To provide a system for selecting a processing device that can run an initial service and manages at least one resource, wherein the system allows to increase the extensibility of an initial service, to increase the stability of a running service, and to improve the utilization of the resources provided by several processing devices, it is suggested that, for each initial service two extension services are determined, wherein each extension service defines a set of resources for further extension; a reservation mode that indicates an extension service is assigned to each processing device that guarantees this extension service to be reserved for the initial service; and a processing device is only selected, if a reservation mode is assigned to it.