一种高效的服务组合优化算法

随着功能性属性相同而非功能性属性各异的Web服务的大量涌现,如何在服务组合业务流程中为各个任务选择相应的组件服务以达到组合服务的QoS(quality of service)最大化,并在此基础上满足不同用户的需求,已成为了国内外研究的热点.由于该问题的复杂性(NP-hard),目前存在的大多数方法都并不十分适合需要相对精确、实时决策的Web服务组合系统.因此,本文提出了一种基于凸包构建的组合服务优化算法(CM-HEU)用以解决QoS感知的服务组合优化问题.CM-HEU首先通过对组合服务中的每组任务进行凸包构建,以减少搜索空间.然后通过对初始解向量的多次升级和一次降级操作以达到全局优化的目标.实验表明:相对于现阶段存在的一些主流方法,CM-HEU不仅能得到一个比较理想的结果,并且具有良好的效率.

An efficient algorithm for QoS-aware service composition

With the rapid increasing number of the independently developed web services that provide the same functionality but differ in quality of service(QoS),how to select corresponding component services for each task of a specific service composition process in the way that maximizes the aggregation QoS value,while satisfying the constraints set by the end-users is practice known as an NP hard problem.Current solutions are not suitable for most real-time decision-making service composition applications which are required to obtain an optimal result in reasonable time.In this paper,we present an approach which addresses the issue of this problem by constructing convex hulls.The proposed heuristic algorithm consists of two steps:first,convex hulls are constructed for reducing the search space,then the multi-objective optimization problem is solved based on M-HEU.The results of the experiments demonstrate that our approach can obtain a close-to-optimal solution in a reasonable amount of time.