因特网上基于节点角色的计算资源共享平台——RB-CRSP

提出了因特网上基于节点角色的计算资源共享平台——RB-CRSP。设计时充分考虑节点的角色性和功能性,把因特网上的网络资源按照角色划分为服务器端节点、协调节点、工作机节点与客户机节点四类实体,通过配合RB-CRSP的应用编程模式,完成并行分布式计算。分析了RB-CRSP中的自适应资源调度策略,该策略考虑了节点的硬件信息与可信誉机制,实现了平台的负载均衡性;在动态的因特网环境下,利用面向工作机的容错方式保证了平台的可靠性。案例程序选择了典型的并行BenchMark程序：N皇后问题,测试结果表明,RB-CRSP可以方便聚集异构环境下的空闲计算资源,平台的性能与机器硬件条件和可靠性密切相关。     

非结构化对等网络中的信誉管理机制

针对因特网上网络资源共享中存在的恶意节点行为,提出并描述了一种非结构化对等网络中的信誉管理机制.该机制使用非集中式的策略,根据节点与应用的需求计算节点的信誉度,具有独立性,不需要其它节点的参入与辅助.把加入对等网络的节点行为划分为恶意行为与友好行为,既可以统计节点对系统的贡献,也可以根据恶意行为而减少节点的信誉度.描述了信誉管理机制的设计与实现,各种节点行为下的仿真实验结果表明,该信誉管理机制是对等网络中一种真实的,高效的、信誉机制良好的资源共享策略.     

利用结构化对等网络构造计算资源共享平台

设计和构建了一个基于结构化对等网络的计算资源共享平台DHT-CRSP。它可以把因特网上用户提交的科学计算作业高效地映射到平台中合适的工作节点上运行,通过容错和安全机制,能保证系统的可靠性和正确性。描述了DHT-CRSP中支持的两种分布式哈希表：Chord协议节点树和CAN协议空间区域;分析了DHT-CRSP中高效的资源匹配算法。通过构建评测环境,运行各种负载与作业场景下的结果表明,DHT-CRSP系统可以获得好的负载均衡性能、低的资源匹配代价,它提供了一种构建高性能的桌面网格平台的新思路。     

P2P网络中一种基于定向查询的分布式信誉系统

P2P网络中的安全问题越来越受到关注,广泛采取的策略是建立信誉系统.提出了一种基于定向查询的分布式P2P信誉系统,节点交互历史表记录与本地节点有交互经验的各节点信息,而本地节点的信誉信息分散存储在交互历史表中各节点上的信誉信息表中.信誉查询时查询节点根据被查询节点交互历史表的信息直接定向到提供被查询节点信誉信息的节点,恶意节点表和表尾信息表保证了信誉信息的安全.仿真实验的结果表明该信誉系统可以有效地减少无效交互的次数,遏制恶意节点对信誉信息的破坏.     

机会路由算法中层次化的辅助信息获取机制

信息辅助型路由是一种依赖额外信息协助节点高效地转发数据包的机会路由机制。然而目前的信息辅助型路由算法中节点间辅助信息的获取以一种洪泛的方式进行,造成了网络资源浪费。针对此问题,提出了一种层次化的辅助信息获取机制。一方面,互为邻居的节点之间进行信息获取,保证信息更新速度较快。另一方面,将节点分为社会性节点和普通节点,使信息的获取主要发生在社会性节点与普通节点之间,以保证信息的网络覆盖率较高。通过有选择性地共享信息可以显著地减少节点间信息获取次数。实验结果表明,在不显著影响路由算法基本性能指标的前提下,该机制可以减少大约80%的辅助信息获取次数。     

Ad hoc网络中的一种自组织网络层安全方案

提出了一种自组织网络层安全方案(self organized network layer security, SONLS),为按需路由的路由形成和数据转发提供了网络层的安全保护.SONLS主要通过信息交叉检查和分布式联合评估的自组织方式来保护网络.SONLS在路由信息中不使用任何加/解密方法,而是通过邻节点之间的相互协作,共同监督和监测节点的行为,并及时地将收集的邻节点的信息进行交叉检查,以判断是否存在可疑节点.网络中所有节点都是对等的.在SONLS采用了一种新的信誉机制,通过分布式联合评估判断可疑节点是否为恶意节点.通过负载分析可以看到,该信誉机制随着时间的推移,可以有效地降低负载.仿真结果显示,SONLS在多个攻击者存在的网络环境下也是有效的.     

VANET中利用分布式TDMA空闲时隙的协作中继方法

车载自组网中的分布式时分多址(TDMA)协议的主要缺陷是未能充分利用无线信道资源,如节点空闲时隙问题。针对车载自组网无中心节点且网络拓扑结构快速变化的特点,提出一种协作中继分布式TDMA方法(CR-DTDMA),以便利用节点空闲时隙协作中继转发数据。CR-DTDMA实现一种网络握手协议来确定协作中继节点,不依赖相关数据传输确认机制,而且网络握手协议的控制信息都采用消息搭载机制传递,不需要发送专门的控制包。分析与模拟表明,CR-DTDMA提高了数据中继转发概率,降低了中继转发时延和丢包率。     

基于本体的P2P网络全局知识视图构造的研究

为了从语义层次上解决P2P资源匹配问题,本体论被引入,试图通过采用可扩展的信息建模工具使得网络资源发现系统能够高效、精确地发现P2P网络资源,同时获得良好的灵活性。然而当前采用的技术要求网络节点共享一个集中的网络资源本体,这种技术不适合高度动态性和分散性的P2P网络。提出一种基于局部本体的P2P网络全局知识视图构建方法,提供了网络资源的全局描述,同时保持了对资源语义的揭示,这种方法不需要网络节点维护一个共享的集中的本体,可扩展性强,对资源的描述更灵活,更适合用于P2P网络资源匹配。     

机载分布式平台的一种集中维护自检控制实现方法

机载分布式平台进行维护自检时,因节点多、节点差异大而导致出现维护自检控制和交互机制复杂、维护周期时间加长等维护安全性问题。提出了一种机载分布式平台集中维护自检控制的实现方法,基于机载分布式平台集中控制机制,可以实现对平台中的多节点、异构节点的统一维护自检,减少了管理和交互的复杂性,支持对检测出的故障信息进行详细报告,提高了分布式平台的可维护性。     

物联网技术在水下作业监控及救援中的应用

研究水下作业监控及救援问题。针对传统的水下作业监测系统中的终端节点不便携带,网络部署和维护成本高,难以自适应采集监控区域内各种水下作业数据和实时预警并实施水下救援等问题,分布式多传感异步网络提出了一种实时水下作业监测及应急救援的物联网技术。以监测分簇为单位构建异步通信网络,部署不同类型的传感器终端节点如温度、湿度、噪声传感器等,基于分布式传输技术针对不同性质的水下作业采集各种类型的水下作业环境和人员定位数据,同时根据监测数据对水下作业人员建立危险预警机制。仿真结果和分析表明,物联网技术对各种类型水下作业实施监测及实现远程数据判读,具有高可靠性的实时预警,并有效地增强了监控网络的生存周期。     

CompuP2P: An Architecture for Internet Computing Using Peer-to-Peer Networks

Internet computing is emerging as an important new distributed computing paradigm in which resource intensive computing is integrated over Internet-scale networks. Over these large networks, different users and organizations share their computing resources, and computations take place in a distributed fashion. In such an environment, a framework is needed in which the resource providers are given incentives to share their resources. CompuP2P is a lightweight architecture for enabling Internet computing. It uses peer-to-peer networks for sharing of computing resources. CompuP2P create dynamic markets of network accessible computing resources, such as processing power, memory storage, disk space, etc., in a completely distributed, scalable, and fault-tolerant manner. This paper discusses the system architecture, functionality, and applications of the proposed CompuP2P architecture. We have implemented a Java-based prototype, and our results show that the system is light-weight and can provide almost a perfect speedup for applications that contain several independent compute-intensive tasks     

A Fair, Secure and Trustworthy Peer-to-Peer Based Cycle-Sharing System

The increased popularity of Grid systems and cycle sharing across organizations requires scalable systems that provide facilities to locate resources, to be fair in the use of those resources, to allow resource providers to host untrusted applications safely, and to allow resource consumers to monitor the progress and correctness of jobs executing on remote machines. This paper presents such a framework that locates computational resources with a peer-to-peer network, assures fair resource usage with a distributed credit accounting system, provides resource contributors a safe environment, for example Java Virtual Machine (JVM), to host untrusted applications, and provides the resource consumers a monitoring system, GridCop, to track the progress and correctness of remotely executing jobs. We present the details of the credit accounting subsystem and the GridCop remote job monitoring subsystem. GridCop and the distributed credit accounting system together enable incremental payments so that the risk for both resource providers and resource consumers is bounded.*This work was supported by NSF CAREER award grant ACI-0238379 and NSF grants CCR-0313026 and CCR-0313033.     

ML-Chord: A multi-layered P2P resource sharing model

In recent years, due to the emergence of P2P technology, people rely on the Internet to share resources. It is believed that the number of users and shared resources will become enormously huge. As a result, many researches have been dedicated to improve the scalability and efficiency of P2P models. In this paper, we propose a multi-layered P2P resource sharing model, called ML-Chord, that assigns nodes into Chord-like layers based on the categories of shared resources. From the experimental results, it shows that ML-Chord is both efficient and scalable.     

基于P2P的教育资源网络设计

在网络中搜索各种教育资源时,通用的搜索引擎很难满足特定的需求。P2P网络是一种有效的资源共享和搜索方式。通过分析P2P网络的基本结构和资源共享特点,提出了一种基于P2P的教育资源网络（PBERN）模型。PBERN是由教育资源实体“自组织”组成的分布式、虚拟、动态和松散的纯P2P网络。     

一种媒体点播系统资源对等搜索模型

媒体点播是网络教育中重要的教学方式,但是目前存在标准不同、共享困难等问题。为此引入P2P技术解决资源共享问题。P2P网络是一种自组织、适应性强、负载均衡、可靠性好的网络,目前被广泛运用于文件共享等领域。文中介绍利用P2P技术实现多个媒体点播系统互联,为用户提供可扩展的查询服务和资源共享平台。通过分析得出互联后的媒体点播系统较单个系统具有许多优点。     

A dynamic framework for integrated management of all types of resources in P2P systems

Traditional Peer-to-Peer (P2P) systems were restricted to sharing of files on the Internet. Although some of the more recent P2P distributed systems have tried to support transparent sharing of other types of resources, like computer processing power, but none allow and support sharing of all types of resources available on the Internet. This is mainly because the resource management part of P2P systems are custom designed in support of specific features of only one type of resource, making simultaneous access to all types of resources impractical. Another shortcoming of existing P2P systems is that they follow a client/server model of resource sharing that makes them structurally constrained and dependent on dedicated servers (resource managers). Clients must get permission from a limited number of servers to share or access resources, and resource management mechanisms run on these servers. Because resource management by servers is not dynamically reconfigurable, such P2P systems are not scalable to the ever growing extent of Internet. We present an integrated framework for sharing of all types of resources in P2P systems by using a dynamic structure for managing four basic types of resources, namely process, file, memory, and I/O, in the same way they are routinely managed by operating systems. The proposed framework allows P2P systems to use dynamically reconfigurable resource management mechanisms where each machine in the P2P system can at the same time serve both as a server and as a client. The pattern of requests for shared resources at a given time identifies which machines are currently servers and which ones are currently clients. The client server pattern changes with changes in the pattern of requests for distributed resources. Scalable P2P systems with dynamically reconfigurable structures can thus be built using our proposed resource management mechanisms. This dynamic structure also allows for the interoperability of different P2P systems.     

利用分布式哈希表构建带副本的检查点

利用分布式哈希表构建了一种带副本的检查点文件共享机制,可以使因特网上的计算资源共享平台由于节点异常退出时恢复或重新启动任务的执行.所有关于该检查点文件的操作都是在非集中式的分布式哈希表中完成,可以很好的跟踪、共享、回收在存储点上的检查点文件,很少需要后台服务器的参入与合作.把检查点保存在其相应的存储点上,通过哈希表中的标准函数来访问指向存储点的指针,最终完成检查点文件的基本操作.仿真结果表明:本文的检查点机制比传统的检查点策略具有比较快的任务通信轮回时间,同时计算平台也可以获得比较好的任务吞吐量,减少通信的负载.     

支持访问控制的P2P大规模遥感数据分发系统

遥感数据日益增长,大规模遥感数据分发对集中分发服务器构成了巨大压力。充分利用参与下载节点的网络资源,提出并实现了一种支持访问控制的P2P大规模遥感数据分发系统。遥感数据分发系统分为遥感数据管理平台和遥感数据客户端两部分,遥感数据管理平台包含共享分发平台网站、云存储、种子资源服务器和跟踪服务器4个组件,遥感数据各客户端和种子资源服务器构成P2P网络。设计了包括共享分片、分片选择、跟踪器通信等的P2P协议,实现的遥感数据分发系统能够上传遥感数据并自动做种,支持对用户的访问控制。根据用户权限进行下载,各下载节点共享分片,然后基于类Bittorrent协议来加速遥感数据的分发。实验结果表明,实现的大规模遥感数据分发系统的功能完善,在多节点下载时具备良好的并发性能,能够满足大规模遥感数据分发的需要。     

Multi-QoS constrained and Profit-aware scheduling approach for concurrent workflows on heterogeneous systems

The execution of a workflow application can result in an imbalanced workload among allocated processors, ultimately resulting in a waste of resources and a higher cost to the user. Here, we consider a dynamic resource management system in which processors are reserved not for a job but only to run a task, thus allowing a higher resource usage rate. This paper presents a scheduling algorithm that manages concurrent workflows in a dynamic environment in which jobs are submitted by users at any moment in time, on shared heterogeneous resources, and constrained to a specified budget and deadline for each job. Recent research attempted to propose dynamic strategies for concurrent workflows but only addressed fairness in resource sharing among applications while minimizing the execution time. The Multi-QoS Profit-Aware scheduling algorithm (MQ-PAS) proposed here is able to increase the profit achieved by the provider by considering the budget available for each job to define tasks priorities. We study the scalability of the algorithm with different types of workflows and infrastructures. The experimental results show that our strategy improves provider revenue significantly and obtains comparable successful rates of completed jobs.