A novel heuristic algorithm for QoS-aware end-to-end service composition.
ABSTRACT Many works have been carried out to find the efficient algorithms for QoS-aware service composition in recent years. Nevertheless, on one hand, some of these works only consider the local QoS attributes in Web services composition; on the other hand, some ideas derived from QoS selection algorithms for network routing are directly applied in service composition without any adaption. A service composition model with end-to-end QoS constraints has been presented in this paper. An improved heuristics HCE based on the observation of characteristic of end-to-end service composition is proposed as a novel solution. Simulation results reveal the better performance of proposed heuristic compared to the other two heuristics, HMCOP and generic CE algorithm.
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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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ABSTRACT: Composite services are widely popular for solving complex problems where the required QoS levels are often demanding. The composite service that provides the best utility while meeting the QoS requirements has to be found. This paper proposes a network model where many complementary candidates could be selected for each service class to improve the benefits, while the conventional model limits the selection to a single service candidate or service level per service class. The selection of services step is NP-hard because it can be reduced to a multi-constraint knapsack problem. Yet, the decision has to be reached rapidly so that it does not increase the overall workflow time. Large-size networks and problems with high restriction levels (strong QoS requirements) are the most problematic. Traditional multiple-constrained-shortest-path (MCSP) heuristics are improved in this paper using the novel concept “potential feasibility”. When our modified MCSP heuristic algorithms are compared to the CPLEX solver, one of them demonstrates a significantly smaller average runtime. Further, it provides solutions within a 2.6 percent optimality gap on average for small networks, and a 10 percent optimality gap on average for large networks, regardless of the restriction level. Our algorithm uses a general utility function, not derived from the QoS parameters.IEEE Transactions on Services Computing 01/2015; 8(1):79-91. DOI:10.1109/TSC.2014.2299547 · 1.99 Impact Factor
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ABSTRACT: In this paper three optimization algorithms were used in order to solve the problem of dynamic composition of Web services with Quality of Service (QoS). This combinatorial optimization problem arises when multiple services, which provide subfunctions for a complete function, are aggregated in an execution flow and presented to the user as a single service. This problem has been modeled in the context of two deterministic and one stochastic algorithms, aiming to determine the best flow in terms of QoS. Besides, a performance evaluation was executed considering the composition algorithms in some scenarios and comparing them in terms of response time and quality of the obtained solution. The stochastic algorithm proved to be more advantageous for these scenarios due the deadline exploitation on the search for an optimal solution, although it does not provide guarantees of optimality.Proceedings of the 19th Brazilian symposium on Multimedia and the web; 11/2013