An analytic/empirical study of distributed sorting on a local areanetwork

A model for distributed sorting on a local area network (LAN) is presented. This model, contrary to the conventional model, takes into account both local processing time and communication time. This model is intended to provide a framework within which the performances of various distributed sorting algorithms are analyzed and implemented on Ethernet-connected Sun workstations. The empirical results by and large agree with the predictions derivable from the model. They show that local processing, particularly sorting of local subfiles, dominates the whole process, as far as response time is concerned. All algorithms examined have similar asymptotic behavior for large files. For medium-sized files, the degree of communication parallelism has a great impact on algorithm performance     

Reliability-aware scheduling strategy for heterogeneous distributed computing systems

Heterogeneous computing systems are promising computing platforms, since single parallel architecture based systems may not be sufficient to exploit the available parallelism with the running applications. In some cases, heterogeneous distributed computing (HDC) systems can achieve higher performance with lower cost than single-machine supersystems. However, in HDC systems, processors and networks are not failure free and any kind of failure may be critical to the running applications. One way of dealing with such failures is to employ a reliable scheduling algorithm. Unfortunately, most existing scheduling algorithms for precedence constrained tasks in HDC systems do not adequately consider reliability requirements of inter-dependent tasks. In this paper, we design a reliability-driven scheduling architecture that can effectively measure system reliability, based on an optimal reliability communication path search algorithm, and then we introduce reliability priority rank (RRank) to estimate the task’s priority by considering reliability overheads. Furthermore, based on directed acyclic graph (DAG) we propose a reliability-aware scheduling algorithm for precedence constrained tasks, which can achieve high quality of reliability for applications. The comparison studies, based on both randomly generated graphs and the graphs of some real applications, show that our scheduling algorithm outperforms the existing scheduling algorithms in terms of makespan, scheduling length ratio, and reliability. At the same time, the improvement gained by our algorithm increases as the data communication among tasks increases.     

Object orientation in heterogeneous distributed computing systems

The basic properties of object orientation and their application to heterogeneous, autonomous, and distributed system to increase interoperability ar examined. It is argued that object-oriented distributed computing is a natural step forward from client-server systems. To support this claim, the differing levels of object-oriented support already found in commercially available distributed systems-in particular, the distributed computing environment of the open software foundation and the Cronus system of Bolt Beranek, Newman (BBN)-are discussed. Emerging object-oriented systems and standards are described, focusing on the convergence toward a least-common-denominator approach to object-oriented distributed computing embodied by the object management group's common object request broker architecture     

Achieving mutual exclusion in a distributed computing environment

A distributed control algorithm, called MEAL, is presented for achieving mutual exclusion in a distributed computing environment. It requires only (N + 2) messages per critical section entry, in the no failures case; N being the number of nodes in the distributed system. Few assertions are proved to verify the correct functioning of MEAL. Possible modification to make it resilient, in case of node failures, are also suggested.     

Framework for distributed video surveillance in heterogeneous environment

In order to overcome the disadvantages of traditional centralized video monitoring system or distributed systems based on wired network, we propose a framework for distributed video surveillance in heterogeneous environment. Video flows are compressed with the scalable video encoding standard MPEG-4 and transmitted over lnternet or wireless network. Video surveillance can be performed wherever there is Internet or mobile telephone signal. The feasibility of this framework has been demonstrated with a prototype implementation. The system is cheaper and easier to achieve with simple equipments, so it can be widely used in practice.     

A uniform approach for programming distributed heterogeneous computing systems

Large-scale compute clusters of heterogeneous nodes equipped with multi-core CPUs and GPUs are getting increasingly popular in the scientific community. However, such systems require a combination of different programming paradigms making application development very challenging.In this article we introduce libWater, a library-based extension of the OpenCL programming model that simplifies the development of heterogeneous distributed applications. libWater consists of a simple interface, which is a transparent abstraction of the underlying distributed architecture, offering advanced features such as inter-context and inter-node device synchronization. It provides a runtime system which tracks dependency information enforced by event synchronization to dynamically build a DAG of commands, on which we automatically apply two optimizations: collective communication pattern detection and device-host-device copy removal.We assess libWater’s performance in three compute clusters available from the Vienna Scientific Cluster, the Barcelona Supercomputing Center and the University of Innsbruck, demonstrating improved performance and scaling with different test applications and configurations.     

基于Java技术的分布式计算环境研究

J2EE具有强大的分布式处理能力,其Rmi、Jini和JavaSpaces技术为实现异构的分布式计算环境提供了坚实的技术基础。JavaSpaces是建立在Jini之上的,它可以作为一种共享分布式通信和对象存储的机制。针对分布式计算环境的任务分解、并行同步与通信控制等特点,提出了基于Java技术的分布式计算环境。应用实例表明,该环境能够在异构的复杂系统中有效地进行分布式计算。     

Reasoning on infeasibility in distributed collaborative computing environment

Collaborative computing is a new communication technology that makes it possible to extend model formulation, management, and analysis into a geographically distributed group environment. The forms of communication may vary from asynchronous hypermedia teamwork via the Internet to multipoint desktop video conferencing. The latter presents the maximal potential for integrating shared quantitative model analysis with real-time/asynchronous geographically distributed electronic meetings. Infeasibility diagnosis and reasoning on conflict resolution are known to be important parts of an evolving approach to linear programming model analysis. In the new distributed environment, several specific decision support issues related to infeasibility analysis emerge. One is the learning mechanism for capturing group knowledge on infeasibility resolution that is generated during the collaborative sessions of model analysis. The other new decision support component is a coordination protocol that is capable of linking individual activities and software transactions for the support of group reasoning on infeasibility analysis. This paper addresses these issues on the basis of committee models for infeasibility resolution and the neural network approach. Examples of modeling cases are based on experiments using a multiple criteria model for support of resource allocation in a distributed electronic meeting, and the case of model-based diagnosis that the group is involved in.     

分布异构环境下数据库访问技术的研究

详细分析了当前分布异构数据库访问技术的研究现状和发展趋势,结合Web Services的优势构造了一个基于Web Services的分布异构数据库访问系统,并阐述了系统的实现过程。该系统能够有效地支持分布式数据查询,数据源透明并且支持跨平台检索。     

A comprehensive agent-based architecture for intelligent information retrieval in a distributed heterogeneous environment

The Internet has become the global infrastructure supporting information acquisition and retrieval from many heterogeneous data sources containing high-speed text and rich multimedia images, audio, and video. AgentRAIDER is an ongoing research project at Texas Tech University designed to develop a comprehensive architecture for an intelligent information retrieval system with distributed heterogeneous data sources. The system is designed to support intelligent retrieval and integration of information from the Internet. Current systems of this nature focus only on specific aspects of the distributed heterogeneous problem such as database queries or information filtering. Consequently, these concepts and others have never been successfully integrated into a unified, cohesive architecture. This paper discusses the design and implementation of the AgentRAIDER system and identifies areas for applications of the system in various domains.     

An effective authentication mechanism for ubiquitous collaboration in heterogeneous computing environment

With the advent of new generation of mobile access devices such as smartphone and tablet PC, there is coming a need for ubiquitous collaboration which allows people to access information systems with their disparate access devices and to communicate with others in anytime and in anywhere. As the number of collaborators with a large number of disparate access devices increases in ubiquitous collaboration environment, the difficulties for protecting secured resources from unauthorized users as well as unsecured access devices will increase since the resources can be compromised by inadequately secured human and devices. Therfore, authentication mechanism for access of legitimate participants is essential in ubiquitous collaboration environment. In this paper we present an efficient authentication mechanism in ubiquitous collaboration environment. We show that proposed scheme is secure through security analysis and is efficient through the experimental results obtained from the practical evaluation of the scheme in ubiquitous collaboration environment.     

A high performance algorithm for static task scheduling in heterogeneous distributed computing systems

Effective task scheduling is essential for obtaining high performance in heterogeneous distributed computing systems (HeDCSs). However, finding an effective task schedule in HeDCSs requires the consideration of both the heterogeneity of processors and high interprocessor communication overhead, which results from non-trivial data movement between tasks scheduled on different processors. In this paper, we present a new high-performance scheduling algorithm, called the longest dynamic critical path (LDCP) algorithm, for HeDCSs with a bounded number of processors. The LDCP algorithm is a list-based scheduling algorithm that uses a new attribute to efficiently select tasks for scheduling in HeDCSs. The efficient selection of tasks enables the LDCP algorithm to generate high-quality task schedules in a heterogeneous computing environment. The performance of the LDCP algorithm is compared to two of the best existing scheduling algorithms for HeDCSs: the HEFT and DLS algorithms. The comparison study shows that the LDCP algorithm outperforms the HEFT and DLS algorithms in terms of schedule length and speedup. Moreover, the improvement in performance obtained by the LDCP algorithm over the HEFT and DLS algorithms increases as the inter-task communication cost increases. Therefore, the LDCP algorithm provides a practical solution for scheduling parallel applications with high communication costs in HeDCSs.     

Deadline and energy constrained dynamic resource allocation in a heterogeneous computing environment

Energy-efficient resource allocation within clusters and data centers is important because of the growing cost of energy. We study the problem of energy-constrained dynamic allocation of tasks to a heterogeneous cluster computing environment. Our goal is to complete as many tasks by their individual deadlines and within the system energy constraint as possible given that task execution times are uncertain and the system is oversubscribed at times. We use Dynamic Voltage and Frequency Scaling (DVFS) to balance the energy consumption and execution time of each task. We design and evaluate (via simulation) a set of heuristics and filtering mechanisms for making allocations in our system. We show that the appropriate choice of filtering mechanisms improves performance more than the choice of heuristic (among the heuristics we tested).     

Distributed object management integrating distributed information in heterogeneous environment

Organizations today need an optimized environment that builds and integrates diverse operating systems, hardware and applications. Distributed Computing provides us with a facility to transparently access all data, resources in the network. Current Research, projects that distributed object management concept along with the distributed computing environment can provide a single interface to manage the complexities of a heterogeneous environment. Using a uniform framework based on the DCE standard, we attempt to create an Object Oriented Distributed Computing Environment that will help us create open distributed applications with location independence for client applications in a multivendor network.

A better model for Open Distributed Computing aided by Object Oriented concepts is offered. Some of the research issues in realizing such a model are contemplated. We integrate an Object Manager with the OSF' DCE and discuss its benefits.     

A solution of multidisciplinary collaborative simulation for complex engineering systems in a distributed heterogeneous environment

This paper presents an integrated approach to multidisciplinary collaborative simulation for complex engineering systems. The formulized paradigm of multidisciplinary collaborative simulation for com- plex engineering systems is principally analyzed. An IEEE HLA and web services based framework is proposed to provide a heterogeneous, distributed and collaborative running environment where multidisciplinary modeling, running management and post-processing of collaborative simulation are undertaken. The mecha...     

Alphorn: a remote procedure call environment for fault-tolerant,heterogeneous, distributed systems

Alphorn, a software environment for programming distributed computer systems, is described. Programs running on different computers, possibly of different types and running different operating systems, communicate in a client-server relationship by means of remote procedure calls. This efficient construct structures programs neatly. The paper covers distributed process control, Alphorn's object-based programming style, remote procedure calls, the service interface language, configuration, runtime and debugging, and fault tolerance support     

异构分布环境下数据获取与多态发布

随着生产全球化和协作化的发展,企业生产与外界的交互和相互依赖日益密切,出现了如何按照数据消费者的需求将企业内部多样分布的数据友好地向外发布的问题。为了解决这一问题,提出了一种基于XML和J2EE的数据获取与发布技术,并以一个报表生成系统的设计为例阐明这一技术。利用XML可以方便、准确地描述企业的数据并且可以灵活地将数据发布到Web上,而J2EE可以将异构分布的企业信息系统与Web集成起来。     

A language and programming environment for high-performance parallel computing on heterogeneous networks

An mpC language designed specifically for programming high-performance computations on heterogeneous networks is described. An mpC program explicitly defines an abstract computing network and distributes data, computations, and communications over it. At runtime, the mpC programming environment uses this information and that about the actual network to distribute the processes over the actual network so as to execute the program in the most efficient way. Experience in using mpC for solving problems on local networks consisting of heterogeneous workstations is discussed.     

广域网分布式计算系统透明内存设计与实现

分布式应用污染本地内存,造成大量页错误从而影响本地性能,为了解决该问题,提出了一种多优先级透明内存使用方法.该方法根据本地负载的变化,动态改变分配给分布式应用的内存量,并且对分布式任务划分了不同的优先级,使优先级低的任务占用更少的内存资源从而保障高优先级的任务.通过搭建原型系统进行试验,结果表明了该方法可以保证分布式应用的透明性,并提高贡献内存的使用效率.