Hybrid Optimization Algorithm for Large-Scale QoS-Aware Service Composition

Abstract

In this paper we present a hybrid approach for automatic composition of Web\nservices that generates semantic input-output based compositions with optimal\nend-to-end QoS, minimizing the number of services of the resulting composition.\nThe proposed approach has four main steps: 1) generation of the composition\ngraph for a request; 2) computation of the optimal composition that minimizes a\nsingle objective QoS function; 3) multi-step optimizations to reduce the search\nspace by identifying equivalent and dominated services; and 4) hybrid\nlocal-global search to extract the optimal QoS with the minimum number of\nservices. An extensive validation with the datasets of the Web Service\nChallenge 2009-2010 and randomly generated datasets shows that: 1) the\ncombination of local and global optimization is a general and powerful\ntechnique to extract optimal compositions in diverse scenarios; and 2) the\nhybrid strategy performs better than the state-of-the-art, obtaining solutions\nwith less services and optimal QoS.\n