software platform. The focus lies on distributed directory services and models for secure and robust data propagation in TCP/IP networks. For data propagation, a new application, InfoBroker, has been designed and implemented to facilitate integration between Feedback and other medical IT support systems. The directory services, introduced in this thesis as the Feedback Directory Services, have been designed on the architectural level. A combination of CORBA and Java Enterprise Edition is suggested as the implementation platform.

The business pressures which companies and organisations encounter are steadily growing. They continuously have to improve their efficiency to keep up with these new developments. One very important aspect in doing so is the reinforced adoption of computer based information systems. This paper focuses on a computer based system which is able to automate everyday business communication between distributed team members. Reliable and confidential message delivery, event notification, the integration of different end devices (mobile phones, PCs etc.) and the message transport across different networks (wireless, wired) have been allocated as the main system requirements. Based on these requirements the performance of two middleware technologies, namely CORBA and Web services, has been compared. The result of this comparison was that both technologies are suited to use for implementing such a system but both too, have strengths and weaknesses in achieving the stated requirements. CORBA for example, due to several supporting, already included services, allows the programmer to concentrate on the application development itself and use these services to ensure reliable and confidential message transmission. Additionally, CORBA is very efficient in using the bandwidth of the underlying communication network, but makes higher demands to the memory space available on clients. This is critical, if clients are mobile devices with limited resources. Web service technology is much more modest than CORBA with respect to the client side memory space, but message transmission requires much more bandwidth. Further one there are no built-in security and reliability services available for Web services, like there are for CORBA. Hence it is up the application programmer to manually implement these features; however he has not necessarily develop everything from scratch but can resort to already existing specifications, still having the freedom of developing specially tailored features. In short could be stated that CORBA is more consequential and consistent and WS technology is more adjustable and flexible.

This work address the adding, removing and upgrading of network elements in a computer network at run-time. This is already accomplished by Sun Microsystems Jini architecture, but we have investigated if it is possible to create a maintenance system that can handle this, using CORBA. We also want the manual intervention to be minimal. We have discovered that it is possible to create such a system, using CORBA, and that this solution also can handle upgrading a network element at run-time. This report outlines the design of this system, realizing automatic run-time network maintenance.

Development of distributed real-time applications, in contrast to best effort applications, traditionally have been a slow process due to the lack of available standards, and the fact that no commercial off the shelf (COTS) distributed object computing (DOC) middleware supporting real-time requirements have been available to use, in order to speed up the development process without sacrificing any quality. Standards and DOC middlewares are now emerging that are addressing key requirements of real-time systems, predictability and efficiency, and therefore, new possibilities such as component decomposition of real-time systems arises. A number of component decomposed architectures of the distributed active real-time database system DeeDS is described and discussed, along with a discussion on the most suitable DOC middleware. DeeDS is suitable for this project since it supports hard real-time requirements and is distributed. The DOC middlewares that are addressed in this project are OMG's Real-Time CORBA, Sun's Enterprise JavaBeans, and Microsoft's COM/DCOM. The discussion to determine the most suitable DOC middleware focuses on real-time requirements, platform support, and whether implementations of these middlewares are available.

Orientador : Maria Beatriz Felgar de Toledo / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Matematica, Estatistica e Computação Cientifica / Made available in DSpace on 2018-08-03T14:52:35Z (GMT). No. of bitstreams: 1 Kasprzak_Gustavo_M.pdf: 3857848 bytes, checksum: fd2d568076f405b873024e893780358a (MD5) Previous issue date: 2003 / Resumo: Sistemas Gerenciadores de Workflow (SGWFs) tradicionais gerenciam instâncias de workflow e suas respectivas atividades de forma independente. Atividades têm, usualmente, granularidade grossa, longa duração e são altamente dependentes dos processos aos quais elas pertencem. Além disso, utilizam em suas execuções aplicações e outros recursos compartilhados (ex., arquivos e bancos de dados). A semântica das atividades, incluindo suas respectivas aplicações e recursos compartilhados, não é conhecida pelo SGWF. Como resultado, é possível que a execução concorrente de atividades de workflow conflitantes gere inconsistências de dados, além de invocações e acessos indevidos a aplicações e recursos. Assim, utilizando o WorkToDo como SGWF de estudo, apresentamos neste trabalho dois mecanismos de sincronização de atividades que permitem a execução de atividades de forma mutuamente exclusiva e a manutenção de requisitos de ordenação entre essas atividades. Apresentamos, ainda, algumas extensões aos mecanismos de detecção e tratamento de falhas de atividades do WorkToDo, de forma a torná-los mais poderosos e robustos / Abstract: Traditional Workflow Management Systems (WfMSs) manage workflow instances and their respective activities in a independent formo Activities usually have coarse granularity, are long-lived and are highly process-dependent. Moreover, they use shared applications and other resources (ex., files and data bases). The semantics of the activities, including their respective applications and shared resources, is not known by the WfMS. As a result, it is possible that the concurrent execution of conflicting workflow activities generates data inconsistencies, in addition to improper invocation and access to applications and resources. Thus, using WorkToDo as the WfMS of study, we present in this work two activity synchronization mechanisms that allow the execution of activities in a mutually exclusive form and the maintenance of ordering requirements between these activities. We still present some extensions to activity failure detectionjhandling mechanisms oí the WorkToDo to make them more powerful and robusto / Mestrado / Ciência da Computação / Mestre em Ciência da Computação