A lower bound on the probability of conflict under nonuniform access in database systems

Past performance analyses of resource sharing systems have often assumed uniform resource access distributions. This assumption is made for reasons of computational tractability. In some of these analyses it has been conjectured that such an assumption is optimistic, in the sense that it minimizes the probability of resource conflict. In this paper we give conditions on access distributions for which the above conjecture is true and show that these conditions are satisfied for two natural probabilistic models. Our technique can be applied to other resource contention problems.Research supported by NSF and NSA under Grant DMS-9001295.     

基于混序组织的信息管理模型

信息资源的整合与共享管理是当前电子政务建设中的难题之一。应用迪伊·霍克(Dee Hock)混序组织理念和方法构建了一种资源共享的信息管理模型,以期为电子政务的信息资源整合与共享提供一种实现途径。通过对混序组织原理的分析和混序组织成员协作关系的分析,构建混序组织成员之间信息沟通与资源共享的管理模型,并将其应用于电子政务信息资源整合与共享的系统设计之中,进而创建了一种通用的信息资源整合与共享模型,也用此模型分析了政府部门行政审批系统、社会信用管理体系等信息资源整合与共享问题,为具有混序组织特征的电子政务信息资源整合与共享管理提供一种软系统架构模型和过程方法。     

一种基于分布对象技术的Agent计算框架

随着ＣＯＲＢＡ等分布计算技术的发展,分布式应用开始关注系统的可靠性,可用性,开放性,计算资源共享与可重用等问题。面向Ａｇｅｎｔ的分布计算技术是解决上述问题的有效手段。文中基于面向Ａｇｅｎｔ的计算观点,论述了分布式应用及其内部分布对象之间的关系,并针对系统可靠性以及可用性的需求,在ＣＯＲＢＡ平台上实现了一个Ａｇｅｎｔ框架,用于构造面向Ａｇｎｅｔ的分布式应用。     

基于区块链的分布式资源共享模型设计

计算机的资源共享为解决网络中计算机资源分布与计算能力需求不平衡、计算机资源浪费等问题提供了一种有效的解决方式。但是,传统计算机资源共享体系一般采用任务分配的方式,用户很难直接接触共享资源,此外,任务的分配调度都由中心节点统一管理,一旦中心节点受到破坏,那么资源共享体系的正常工作将难以为继。针对上述问题,本文提出一种分布式的资源共享模型,通过引入区块链私链来搭建资源共享模型的底层架构,以P2P的方式直接面对用户提供共享资源。本文对资源共享模型的关键实现机制进行分析,并且构建一个分布式的计算网络真正实现计算机资源共享。经过对资源共享模型在工作过程中CPU和内存使用情况的验证分析,验证了该模型能够有效提升计算机资源的使用效率,提升整体的计算能力。     

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.     

Analysis of modularly composed nets by siphons

This paper uses siphons to analyze the class of Petri nets constructed by a modular approach by Jeng and DiCesare (1995) for modeling manufacturing systems with shared resources. A resource point of view is taken. First the behavior of each resource is modeled using resource control nets, strongly connected state machines with one place being marked initially. Interactions among the resources are modeled through merging of common transition subnets. This paper provides conditions, expressed in terms of siphons, under which reversibility and liveness of the integrated model are obtained. Relations between siphons and circular-wait are formally established. Superiority of the siphon-based analysis over a previous analysis using circular wait is shown     

基于OAuth2.0的资源共享机制RSBO

共享资源重要的问题就是安全,本文针对目前主流的资源共享机制存的安全问题,如身份认证授权安全问题、用户信息泄露等问题,同时当资源在不同用户不同平台间进行共享时,用户需对资源进行分散重复存储等,造成冗余存储及空间浪费.本文针这些问题,提出了一种基于OAuth2.0协议的资源共享机制RSBO(Resource Sharing based OAuth2.0)并对其进行阐述,RSBO利用OAuth2.0协议认证授权的访问令牌原理,为共享资源创建资源令牌,该机制解决了用户信息泄露及冗余存储等问题,一次授权,实现多用户跨平台的资源共享.     

Deadlock resolution strategy for automated manufacturing systems including conjunctive resource service

Automated manufacturing systems (AMSs) can process different parts according to operation sequences sharing a finite number of resources. In these systems, deadlock situations can occur so that the flow of parts is permanently inhibited, and the processing of jobs is partially or completely blocked. Hence, one of the tasks of the control system is ruling resource allocation to prevent such situations from occurring. A large part of the existing literature focused on systems in which every operation is performed by only one resource. This paper proposes a deadlock strategy to avoid deadlock conditions in more complex systems where multiple resource acquisitions are allowed to complete a working operation conjunctive resource service system (CRSS). The AMS structure and dynamics is described by a colored timed Petri net model, suitable for following resource changes and working procedure updating. Moreover, digraphs characterize the complex interactions between resources and jobs so that the conditions for the deadlock occurrence are derived. Finally, an event-based controller is defined to avoid deadlock in CRSSs on the basis of the system state knowledge and of the given priority law ruling the concurrent job selection.     

基于网格的CSCL资源共享平台的研究

资源共享一直是协作学习研究的一个热点.本文针对当前协作学习系统在资源共享及管理方面存在的问题,运用网格计算技术搭建一个平台,实现资源的有效共享及统一管理,消除资源孤岛,优化资源调度.提出了系统的结构模型,讨论了其访问模型,并实现了网格管理器的四种网格服务.     

Buffer-Sharing Techniques in Service-Guaranteed Video Servers

Advances in networking and storage technology have made it possible to deliver on-demand services over networks such as the emerging video-on- demand (VOD) applications. Although a variety of studies have been focused on designing video servers suitable for VOD applications, the number of concurrent on-demand services supported by such servers is often limited by the I/O bandwidth of the storage systems. Recently, several researchers have focused on providing guaranteed services instead of on-demand services in a VOD system. A service is said to be guaranteed if every viewer can be served within a specified waiting time after the video has been subscribed. This paper describes a model called a buffer-sharing autonomy, which combines batching and bridging techniques to provide guaranteed services to VOD systems. We also describe how buffer-sharing techniques can be used in this model to provide the same services with fewer buffer resource through the use of playback-rate alteration. Additionally, in order to make buffer sharing efficient, it is important to group appropriate video streams together to share buffer resource. Four grouping policies are proposed for this purpose and the benefits yielded are also analyzed and compared. Finally, the results of our experiments show that the proposed buffer-sharing techniques promise the provision of guaranteed video services at low cost.     

Multi-objective Reinforcement Learning for Responsive Grids

Grids organize resource sharing, a fundamental requirement of large scientific collaborations. Seamless integration of Grids into everyday use requires responsiveness, which can be provided by elastic Clouds, in the Infrastructure as a Service (IaaS) paradigm. This paper proposes a model-free resource provisioning strategy supporting both requirements. Provisioning is modeled as a continuous action-state space, multi-objective reinforcement learning (RL) problem, under realistic hypotheses; simple utility functions capture the high level goals of users, administrators, and shareholders. The model-free approach falls under the general program of autonomic computing, where the incremental learning of the value function associated with the RL model provides the so-called feedback loop. The RL model includes an approximation of the value function through an Echo State Network. Experimental validation on a real data-set from the EGEE Grid shows that introducing a moderate level of elasticity is critical to ensure a high level of user satisfaction.     

The resource access authorization route problem in a collaborative manufacturing system

Most of collaborative manufacturing systems are based on or involved in distributed information systems. Access control model, as an important infrastructure facility of information system, is frequently employed to control the resource sharing and cooperation in a collaborative manufacturing system. However, Configuring and running an access control model in a collaborative manufacturing system is a more complex problem. The reason is that there are more resources to be accessed and more complex security policies and rules from different partners to be obeyed in such a system than these in an individual information system. Un-intuitional semantic of security policies directly result in administrators’ confusion in judging the legitimacy of authorization actions. They don’t even know which authorization actions should be performed and what performing order should be executed by. So, it is necessary to configure an authority action sequence, including an authority action set and the performing order, to help the administrators to perform the given authorization task without violating these multisource security policies and rules. In this paper, how to configure the authority action sequence is defined as an authorization route problem at first. Then, the problem is modeled as a classical planning problem and a GraphPlan algorithm is revised to solve it. Based on the modeled problem and the revised algorithm, a prototype system named PolicyProber is developed to provide an authority action sequence for administrators in a visual way. Several cases are used to demonstrate the effectiveness of the presented model, method and algorithm. The research achievements and its application in industry can help administrators make correct decisions, which can strength the safety of a collaborative manufacturing system indirectly.     

A Port Graph Calculus for Autonomic Computing and Invariant Verification

From our previous work on biochemical applications, the structure of port graph (or multigraph with ports) and a rewriting calculus have proved to be well-suited formalisms for modeling interactions between proteins. Then port graphs have been proposed as a formal model for distributed resources and grid infrastructures, where each resource is modeled by a node with ports. The lack of global information and the autonomous and distributed behavior of components are modeled by a multiset of port graphs and rewrite rules which are applied locally, concurrently, and non-deterministically. Some computations take place wherever it is possible and in parallel, while others may be controlled by strategies. In this paper, we first introduce port graphs as graphs with multiple edges and loops, with nodes having explicit connection points, called ports, and edges attaching to ports of nodes. We then define an abstract biochemical calculus that instantiates to a rewrite calculus on these graphs. Rules and strategies are themselves port graphs, i.e. first-class objects of the calculus. As a consequence, they can be rewritten as well, and rules can create new rules, providing a way of modeling adaptive systems. This approach also provides a formal framework to reason about computations and to verify useful properties. We show how structural properties of a modeled system can be expressed as strategies and checked for satisfiability at each step of the computation. This provides a way to ensure invariant properties of a system. This work is a contribution to the formal specification and verification of adaptive systems and to theoretical foundations of autonomic computing.     

网络控制系统中动态调度策略与控制器的综合设计

针对CAN网下的网络控制系统（NCS）,提出一种动态闭环调度策略．通过网络监测器周期地在线获取当前的网络服务质量,估计当前可利用的网络带宽等参数,实时地调整控制系统的采样周期以适应网络中信息流的变化。将采用动态闭环调度策略的变采样周期NCS建模为一类具有参数不确定性的离散系统,研究了系统的鲁棒稳定性和控制器的设计方法．仿真结果表明所提出的综合设计方法对改善网络的运行能力和保证系统稳定性是有效的。     

Liveness and Boundedness Preservations of Sharing Synthesis of Petri Net Based Representation for Embedded Systems

Petri net based Representation for Embedded Systems (PRES+) is an outstanding methodology for analysis, modeling and verification of embedded systems. State space explosion is an awful problem for PRES+ to model and analyze large complex embedded systems. In order to solve this problem, we concern with a method for expending PRES+ model by using synthesis approach. A kind of sharing synthesis operation for PRES+ is proposed in this paper. Under some conditions liveness and boundedness will be preserved by using this sharing synthesis approach. An applicable example in the form of an embedded control system illustrates the useful of our synthesis method. These results can be nicely used to investigate dynamic properties of large embedded systems.     

A hybrid approach based on genetic algorithms and (max, +) algebra for network applications

The following work addresses the problem of scheduling operations on a flow network, as well as alignment (path) allocation. This is a multi-objective problem, and this paper proposes a solution method through a hybrid approach based on a genetic algorithm in conjunction with (max, +) algebra. A concise system abstraction is proposed through a non-linear (max, +) model. This model describes the main optimization constraints which dictate the behavior of the mutation and crossover operations in the genetic algorithm. Additionally, each individual in the population represents the value assignment of the decision variables, which linearizes the (max, +) model. A hierarchic genetic structure is proposed for individuals such that variable dependence is modeled. For each individual, the (max, +)-linear model is solved through a matrix product which determines the daters for alignment enabling for transfer operations. The study is extendable to complex net-structured systems of different nature.     

On-Line Resource Management with Application to Routing and Scheduling

We propose a framework to model on-line resource management problems based on an on-line version of positive linear programming. We consider both min cost problems and max benefit problems and propose logarithmic competitive algorithms that are optimal up to a constant factor. The proposed framework provides a general methodology that applies to a wide class of on-line problems: shop scheduling, packet routing, and in general a class of packing and assignment problems. Previously studied problems as on-line multiprocessor scheduling and on-line virtual circuit routing can also be modeled within this framework. Received December 18, 1996; revised March 2, 1997.     

Behavioral modeling and formal verification of a resource discovery approach in Grid computing

Grid computing is the federation of resources from multiple locations to facilitate resource sharing and problem solving over the Internet. The challenge of finding services or resources in Grid environments has recently been the subject of many papers and researches. These researches and papers evaluate their approaches only by simulation and experiments. Therefore, it is possible that some part of the state space of the problem is not analyzed and checked well. To overcome this defect, model checking as an automatic technique for the verification of the systems is a suitable solution. In this paper, an adopted type of resource discovery approach to address multi-attribute and range queries has been presented. Unlike the papers in this scope, this paper decouple resource discovery behavior model to data gathering, discovery and control behavior. Also it facilitates the mapping process between three behaviors by means of the formal verification approach based on Binary Decision Diagram (BDD). The formal approach extracts the expected properties of resource discovery approach from control behavior in the form of CTL and LTL temporal logic formulas, and verifies the properties in data gathering and discovery behaviors comprehensively. Moreover, analyzing and evaluating the logical problems such as soundness, completeness, and consistency of the considered resource discovery approach is provided. To implement the behavior models of resource discovery approach the ArgoUML tool and the NuSMV model checker are employed. The results show that the adopted resource discovery approach can discovers multi-attribute and range queries very fast and detects logical problems such as soundness, completeness, and consistency.     

一类Petri网—S4R的死锁预防策略

S4R网作为一种特殊的Petri网子类,与S' PR网相比可以建模更为复杂的、拥有多个并行加工进程的资源分配系统。针对S4R网提出了一种综合的死锁预防策略。利用MIP检验由S4R网建模的柔性制造系统的活性,在新的信标控制概念的基础上对需要控制的系统进行控制。再利用MIP检验受控网系统的活性,进一步控制不活的网系统。避免了对一些网不必要的控制以及一些网过于保守的控制,得到许可行为较多的控制器。     

云制造环境下对称型企业制造资源共享演化博弈分析

为解决复杂制造业在制造资源共享和协同合作方面的难题,构建了云制造环境下制造资源共享的演化博弈模型。该模型揭示出资源服务提供企业和资源服务需求企业之间制造资源共享的演化作用关系,并基于系统动力学软件建立SD模型,对比分析不同参数变化对演化结果的影响。研究表明初始共享比例、平台管理能力系数、资源转化能力系数、资源协同能力系数、信息化效益系数、技术损失风险系数、渠道成本系数、惩罚成本系数、信任程度系数以及激励系数对博弈企业双方的策略演化结果均具有显著影响,促进云平台中企业信息互通、资源共享,须从上述方面管理改进。