摘要
HLA是为解决分布式仿真应用间的互操作性和可重用性而提出的通用仿真技术框架,在军事、交通、教育、娱乐等领域得到了广泛的应用。但是HLA仅规定了各个仿真应用相互协调运行的关键要素,而对仿真资源的动态管理和合理分配等问题缺乏考虑。网格是近年来国际上兴起的一项重要的信息技术,为实现大规模范围内的资源共享和协同工作提供了必要的功能和机制。网格的优势是解决资源的动态分配与监控问题,这能够解决目前HLA仿真的局限性。因此,将网格技术与HLA仿真框架结合,构建分布式仿真网格,可以实现良好的可扩展性、较强容错性能、支持大型仿真应用的平台。目前,国内外对分布式仿真网格已经做了大量的研究,但许多都是面向特定应用领域或尚处初级阶段,平台的可扩展能力、容错能力、自动配置能力都还存在不足之处。
本文的主要工作是通过集成浙江大学CAD&CG国家重点实验室的交互式可视化网格系统GVis和基于HLA的高可扩展性仿真运行框架HIVE,实现了分布式仿真网格系统GDSS。GDSS提供了大规模仿真应用的实时交互能力,通过网格服务管理分布式仿真资源,从而弥补了HLA大规模分布仿真系统在资源的动态调度、负载平衡上的不足。
本文的另一个贡献是对GDSS平台可扩充性的设计,将GVis系统的网格支撑环境层、GVis门户和仿真框架层HIVE分别扩展成运行时环境层GRE、网格门户层GDSSPortal、网格仿真框架层GHIVE,组成三层体系结构。系统的三层相对独立,分别提供不同的功能。GRE提供大规模网络环境中的网格资源管理、信息管理和仿真任务管理以及仿真数据管理、仿真环境部署,为仿真应用提供网格支撑环境。GDSSPortal为用户提供访问仿真服务并与仿真服务进行交互操作的功能界面。GHIVE实现了基于HLA的高可扩展性仿真运行框架,具有高效的通信与数据过滤机制,并提出统一对象模型以支持HLA仿真平台和绘制平台的整合。该三层体系结构功能定位明确,层次清晰,耦合性低,具有可扩展性、跨平台性、独立性。
GDSS系统通过GRE、GDSSPortal、GHIVE之间的相互交互,解决了分布式仿真网格系统中的一些关键性问题,包括仿真资源和仿真作业任务的动态管理与调度、仿真运行环境的自动部署等。GDSS系统是一个功能较为全面的分布式仿真网格系统,具有较高的实际应用价值。
The High Level Architecture (HLA) is a general purpose architecture for simulation reuse and interoperability. It is applied to various areas such as military, transportation, education and entertainment. However, it provides only key interfaces for collaborative operations during simulation stages, and has little considerations on dynamic management and allocations for simulation resources. Grid technology is an important information technology arising these years. It provides functions and mechanisms for large-scale resource sharing and collaboration. It shows its advantages in dynamic discovery, allocation and monitoring of resouces, which can solve the limitations of HLA simulations. Therefore, it is necessary to integrate Grid and HLA together to construct distributed simulation grid that takes advantages of both technologies to achieve scalability, fault tolerance performance and support large-scale simulation. Currently, there are lots of researches on distributed simulation grid in and out of China. However, most of them are application oriented or still at initial stages so that they are inferior in platform scalability, fault tolerance performance or dynamic deployment capabilities.
This paper focuses on designing and implementing a Grid-based Distributed Simulation System (GDSS) by intergrating a Grid-based Visuallization system GVis and a highly scalable HLA-based simulation framework HIVE, both of which are developed in the State Key Lab of CAD&CG, Zhejiang University. GDSS provides realtime interaction capability for large-scale simulations, meeting requirements of dynamic scheduling and load balancing for HLA-based large-scale distributed simulation systems by providing grid services for simulation resource management.
Another contribution of this paper is its design for platform scalability. GDSS is implemented in a three-layer architecture, which includes a runtime environment layer GRE, a grid portal layer GDSSPortal and a simulation framework GHIVE, which are established by extending the runtime supporting module and gird portal in GVis, HLA-based simulation framework HIVE, respectively. The three layers provide different functions and are independent of each other. GRE provides large-scale network environments for grid resource management, information management, simulation task management and data management, operating as a grid supporting environment. GDSSPortal provides users functions of accesing simulation services and interacting with them. GHIVE provides a highly scalable HLA-based simulation operation framework, an efficient communication and data filtering mechanism, and a Unified Object Model to intergrate with redering platforms. The three layers are indepent of each other and thus the architecture is scalable and cross-platform.
By interactions among GRE, GHIVE, and GDSSPortal, GDSS solves critical problems for distributed simulation grid system, inclucing dynamic resource management and scheduling, dynamic task management and scheduling, automatic deployment of simulation environment. GDSS is a functional distributed simulation grid system. It is proved to be really practical and useful.
引文
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