1. A method of uniquely identifying resources, comprising steps of: modeling the resources using a hierarchical schema, wherein classes in the schema correspond to resource types and wherein instances in the schema represent individual resources, each instance being associated with one of the classes according to the resource type of the individual resource represented by the instance; and defining, at a topmost class of the hierarchical schema, a naming rule property and an instance identity property, wherein: each class at levels of the hierarchical schema beneath the topmost level inherits the naming rule property and the instance identity property; a value of the naming rule property for a selected class identifies properties of the selected class that enable instances of the selected class to have unique identities; and an instance of the selected class specifies the unique identity for that instance, using the identified properties for the selected class.