Information collection services for QoS-Aware mobile applications

Efficient resource provisioning that allows for cost-effective enforcement of application QoS relies on accurate system state information. However, maintaining accurate information about available system resources is complex and expensive, especially in mobile environments where system conditions are highly dynamic. Resource provisioning mechanisms for such dynamic environments must therefore be able to tolerate imprecision in system state while ensuring adequate QoS to the end-user. In this paper, we address the information collection problem for QoS-based services in mobile environments. Specifically, we propose a family of information collection policies that vary in the granularity at which system state information is represented and maintained. We empirically evaluate the impact of these policies on the performance of diverse resource provisioning strategies. We generally observe that resource provisioning benefits significantly from the customized information collection mechanisms that take advantage of user mobility information. Furthermore, our performance results indicate that effective utilization of coarse-grained user mobility information renders better system performance than using fine-grained user mobility information. Using results from our empirical studies, we derive a set of rules that supports seamless integration of information collection and resource provisioning mechanisms for mobile environments. These results have been incorporated into an integrated middleware framework AutoSeC (Automatic Service Composition) to provide support for dynamic service brokering that ensures effective utilization of system resources over wireless networks.