Next-generation distributedinteractivesimulations have stringent quality of service (QoS) requirements for throughput, latency, and scalability, as well as requirements for a flexible communication infrastructure to...
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ISBN:
(纸本)076950616X
Next-generation distributedinteractivesimulations have stringent quality of service (QoS) requirements for throughput, latency, and scalability, as well as requirements for a flexible communication infrastructure to reduce software lifecycle costs. The CORBA Event Service provides a flexible model for asynchronous communication among distributed and collocated objects. However, the standard CORBA Event Service specification lacks important features and QoS optimizations required by distributedinteractivesimulation systems. This paper makes five contributions to the design, implementation and performance measurement of distributedinteractivesimulation systems. First, it describes how the CORBA Event Service can be implemented to support key QoS features. Second, it illustrates how to extend the CORBA Event Service so that it is better suited for distributedinteractivesimulations. Third, it describes how to develop efficient event dispatching and scheduling mechanisms that can sustain high throughput. Fourth, it describes how to use multicast protocols to reduce network traffic transparently and to improve system scalability. Finally, it illustrates how an Event Service framework can be strategized to support configurations that facilitate high throughput, predictable bounded latency, or some combination of each.
The High Level Architecture (HLA) is a general purpose architecture for simulation reuse and interoperability. In September 1996, the Under Secretary of Defense for Acquisition and Technology signed a letter establish...
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The High Level Architecture (HLA) is a general purpose architecture for simulation reuse and interoperability. In September 1996, the Under Secretary of Defense for Acquisition and Technology signed a letter establishing the HLA as the architecture for Department of Defense (DOD) simulations. The Joint Communication Simulator (JCS) is a RF signal environment generator currently in development for the USN and USAF for development test and evaluation (DT&E) applications. System design challenges include all implications of interactive, realtime, embedded, coherent, distributed, and heterogeneous live/virtual simulation. A requirement for 100% repeatability indicated a point design using guaranteed delivery, time stamp-ordered HLA concepts at all levels of modeling. Performance requirements implied the use of PowerPC-based Mercury Computer Systems multiprocessor equipment. To our knowledge, no HLA Run time Infrastructure (RTI - the distributed backbone for HLA services) was available for direct application or adaptation. This paper presents the JCS system design as a case study of the both the conceptual and implementation applicability of HLA in this difficult context. Specific technical topics to be covered include an overview of JCS requirements, an overview of the modeling concept and system architecture in terms of the HLA, a definition of the subset of RTI functionality and HLA interface specification applied, and an overview of the RTI subset implementation. In addition, it addresses the political questions of HLA compliance, the openness of RTI designs and implementations, and the issue of RTI certification.
This article discusses prerequisites and possible methods of Matlab/HLA integration and presents a novel concept of an HLA interface that is suitable for interactive usage. The result of a performance comparison study...
ISBN:
(纸本)9780769508375
This article discusses prerequisites and possible methods of Matlab/HLA integration and presents a novel concept of an HLA interface that is suitable for interactive usage. The result of a performance comparison study of a demonstration program on different Matlab/HLA interface implementations is given.
We examine various modeling and simulationapplications of cluster computing using a Beowulf cluster. These applications are used to investigate the performance of our cluster in terms of computational speedup, scalab...
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We examine various modeling and simulationapplications of cluster computing using a Beowulf cluster. These applications are used to investigate the performance of our cluster in terms of computational speedup, scalability, and communications. The applications include solution of linear systems by Jacobi iteration, distributed image generation, and the finite difference time domain solution of Maxwell's equations. It is observed that the computational load for these applications must be large compared to the communication overhead to take advantage of the speedup obtained using parallel computing. For the applications reviewed, this condition is increasingly satisfied as the problem size becomes larger or as higher resolution is required.
This paper describes a time warp mechanism designed to exploit temporal uncertainty (TU) in distributedsimulation. Novel in the proposed approach are: a formal event model where events are assigned time intervals ins...
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This paper describes a time warp mechanism designed to exploit temporal uncertainty (TU) in distributedsimulation. Novel in the proposed approach are: a formal event model where events are assigned time intervals instead of usual punctual timestamps; an aggressive cancellation technique which shifts overheads from communications to computation; and an implementation in Java which deploys a framework for distributedsimulations over the Internet. The paper introduces the time warp mechanism and reports some experimental results using a large PCS model. The experiments confirm that TU is able to speedup simulation without compromising the accuracy of the results.
The HLA-RTI provides a general-purpose network communication mechanism for distributed virtual environments (DVE), but it does not support stream transmission and control directly. This paper illustrates a presentatio...
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The HLA-RTI provides a general-purpose network communication mechanism for distributed virtual environments (DVE), but it does not support stream transmission and control directly. This paper illustrates a presentational audio-video continuous-media retrieval application over RTI, which is an extension to our previous paper "An approach for stream transmission over HLA-RTI in distributed virtual environments" (IEEE DiS-RT1999 internationalworkshop). This extension focuses on how to control stream retrieval using the mechanisms provided by HLA-RTI.
We focus on distributedsimulation based on local time warp deployed over several sites connected through an interconnection network (a loosely coupled domain). We propose and study a mechanism to tune elaboration acc...
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We focus on distributedsimulation based on local time warp deployed over several sites connected through an interconnection network (a loosely coupled domain). We propose and study a mechanism to tune elaboration according to varying communication performances, to reduce resource consumption and rollback costs that result from unpredictable network behavior. The mechanism is composed of two parts that operate in a completely distributed way: a local elaboration rate control and a message flow control. The experimental study is conducted through emulation to exert a control on injected delays. Our results show that the mechanism is able to globally tune the entire simulation, so as to reduce the escalation of allocated computational resources and the cost of rollbacks. As delays disappear the mechanism allows elaboration to resume normal rate.
This paper describes the implementation of RTI-Kit, a modular software package to realize runtime infrastructure (RTI) software for distributedsimulations such as those for the High Level Architecture. RTI-Kit softwa...
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This paper describes the implementation of RTI-Kit, a modular software package to realize runtime infrastructure (RTI) software for distributedsimulations such as those for the High Level Architecture. RTI-Kit software spans a wide variety of computing platforms, ranging from tightly coupled machines such as shared memory multiprocessors and cluster computers to distributed workstations connected via a local area or wide area network. The time management, data distribution management, and underlying algorithms and software are described.
Control computer systems for automatic logistic systems contain reactive modules, which are usually tested on-site, in conjunction with the real environment. This leads to high test costs and unsatisfactory test cover...
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Control computer systems for automatic logistic systems contain reactive modules, which are usually tested on-site, in conjunction with the real environment. This leads to high test costs and unsatisfactory test coverage. Environment simulation models offer an execution environment for customizable, in-house testing. The architecture and process model of WATIS/sup 2/, a flexible, efficient and expansible environment simulation system for automatic logistic systems are presented. Experiments in an industrial environment show a high model reuse rate and a significant improvement of baseline software development regarding software quality and project cost, in this way justifying a systematic application of WATIS/sup 2/.
One of the services provided by the High Level Architecture (HLA) Run-time Infrastructure (RTI) is data distribution management (DDM), which aims to make data communication more efficient by sending data to only those...
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One of the services provided by the High Level Architecture (HLA) Run-time Infrastructure (RTI) is data distribution management (DDM), which aims to make data communication more efficient by sending data to only those federates requiring the data. Several DDM methods, notably region and grid-based, have been proposed and some of them have been implemented in RTI. We first briefly discuss grid-based and region-based DDM and their advantages and disadvantages, and then a new hybrid approach is proposed. Our simulations show that in some situations, the hybrid approach can reduce both the number of irrelevant messages of the grid-based DDM and the number of matching of the region-based approach.
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