An Access Control Framework for Reflective Middleware

Reflective middleware opens up the implementation details of middleware platform and applications at runtime for improving the adaptability of middleware-based systems. However,such openness brings new challenges to access control of the middleware-based systems. Some users can access the system via reflective entities,which sometimes cannot be protected by access control mechanisms of traditional middleware. To deliver high adaptability securely,reflective middleware should be equipped with proper access control mechanisms for potential access control holes induced by reflection. One reason of integrating these mechanisms in reflective middleware is that one goal of reflective middleware is to equip applications with reflection capabilities as transparent as possible. This paper studies how to design a reflective J2EE middleware - PKUAS with access control in mind. At first,a computation model of reflective system is built to identify all possible access control points induced by reflection. Then a set of access control mechanisms,including the wrapper of MBeans and a hierarchy of Java class loaders,are equipped for controlling the identified access control points. These mechanisms together with J2EE access control mechanism form the access control framework for PKUAS. The paper evaluates the security and the performance overheads of the framework in quality and quantity.     

An Asynchronous Messaging Model with Time Independent Invocation Based on Distributed Objects

An asynchronous message invocation mechanism of distributed object middleware in the business heterogeneous and integrated platform is studied in this paper. On the basis of the analysis of currently existing distributed object middleware supporting callback and poller, an asynchronous messaging model with time independent invocation is proposed to deal with the problem of time independent asynchronous invocation that neither of the two above-mentioned mechanisms supports. In this model, message picking-up, packing and transforming arc implemented by Message Conversion Layer （MCL）, and a Software Route Agent （SPA） is designed to store and transmit message. The model can support message invocation asynchronously and time independent invocation effectively. At the same time, it also can support message service quality control. Finally the algorithm and implementation of software route agent are given.     

esign of power controller in CDMA system with power and SIR error minimization

In this paper, an uplink power control problem is considered for code division multiple access （CDMA） systems. A distributed algorithm is proposed based on linear quadratic optimal control theory. The proposed scheme minimizes the sum of the power and the error of signal-to-interference ratio （SIR）. A power controller is designed by constructing an optimization problem of a stochastic linear quadratic type in Krein space and solving a Kalman filter problem.     

Design of power controller in CDMA system with power and SIR error minimization

In this paper, an uplink power control problem is considered for code division multiple access (CDMA) systems. A distributed algorithm is proposed based on linear quadratic optimal control theory. The proposed scheme minimizes the sum of the power and the error of signal-to-interference ratio (SIR). A power controller is designed by constructing an optimization problem of a stochastic linear quadratic type in Krein space and solving a Kalman filter problem.     

Usage control mechanism for securing the multi-organizational grid

Security is a fundamental but challenging issue in the dynamic and multi-organizational computational grid. Focusing on the closed system, traditional access control model considered static authorization decisions based on pre-assigned permissions. To facilitate collaborations and interoperations across the grid, we propose a usage control mechanism for computational grid. Our mechanism is based on the usage control model. By leveraging continuous usage control on grid services and monitoring the status and behaviors of the subjects involved in the collaborations, our mechanism improves collaboration＇s security. Furthermore, our mechanism enables richer and finer-grained control over authorizations on resources and services involved in collaborations and interoperations than that of traditional access control mechanisms. Our mechanism can contribute to maintain the security and interests of the service providers in the grid environment.     

Using Tensilica Xtensa configures a dual-core processor based-on SoC

In this paper, we proposed a multi-core processor, which is based on system-on-chip （SoC） architecture and established by configurable processor via Tensilica Xtensa LX2. The purpose of this paper is to describe the heterogeneous configurable dual-core processor, in which one core is responsible host operating control for the system and the other is as an extension of digital signal processing applications. However, the designed core not only owns its local memory, but also shares a common data-memory. We also put virtual memory in this proposed processors, this addition memory allows processor easily to handle a more complex application programs while two cores are able to share a unified data-memory in different kinds tasks, simultaneously. The advantages of the proposed structure can avoid and reduce many hard-wired of memory and interface respectively. For bus managing, a single bus as interface is proved. In this bus system an arbitration mechanism is added to handle the communication between cores and to distribute the priority of access request, in order to ensure that those cores operation under synchronously.     

A grid middleware for distributed Java computing with MPI binding and process migration supports

“Grid” computing has emerged as an important new research field. With years of efforts, grid researchers have successfully developed grid technologies including security solutions,resource management protocols, information query protocols, and data management services. How-ever, as the ultimate goal of grid computing is to design an infrastructure which supports dynarnic,cross-organizational resource sharing, there is a need of solutions for efficient and transparent task re-scheduling in the grid. In this research, a new grid middleware is proposed, called G-JavaMPI. This middleware adds the parallel computing capability of Java to the grid with the support of a Grid-enabled message passing interface (MPI) for inter-process communication between Java processes executed at dif-ferent grid points. A special feature of the proposed G-JavaMPI is the support of Java process migration with post-migration message redirection. With these supports, it is possible to migrate executing Java process from site to site for continuous computation, if some site is scheduled to be turned down for system reconfiguration. Moreover, the proposed G-JavaMPI middleware is very portable since it requires no modification of underlying OS, Java virtual machine, and MPI package. Preliminary performance tests have been conducted. The proposed mechanisms have shown good migration efficiency in a simulated grid environment.     

Framework and Algorithm for Grid QoS Infrastructure in Optical Burst Switching Networks with GMPLS Support

Recently, in order to satisfy the requirements of all kinds of high-performance computing and transmission applications, researchers begin to focus on grid technology and have made lots of research work. Among the corresponding aspects, a complete and feasible grid framework is rather pivotal to provide nontrivial QoS guarantee in this grid architecture, which should include Grid application layer, Grid middleware layer, and network layer, even the concrete resources. In this paper, a novel architecture for Grid QoS infrastructure is proposed based on other architectures suggested by Globus project, Global Grid forum and IETF. The architecture is complete and consists of three QoS layers from top to bottom including Grid application, middleware and network layer. In addition, the algorithm based on advance resource reservation is also provided and described in optical burst switching （OBS） networks with GMPLS（Generalized Multi-Protocol Label Switching） support. The algorithm with pruned topology and shared risk links group constraints is designed for supporting the realization of routing function in the architecture. Extensive simulations with dynamic traffic are made to prove the validity and properness.     

Fault-tolerant grid architecture and practice

Grid computing emerges as effective technologies to couple geographically dis-tributed resources and solve large-scale computational problems in wide area networks. The fault tolerance is a significant and complex issue in grid computing systems. Various techniques have been investigated to detect and correct faults in distributed computing systems. Unreliable fault detection is one of the most effective techniques. Globus as a grid middleware manages resources in a wide area network. The Globns fault detection service uses the well-known techniques basedon unreliable fault detectors to detect and report component failures. However, more powerful techniques are required to detect and correct both system-level and application-level faults in agrid system, and a convenient toolkit is also needed to maintain the consistency in the grid. Afault-tolerant grid platform (FTGP) based on an unreliable fault detector and the Globus faultdetection service is presented in this paper. The platform offers effective strategies in such threeaspects as grid key components, user tasks, and high-level applications.     

On Model, Memory Management and Interface in EDBMS/3

Engineering application domains need database management systems to supply them with a good means of modeling,a high data access efficiency and a language interface with strong functionality.This paper presents a semantic hypergraph model based on relations,in order to express many-to-many relations among objects belonging to different semantic classes in engineering applications.A management mechanism expressed by the model and the basic data of engineering databases are managed in main memory.Especially,different objects are linked by different kinds of semantics defined by users,therefore the table swap,the record swap and some unnecessary examinations ar reduced and the access efficiency of the engineering data is increased.C language interface that includes some generic and special functionality is proposed for closer connection with application programs.     

一种基于松弛时间的服务网格资源能力预留机制

通过资源能力预留为网格服务提供确定的QoS保证是实现服务网格QoS管理的基础和关键.针对确定性资源能力预留的"资源能力碎片"问题,提出了一种支持松弛时间的灵活资源能力预留机制,并设计了支持松弛时间的资源预留请求接纳控制算法.在CROWN的节点服务器上实现了该机制,并通过仿真实验进行性能评价.结果表明,和已有的确定型预留机制相比,支持松弛时间的资源能力预留机制,使资源能力调度具有更多的自主性,可显著地提高网格资源的综合利用效率.     

基于Jini技术的RFID中间件平台

随着社会生产力的发展,科学技术的不断进步,射频识别（Radio Frequency Identification,RFID）技术近年来由于其显著的优点得到了广泛的应用,为了让作为RFID系统神经中枢的RFID中间件可以更好、更快地得到应用,使其能适应更多的应用需求,对现有的RFID中间件进行改进与优化是十分必要的,本文研究基于Java的分布式系统—Jini,给出基于Jini的RFID中间件平台的总体架构,利用RMI通信方式,实现RFID设备（虚拟的设备）在Jini环境下的自动识别、RFID中间件在Jini环境下的自动配置和管理以及RFID设备的＂即插即用＂的功能,同时对RFID中间件在Jini环境下的管理进一步地进行优化,使得基于EPCglobal标准的RFID中间件的设备配置与管理能在分布式环境下高效地运行。最后在实验中验证RFID中间件在Jini平台中的＂即插即用＂性。本文为RFID中间件与现代技术的结合提供思路和方法参考。     

Supporting dynamic access to virtualized data resources via WSRF-based services

Today grid applications require not only lots of computational power but data at a very large scale too. Although grid computing was initially conceptualized as the technology that focuses on solving compute-intensive problems, this focus has gradually shifted to applications where data is distributed over various locations. Access to these data resources stored in heterogeneous grid storage systems located at geographically distributed virtual organizations in an integrated and uniform way is a challenging problem. The Web Services Resource Framework (WSRF) has recently emerged as the standard for the development and integration of grid services. This paper proposes and presents Gravy4WS, a middleware architecture based on WSRF Web services that enables the dynamic access to virtualized grid data resources. A novel scheduling algorithm called DCE (Delegating-Cluster-Execution based Scheduling) is proposed to improve load balancing of the system. The implementation of Gravy4WS using WSRF libraries and services provided by Globus Toolkit 4 is described together with its performance evaluation.     

An approach to enhance the efficiency of opportunistic grids

Opportunistic grid computing middleware has as a main concern the need to preserve the performance of the local applications running on machines that donate resources to the grid. This concern, together with the fact that it happens in an extremely dynamic environment, causes the adoption of a treatment based on thetextitbest‐effort principle for grid applications. This means that efficient application management schemes are usually not employed, which results in less than optimal performance as grid applications often need to be restarted due to (often temporary) resource claims by local user applications. This paper presents a method to improve the performance of grid applications, taking into account resource usage profiles for local applications, trying to identify when such resource claims are temporary and avoiding costly actions such as the migration of grid tasks. The approach is proposed as an extension to the InteGrade middleware and its evaluation shows promising results for the efficient management of grid applications. Copyright © 2011 John Wiley & Sons, Ltd.     

The application hosting environment: Lightweight middleware for grid-based computational science

Grid computing is distributed computing performed transparently across multiple administrative domains. Grid middleware, which is meant to enable access to grid resources, is currently widely seen as being too heavyweight and, in consequence, unwieldy for general scientific use. Its heavyweight nature, especially on the client-side, has severely restricted the uptake of grid technology by computational scientists. In this paper, we describe the Application Hosting Environment (AHE) which we have developed to address some of these problems. The AHE is a lightweight, easily deployable environment designed to allow the scientist to quickly and easily run legacy applications on distributed grid resources. It provides a higher level abstraction of a grid than is offered by existing grid middleware schemes such as the Globus Toolkit. As a result, the computational scientist does not need to know the details of any particular underlying grid middleware and is isolated from any changes to it on the distributed resources. The functionality provided by the AHE is ‘application-centric’: applications are exposed as web services with a well-defined standards-compliant interface. This allows the computational scientist to start and manage application instances on a grid in a transparent manner, thus greatly simplifying the user experience. We describe how a range of computational science codes have been hosted within the AHE and how the design of the AHE allows us to implement complex workflows for deployment on grid infrastructure.     

基于遥感数据访问与集成的网格中间件

借助数据网格强大的数据管理功能，可以整合分散复杂的遥感数据，为遥感数据处理提供一致的存取环境。遥感数据访问与集成网格中间件的研究目的是为访问分散的、异构的遥感数据提供统一的网格服务接口，使孤立的遥感数据之间实现资源共享。该文利用OGSA-DAI设计，实现了遥感数据访问和集成网格服务，构建了一个高性能遥感数据共享系统，分析了系统的关键性技术及实际应用。     

分布式应用中的访问控制规范的研究

针对分布式系统中安全服务规范给安全策略管理带来的不便,文章给出了一个针对分布式系统的访问控制策略设计和管理的访问控制模型,将此模型融入到分布式应用系统程序中,使用视图策略语言来描述访问控制策略,实现对安全访问策略行之有效的管理,并可以进行静态类型检测以保证规范的一致性。文章最后给出了分布式应用程序中执行VPL表示的访问控制策略的基础结构。     

基于JDBC驱动扩展OGSA-DAI访问数据库的探讨

网格计算如今变得越来越流行,但这并不意味着它是易于使用,部署和开发的。 OGSA-DAI是一款能够在网格中开发和管理数据库的中间件。我们目前所做的工作是用SUN公司JDBC接口的一个应用来扩展OGSA-DAI的网格中间件,使用Java语言来访问数据库。本次应用使用OGSA的代客户端API ,目的是提供一种简单而众所周知的方法,使新的和现有的开发人员及应用程序能够在网格中使用OGSA-DAI中间件来操作数据库。     

Economics‐inspired decentralized control approach for adaptive grid services and applications

Grid technologies facilitate innovative applications among dynamic virtual organizations, while the ability to deploy, manage, and properly remain functioning via traditional approaches has been exceeded by the complexity of the next generation of grid systems. An important method for addressing this challenge may require nature‐inspired computing paradigms. This technique will entail construction of a bottom‐up multiagent system; however, the appropriate implementation mechanism is under consideration in order for the autonomous and distributed agents to emerge as a controlled grid service or application. A credit card management service in economic interactions is considered in this article for a decentralized control approach. This consideration is based on a preliminarily developed ecological network‐based grid middleware that has features desired for the next generation grid systems. The control scheme, design, and implementation of the credit card management service are presented in detail. The simulation results show that (1) agents are accountable for their activities such as behavior invocation, service provision, and resource utilization and (2) generated services or applications adapt well to dynamically changing environments such as agent amounts as well as partial failure of agents. The approach presented herein is beneficial for building autonomous and adaptive grid applications and services. © 2006 Wiley Periodicals, Inc. Int J Int Syst 21: 1269–1288, 2006.