creators_name: Alrifai, Mohammad creators_name: Risse, Thomas type: conference_item datestamp: 2009-04-06 19:11:17 lastmod: 2009-04-23 03:33:03 metadata_visibility: show title: Combining Global Optimization with Local Selection for Efficient QoS-aware Service Composition ispublished: pub full_text_status: public pres_type: paper abstract: The run-time binding of web services has been recently put forward in order to support rapid and dynamic web service compositions. With the growing number of alternative web services that provide the same functionality but differ in quality parameters, the service composition becomes a decision problem on which component services should be selected such that user’s end-to-end QoS requirements (e.g. availability, response time) and preferences (e.g. price) are satisfied. Although very efficient, local selection strategy fails short in handling global QoS requirements. Solutions based on global optimization, on the other hand, can handle global constraints, but their poor performance renders them inappropriate for applications with dynamic and realtime requirements. In this paper we address this problem and propose a solution that combines global optimization with local selection techniques to benefit from the advantages of both worlds. The proposed solution consists of two steps: first, we use mixed integer programming (MIP) to find the optimal decomposition of global QoS constraints into local constraints. Second, we use distributed local selection to find the best web services that satisfy these local constraints. The results of experimental evaluation indicate that our approach significantly outperforms existing solutions in terms of computation time while achieving close-tooptimal results. date: 2009-04 pagerange: 881-881 event_title: 18th International World Wide Web Conference event_location: Madrid, Spain event_dates: April 20th-24th, 2009 event_type: conference refereed: TRUE citation: Alrifai, Mohammad and Risse, Thomas (2009) Combining Global Optimization with Local Selection for Efficient QoS-aware Service Composition. In: 18th International World Wide Web Conference, April 20th-24th, 2009, Madrid, Spain. document_url: http://www2009.eprints.org/89/1/p881.pdf document_url: http://www2009.eprints.org/89/2/alrifai_v2.0.ppt