International Business Machines Corporation

Douglas J Lorch

Richard L Mattson

Henry Martin Gladney

In a distributed processing system network in which at least one node operates as a source location having access to data objects of a database, and at least one other node operates as a replica location storing replicas of data objects from the source location, managing obsolescence of the replicas is performed by having the replica locations submitting requests to the source location for ascertaining obsolescence of data objects. The source location, responsive to a request from a requesting replica location, extracts identifiers of a set of obsolete objects and communicates them to the requesting replica location. Upon receiving the identifiers, the requesting location renders inaccessible those data objects corresponding to the identifiers received. The source location then removes those identifiers that have been communicated to the requesting replica location.

Communication for version management in a distributed information service

In a distributed processing system having a source node accessing data objects from a database and a replica node storing replicas of requested source data objects received from the source location, the impact to replicas caused by a change in a source data object is calculated by assigning a version number to the change. An identifier of the portion of the source database affected by the change is generated, as well as a list of replicas containing objects from the affected portion of the database. For a replica location communicating with the source location, a table of the replicas from the list is then recorded along with the version number for communicating to the replica location.

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Douglas J Lorch