Abstract: Messages at nodes of a distributed data system are processed asynchronously. Each data atom shared by a pair of nodes is characterized by dipole halves maintained at each node including an access control characteristic, a quality control characteristic, and a pair of rank values. A rank value is a value which monotonically increases (with respect to time) with each significant event. A message from a paired node requesting a change to a dipole half at this node includes the set of rank values at the paired node for the shared data atom. This node compares the rank values which it maintains with those received from the paired node and, based upon the result, selectively rejects or processes the request.

Abstract: A method for dynamic replication of data under distributed system control to control the utilization of resources in a multiprocessing, distributed data base system. Previously, systems providing for data replication at nodes of a multiprocessing, distributed data base system required that a central node maintain control, or that replicated data be synchronized by immediately conforming all copies of an updated data item. By this invention, requests for access to data of a specified currency are permitted and conformation of updated data is selectively deferred by use of a control procedure implemented at each node and utilizing a status and control (SAC) filed at each node which describes that node's view of the status for shared data items at other nodes.