A Continuation Based Middleware to Experiment with Economy Based Service Scheduling

Service-oriented computing is posing new challenges in the management of computational resources. They are considered as a network-available commodity to perfom some tasks and their provision should account both for user- and provider-dependent Quality-of-Service (QoS) requirements. In this scenario, the possibility to manage the execution of services is advisable to be able to control their provision, so that providers can make different decisions on the QoS they provide their services with according to the requirements of new service requests. In this work we present a middleware architecture to implement service providers featuring flexible control of services by explicitly controlling the suspension and resuming of service execution. The middleware uses program "continuations" as the basic mechanism to control service execution at programming level rather than using operating system facilities. In order to test the proposed middleware we developed a service provider implementing a budget-based resource-sharing scheduling algorithm. Different tests show that the provider is able to meet QoS requirements in terms of cost associated to a service request, still assuring the possibility to run all the received requests