This paper is proposing a new platform for implementing services in future service oriented architectures. The basic premise of our proposal is that by combining large volume of uncontracted resources with small clusters of dedicated resources, we can dramatically reduce the amount of dedicated resources while the goodput provided by the overall system remains at a high level. This paper presents particular strategies for implementing this idea for a particular class of applications. We performed very detailed simulations on synthetic and real traces to evaluate the performance of the proposed strategies. Our findings on compute-intensive applications show that preemptive reallocation of resources is necessary for assured services. The proposed preemption based scheduling heuristic can significantly improve utilization of the dedicated resources by opportunistically offloading the peak loads on uncontracted resources, while keeping the service quality virtually unaffected.