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对动态合同网协议进行了改进,提出了一种改进的动态合同网协议。管理者进行决策时不仅考虑信任度还综合相应的承包商代价。此外,给出了此动态合同网协议的算法。经过在REPAST平台上的实验,证明了IDCNP协议在运算时间及通信量方面的优越性。 相似文献
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为了适应更为复杂的系统环境应用,提出一种具有容错功能的动态合同网算法。该算法引入任务时限概念以监测系统中的承包商主体,发现故障承包商主体以后,通过撤销承包合同和重新发布任务来保证系统的任务完成率,并重新定义信任度的更新准则;管理器能避免将任务分发给故障承包商,有效减少出错任务的数目,并将故障承包商无法完成的任务二次转发,具有容错能力。实验结果证明了算法的有效性。 相似文献
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Umesh Deshpande Arobinda Gupta Anupam Basu 《IEEE transactions on systems, man, and cybernetics. Part B, Cybernetics》2005,35(2):345-358
The contract net protocol (CNP) is a widely used coordination mechanism in multiagent systems. It has a lot of communication overhead due to the broadcast of the task announcements. The performance of the CNP degrades drastically when the number of communicating agents and the number of tasks announced increases. Hence, it has problems of scalability. In order to overcome this limitation, an instance-based learning (IBL) mechanism is designed that uses previously stored instances in order to select a target agent. This avoids the expensive bidding process. The scheme is implemented in a simulated distributed hospital system where the CNP is used for resource sharing across hospitals. Experimental results demonstrate that with the incorporation of the IBL, the system performance improves significantly. The system is better scalable with respect to the number of tasks. 相似文献
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Present manufacturing systems are facing significant challenges concerning their adaptability. Holonic manufacturing systems are among the technologies that can provide solutions to such requests, if certain conditions are met. As being included in the class of semi-heterarchical control architectures, holonic systems need appropriate coordination and planning schemes, together with validation tools to increase the beneficiaries’ trust. This paper proposes a coordination scheme for holonic systems, based on a mix between contract net protocol and distributed constraint satisfaction problems. The distinct phases of this method are explained, with details referring to the adaptation of contract net protocol. About the constraint satisfaction mechanism, a guide is provided on how a manufacturing problem can be expressed according to this formalism. To validate the introduced coordination scheme, a coloured Petri net model was developed. This allowed several simulation experiments for scenarios regarding a manufacturing system with four robots to be carried out. The obtained solutions showed that the proposed method can determine both the right holarchy related to the manufacturing goal, and optimal plans for robots. Moreover, as proven by the reachability graphs obtained for different goals, the proposed method reached correct results for all goals and diverse constraints, and it determined all possible solutions. An advantage is about how knowledge possessed by different types of holons is efficiently used, without producing an increased communication load. In conclusion, our method can ensure the right trade-off between complexity and optimality, and the attached model can constitute the required link between design and implementation, thus contributing to an easier deployment of holonic systems. 相似文献
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《Journal of Computer and System Sciences》2006,72(7):1226-1237
Composite web services provide promising prospects for conducting cross-organizational business transactions. Such transactions: are generally complex, require longer processing time, and manipulate financially critical data. It is therefore crucial to ensure stronger reliability, higher throughput and enhanced performance of transactions. In order to meet these requirements, this paper proposes a new commit protocol for managing transactions in composite web services. Specifically, it aims to improve the performance by reducing network delays and the processing time of transactions. The proposed protocol is based on the concept of tentative commit that allows transactions to tentatively commit on the shared data of web services. The tentative commit protocol avoids resource blocking thus improving performance. The proposed protocol is tested through various simulation experiments. The outcomes of these experiments show that the proposed protocol outperforms existing protocols in terms of transaction performance. 相似文献
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随着Web服务应用范围的不断扩展,灵活的消息传递机制在许多复杂网络应用中变得越来越重要。针对目前Web服务同步调用机制存在的不足,提出了异步Web服务的解决方案。分析了异步Web服务消息传递机制,以及在.NET框架中实现异步Web服务的原理,并通过实例探讨了异步Web服务在.NET框架中的实现方法。 相似文献
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针对合同网协议协商机制缺乏问题求解质量与效率分析的情况,设定假设条件,构建马尔可夫链模型,得出了利用目前已有的合同类型无法保证全局收敛的结论.在此基础上,提出了变邻域合同系的概念,通过分析控制方式对收敛性的影响,得出了集中式控制可以保证全局收敛以及分布式控制以概率保证全局收敛的结论,并设计了概率的计算方法.采用Doebin理论,对应用变邻域合同系的收敛速率进行分析,得出了集中式控制收敛速率与分布式控制收敛速率的上下界估计. 相似文献
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Neural networks-based adaptive bidding with the contract net protocol in multi-robot systems 总被引:1,自引:0,他引:1
This paper investigates the effectiveness of using the Contract Net Protocol, an auction type system, for controlling task
allocation among a group of robots, and presents and evaluates a strategy of using Artificial Neural Networks to formulate
adaptive bids within the framework of the Contract Net Protocol. The robots were used in a foraging environment and showed
that excellent communication among robots leads to a need for a social control mechanism for managing the robots, such as
the Contract Net Protocol. The experiments also confirmed that a moderate benefit can be gained by using adaptive bidding
within the framework of the Contract Net Protocol. 相似文献
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Xitong Li Yushun Fan Stuart Madnick Quan Z. Sheng 《Information and Software Technology》2010,52(3):304-323
ContextWith the increasing popularity of Service Oriented Architecture (SOA), service composition is gaining momentum as the potential silver bullet for application integration. However, services are not always perfectly compatible and therefore cannot be directly composed. Service mediation, roughly classified into signature and protocol ones, thus becomes one key working area in SOA.ObjectiveAs a challenging problem, protocol mediation is still open and existing approaches only provide partial solutions. Further investigation on a systematic approach is needed.MethodsIn this paper, an approach based on mediator patterns is proposed to generate executable mediators and glue partially compatible services together. The mediation process and its main steps are introduced. By utilizing message mapping, a heuristic technique for identifying protocol mismatches and selecting appropriate mediator patterns is presented. The corresponding BPEL templates of these patterns are also developed.ResultsA prototype system, namely Service Mediation Toolkit (SMT), has been implemented to validate the feasibility and effectiveness of the proposed approach.ConclusionThe approach along with the prototype system facilitate the existing practice of protocol mediation for Web services composition. 相似文献
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M. Brian Blake Daniel R. Kahan Michael Fitzgerald Nowlan 《Distributed and Parallel Databases》2007,21(1):39-58
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 相似文献
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Francisco García‐Sánchez Luís Álvarez Sabucedo Rodrigo Martínez‐Béjar Luís Anido Rifón Rafael Valencia‐García Juan Miguel Gómez 《Expert Systems》2011,28(5):416-436
The increasing volume of eGovernment‐related services is demanding new approaches for service integration and interoperability in this domain. Semantic web (SW) technologies and applications can leverage the potential of eGovernment service integration and discovery, thus tackling the problems of semantic heterogeneity characterizing eGovernment information sources and the different levels of interoperability. eGovernment services will therefore be semantically described in the foreseeable future. In an environment with semantically annotated services, software agents are essential as the entities responsible for exploiting the semantic content in order to automate some tasks, and so enhance the user's experience. In this paper, we present a framework that provides a seamless integration of semantic web services and intelligent agents technologies by making use of ontologies to facilitate their interoperation. The proposed framework can assist in the development of powerful and flexible distributed systems in complex, dynamic, heterogeneous, unpredictable and open environments. Our approach is backed up by a proof‐of‐concept implementation, where the breakthrough of integrating disparate eGovernment services has been tested. 相似文献
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In the web services environment, service level agreements (SLA) refers to mutually agreed understandings and expectations between service consumers and providers on the service provision. Although management of SLA is critical to wide adoption of web services technologies in the real world, support for it is very limited nowadays, especially in web service composition scenarios. There lacks adequate frameworks and technologies supporting various SLA operations such as SLA formation, enforcement, and recovery. This paper presents a novel agent-based framework which utilises the agents’ ability of negotiation, interaction, and cooperation to facilitate autonomous SLA management in the context of service composition provision. Based on this framework, mechanisms for autonomous SLA operations are proposed and discussed. Results from simulations show that by integrating agents and web services the framework can address issues of SLA management drawn from sophisticated service composition scenarios. 相似文献
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Using web services to expose applications over the Internet is now a widely accepted practice. Currently, there are several ongoing efforts that provide ways to effectively compose web services distributed across different organizations. One of the problems underlying the deployment of such composite services on the web, however, is service co-allocation that arises when a composite service needs to ensure all the required component services to be available for execution at the same time. Motivated by this, this paper presents a new decentralized protocol, named web service co-allocation protocol (WSCP), which can facilitate fast execution of composite web services. The proposed framework is an enhancement of the famous two phase commit protocol through the incorporation of tentative hold phase as well as the employment of a new high performance backoff protocol developed to better address the dynamics of the service co-allocation problem. The simulation results show that the proposed approach yields significant improvements over existing protocols. 相似文献