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Tarcisio Da ,rocha - One of the best experts on this subject based on the ideXlab platform.
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Open Transaction services for dynamic environments
[s.n.], 2018Co-Authors: Tarcisio Da ,rochaAbstract:Orientador: Maria Beatriz Felgar de ToledoTese (doutorado) - Universidade Estadual de Campinas, Instituto de ComputaçãoResumo: Tecnicas de processamento de transações tem sido de grande importancia no que diz respeito a preservação da correção em diversas areas da computação. Devido a funções como, garantir a consistencia de dados, a recuperação de falhas e o controle de concorrencia, transações são consideradas blocos de construção apropriados para a estruturação de sistemas confiaveis. Contudo, desenvolver tecnicas de apoio a transações 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 transações e grandes atrasos na execução das tarefas transacionais. O segundo obstaculo esta na crescente flexibilização do conceito de transação. Isso ocorre porque os requisitos transacionais exigidos pelas aplicações atuais estão se tornando mais variados, indo al'em das propriedades tradicionalmente definidas para uma transação. Nesse contexto, esta tese aborda a viabilização de serviços de transações abertos, ou seja, capazes de terem sua estrutura e comportamento configurados pelos programadores de aplicações como um meio de atender a requisitos especificos do dominio de suas aplicações. Como parte desse estudo foi proposto um modelo que abstrai alguns elementos arquiteturais como jumpers, slots e demultiplexadores que podem ser usados na especificação de pontos de configuração em serviços de transação. Esse modelo e implementado como uma camada acima de um modelo de componentes existente. Com isso, desenvolvedores de serviços de transação passam a contar com esses elementos abertos alem daqueles disponibilizados por abordagens tradicionais baseadas em componentes. Para confirmar os beneficios em usabilidade, flexibilidade e extensão, esta tese apresenta dois serviços de transação abertos que foram especificados com base no modelo proposto. O primeiro serviço faz parte de uma plataforma de transações adaptavel para ambientes de computação movel. O segundo serviço faz parte de um sistema que prove adaptação dinamica de protocolos de efetivação (commit) de transações. Segundo os testes realizados, a abordagem apresentada nesta tese trouxe a esses serviços a capacidade de atender requisitos de aplicações de diferentes dominios.Abstract: Transaction processing techniques are considered important solutions on preserving correctness in several fields of computing. Due their functions such as, failure recovery and concurrency control, Transactions are considered appropriated building blocks for structuring reliable systems. Despite its advantages, to develop Transaction systems for dynamic environments is not an easy task. The first problem is the dynamism - the resource availability can vary unexpectedly. This can cause the following side effects: high Transaction abort rates and relevant delays of Transaction operations. The second problem is the flexibilization of the Transaction Concept. The Transactional requirements are becoming more diversified - they extrapolate the bounds of the traditional Transactional properties. In this context, this thesis approaches the practicability of open Transaction services that can be configured by the application programmers for attending specific requirements of different application domains. This thesis includes a model that abstracts some architectural elements (slots, jumpers and demultiplexers) that can be used for specifying configuration points in Transaction services. To confirm its benefits on usability, flexibility and extension, this thesis presents two open Transaction services that were specified based on the proposed model. The first service is part of an adaptable Transaction platform for mobile computing environments. The second service is part of a system that provides dynamic adaptation of commit protocols. According the accomplished tests, the approach presented in this thesis is able to give to these services the capacity of attending the requirement of applications in different domains.DoutoradoSistemas DistribuidosDoutor em Ciência da Computaçã
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Open Transaction services for dynamic environments
2017Co-Authors: Tarcisio Da ,rochaAbstract:Resumo: Tecnicas de processamento de transações tem sido de grande importancia no que diz respeito a preservação da correção em diversas areas da computação. Devido a funções como, garantir a consistencia de dados, a recuperação de falhas e o controle de concorrencia, transações são consideradas blocos de construção apropriados para a estruturação de sistemas confiaveis. Contudo, desenvolver tecnicas de apoio a transações 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 transações e grandes atrasos na execução das tarefas transacionais. O segundo obstaculo esta na crescente flexibilização do conceito de transação. Isso ocorre porque os requisitos transacionais exigidos pelas aplicações atuais estão se tornando mais variados, indo al´em das propriedades tradicionalmente definidas para uma transação. Nesse contexto, esta tese aborda a viabilização de serviços de transações abertos, ou seja, capazes de terem sua estrutura e comportamento configurados pelos programadores de aplicações como um meio de atender a requisitos especificos do dominio de suas aplicações. Como parte desse estudo foi proposto um modelo que abstrai alguns elementos arquiteturais como jumpers, slots e demultiplexadores que podem ser usados na especificação de pontos de configuração em serviços de transação. Esse modelo e implementado como uma camada acima de um modelo de componentes existente. Com isso, desenvolvedores de serviços de transação passam a contar com esses elementos abertos alem daqueles disponibilizados por abordagens tradicionais baseadas em componentes. Para confirmar os beneficios em usabilidade, flexibilidade e extensão, esta tese apresenta dois serviços de transação abertos que foram especificados com base no modelo proposto. O primeiro serviço faz parte de uma plataforma de transações adaptavel para ambientes de computação movel. O segundo serviço faz parte de um sistema que prove adaptação dinamica de protocolos de efetivação (commit) de transações. Segundo os testes realizados, a abordagem apresentada nesta tese trouxe a esses serviços a capacidade de atender requisitos de aplicações de diferentes dominios.Abstract: Transaction processing techniques are considered important solutions on preserving correctness in several fields of computing. Due their functions such as, failure recovery and concurrency control, Transactions are considered appropriated building blocks for structuring reliable systems. Despite its advantages, to develop Transaction systems for dynamic environments is not an easy task. The first problem is the dynamism - the resource availability can vary unexpectedly. This can cause the following side effects: high Transaction abort rates and relevant delays of Transaction operations. The second problem is the flexibilization of the Transaction Concept. The Transactional requirements are becoming more diversified - they extrapolate the bounds of the traditional Transactional properties. In this context, this thesis approaches the practicability of open Transaction services that can be configured by the application programmers for attending specific requirements of different application domains. This thesis includes a model thatAbstracts some architectural elements (slots, jumpers and demultiplexers) that can be used for specifying configuration points in Transaction services. To confirm its benefits on usability, flexibility and extension, this thesis presents two open Transaction services that were specified based on the proposed model. The first service is part of an adaptable Transaction platform for mobile computing environments. The second service is part of a system that provides dynamic adaptation of commit protocols. According the accomplished tests, the approach presented in this thesis is able to give to these services the capacity of attending the requirement of applications in different domain
Reda Salama - One of the best experts on this subject based on the ideXlab platform.
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Database Support for Synchronous Collaboration in the Web
2008Co-Authors: Jens Thamm, Stephan Wilke, Lutz Wegner, Reda SalamaAbstract:Abstract: The ubiquitous nature of the World Wide Web provides the ideal framework for spontaneous collaboration of disjoint users. However, for Computer Supported Collaborative Work (CSCW) to actually function in the Web, added coordination is needed. Firstly, a globally consistent state of the data must be maintained through some extended Transaction Concept. This is typically the task of a database system. Secondly, a suitable engine at the client side must permit setting a focus on the shared data. Any concurrent activities of other users which happen to stretch into a user’s viewport must also be made visible. Finally, the client must provide mechanisms for moving among the data (objects), for concurrency awareness, and for manipulation of the data. Clearly, such an approach goes beyond the groupware solutions which are based on whiteboard and telepointer methaphers, as they seldom allow immersion into a structured object space. Here, we present a complete and detailed description of a very compact, yet extensible solution to this task. It consists of a standard Web browser with Tcl plug-in and an extremely small applet (less than 3 KB) as interface generator on the client side. On the server side we employ an object-relational database engine wrapped by a Tcl-based command interpreter for a navigational language. Server and client communicate via stream sockets. Other client-side solutions, e.g. ones based on Java, are discussed
Gustavo Alonso - One of the best experts on this subject based on the ideXlab platform.
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exception handling in workflow management systems
IEEE Transactions on Software Engineering, 2000Co-Authors: Claus Hagen, Gustavo AlonsoAbstract:Fault tolerance is a key requirement in process support systems (PSS), a class of distributed computing middleware encompassing applications such as workflow management systems and process centered software engineering environments. A PSS controls the flow of work between programs and users in networked environments based on a "metaprogram" (the process). The resulting applications are characterized by a high degree of distribution and a high degree of heterogeneity (properties that make fault tolerance both highly desirable and difficult to achieve). We present a solution for implementing more reliable processes by using exception handling, as it is used in programming languages, and atomicity, as it is known from the Transaction Concept in database management systems. We describe the mechanism incorporating both Transactions and exceptions and present a validation technique allowing to assess the correctness of process specifications.
Frank Leymann - One of the best experts on this subject based on the ideXlab platform.
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supporting business Transactions via partial backward recovery in workflow management systems
BTW, 1995Co-Authors: Frank LeymannAbstract:Workflow management systems are used today to realize advanced, distributed application systems, e.g. to support and control real world business processes like office procedures. With the increase of sophistication of these application systems a flexible Transaction Concept is required to be added to the workflow management system. Business processes exploiting such advanced Transaction features are often referred to as “business Transactions„. We propose to support business Transactions by compensation based partial backward recovery of the control flow within an instance of a business process. Work units of a business process which are defined to be potentially subject to such kind of recovery are introduced as “spheres of joint compensation„ For the workflow management system IBM FlowMark we show in detail how its metcunodel can be extended to support spheres of joint compensation.
Jan Peciva - One of the best experts on this subject based on the ideXlab platform.
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active Transaction approach for collaborative virtual environments
International Conference on Virtual Reality, 2006Co-Authors: Jan PecivaAbstract:Active Transactions is a novel approach for Collaborative Virtual Environments (CVE). It is based on the Transaction Concept from database systems, however it was adapted to fit better the requirements of CVE.The Transactions brings new benefits for CVE. They guarantee atomic execution of their updates. They provide advanced consistency guarantees that may result in simpler application design, and the speculative Transaction execution enables to exploit prediction algorithms to provide an user with high responsiveness.The Transaction Concept is combined with active replication of the scene data. Active replication enables some performance optimizations of the Transaction Concept. Therefore, we call it active Transaction approach.