Optimizing Web Service Composition Based on QoS Negotiation

For economic and practical reasons, an automated QoS negotiation for platform and language independent Web Services provided by different providers which can be monitored and enforced by SLA, checks the agreed-upon service levels becomes increasingly important. This paper proposes a mechanism for Web Service composition based on SLA. This mechanism implements the optimizing Web Service composition combining performance optimization, price optimization, and payload optimization when meeting the requirements of SLA. In this mechanism, the WSLA describes SLS will be transmitted to Web Service composition manager and the negotiation will be carried out between different Web Services. The negotiation arithmetic is based on performance optimization, cost optimization, and payload balance optimization to optimize the Web Service composition. This will not only provide quantitative QoS guarantee for requestor, but also improve the performance-to-cost ratio. Based on service optimization rate, the candidate Web Services are ordered and selected to accomplish the required task. Simulation experiment provided by this paper shows our mechanism is better than the random Web Service composition used generally at present in the aspect of performance-to-cost ratio and the business volume.