QoS-Aware Service Selection in Geographically Distributed Clouds

As more and more services are offered in clouds, it is possible to meet the diverse demands of users via service composition. Selecting the optimal set of services, in terms of QoS, is the crucial issue when many functionally equivalent services are available. In this paper, we investigate the service selection problem under the service replica limitation constraint. The objective is to select the optimal service set which brings out the minimal response time. We estimate the communication latency with the network coordinate system. Based on the estimated latencies and service composition paradigm, our selection algorithms find the services which will result in low latency under various replica limitation constraints. We evaluate our approaches via extensive simulations, the experimental results of which show that our algorithms work efficiently.