基于Struts的权限管理系统研究与实现

本文介绍了Struts的一些特点,阐述了三种常用的访问控制的方法,说明了基于Struts权限管理系统的基本原理和实现的技术。     

Task dynamics in self-organising task groups: expertise, motivational, and performance differences of specialists and generalists

Multi-agent simulation is applied to explore how different types of task variety cause workgroups to change their task allocation accordingly. We studied two groups, generalists and specialists. We hypothesised that the performance of the specialists would decrease when task variety increases. The generalists, on the other hand, would perform better in a high task variety condition. The results show that these hypotheses were only partly supported because both learning and motivational effects changed the task allocation process in a much more complex way. We conclude that although no task variety leads to specialisation and high task variety leads to generalisation, in general, performance is better when task variety is low. Further, in case of no task variety, specialists outperform generalists. In case of moderate variety the opposite is true. With high task variety, since there is no space for any expertise and motivational development, the behaviour of specialists and generalists becomes more similar, and, consequently also their performance.     

Replica Placement Strategies in Data Grid

Replication is a technique used in Data Grid environments that helps to reduce access latency and network bandwidth utilization. Replication also increases data availability thereby enhancing system reliability. The research addresses the problem of replication in Data Grid environment by investigating a set of highly decentralized dynamic replica placement algorithms. Replica placement algorithms are based on heuristics that consider both network latency and user requests to select the best candidate sites to place replicas. Due to dynamic nature of Grid, the candidate site holds replicas currently may not be the best sites to fetch replicas in subsequent periods. Therefore, a replica maintenance algorithm is proposed to relocate replicas to different sites if the performance metric degrades significantly. The study of our replica placement algorithms is carried out using a model of the EU Data Grid Testbed 1 [Bell et al. Comput. Appl., 17(4), 2003] sites and their associated network geometry. We validate our replica placement algorithms with total file transfer times, the number of local file accesses, and the number of remote file accesses.     

X窗口系统中应用程序构造技术探讨

介绍了X窗口系统环境下应用程序界面的自动生成技术,其中包括Motif编程模型及有关概念;应用程序构造器生成应用程序界面的过程;应用程序构造器的机理及构造器创建应用程序的完善。     

A resource broker with an efficient network information model on grid environments

This paper describes a resource broker whose main function is to match available resources to user needs. The resource broker provides a uniform interface for accessing available and appropriate resources via user credentials. We also focus on providing approximate measurement models for network-related information using NWS for future scheduling and benchmarking. We first propose a network measurement model for gathering network-related information (including bandwidth, latency, forecasting, error rates, etc.) without generating excessive system overhead. Second, we constructed a grid platform using Globus Toolkit that integrates the resources of five schools in Taichung integrated grid environment resources (TIGER). The resource broker runs on top of TIGER. Therefore, it provides security and current information about available resources and serves as a link to the diverse systems available in the Grid.

基于URL的Java语言网络通讯机制和程序设计

介绍了Java语言的URL网络通讯机制。基于URL类理论和方法,建立了一条和所选资源联接的通讯线路,并利用该网络线路进行读写资源信息流等操作。     

一种基于灵活市场的区分服务网络定价策略

基于区分服务的网络模型,提出了一种新的灵活市场的定价策略。为了使定价策略能够更好地应用在区分服务网络中,在边界路由器中使用了探测和反馈机制,并且对灵活市场定价策略中的竞标值进行了归一化处理。通过仿真实验验证了基于区分服务模型的灵活市场定价策略的自适应性。     

主动网络中CPU和带宽资源分配的公平性

传统的包调度方案能实现单一资源分配的公平性,但不能直接应用于主动网络中的主动节点上,因为主动节点包含多种相互关联的资源。提出一种能实现在主动节点中公平分配资源的包调度算法。仿真实验结果显示,该算法能在主动流之间实现CPU和带宽资源的有效公平分配。     

Abstract Models of Storage

This note is a historical survey of Christopher Strachey's influence on the development of semantic models of assignment and storage management in procedural languages.     

用于高速列车移动网络的资源分配实时算法

误码率高、频繁中断的高速列车移动场景宜采用多宿主容迟网络。但其资源分配计算复杂,实时性较差。基于效用差分法设计初始化过程资源分配算法,以保证过程中每一步的效用单调不减,算法时间复杂度降至O(n)。