1. A method for scheduling execution of work units in a data processing system including a plurality of resources, a relationship being established among different resources in the plurality of resources, wherein for a work unit the method comprises: providing from a workload database, to an application executing in a scheduling server computer, a definition of the work unit, the definition of the work unit including an execution specification section and an indication of a formal resource required by the work unit, each formal resource indicating a property of the formal resource and a formal relationship with at least one other formal resource, a formal resource being a definition corresponding to a set of resources in the plurality of resources, wherein by specifying the formal resource, the formal resource to resolve to any suitable resource in the corresponding set of resources, wherein the formal relationship belongs to one of a plurality of predefined categories of relationships between resources, the definition of the work unit including an indication of the category to which the formal relationship belongs; resolving the formal resource into a resource from the corresponding set of resources such that the resource possesses the property and satisfies the formal relationship indicated in the formal resource; and submitting, over a data network, the work unit on the resource corresponding to the formal resource.