网格环境下的Web数据库系统

近来网格技术的研究已成为研发的热点.本文介绍了当前网格技术的发展和应用状况,同时指出现有的网格应用大都使用文件系统来保存数据,而要支持更大范围的应用和提高数据的存储和访问效率,必须将数据库系统集成入网格.本文在分析了网格的两种体系结构的基础上,提出将数据库系统纳入网格的方法,给出了系统结构和验证实例并阐明了系统工作流程,为网格应用的进一步开发奠定了基础.     

面向网格服务的标准件库系统集成

基于开放网格服务体系结构提出了面向服务的标准件库系统集成的体系结构．将标准件库系统中与数据库、CAD系统交互的功能组件封装在网格服务容器中，并与后台数据库一起部署成为网格服务节点，现有的标准件库系统只需提供服务的行为接口即可方便地集成到网格环境中．开发部署了一类标准件库网格服务节点，验证了该体系结构和实现技术的有效性．     

适用于柔性制造的CISSCAx系统的研制

CAx系统是CIMS工程中常见的应用系统。不同CAx系统间的信息共享是实现系统集成过程中要解决的基本问题。本文分析了CISSCAx系统的实现途径，主要采用扩展商品化的数据库适合工程应用，建立基于STEP标准的工程数据库，解决自动化设计中的信息共享问题。     

基于网格服务的数据发布系统

网格的核心任务是管理分布在Internet广域环境中的各种类型的软硬件资源，为基于Internet的分布式应用提供一个统一的、虚拟的共享资源的计算平台。如何将数据库资源并入现有的网格架构，满足更加广泛的网格应用的数据访问需求，已经成为一项亟待解决的课题。文章提出了一套网格环境中的数据发布系统的设计方案，以网格服务的形式封装对数据库的访问，实现跨越异构网络环境、异构操作系统环境和异构数据库平台的统一访问模式，从而将数据库资源加入到网格环境中。     

网格在访问数据库技术中的应用

为了满足在民用和商用领域中统一且灵活地进行数据库资源共享的要求，设计了一个网格数据库系统GDB(grid database)，该系统将网格技术应用于访问数据库技术中，弥补了当前访问数据库技术及网格数据库系统的不足，实现了数据库资源的有效整合．实践表明，本系统有着广阔的应用前景．     

网格环境下多数据源的协同查询

伴随网格技术的日益发展，作为对数据应用需求的快速回应，在数据网格之后又出现了网格数据库的概念，其中查询又是数据库应用中一个使用频繁的核心功能，由于每个节点上的数据库可能只包含所需信息的一部分，而且查询操作还涉及到数据库异构性、通信开销等问题，这些都给网格环境下的数据库查询性能带来了新的困难。为了提高网格环境下数据库查询的性能，提出了一种运用协同（CSCW）机制来协调网格用户的查询操作的方法，这不仅体现了系统的协同性，而且降低了数据传输开销，还提高了查询效率。     

网格环境下的异构空间数据库集成技术

网格建立在服务的基础之上,使得空间数据库在网格环境中面临着如何提供相应的数据库服务、异构系统间的空间数据集成、空间数据如何进行互操作等问题。该文针对网格环境下异构空间数据库之间数据集成的困难,提出将OGSA-DAI中间件技术引入到空间数据库系统应用中,对OGSA-DAI进行空间数据访问的扩展,以实现异构空间数据库的有效集成,通过一个应用实例验证该方法的可行性。     

系统集成中网格计算的调度

针对大型软件项目系统集成过程中存在的潜在问题,通过对网格计算、调度策略、回归测试的优化的分析研究,提出高效的、占用软硬件资源合理的系统集成解决方案。并且以自己工作中的软件开发系统集成项目经验为例,详细论述了网格计算在系统集成中的应用。     

项目管理信息系统集成及其发展趋势

介绍了项目管理系统集成的概念、现状和存在的问题，通过国内外集成模型和实例介绍了项目管理系统集成的具体应用，对目前系统集成的主要方法和今后的发展方向进行了探讨。本文还首次提出了基于本体论的项目管理系统集成方法和项目网格的概念。     

网格环境下的数据库安全与密码管理

本文阐述了网格环境下的数据库安全与加密技术，给出了一种将加密数据库集成入网格的结构以及网格环境下的密码管理方法。     

Grid Computing in China

Grid computing presents a new trend to distributed computation and Internet applications, which can construct a virtual single image of heterogeneous resources, provide uniform application interface and integrate widespread computational resources into super, ubiquitous and transparent aggregation. In the adoption of Grid computing, China, who is facing more resource heterogeneity and other specific demands, has put much effort on both research and practical utilization. In this paper, we introduce the major China Grid research projects and their perspective applications. First we give the overview of the four government-sponsored programs in Grid, namely the China National Grid, ChinaGrid, NSFC Grid, and ShanghaiGrid. Then we present six representative ongoing Grid systems in details, which are categorized into Grid middleware and Grid application. This paper provides the general picture of Grid computing in China, and shows the great efforts, devotion and confidence in China to use Grid technology to boost the society, economics and scientific research.     

Distributed data mining on Agent Grid: Issues,platform and development toolkit

Centralized data mining techniques are widely used today for the analysis of large corporate and scientific data stored in databases. However, industry, science, and commerce fields often need to analyze very large datasets maintained over geographically distributed sites by using the computational power of distributed systems. The Grid can play a significant role in providing an effective computational infrastructure support for this kind of data mining. Similarly, the advent of multi-agent systems has brought us a new paradigm for the development of complex distributed applications. During the past decades, there have been several models and systems proposed to apply agent technology building distributed data mining (DDM). Through a combination of these two techniques, we investigated the critical issues to build DDM on Grid infrastructure and design an Agent Grid Intelligent Platform as a testbed. We also implement an integrated toolkit VAStudio for quickly developing agent-based DDM applications and compare its function with other systems.     

Workflow-Based Data Parallel Applications on the EGEE Production Grid Infrastructure

Setting up and deploying complex applications on a Grid infrastructure is still challenging and the programming models are rapidly evolving. Efficiently exploiting Grid parallelism is often not straight forward. In this paper, we report on the techniques used for deploying applications on the EGEE production Grid through four experiments coming from completely different scientific areas: nuclear fusion, astrophysics and medical imaging. These applications have in common the need for manipulating huge amounts of data and all are computationally intensive. All the cases studied show that the deployment of data intensive applications require the development of more or less elaborated application-level workload management systems on top of the gLite middleware to efficiently exploit the EGEE Grid resources. In particular, the adoption of high level workflow management systems eases the integration of large scale applications while exploiting Grid parallelism transparently. Different approaches for scientific workflow management are discussed. The MOTEUR workflow manager strategy to efficiently deal with complex data flows is more particularly detailed. Without requiring specific application development, it leads to very significant speed-ups.     

A survey on approaches to gridification

The Grid shows itself as a globally distributed computing environment, in which hardware and software resources are virtualized to transparently provide applications with vast capabilities. Just like the electrical power grid, the Grid aims at offering a powerful yet easy‐to‐use computing infrastructure to which applications can be easily ‘plugged’ and efficiently executed. Unfortunately, it is still very difficult to Grid‐enable applications, since current tools force users to take into account many details when adapting applications to run on the Grid. In this paper, we survey some of the recent efforts in providing tools for easy gridification of applications and propose several taxonomies to identify approaches followed in the materialization of such tools. We conclude this paper by describing common features among the proposed approaches, and by pointing out open issues and future directions in the research and development of gridification methods. Copyright © 2007 John Wiley & Sons, Ltd.     

Performance analysis of allocation policies for interGrid resource provisioning

Several Grids have been established and used for varying science applications during the last years. Most of these Grids, however, work in isolation and with different utilisation levels. Previous work has introduced an architecture and a mechanism to enable resource sharing amongst Grids. It has demonstrated that there can be benefits for a Grid to offload requests or provide spare resources to another Grid. In this work, we address the problem of resource provisioning to Grid applications in multiple-Grid environments. The provisioning is carried out based on availability information obtained from queueing-based resource management systems deployed at the provider sites which are the participants of the Grids. We evaluate the performance of different allocation policies. In contrast to existing work on load sharing across Grids, the policies described here take into account the local load of resource providers, imprecise availability information and the compensation of providers for the resources offered to the Grid. In addition, we evaluate these policies along with a mechanism that allows resource sharing amongst Grids. Experimental results obtained through simulation show that the mechanism and policies are effective in redirecting requests thus improving the applications’ average weighted response time.     

Practical Experience from Porting and Executing the Wien2k Application on the EGEE Production Grid Infrastructure

While the Grid promises to deliver a large number of computation nodes to a user, this computation power is not usable without the proper adaption of the application for the Grid. In this paper, we describe the methods used to port and execute a particular application, Wien2k, on the EGEE production Grid. First, the process of porting the application is described. Then, we investigate the measures necessary to execute the application in this production Grid environment efficiently. Although the focus is on this special application, we describe generic methods which can be applied to all applications. We specifically address: Creating a workflow from an application and mapping this workflow to a Grid workflow using the activity attraction pattern. We discuss workflow engines which support cycles in their application workflow. We investigate naïve and worker scheduling techniques. A short introduction into licensing on the Grid is given. Optimisation techniques such as deployment re-use are discussed. Different data transfer mechanisms, centralised data transfer, data re-use, storage element data transfer, and peer-to-peer data transfer are compared. The paper is concluded with suggestions for further workflow porting.     

An overview of S-OGSA: A Reference Semantic Grid Architecture

The Grid's vision, of sharing diverse resources in a flexible, coordinated and secure manner through dynamic formation and disbanding of virtual communities, strongly depends on metadata. Currently, Grid metadata is generated and used in an ad hoc fashion, much of it buried in the Grid middleware's code libraries and database schemas. This ad hoc expression and use of metadata causes chronic dependency on human intervention during the operation of Grid machinery, leading to systems which are brittle when faced with frequent syntactic changes in resource coordination and sharing protocols.The Semantic Grid is an extension of the Grid in which rich resource metadata is exposed and handled explicitly, and shared and managed via Grid protocols. The layering of an explicit semantic infrastructure over the Grid Infrastructure potentially leads to increased interoperability and greater flexibility.In recent years, several projects have embraced the Semantic Grid vision. However, the Semantic Grid lacks a Reference Architecture or any kind of systematic framework for designing Semantic Grid components or applications. The Open Grid Service Architecture (OGSA) aims to define a core set of capabilities and behaviours for Grid systems. We propose a Reference Architecture that extends OGSA to support the explicit handling of semantics, and defines the associated knowledge services to support a spectrum of service capabilities. Guided by a set of design principles, Semantic-OGSA (S-OGSA) defines a model, the capabilities and the mechanisms for the Semantic Grid.We conclude by highlighting the commonalities and differences that the proposed architecture has with respect to other Grid frameworks.     

Monte Carlo methods for matrix computations on the grid

Many scientific and engineering applications involve inverting large matrices or solving systems of linear algebraic equations. Solving these problems with proven algorithms for direct methods can take very long to compute, as they depend on the size of the matrix. The computational complexity of the stochastic Monte Carlo methods depends only on the number of chains and the length of those chains. The computing power needed by inherently parallel Monte Carlo methods can be satisfied very efficiently by distributed computing technologies such as Grid computing. In this paper we show how a load balanced Monte Carlo method for computing the inverse of a dense matrix can be constructed, show how the method can be implemented on the Grid, and demonstrate how efficiently the method scales on multiple processors.     

DynaGrid: A dynamic service deployment and resource migration framework for WSRF-compliant applications

Large-scale Grid is a computing environment composed of Internet-wide distributed resources shared by a number of applications. Although WSRF and Java-based hosting environment can successfully deal with the heterogeneity of resources and the diversity of applications, the current Grid systems have several limitations to support the dynamic nature of large-scale Grid.This paper proposes DynaGrid, a new framework for building large-scale Grid for WSRF-compliant applications. Compared to the existing Grid systems, DynaGrid provides three new mechanisms: dynamic service deployment, resource migration, and transparent request dispatching. Two core components, ServiceDoor and dynamic service launcher (DSL), have been implemented as WSRF-compliant Web services to realize DynaGrid, which are applicable to any Java-based WSRF hosting environment. We construct a real testbed with DynaGrid on the Globus Toolkit 4 and evaluate the effectiveness of our framework using two practical applications. The evaluation results show that dynamic service deployment and resource migration in DynaGrid bring many advantages to large-scale Grid in terms of performance and reliability with minimal overhead.