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Efficient composition of semantic web services with end-to-end QoS optimization

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3 Author(s)
Xu, Bin ; Tsinghua National Laboratory for Information Science and Technology, Department of Computer Science and Technology, Tsinghua University, Beijing 100084, China ; Luo, Sen ; Yan, Yixin

The efficiency of OoS-aware service composition is important since most service composition problems are known to be NP-hard. With the growing number of web services, service composition is like a decision problem on selecting services or/and execution plans to satisfy the users' end-to-end OoS requirements (e.g. response time, throughput). Composite services with the same functionality may have different execution plans, which may cause different end-to-end OoS. This paper presents a model combining semantic data-links and OoS, which leads to an efficient approach to automatic construction of a composite service with optimal end-to-end OoS. The approach is based on a greedy algorithm to select both services and execution plans for composite services. Empirical and theoretical analyses of the approach show that its time complexity is O(mn2) for a repository with n services and an ontology with m concepts. Moreover, the approach increases linearly in time when using an index to search services in the repository. Tests with a repository with 20 000 services and an ontology with 300 000 concepts show that the algorithm significantly outperforms current existing algorithms in terms of composition efficiency while achieving optimal end-to-end qoS.

Published in:

Tsinghua Science and Technology  (Volume:15 ,  Issue: 6 )