1. A method of operating a distributed data processing system including a plurality of independent remotely located user computers that process user data in user databases and at least one object broker computer, the user computers being interconnected with the object broker computer by data communication hardware over a data communication network, the user computers being operative to perform data operations of storing, updating, and retrieving user data items in response to user commands, comprising the steps of: (a) for a subject at one of the user computers for which data is to be processed in the system, creating an object instance by assigning a unique object identifier to data items associated with the subject by: (a1) providing a global object identification address space corresponding to a range of object identifiers for association with a plurality of subjects; and (a2) allocating a predetermined range of object identifiers within the global object identification address space to each remotely located user computer; (b) storing the data items associated with the subject at the user computer in association with the object identifier; (c) at the object broker computer, storing the locations of the user computers in a mapping table in association with object identifiers; (d) in response to a query to the object broker computer for data relating to a particular subject in question, retrieving a selected object identifier for the subject in question; (e) in response to retrieval of an object identifier for the subject in question in the preceding step, retrieving the location of a remote user computer associated with the selected object identifier; and (f) retrieving data stored at the remote user computer associated with the selected object identifier via the data communication network.