1. A method for computing, comprising: specifying a data processing system using a logical system definition, which defines logical system components having respective functionalities, including at least one logical server, and a topology for interconnecting the logical system components; representing the logical system components using respective logical objects in a hierarchical object model; representing physical resources of a grid computer system using physical objects in the hierarchical object model, including grid servers comprising both physical and virtual servers; automatically mapping the logical objects to at least some of the physical objects, so as to allocate the physical resources to carry out the respective functionalities of the logical system components, wherein a plurality of grid servers, including at least one virtual server, are assigned to the at least one logical server; and configuring and activating the allocated physical resources so as to cause the grid computer system to function as the data processing system, in accordance with the logical system definition.