Interest in the Web services (WS) composition (WSC) paradigm is increasing tremendously. A real shift in distributed computing history is expected to occur when the dream of implementing Service-Oriented Architecture ...
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Interest in the Web services (WS) composition (WSC) paradigm is increasing tremendously. A real shift in distributed computing history is expected to occur when the dream of implementing Service-Oriented Architecture (SOA) is realized. However, there is a long way to go to achieve such an ambitious goal. In this paper, we support the idea that, when challenging the WSC issue, the earlier that the inevitability of failures is recognized and proper failure-handling mechanisms are defined, from the very early stage of the composite WS (CWS) specification, the greater are the chances of achieving a significant gain in dependability. To formalize this vision, we present the FENECIA (Failure Endurable Nested-transaction based execution of Composite Web services with Incorporated state Analysis) framework. Our framework approaches the WSC issue from different points of view to guarantee a high level of dependability. In particular, it aims at being simultaneously a failure-handling-devoted CWS specification, execution, and quality of service (QoS) assessment approach. In the first section of our framework, we focus on answering the need for a specification model tailored for the WS architecture. To this end, we introduce WS-SAGAS, a new transaction model. WS-SAGAS introduces key concepts that are not part of the WS architecture pillars, namely, arbitrary nesting, state, vitality degree, and compensation, to specify failure-endurable CWS as a hierarchy of recursively nested transactions. In addition, to define the CWS execution semantics, without suffering from the hindrance of an XML-based notation, we describe a textual notation that describes a WSC in terms of definition rules, composability rules, and ordering rules, and we introduce graphical and formal notations. These rules provide the solid foundation needed to formulate the execution semantics of a CWS in terms of execution correctness verification dependencies. To ensure dependable execution of the CWS, we present
In this paper we look at the application of XML data management support in scientific data analysis workflows. We describe a software infrastructure that aims to address issues associated with metadata management, dat...
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In this paper we look at the application of XML data management support in scientific data analysis workflows. We describe a software infrastructure that aims to address issues associated with metadata management, data storage and management, and execution of data analysis workflows on distributed storage and compute platforms. This system couples a distributed, filter-stream based dataflow engine with a distributed XML-based data and metadata management system. We present experimental results from a biomedical image analysis use case that involves processing of digitized microscopy images for feature segmentation.
Several choices have to be made during the design process of active tag based systems. Since the number of properties that must be decided before production and wide-scale deployment is relatively high, the use of rea...
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ISBN:
(纸本)9781424463138;9781424463145
Several choices have to be made during the design process of active tag based systems. Since the number of properties that must be decided before production and wide-scale deployment is relatively high, the use of real experiments in the design phase may be prohibitive. We propose the use of emulation for performing large-scale experiments with active tag based systems easily and in a repeatable manner. Such experiments can be used to validate the behavior of the system, and to decide the values for various system parameters. We illustrate this approach by experimental results obtained with an emulation framework that we designed and implemented for a pedestrian localization active tag based system.
The techniques of formal experimental design and analysis are powerful tools for scientists and engineers. However, these techniques are currently underused for experiments conducted with computer models. This has mot...
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The techniques of formal experimental design and analysis are powerful tools for scientists and engineers. However, these techniques are currently underused for experiments conducted with computer models. This has motivated the incorporation of experimental design functionality into the Nimrod tool chain. Nimrod has been extensively used for exploration of the response of models to their input parameters;the addition of experimental design tools will combine the efficiency of carefully designed experiments with the power of distributed execution. This paper describes the incorporation of one type of design, the fractional factorial design, and associated analysis tools, into the Nimrod framework. The result provides a convenient environment that automates the design of an experiment, the execution of the jobs on a computational grid and the return of results, and which assists in the interpretation of those results. Several case studies are included which demonstrate various aspects of this approach.
This demonstration shows the implementation of a cooperative and coordinated robotic task in the soccer domain. Two Sony AIBO robots are placed on a soccer field with the task of passing a ball (Figure 1). Initially t...
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This demonstration shows the implementation of a cooperative and coordinated robotic task in the soccer domain. Two Sony AIBO robots are placed on a soccer field with the task of passing a ball (Figure 1). Initially the robots search for the ball, and when they have located it, they exchange their local information about its position. This information is used to decide which robot will pass the ball (i.e. take the Passer role) and which robot will intercept it (i.e. take the Receiver role). The Passer robot reaches the ball, grabs it and turns to the Receiver. In the meanwhile, the Receiver moves to a predefined distance to the Passer. When both the Passer and Receiver robots have completed these tasks, they synchronize and execute, respectively, a pass and an intercept behavior. At the end of the execution, a final synchronization is performed. The robots exchange information about the outcome of the behavior, and they repeat the plan.
We describe a mechanism based on distributed Event-Condition-Action (ECA) rules that supports data coordination in a multidatabase setting. The proposed mechanism includes an ECA rule language and a rule execution eng...
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We describe a mechanism based on distributed Event-Condition-Action (ECA) rules that supports data coordination in a multidatabase setting. The proposed mechanism includes an ECA rule language and a rule execution engine that transforms rules when they are first posted, and then coordinates their execution. Like traditional ECA rules, our ECA rule language has three parts: an event language, a condition language, and an action language. The event language provides a set of operators with a formal semantics for a multidatabase environment, and which allows a wide variety of composite events. The condition language provides Boolean algebra operators that take as operands either composite or simple conditions. The action language provides a conjunction of simple or composite actions. The execution model partitions rules to more easily manageable forms, distributes them to relevant databases, monitors their execution and composes their evaluations. The mechanism has been designed in a manner that minimizes the number of messages that need to be exchanged over the network. We have also conducted an experimental evaluation to compare the implementation with a naive centralized execution model. The paper also presents a prototype implementation as well as experimental results on its performance. This work is part of an on-going project intended to develop data coordination techniques for data sharing settings.
Although instantaneous and free communication simplifies multi-agent partially observable Markov decision processes (POMDPs) to single-agent POMDPs, in practice, communication is not free and reducing the amount of co...
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ISBN:
(纸本)9781424408276
Although instantaneous and free communication simplifies multi-agent partially observable Markov decision processes (POMDPs) to single-agent POMDPs, in practice, communication is not free and reducing the amount of communication is often desirable. We present a novel approach for using a DAG to maintain and reason the possible joint beliefs of the team at the less cost of memory, by which communication decisions are made in a decentralized style. Our algorithm, called DAG-DEC-COMM, makes a tradeoff between the performance achieved by the team and the amount of communication used in planning. The experimental results on the benchmark problem show that our approach drastically reduces the communication with a significant decrease in storing the possible joint beliefs while improving the performance of distributed execution.
As system complexity increases, the role of Model Based Development is more and more important. Several modeling formalisms are widely used when considering the area of hardware-software co-design of embedded systems....
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ISBN:
(纸本)9781424408504
As system complexity increases, the role of Model Based Development is more and more important. Several modeling formalisms are widely used when considering the area of hardware-software co-design of embedded systems. The goal of the work presented in this paper is to contribute for the usage of Petri nets as the system-level specification language. Techniques for system model partitioning into components are a major concern within co-design methodologies. This paper proposes a net operation, called net splitting, able to decompose a Petri net model into Petri net sub-models using synchronous communication channels. The operation is based on the definition of a valid cutting set. Specific rules are presented in order to obtain the sub-models from the initial one. The generated sub-models are associated with components to be executed concurrently, allowing a distributed execution of the initial model. On the other hand, at the implementation level, it is necessary to accommodate a severe deviation on synchronous communication channel execution semantics (as far as the components are in execution in different controllers and zero time delay is not possible to obtain). For some specific situations, initial model properties are not preserved considering execution of components obtained after net splitting operation. Although, it is possible to anticipate the impact of using specific communication channels models at the implementation level. For that end, a second step on property verification is needed in order to validate a specific partitioning solution. An illustrative example applying the referred mechanisms is presented.
Level 2 probabilistic risk assessments of nuclear plants (analysis of radionuclide release from containment) may require hundreds of runs of severe accident analysis codes such as MELCOR or RELAP/SCDAP to analyze poss...
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ISBN:
(纸本)1424404207
Level 2 probabilistic risk assessments of nuclear plants (analysis of radionuclide release from containment) may require hundreds of runs of severe accident analysis codes such as MELCOR or RELAP/SCDAP to analyze possible sequences of events (scenarios) that may follow given initiating events. With the advances in computer architectures and ubiquitous networking, it is now possible to utilize multiple computing and storage resources for such computational experiments. This paper presents a system software infrastructure that will support execution and analysis of multiple dynamic event-tree simulations on distributed environments. The infrastructure will allow for 1) the testing of event tree completeness, and, 2) the assessment and propagation of uncertainty on the plant state in the quantification of event trees.
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