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Lei Yang, Yu Dai and Bin Zhang
College of Information Science and Engineering
Northeastern University
Shenyang, Liaoning, P.R. China
E-mail: yanglei@mail.neu.edu.cn
Web services run in a highly dynamic environment, as a result of which the QoS
will change relatively frequently. In order to make the composite service adapt to such
dynamic property of web services, we propose an adaptive approach for web service
composition. This approach uses an EX-QoS model which makes the approach applicable
in the decentralized service composition to achieve global optimization. Besides this,
in order to make the composite service adjust itself quickly when execution problems
occur, this paper uses replacement composite services backed up before the execution.
Then, when a service fails, the composite service can easily switch to the replacement
without affecting the runtime performance. In order to preserve the availability of the replacement,
a re-selection for updating the replacement is used which is on the basis of a
performance prediction to make the re-selection complete as early before the invocation
of the failed service as possible. Experiments show that the proposed solutions have better
performance in supporting the adaptive decentralized service composition.
Received March 16, 2008; accepted October 24, 2008.
Communicated by Chi-Sheng Shih.
* This work was supported by the National Natural Science Foundation of China (No. 60773218).