A Penalty-based Genetic Algorithm for QoS-Aware Web Service Composition with Inter-Service Dependencies and Conflicts
DOI: 10.1109/CIMCA.2008.104 Conference: 2008 International Conferences on Computational Intelligence for Modelling, Control and Automation (CIMCA 2008), Intelligent Agents, Web Technologies and Internet Commerce (IAWTIC 2008), Innovation in Software Engineering (ISE 2008), 10-12 December 2008, Vienna, Austria
In Web service based systems, new value-added Web services can be constructed by integrating existing Web services. A Web service may have many implementations, which are functionally identical, but have different quality of service (QoS) attributes, such as response time, price, reputation, reliability, availability and so on. Thus, a significant research problem in Web service composition is how to select an implementation for each of the component Web services so that the overall QoS of the composite Web service is optimal. This is so called QoS-aware Web service composition problem. In some composite Web services there are some dependencies and conflicts between the Web service implementations. However, existing approaches cannot handle the constraints. This paper tackles the QoS-aware Web service composition problem with inter-service dependencies and conflicts using a penalty-based genetic algorithm (GA). Experimental results demonstrate the effectiveness and the scalability of the penalty-based GA.
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- "In addition, it is not guaranteed to eliminate all conflicts. In , a method of sorting service selection results by the conflict degrees is used in a genetic algorithm, and the multi-objective QoS conflicts can be decreased by this algorithm. However, the conflicts produced by service dependent relationships can not be solved by this method. "
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ABSTRACT: When there are a lot of candidate component services in Web services composition, the suitable component services need to be selected. The service selection conflicts often occur due to the functional dependency relationships between component services. Therefore, a service selection conflict avoidance algorithm is presented. First, a formal service selection model is presented to reflect the component services, the process of service composition and the functional dependency relationships of component services. Then, based on the presented model, a service selection algorithm to avoid service conflicts is designed by using a conflict mediation mechanism, which supports multilevel backtracking and service reselection. Finally, the performance of the algorithm is tested by simulation experiments. The experiment results indicate that a service composition without any service conflict can be accomplished rapidly via the presented algorithm.
Available from: Maolin Tang
- "In the web service selection, both dependency constraints and conflict constraints must be considered. Although various optimal web service selection problems have been intensively studied and different approaches have been proposed in the past few years , , , , , , , , , , , , the study on the optimal web service selection problem with constraints remains open. From the computational point of view, the web service selection problem is a typical constrained combinatorial optimization problem. "
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ABSTRACT: Web service composition is an important problem in web service based systems. It is about how to build a new value-added web service using existing web services. A web service may have many implementations, all of which have the same functionality, but may have different QoS values. Thus, a significant research problem in web service composition is how to select a web service implementation for each of the web services such that the composite web service gives the best overall performance. This is so-called optimal web service selection problem. There may be mutual constraints between some web service implementations. Sometimes when an implementation is selected for one web service, a particular implementation for another web service must be selected. This is so called dependency constraint. Sometimes when an implementation for one web service is selected, a set of implementations for another web service must be excluded in the web service composition. This is so called conflict constraint. Thus, the optimal web service selection is a typical constrained combinatorial optimization problem from the computational point of view. This paper proposes a new hybrid genetic algorithm for the optimal web service selection problem. The hybrid genetic algorithm has been implemented and evaluated. The evaluation results have shown that the hybrid genetic algorithm outperforms other two existing genetic algorithms when the number of web services and the number of constraints are large.
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ABSTRACT: One of the most important works in technology of web service is web service composition. In the recent years numerous studies to develop methods to build composite web services is carried out but making composite web service yet is a complex issue. In this paper a QOS-aware method based on imperialist competition algorithm for web services selection is proposed. In this method called ICA-WSS, web service selection is done based on QOS parameters. ICA-WSS takes an abstract process and a set of all candidate web services and tries to find an optimal combination based on QOS parameters. In comparison to QQDSGA without considering QOE parameters, ICA-WSS finds better combination in term of value of objective function. Experimental results endorse that ICA-WSS is an efficient algorithm with good convergence for solving problem of web service composition.
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