Routing direction determination in regular networks based on configurable circuits

We consider the problem of finding short paths in a regular network such as a k-ary n-cube. This problem is a basic aspect of routing and has to be implemented with a very high performance for cluster and parallel computer networks. To achieve this, a scalable reconfigurable circuit is proposed that covers many popular topologies at acceptable cost. As a demonstration, the application to a modestly complex topology is shown in detail (“Multi-Mesh” introduced by Das et al. [D. Das, M. De, B.P. Sinha, A network topology with multiple meshes, IEEE Transactions on Computers 48 (5) (1999) 536–551]).

The achieved flexibility is much higher than that of previously reported reconfigurable circuits for the same purpose such as interval routing [R.B. Tan, J. van Leeuwen, Compact routing methods: a survey, in: Proceedings of the Colloquium on Structural Information and Communication Complexity (SICC94), School of Computer Science, Carleton University, Ottawa, 1995, pp. 99–109] or bit-pattern-associative routing [D.H. Summerville, J.G. Delgado-Frias, S. Vassiliadis, A flexible bit-pattern-associative router for interconnection networks, IEEE Transactions on Parallel and Distributed Systems 7 (5) (1996) 477–485]. The proposed circuit extends the domain of application-specific reconfigurable circuits beyond the areas of signal processing and cryptography, where most work is currently done.     

网络计算中间件

网络计算中间件是随着互联网的发展而于20世纪90年代兴起的一类基础软件,网络计算中间件为各种网络应用系统的开发、部署、运行和管理提供了有力支持.随着信息网络技术和软件服务工程的快速发展,网络计算中间件又被赋予了新的内涵,首先从网络计算环境出发,就基础中间件、应用集成中间件和领域应用框架的基本概念和主要技术作较全面的诠释;然后聚焦于云计算和物联网等网络计算的热点研究方向,从中间件的角度指出当前值得关注的某些挑战性研究课题和需要深入探索的若干关键技术.     

基于云计算的数据安全风险及防范策略探讨

云计算依托计算机网络系统,目前已经成为人们生活的重要部分,随着网络化、虚拟化生活的加速发展,诸如Google、Microsoft、Apple、Amazon、IBM等互联网IT和手机、网络运营商巨头开始重新定位企业发展的战略核心.云计算作为IT商业计算模型,它将计算任务分布在各种类型的广域网络和局域网络组成计算机网络系统,使用户能够借助网络按需获取计算力、存储空间和信息服务.云计算的用户通过PC、手机以及其他终端连接到网络使用云资源;随着云计算的广泛应用,云计算的环境安全环境、数据安全成为突出问题,如何保障云计算的安全成为当前急需解决的问题.本文介绍了云计算相关概念,以及对云计算数据安全风险进行分析,并提出了防范策略.     

基于网络环境下的个人计算机安全与防护措施

因特网的普及对人们的生活和工作方式产生巨大的影响,人们在享受网络技术带来的便利的同时,也深受病毒破坏带来的苦恼。TCP/IP协议的局限,操作系统的漏洞,以及病毒技术的快速发展,要求用户重视网络环境下的个人计算机安全与防护措施。     

一种实用、高效的虚拟远程超级计算环境

远程计算是指用户在本地计算机上通过互联网利用远程超级计算机上计算资源的技术.传统的远程计算方式是用户通过telnet协议登录到远程机器上完成各项任务.这种方式在高速、稳定的网络环境下效率是很高的.但是当网络条件比较差时,如在低带宽、不稳定的网络上,这种方式会严重影响用户的工作效率.提出并实现了一个远程虚拟计算环境,它所采用的计算方式可有效完成在低带宽、不稳定的网络环境下效率较低甚至无法完成的远程计算,其中使用了如检查点设置/恢复、压缩传送、目录树传送等技术以达到尽量减少网络流量的目的.实践证明,这在我国当前的网络条件下是一种高效的远程计算方法.     

基于网络环境下的个人计算机安全与防护措施

因特网的普及对人们的生活和工作方式产生巨大的影响,人们在享受网络技术带来的便利的同时,也深受病毒破坏带来的苦恼。TCP／IP协议的局限,操作系统的漏洞,以及病毒技术的快速发展,要求用户重视网络环境下的个人计算机安全与防护措施。     

Designing a resource broker for heterogeneous grids

Grids provide uniform access to aggregations of heterogeneous resources and services such as computers, networks and storage owned by multiple organizations. However, such a dynamic environment poses many challenges for application composition and deployment. In this paper, we present the design of the Gridbus Grid resource broker that allows users to create applications and specify different objectives through different interfaces without having to deal with the complexity of Grid infrastructure. We present the unique requirements that motivated our design and discuss how these provide flexibility in extending the functionality of the broker to support different low‐level middlewares and user interfaces. We evaluate the broker with different job profiles and Grid middleware and conclude with the lessons learnt from our development experience. Copyright © 2007 John Wiley & Sons, Ltd.     

Decentralized Network Management Using Distributed Artificial Intelligence

Centralized approaches to Network Management have demonstrated a clear inadequacy for efficient management of large and heterogeneous computer networks. Considerable research is being carried out on decentralized approaches for network management. This paper presents the work on a practical application of Distributed Artificial Intelligence for computer network management. The objective is to implement a software platform using only Intelligent Autonomous Agents, integrated with the SNMP environment.     

Orchard: Exploring Multivariate Heterogeneous Networks on Mobile Phones

People are becoming increasingly sophisticated in their ability to navigate information spaces using search, hyperlinks, and visualization. But, mobile phones preclude the use of multiple coordinated views that have proven effective in the desktop environment (e.g., for business intelligence or visual analytics). In this work, we propose to model information as multivariate heterogeneous networks to enable greater analytic expression for a range of sensemaking tasks while suggesting a new, list-based paradigm with gestural navigation of structured information spaces on mobile phones. We also present a mobile application, called Orchard, which combines ideas from both faceted search and interactive network exploration in a visual query language to allow users to collect facets of interest during exploratory navigation. Our study showed that users could collect and combine these facets with Orchard, specifying network queries and projections that would only have been possible previously using complex data tools or custom data science.     

云计算时代对信息安全的影响及对策分析

当前,信息技术渗透到人类社会生活的各个环节,这其中,云计算发展可谓异军突起,它将智能网络、虚拟技术、资源调度、无线网络和3G等前沿技术相融合,展现出良好的应用前景和巨大的潜力。云计算是一种基于Internet的、新兴的计算机应用技术。其远景是以互联网为基础,为广大互联网用户提供安全可靠、方便快捷的互联网服务和强大的计算能力。在云计算环境下,信息安全问题不但是云计算面临的首要问题,而且将成为决定云计算发展的规模和前景的决定性问题。通过从云计算的概念、特征和及目前已存在的问题出发,浅析云计算环境下的信息安全问题。     

Network system and world wide web security

The Internet was developed in 1965 for academic and military use. Thirty-one years later, it is regarded as the ‘information superhighway’ with almost one billion computer networks and well over a billion users projected to be using the Internet by the end of the century [1]. In essence, the open design of the Internet, geared towards the ease of communication and rapid development, has led to a severe lax in system security. As new developments (for example, the world wide web) and application of information technology emerge, so do the possibilities of hostile attacks on local area networks (LANS) and wide area networks (WANs). Therefore, the security aspects of the Internet and the world wide web must be carefully scrutinized. This paper outlines the security aspects of network systems and the world wide web.     

Validating and Scaling the MicroGrid: A Scientific Instrument for Grid Dynamics

Large-scale Grids that aggregate and share resources over wide-area networks present major challenges in understanding dynamic application and resource behavior for performance, stability, and reliability. Accurate study of the dynamic behavior of applications, middleware, resources, and networks depends on coordinated and accurate modeling of all four of these elements simultaneously. We have designed and implemented a tool called the MicroGrid which enables accurate and comprehensive study of the dynamic interaction of applications, middleware, resource, and networks. The MicroGrid creates a virtual Grid environment – accurately modeling networks, resources, the information services (resource and network metadata) transparently. Thus, the MicroGrid enables users, Grid researchers, or Grid operators to study arbitrary collections of resources and networks. The MicroGrid includes the MaSSF online network simulator which provides packet-level accurate, but scalable network modeling. We present experimental results with applications which validate the implementation of the MicroGrid, showing that it not only runs real Grid applications and middleware, but that it accurately models both their and underlying resource and network behavior. We also study a range of techniques for scaling a critical part of the online network simulator to the simulation of large networks. These techniques employ a sophisticated graph partitioner, and a range of edge and node weighting schemes exploiting a range of static network and dynamic application information. The best of these, profile-driven placement, scales well to online simulation of large networks of 6,000 nodes using 24 simulation engine nodes.     

Using Bayesian networks for monitoring computer users

The structure and methods of a knowledgebase are discussed. This knowledgebase is considered to be a component part of personal expert systems designed for monitoring computer users and computer environments with a view to detecting a harmful effect of computers on the state of health of computer users and making recommendations concerning the neutralization of this effect. Such expert systems are based on Bayesian networks that have a simple topology and represent random relations between harmful conditions of a computer environment and the state of help of users.Translated from Kibernetika i Sistemnyi Analiz, No. 6, pp. 3–15, November–December 2004.This revised version was published online in April 2005 with a corrected cover date.     

Mining constrained frequent itemsets from distributed uncertain data

Nowadays, high volumes of massive data can be generated from various sources (e.g., sensor data from environmental surveillance). Many existing distributed frequent itemset mining algorithms do not allow users to express the itemsets to be mined according to their intention via the use of constraints. Consequently, these unconstrained mining algorithms can yield numerous itemsets that are not interesting to users. Moreover, due to inherited measurement inaccuracies and/or network latencies, the data are often riddled with uncertainty. These call for both constrained mining and uncertain data mining. In this journal article, we propose a data-intensive computer system for tree-based mining of frequent itemsets that satisfy user-defined constraints from a distributed environment such as a wireless sensor network of uncertain data.     

A parallel language and its programming system for heterogeneous networks

The paper presents a new parallel language, mpC, designed specially for programming high‐performance computations on heterogeneous networks of computers, as well as its supportive programming environment. The main idea underlying mpC is that an mpC application explicitly defines an abstract network and distributes data, computations and communications over the network. The mpC programming environment uses, at run time, this information as well as information on any real executing network in order to map the application to the real network in such a way that ensures the efficient execution of the application on this real network. Experience of using mpC for solving both regular and irregular real‐life problems on networks of heterogeneous computers is also presented. Copyright © 2000 John Wiley & Sons, Ltd.     

超算环境科学工作流应用平台的引擎设计和资源调度

高性能计算机体系结构的复杂性对使用者提出了更高要求;而且在工程实际和科学实验中,通常需要使用多种应用软件相互协作才能解决复杂问题。围绕超算资源的易用性和多类软件的集成以及协作需求,开发了超算环境下的科学工作流应用平台,设计了异步并发的流程执行引擎,采取调度算法和调度器、引擎相分离的设计策略,给出了资源调度方案。提出了局部资源池化技术和资源预约算法,并比较分析了五种常用调度算法的性能,给出了算法选择的建议。实际应用表明设计的引擎能够支撑复杂工作流的灵活执行方式,给出的资源调度方案能够满足超算环境下工作流应用的高效执行。     

计算机网络安全技术探析

信息时代,计算机网络技术已经涉及到人类生产生活的各个方面。由于计算机网络使用的广泛性、技术的复杂性等原因,计算机网络安全一直是该领域中一大难题。为了加强计算机网络的安全管理,为网络用户提供一个更为安全的网络环境,必须运用先进的技术加强计算机网络的防护。本文主要从计算机网络信息加密技术、防火墙技术、新型防火墙技术等几个方面来进行探析。     

Developing technologies for broad-network concurrent computing

Recent developments in networking infrastructures, computer workstation capabilities, software tools, and programming languages have motivated new approaches to broad-network concurrent computing. This paper describes extensions to concurrent computing which blend new and evolving technologies to extend users' access to resources beyond their local network. The result is a concurrent programming environment which can dynamically extend over network and file system boundaries to envelope additional resources, to enable multiple-user collaborative programming, and to achieve a more optimal process mapping. Additional aspects of the derivative environment feature extended portability and support for the accessing of legacy codes and packages. This paper describes the advantages of such a design and how they have been implemented in the environment termed “IceT”.     

Window flow control in computer communication networks

Computer communication networks are basically resource sharing systems and are used for an efficient exchange of information among remote users. Performance (throughput, delay and power) of a computer network depends upon the intensity of data and/or information traffic. If a network's traffic is allowed to increase beyond certain limits, its performance rapidly degrades. In order to keep data traffic under control, some restrictions are applied at various levels of computer communication networks. These restrictions are usually referred to as flow control techniques.

This paper deals with window (also called end-to-end or entry-to-exit) flow control in computer communication networks. In this method, a source node is allowed to have only a limited number of unacknowledged messages, usually termed as “window size”, at a time. Flow control, in this paper, is discussed in the context of three computer communication switching techniques: packet switching, virtual cut-through switching and quasi cut-through switching. The analysis of window flow control is based upon simulation of a typical store-and-forward computer network. Several simulation results are presented to illustrate the effects of window flow control on various computer communication switching techniques.