CORBA环境下的动态负载平衡研究

【作者】 杨圣云；

【导师】 房鼎益；

【作者基本信息】 西北大学 ， 计算机软件， 2001， 硕士

【摘要】 随着网络技术和PC的发展，分布式计算系统已广泛应用于企业级应用服务。分布式对象计算平台CORBA为集成异构环境下的分布式应用提供了强有力的技术支持。通常，网络环境下的应用系统是异构的，即它们可能由不同的编程模型和编程语言实现，并可能分布在不同的硬件和操作系统的主机上。CORBA为异构环境下的应用对象之间的交互提供了一个有效的交互和通讯平台，简化了应用系统的开发。典型的CORBA应用由多个对象组成，这些对象可能分布在不同的主机上。因此平衡系统负载将是改善和提高应用系统整体性的关键。本文详细分析了传统的分布式系统中负载平衡技术，并分析讨论了已有的关于CORBA环境下的负载平衡策略存在的主要问题。在此基础上提出一个新的CORBA环境下的分布式动态负载平衡模型，详细讨论它的负载平衡策略，如：信息策略，传输策略，定位策略，迁移策略，并且给出若干负载指标，实现了基于最短总体期望响应时间策略的负载平衡系统。在伪随机分布和伪正态分布的请求下，测试了此系统的性能，同时也对比测试了市场上能够见到的负载平衡系统Smart Agent。结果显示我们的系统的整体性能好于Smart Agent。本文最后讨论与负载平衡相关的可扩展性，安全性和容错性等问题。更多还原

【Abstract】 With the development of technologies of network and PC, distributed computing systems play an important role in enterprise applications. Distributed object computing platform CORBA is a powerful technology to integrating diverse applications within distributed heterogeneous environments. Applications in network environments are "very heterogeneous", that means, they may be composed of component with different programming models and different programming languages, and may be spread over platforms with different hardware architectures and operating systems. CORBA supports transparent communications within application objects in heterogeneous environments and convenient development to application systems. Typical CORBA applications are complex systems consisting of a large number of objects and using a large number of machines. Balancing loads of systems is important to improve the overall system performance. The thesis analyses load balancing technologies used by the traditional distributed systems and details flaws of existed load balancing technologies in CORBA. The thesis describes a new prototype in CORBA environment, and discusses load-balancing policies, including information policy, transmission policy, location policy, and migration policy that are adapted to supporting CORBA environment requirements, and presents several load indices. The model based on shortest overall excepted delay routing is implemented on Visibroker for C++ 4.0. We test the implementation by sending requests from clients to it as a stream of psuedo-random distribution or psuedo-normal distribution, and also test the Smart Agent from Borland corp. that distributes requests to objects in the round-robin algorithm. The experiment shows that the overall performance of the model in the thesis is better than that of the Smart Agent. Finally, we discuss scalability, security and fault-tolerance that tight with the load balancing system. Yang sheng-yun Directed by: Fang ding-yi更多还原