共查询到18条相似文献,搜索用时 125 毫秒
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为每个服务节点选择一个服务实例,形成在满足全局QoS限制的条件下,具有综合QoS最优的执行计划是服务选择的关键问题.本文分析了优化目标,提出了基于自适应变异遗传算法(self-Adaptive Mutation Genetic Algorithm,AMGA)求解服务选择的组合优化问题.在算法中,适应度函数设计采用对执行计划聚合QoS属性值与约束条件的偏差量作为惩罚约束,变异算子设计采用对服务实例的优良程度自适应的变异概率,提高了基因改良的效率,并引入指数衰减函数保证了算法的收敛性.实验结果表明,基于AMGA算法的服务选择策略比现有基于其它遗传算法的策略能够获得更优的解. 相似文献
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基于量子遗传算法的QoS路由算法 总被引:6,自引:2,他引:4
多约束的QoS路由问题是NP完全问题.量子遗传算法是基于量子计算理论的新遗传算法,具有种群多样性、收敛速度快和全局寻优的特点.将量子遗传算法引入多约束QoS路由计算,提出了一种基于量子遗传算法的QoS路由算法,给出了算法实现的方法和具体流程.实验结果表明,通过该算法得到的QoS路由不但能满足QoS约束要求,同时可以均衡链路负载,减少路由拥塞. 相似文献
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针对传统多约束路由选择算法计算负担重的问题,论文提出了一种基于遗传算法与带权宽度优先搜索融合的QoS组播路由算法.所提方法融合了遗传算法与带权宽度优先搜索方法,在分组丢包率、带宽、时延抖动、时延等QoS条件约束下,通过所提算法快速得到备选路径,并获取最优的组播路径.在仿真实验中,将所提算法与LDT进行了相比,实验结果表明,论文所提算法可以解决多约束条件下的QoS分组路由问题,并能够有效降低计算负载、减少算法执行时间. 相似文献
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在Web环境中,服务是千变万化的,满足相同功能的服务可能会有多个,这些服务具有不同的Qos参数,如何从中选择满足模板中各服务节点功能需求的具体服务,形成一个可执行的组合服务流程来完成用户的需求,成为服务组合中的一个关键问题.在基于模板的服务组合基础之上,提出一种解决模板选择和服务选择过程中的Qos最优化问题的模型,建立模板Qos模型,保证最大概率选择到Qos最优模板.在模板的节点选择服务过程中基于改进多目标遗传算法,同时优化多个QoS参数,最终产生一组满足约束条件的QoS最优服务组合流程集.实验结果表明了算法具有良好的可行性和有效性. 相似文献
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一种服务聚合中QoS全局最优服务动态选择算法 总被引:53,自引:2,他引:53
Web服务作为一种新型的Web应用模式,近年来得到了迅速的发展.如何动态地把现存的各种Web服务整合起来以形成新的、满足不同用户需求的、增值的复杂服务已成为新的应用需求和研究热点.针对现有服务聚合中服务选择技术的不足,提出了一种解决服务聚合中服务动态选择QoS全局最优化问题的实现算法GODSS(global optimal of dynamic Web services selection).算法的主要思想是把服务动态选择全局最优化问题转化为一个带QoS约束的多目标服务组合优化问题,利用多目标遗传算法的智 相似文献
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Neeraj Kumar Rahat Iqbal Naveen Chilamkurti Anne James 《Simulation Modelling Practice and Theory》2011,19(9):1933-1945
Over the years, multihop Wireless Mesh Networks (WMNs) are providing cost effective services to the end users such as Video on demand (VoD), Voice over IP (VoIP), and Video conferencing in an efficient manner. Most of these services require an efficient service selection mechanism that can provide Quality of Service (QoS) in presence of various constraints such as delay, jitter, and service availability. In presence of these constraints, multi-constraint QoS aware service selection in WMNs is an NP-hard problem. In this paper, we propose an ant colony based multi constraints QoS aware service selection (QSS) algorithm. In the proposed algorithm, ants are launched from source node. The best path is chosen based upon the defined cost effective (CE) metric in presence of constraints. The constraints are chosen both from network and user perspectives. The goodness of the chosen path is determined by the CE metric. Moreover, ants are not launched randomly from the source node. They are launched based upon the guided search evaluation (GSE) criterion. This criterion is also used if the two paths have the same CE metric. The simulation results show that the proposed algorithm is more effective than the earlier improved ant colony QoS routing algorithm (IAQR) algorithm with respect to convergence, end-to-end delay (jitter), and service availability. Specifically, the service availability increases by 35–50% in the proposed QoS aware scheme compared to IAQR algorithm. 相似文献
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一种带约束的多目标服务质量路由算法 总被引:6,自引:0,他引:6
多约束服务质量(QoS)路由是要求在多个约束条件下计算满足所有独立限制条件的可行路径.将这种NPC问题转化为一种带约束条件的多目标优化问题,根据多目标遗传算法的智能优化原理,提出一种多目标QoS路由算法来产生一组最优非劣路由.理论分析和实验结果表明,使用带约束的多目标遗传算法是解决多约束QoS路由的有效途径,能对提高网络性能起到重要作用. 相似文献
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《Computer Networks》2008,52(5):1093-1104
A novel quickly convergent population diversity handling genetic algorithm (CoDiGA) is presented for web service selection with global Quality-of-Service (QoS) constraints. CoDiGA is characterized by good stability and quick convergence. In CoDiGA, an enhanced initial population policy and an evolution policy are proposed based on population diversity and a relation matrix coding scheme. The integration of the two policies overcomes shortcomings resulting from randomicity of genetic algorithm, such as slow convergence, great variance among the running results, soaring overhead along with increasing size of composition. The simulation results on web service selection with global QoS constraints have shown that prematurity was overcomed effectively, and convergence and stability of genetic algorithm were improved greatly. 相似文献
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秦汝烈 《计算机工程与应用》2009,45(3):66-69
基于QoS优化的全局Web服务选择涉及多目标和多阶段的服务合成,以及各种QoS属性的折衷,如可信性、可用性和声望等,因此提出了适当的基因算法来处理服务选择问题。由于发现质量驱动的Web服务选择是一个NP-hard问题,实际的多目标或QoS标准并不总是明确的,常常包含模糊元素。着重研究多目标Web服务选择过程中模糊QoS属性和适应进化函数之间的关系,以及如何调节个体模糊QoS属性以实现整个种群进化的问题。 相似文献
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基于语义的QoS感知Web服务发现机制 总被引:1,自引:1,他引:0
随着提供相同功能的Web服务数量的日益增多,服务质量(Quality of Service,QoS)成为用户选择Web服务的重要考虑因素.目前,通过对服务QoS属性在语法层匹配来提供Web服务选取的机制不能很好地满足复杂QoS属性匹配的要求.研究了基于用户QoS需求偏好,将用户需求的QoS与候选服务的QoS进行语义比较,结合约束规划(Constraint Programming)方法,在语义层匹配Web服务的QoS属性,选取满足匹配要求的服务,最后对满足QoS属性值约束的候选服务进行优化选择处理,获取最终匹配的候选服务. 相似文献
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Mu Li Danfeng Zhu Ting Deng Hailong Sun Huipeng Guo Xudong Liu 《Service Oriented Computing and Applications》2013,7(3):181-197
Services composition technology provides a promising way to create new services in services-oriented architecture. However, some challenges are hindering the application of services composition. One of the major challenges encountered by composite services developer is how to effectively select a set of services across different autonomous regions (e.g., organization or business) to instantiate a composite service which can satisfy user’s QoS constraints. To solve QoS-aware Web service composition problem, this paper proposes a global optimization selection (GOS) approach based on prediction mechanism for QoS values of local services. The GOS includes two parts. First, the local preprocessing service selection algorithm can be used to increase composite services performance in run-time by predicting the change of service quality parameters. Second, GOS aims at enhancing the run-time performance of global selection by reducing QoS aggregation operations. The simulation results show that the GOS has excellent selection and lower execution cost than existing approaches. 相似文献