Most common object models of distributed object systems have a limited set of object-oriented features, lacking the advanced features of `polymorphism' (an abstraction mechanism that represents a quality or state of being able to assume different forms) and `concurrency' (the ability to have more than one thread of execution in an object simultaneously). The lack of support for advanced features is a serious limitation because it restricts the development of new components and limits reuse of existing of components that use these advanced features. As a result, wrappers must be used that hide the advanced features or components must be re-implemented using only the features of the common object model. In this dissertation, a new direction of research centered on a subset of object-oriented languages, specifically statically typed languages, is considered. One of the major drawbacks of existing distributed object systems is that they cater to a broad domain of programming languages including both object-oriented as well as non object-oriented languages. Mapping an object model into a non object-oriented language is a complex task and it does not appear natural to a native language user. The interoperable common object model (ICOM) proposed in this dissertation is an attempt to elevate common object models (with the advanced features of polymorphism and concurrency) closer to the object models of statically typed object-oriented languages. Specific features of the ICOM object model include: remote inheritance, method overloading, parameterized types, and guard methods. The actor model and reflection techniques are used to develop a uniform implementation framework for the ICOM object model in C++ and Modula-3. Prototype applications were implemented to demonstrate the utility of the advanced features of the ICOM object model. The main contributions of this dissertation are: design and implementation of a powerful common object model, an architecture for distributed compilation, and an implementation of a distributed object model using the actor model. / Ph. D.

ITC/USA 2008 Conference Proceedings / The Forty-Fourth Annual International Telemetering Conference and Technical Exhibition / October 27-30, 2008 / Town and Country Resort & Convention Center, San Diego, California / The integrated Network Enhanced Telemetry (iNET) and Test and Training Enabling Architecture (TENA) projects are working to understand how TENA will perform in a Telemetry Network System. This paper discusses a demonstration prototype that is being used to investigate the use of TENA across a constrained test environment simulating iNET capabilities. Some of the key elements being evaluated are throughput, latency, memory utilization, memory footprint, and bandwidth. The results of these evaluations will be presented. Additionally, the paper briefly discusses modeling and metadata requirements for TENA and iNET.

Today’s software engineering and application development trend is to take advantage of reusable software. Much effort is directed towards easing the task of developing complex, distributed, network based applications with reusable components. To ease the task of the distributed systems’ developers, one can use middleware, i.e. a software layer between the operating system and the application, which handles distribution transparently. A crucial feature of distributed server applications is high availability. This implies that they must be able to continue activity even in presence of crashes. Embedding fault tolerance mechanisms in the middleware on top of which the application is running, offers the potential to reduce application code size thereby reducing developer effort. Also, outage times due to server crashes can be reduced, as failover is taken care of automatically by middleware. However, a trade-off is involved: during periods with no failures, as information has to be collected for the automatic failover, client requests are serviced with higher latency. To characterize the real benefits of middleware, this trade-off needs to be studied. Unfortunately, to this date, few trade-off studies involving middleware that supports fault tolerance with application to realistic cases have been conducted. The contributions of the thesis are twofold: (1) insights based on empirical studies and (2) a theoretical analysis of components in a middleware equipped with fault tolerance mechanisms. In connection with part (1) the thesis describes detailed implementation of two platforms based on CORBA (Common Object Request Broker Architecture) with fault tolerance capabilities: one built by following the FT-CORBA standard, where only application failures are taken care of, and a second obtained by implementing an algorithm that ensures uniform treatment of infrastructure and application failures. Based on empirical studies of the availability/performance trade-off, several insights were gained, including the benefits and drawbacks of the two infrastructures. The studies were performed using a realistic (telecommunication) applicationset up to run on top of both extended middleware platforms. Further, the thesis proposes a technique to improve performance in the FT-CORBA based middleware by exploiting application knowledge; to enrich application code with fault tolerance mechanisms we use aspect-oriented programming. In connection with part (2) the thesis models elements of an FT-CORBA like architecture mathematically, in particular by using queuing theory. The model is then used to study the relation between different parameters. This provides the means to configure one middleware parameter, namely the checkpointing interval, leading to maximal availability or minimal response time.

Component Based Development has emerged as economical, reusable, scalable way of developing enterprise as well as embedded software applications. Testing distributed component based systems is difficult when third party components are being used in the development. Many testing methodologies that have been proposed for testing object oriented programs in the literature are being imported into component domain directly or by tuning them. But testing components involves much manual work due to the lack of information of the component. Middleware architectures like, DCOM(Distributed COM), Jini and CORBA(Common Object Request Broker Architecture) are being used in developing the distributed component applications in different vertical domains. In this thesis, a language- Distributed Object Testing Language(DOTL) for specifying the testing process and generation of distributed testing environment for CORBA based applications has been proposed. The language captures required semantics for specifying dummy servers, clients, controlling the testing process, generation of test cases, activating and deactivating objects. Many existing testing techniques can be specified using the semantics provided by the language. Faults occurring in distributed object systems, in addition to the functional errors, can be identifiable using the tool. The language provides abstract types object, argument to specify variables in the testing environment, and operations dealing with these variables to conducts necessary tests. The DOTL has been implemented on MICO(Mico Is CORBA) orb on Linux OS, with mapping of DOTL to CORBA C++.

Orientador: Walter da Cunha Borelli / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-07-23T08:02:09Z (GMT). No. of bitstreams: 1 Macario_CarlaGeovanadoNascimento_M.pdf: 8704471 bytes, checksum: bee9de6493b42d0139961cb43f32cb24 (MD5) Previous issue date: 1997 / Resumo: Este trabalho propõe uma metodologia alternativa para o desenvolvimento e evolução do AIOA, um software para o gerenciamento e análise de dados experimentais, em desenvolvimento na Embrapa. Esta nova metodologia consiste no uso combinado da técnica OMT (Object Modeling Technique) com a linguagem de especificação formal SOL (Specification and Oescription Language), e apresenta facilidades que produzem ga¿n ANTPOT. H¿os no processo de desenvolvimento de software, como a possibilidade de validação e de simulação do sistema, e também a geração de código para sua prototipação. A partir do modelo de classes proposto pela OMT, passa-se à especificação do sistema em SOL, levando-se em conta na elaboração de ambos os modelos, conceitos como reuso, herança e evolução de sistemas. A validação, a simulação e a geração de código do sistema tornam-se possíveis com o uso da ferramenta CASE SOT1(SOL Oesign Tool - Telelogic, Suécia). É apresentada a evolução do ambiente AIOA centralizado até uma versão distribuída, considerando uma arquitetura cliente-servidor com mecanismo CORBA, bem como exemplos de simulação e de validação destes sistemas / Abstract: The present work proposes an alternative methodology for the development and evolution of AIOA, a software environment for the management and analysis of experimental data, being developed at Embrapa, Brazil. This new technique consists of the combined use of OMT (Object Modeling Technique) with the formal specification language SDL (Specification and Description Language), in its 1992 version SDL-92, presenting strong facilities on the software development process, allowing the validation, simulation and eventual code generation for software prototyping. From the system object model and after mapping to SOL-92, the formal specification is generated considering concepts such as reuse, inheritance, and system evolution. The validation, the simulation and code generation of the system is allowed through the use of the CASE tool SOT (SOL Oesign Tool - Telelogic, Sweden). The specification of the centralized AIOA to its evolution to distributed version are presented, validated and simulated. This is followed up with a specialization and validation of thedistributed AIOA, considering an arquitecture client-server with CORBA mechanism / Mestrado / Telecomunicações e Telemática / Mestre em Engenharia Elétrica

Le fonctionnement visuel est sujet à des modification avec le vieillissement sain. Que ce soit l’identification, le traitement ou la perception d’un stimulus visuel, l’avancée en âge peut s’accompagner d’une altération de la vision. Afin d’investiguer les caractéristiques temporelles du traitement visuel dans le vieillissement sain, la présente étude utilise une tâche de reconnaissance d’images achromatiques d’objets communs à l’aide de la technique d’échantillonnage temporel aléatoire. Cette technique permet de révéler les mécanismes oscillatoires visuels en jeux dans la réalisation d’une tâche perceptive. 32 participants, divisés en deux groupes de 16, soit des jeunes adultes (18 - 35 ans) et des personnes âgées entre 60 et 85 ans ont pris part à l’étude. Les résultats qu’offrent la technique d’échantillonnage temporel sont appelés des images de classification (IC) et montrent la variation de l’efficacité du traitement visuel à travers le temps et dans le domaine temps-fréquence. Pour chacun des domaines, les IC sont également décomposées selon leurs spectres de puissance et de phase par une analyse de Fourier. Les résultats montrent des différences significatives entre les groupes pour les IC temporelles et temps-fréquence. De plus, autant dans le domaine temporel que temps-fréquence, ce sont les spectres de phase qui se distinguent significativement entre les deux groupes alors que les spectres de puissance des IC ne diffèrent pas. Il apparaît donc que les mécanismes oscillatoires en jeu pour la réalisation de la tâche de reconnaissance d’objets sont différents d’un groupe à l’autre. Spécifiquement, il s’agirait de la chronologie de leur engagement dans la tâche qui diffère. / Visual function is subject to some modifications with healthy aging. Whether it is the identification, processing, or perception of a visual stimulus, advancing age can be accompanied by an alteration of vision. To investigate the temporal characteristics of visual processing in healthy aging, the present study uses a recognition task of achromatic images of common object using the random temporal sampling technique. This technique reveals the visual oscillatory mechanisms at play in the realization of a perceptual task. 32 participants, divided into two groups of 16, young adults (18-35 years old) and elderly between 60 and 85 years old took part in this study. The results of the temporal sampling technique are called classification images (CI) and show the variation of visual processing efficiency across time and time-frequency domain. For each domain, CIs were also decomposed according to their power and phase spectra by Fourier analysis. The results show significant differences between groups for the time and time-frequency CIs. In addition, both in the time and time-frequency domains, it is the phase spectra that differ significantly between groups whereas the power spectra do not differ. It thus appears that the oscillatory mechanisms involved in carrying out object recognition are different from one group to another. Specifically, it is the timing of the engagement of these oscillatory mechanisms that differs between groups.

Made available in DSpace on 2016-06-02T19:06:00Z (GMT). No. of bitstreams: 1 4732.pdf: 3415662 bytes, checksum: 0b118a8a41e64b0a67c7b0956df6d970 (MD5) Previous issue date: 2012-09-12 / Universidade Federal de Sao Carlos / Immersive, interactive, and collaborative distributed applications, due to their real time and multi-platform characteristics, require a monitoring structure of their functionalities during the development period, which is not fully available in the current monitoring systems, which are usually specific of the languages and platforms in which they are made available. Monitoring systems that require synchronism of distributed objects during the processing is a complex task. Especially in distributed systems from multi-projection where timing is critical to its operation. It is often difficult to check the correct execution of the system. It might be useful for developers and users of such systems to have the ability of identifying, for example, if the reason for the system delay is due to the abusive use of a resource or due to programming mistakes; the identification of which object has crashed, compromising the system as a whole. Distributed object systems, also known as SOA (Service Oriented Architecture), generally use middleware of the broker type in their infrastructure and can have a dynamic number of connected clients or servers when running. There are, in the literature, several tools for the monitoring of performance, resources, debugging, and support, among others, of such systems. Nevertheless, the tools available in the literature are limited to programming languages or platforms that are able to process the monitoring agents related to them. In this work, a tool for the monitoring of distributed object systems is proposed, based on communication described in XML documents, which allows language and platform independence in the such systems development. A structure for the design of tools for the monitoring of distributed object systems is proposed, based on communication described in XML documents, which allows language and platform independence in the such systems development. In addition to the structure that is theoretically founded, the conception of a tool is structured in the manner described and proven in monitoring data from a case study. / Aplicações Distribuídas Imersivas, Interativas e Colaborativas, dadas suas características de tempo real e multiplataformas, demandam uma estrutura de monitoramento de suas funcionalidades, não plenamente disponíveis nos sistemas atuais de monitoramento, em geral específicos das linguagens e plataformas em que são disponibilizadas. Monitorar sistemas que necessitam de sincronismo no processamento de objetos distribuídos é uma tarefa complexa. Principalmente em sistemas distribuídos e de multiprojeção, onde o sincronismo é fundamental para seu funcionamento. Muitas vezes, é difícil apurar o correto funcionamento dos mesmos. Pode ser útil a desenvolvedores e usuários de tais sistemas a capacidade de se identificar, por exemplo, se a lentidão do sistema está sendo ocasionada por: uso abusivo de um recurso; por um erro na programação de um objeto ou; a identificação de qual objeto travou, comprometendo o sistema como um todo. Sistemas de objetos distribuídos, também conhecidos como SOA (Service Oriented Archtecture), geralmente utilizam mediadores do tipo broker em sua infraestrutura e podem ter um número dinâmico de clientes ou servidores conectados quando estão em execução. Existem na literatura diversas ferramentas destinadas ao monitoramento de performance, recursos, depuração, auxílio, manutenção de tais sistemas, etc. Porém, as ferramentas encontradas na literatura são restritas a linguagens ou plataformas que possam processar os agentes de monitoramento vinculados às mesmas. Neste trabalho, é proposta uma estrutura para a concepção de ferramentas para o monitoramento de sistemas de objetos distribuídos baseados em comunicações descritas em documentos XML, o que permite independência de linguagem ou plataforma na concepção de tais sistemas. Além da estrutura que é teoricamente fundamentada, a concepção de uma ferramenta nos moldes estruturados é descrita e provada no monitoramento de um estudo de caso.