Bayanihan: building and studying web-based volunteer computing systems using Java

Project Bayanihan is developing the idea of volunteer computing, which seeks to enable people to form very large parallel computing networks very quickly by using ubiquitous and easy-to-use technologies such as web browsers and Java. By utilizing Java’s object-oriented features, we have built a flexible software framework that makes it easy for programmers to write different volunteer computing applications, while allowing researchers to study and develop the underlying mechanisms behind them. In this paper, we show how we have used this framework to write master-worker style applications, and to develop approaches to the problems of programming interface, adaptive parallelism, fault-tolerance, computational security, scalability, and user interface design.     

The network weather service: a distributed resource performance forecasting service for metacomputing

The goal of the Network Weather Service is to provide accurate forecasts of dynamically changing performance characteristics from a distributed set of metacomputing resources. Providing a ubiquitous service that can both track dynamic performance changes and remain stable in spite of them requires adaptive programming techniques, an architectural design that supports extensibility, and internal abstractions that can be implemented efficiently and portably. In this paper, we describe the current implementation of the NWS for Unix and TCP/IP sockets and provide examples of its performance monitoring and forecasting capabilities.     

The Globus project: a status report

The Globus project is a multi-institutional research effort that seeks to enable the construction of computational grids providing pervasive, dependable, and consistent access to high-performance computational resources, despite geographical distribution of both resources and users. Computational grid technology is being viewed as a critical element of future high-performance computing environments that will enable entirely new classes of computation-oriented applications, much as the World Wide Web fostered the development of new classes of information-oriented applications. In this paper, we report on the status of the Globus project as of early 1998. We describe the progress that has been achieved to date in the development of the Globus toolkit, a set of core services for constructing grid tools and applications. We also discuss the Globus Ubiquitous Supercomputing Testbed Organization (GUSTO) that we have constructed to enable large-scale evaluation of Globus technologies, and we review early experiences with the development of large-scale grid applications on the GUSTO testbed.     

A component-based approach to build a portable and flexible middleware for metacomputing

The huge amount of computing resources in the Internet makes it possible to build metacomputers for solving large-scale problems. Despite the great availability of software infrastructures for managing such systems, metacomputer programming is often based on models that do not appear to be suitable to run applications on wide-area, unreliable, highly-variable networks of computers. In this paper, we present a customisable, Java-based middleware which provides programmers with a portable and flexible framework to run applications over a hierarchical, virtual network architecture. The middleware is designed according to a component-based approach that enables the execution behaviour of each computing node to be customised in order to satisfy application needs. The paper shows some examples of programming model customisation and demonstrates that flexibility can be achieved without significantly compromising performance.     

基于Hadoop框架的TF-IDF算法改进

在分析Hadoop框架与TF-IDF算法的基础上,给出了TF-IDF算法在Hadoop分布式框架下的具体实现。实验表明,在处理大数据量时,与传统方法相比,新方法的效率更高。     

DISCWorld: an environment for service-based matacomputing

We describe our DISCWorld system for wide-area, high-performance metacomputing in which we adopt a high-level, service-based approach. Users’ client programs request combinations of services from a set of server nodes which communicate at a peer-based level. DISCWorld is a constrained metacomputing system, running only the service operations its participating resource administrators have chosen to provide and advertise, and provides a common integration environment for clients to access these services and developers to make them available. We discuss our software architecture and experiences building DISCWorld using Java and CORBA components, and the associated research issues for metacomputing that we are addressing.     

WAMM in the framework of graphical user interfaces for metacomputing management

Current environments for metacomputing generally have tools for managing the resources of a metacomputer but often lack adequate tools for designing, writing, and executing programs. Building an application for a metacomputer typically involves writing source codes on a local node, transferring and compiling codes on every node, and starting their execution. Without such tools, the application development phases can come up against considerable difficulties. In order to alleviate these problems, some graphical user interfaces (GUIs) based on PVM, such as XPVM, Parallel Application Development Environment (PADE) and Wide Area Metacomputing Manager (WAMM) have been implemented. These GUIs integrate a programming environment which facilitates the user in performing the application development phases and the application execution.

This paper outlines the general requirements for designing GUIs for metacomputing management, and compares WAMM, a graphical user interface, with some related works.     

Context-aware agents for user-oriented web services discovery and execution

Service-oriented computing (SOC) suggests that the Internet will be an open repository of many modular capabilities realized as web services. Organizations may be able to leverage this SOC paradigm if their employees are able to ubiquitously incorporate such capabilities and their resulting information into their daily practices. It is impractical to assume that human users will be able to manually search vast distributed repositories at real-time. This paper presents an architecture, Software Agent-Based Groupware using E-services (SAGE), that incorporates the use of intelligent agents to integrate human users with web services. SAGE provides background search and discovery approaches, thus enabling human users to exploit service-based capabilities that were previously too time-consuming to locate and integrate. We present a multi-agent system where each agent learns the rule-based preferences of a human user with regards to their current operational “context” and manages the incorporation of relevant web services. Recommended by: Djamal Benslimane and Zakaria Maamar     

Mobile agent-enabled framework for structuring and building distributed systems on the internet

Mobile agent has shown its promise as a powerful means to complement and enhance existing technology in various application areas. In particular, existing work has demonstrated that MA can simplify the development and improve the performance of certain classes of distributed applications, especially for those running on a wide-area, heterogeneous, and dynamic networking environment like the Internet. In our previous work, we extended the application of MA to the design of distributed control functions, which require the maintenance of logical relationship among and/or coordination of proc- essing entities in a distributed system. A novel framework is presented for structuring and building distributed systems, which use cooperating mobile agents as an aid to carry out coordination and cooperation tasks in distributed systems. The framework has been used for designing various distributed control functions such as load balancing and mutual ex- clusion in our previous work. In this paper, we use the framework to propose a novel ap- proach to detecting deadlocks in distributed system by using mobile agents, which dem- onstrates the advantage of being adaptive and flexible of mobile agents. We first describe the MAEDD (Mobile Agent Enabled Deadlock Detection) scheme, in which mobile agents are dispatched to collect and analyze deadlock information distributed across the network sites and, based on the analysis, to detect and resolve deadlocks. Then the design of an adaptive hybrid algorithm derived from the framework is presented. The algorithm can dynamically adapt itself to the changes in system state by using different deadlock detec- tion strategies. The performance of the proposed algorithm has been evaluated using simulations. The results show that the algorithm can outperform existing algorithms that use a fixed deadlock detection strategy.     

基于网格的分布式虚拟环境仿真海量数据管理

分析了分布式虚拟环境仿真的特点,提出了基于网格的分布式虚拟环境仿真的海量数据管理框架.该框架结构采用分层结构,自底向上依次为网格节点、高性能通信系统、数据存储与处理系统和计算系统.给出了一个基于上述体系结构的原型系统.对该原型系统的仿真结果表明,该海量数据管理体系结构设计符合虚拟环境仿真实时性、稳定性和高可靠性的要求.     

Team Automata for Security: – A Survey –

In [Kleijn, J., Team Automata for CSCW – A Survey –, Petri Net Technology for Communication-Based Systems—Advances in Petri Nets, LNCS 2472, Springer, 2003, 295–320], Kleijn presented a survey of the use of team automata for the specification and analysis of phenomena from the field of computer supported cooperative work, in particular notions related to groupware systems. In this paper we present a survey of the use of team automata for the specification and analysis of some issues from the field of security. In particular, we show how team automata can adequately be used to model and verify various access control policies, multicast/broadcast communication protocols, and general (cryptographic) communication protocols.     

互操作性和部件标准化接口CORBA/DCOM

本文讨论了在网络计算环境下异构分布应用的复杂性，基于部件系统的优点及部件互操作性的重要性。介绍了解决互操作性的接口技术方案的基本概念及当前两种主流标准化接口ＣＯＲＢＡ与ＤＣＯＭ的原理及结构。最后评点了国内研究中应注意的问题。     

Writing concurrent assemblers–a case study in path pascal

This paper describes an investigation into the use of Path Pascal for implementing a number of different concurrent algorithms for an assembler for a subset of the PAL-11A assembly language for the PDP-11 range of computers. The various programs which resulted were run using simulated concurrency under the VMS operating system on a VAX 11-780 computer, and measurements were obtained relating to the performances of the programs on different architectures. The suitability of path expressions for specifying object concurrency in such problems is discussed.     

Mobile Agent Connection Establishment and Management (CEMA)—Message Exchange for Pervasive Computing Environments

Pervasive computing is an emerging technology that offers new possibilities to distributed computing and computer networking; it employs a wide variety of smart, ubiquitous devices throughout an individual's working and living environment. Mobile agents are software entities that can migrate between servers (mobile agent environments) of the network accomplishing various tasks on the behalf of their owners. The objective of this paper is to describe a test and prototyping environment for experimenting with mobile agents in pervasive environments. A prototype environment for a novel, proactive infrastructure is described for mobile agent assisted pervasive computing. In addition, a new message passing algorithm is provided for mobile agent connection establishment and management (CEMA). Simulation results show the performance of the proposed approach.     

LogGP in theory and practice – An in-depth analysis of modern interconnection networks and benchmarking methods for collective operations

Accurate measurement and modeling of network performance is important for predicting and optimizing the running time of high-performance computing applications. Although the LogP family of models has proven to be a valuable tool for assessing the communication performance of parallel architectures, non-intrusive LogP parameter assessment of real systems remains a difficult task. Based on an analysis of accuracy and contention properties of existing measurement methods, we develop a new low-overhead measurement method which also assesses protocol changes in the underlying transport layers. We use the gathered parameters to simulate LogGP models of collective operations and demonstrate the errors in common benchmarking methods for collective operations. The simulations provide new insight into the nature of collective algorithms and their pipelining properties. We show that the error of conventional benchmark methods can grow linearly with the system size.     

An object-oriented framework for developing distributed manufacturing architectures

Management of complexity, changes and disturbances is one of the key issues of production today. Distributed, agent-based structures represent viable alternatives to hierarchical systems provided with reactive/proactive capabilities. In the paper, approaches to distributed manufacturing architectures are surveyed, and their fundamental features are highlighted, together with the main questions to be answered while designing new structures. Moreover, an object-oriented simulation framework for development and evaluation of multi-agent manufacturing architectures is introduced.     

Poincaré–Birkhoff–Witt theorem for Leibniz -algebras

We construct the universal enveloping algebra of a Leibniz n-algebra and we prove that the category of modules over this algebra is equivalent to the category of representations.We also give a proof of the Poincaré–Birkhoff–Witt theorem for universal enveloping algebras of finite-dimensional Leibniz n-algebras using Gröbner bases in a free associative algebra.