Abstract: There are provided compounds of the formula ##STR1## wherein R.sup.1 is a substituted or unsubstituted divalent aliphatic group of 1 to 16 carbon atoms; wherein the substituents are mono or poly and are selected from the group consisting of lower alkyl, aryl and arlkyl, R.sup.3 is selected from the group consisting of same group of values as R.sup.5, R.sup.5 is selected from the group consisting of substituted and unsubstituted alkyl of 1-10 carbon atoms, aryl, cycloalkyl and heterocycloalkyl of 3-8 carbon atoms, wherein the substituents are mono or poly and are selected from the group consisting of lower alkyl, cycloalkyl of 3-8 carbon atoms, lower alkenyl, lower alkynyl, nitro, lower alkoxy, lower alkoxycarbonyl, phenyl loweralkyl, phenyl, mono and polyhalophenyl, phenoxy, mono and polyhalophenoxy, R.sup.6 and R.sup.7 may be the same or different and are hydrogen, alkanoyl or alkoxyalkanoyl, R.sup.7 may also have the same value as R.sup.

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.