Communication for version management in a distributed information service
First Claim
1. A method for managing obsolescence of replicas of data objects, the objects being utilized in multiple nodes of a distributed processing system in which at least one node operates as an object source location having access to a source database containing source data objects and at least one other node operates as an object replica location having means for storing replicas of requested objects received from a source location, each source data object being alterable whereby replicas of altered objects stored at replica locations may become obsolete, comprising the steps of:
- responsive to a request from a first replica location to ascertain obsolescence of data objects, extracting at the source location identifiers of a set of obsolete objects;
communicating said identifiers, if any, as an atomic demand/response transaction to said first replica location;
rendering inaccessible at said first replica location any replicas corresponding to those identifiers received from the source location; and
removing from the source location those identifiers communicated to said first replica location.
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Accused Products
Abstract
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.
251 Citations
10 Claims
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1. A method for managing obsolescence of replicas of data objects, the objects being utilized in multiple nodes of a distributed processing system in which at least one node operates as an object source location having access to a source database containing source data objects and at least one other node operates as an object replica location having means for storing replicas of requested objects received from a source location, each source data object being alterable whereby replicas of altered objects stored at replica locations may become obsolete, comprising the steps of:
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responsive to a request from a first replica location to ascertain obsolescence of data objects, extracting at the source location identifiers of a set of obsolete objects; communicating said identifiers, if any, as an atomic demand/response transaction to said first replica location; rendering inaccessible at said first replica location any replicas corresponding to those identifiers received from the source location; and removing from the source location those identifiers communicated to said first replica location. - View Dependent Claims (2)
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3. A method for locating and rendering inaccessible obsolete versions of data objects, the objects being utilized in multiple nodes of a distributed processing system in which at least one node operates as an object source location having access to a source database containing source data objects and at least one other node operates as an object replica location having means for storing versions of requested objects received from a source location, each source data object being alterable whereby a plurality of versions are created and versions stored at replica locations may become obsolete, the relative obsolescence of each version at any time t being identifiable by a version number corresponding to its position in a temporal sequence, including an oldest version and a most recent version, among versions of source data objects comprising the steps at each source location of:
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maintaining a list of replica locations; maintaining a list of identifiers of obsolete versions of source data objects for each identified replica location; responsive to a request at a time t1 from a first replica location to ascertain obsolescence of at least one data object, extracting from list of identifiers a first subset of identifiers corresponding to versions which have previously been sent to said first replica location, and extracting from the first subset of identifiers, a second subset of identifiers corresponding to versions which are oldest in said temporal sequence at time t1 ; sending the second subset of identifiers to said first replica location as one or more messages in an atomic demand/response sequence, any interruption in the sequence resulting in an abort; and responsive to an acknowledgment from the replica location, deleting the second subset of identifiers from the list of identifiers; and comprising the steps at said first replica location of; sending at least once to each source location employed by this replica location, a signal identifying this replica location; initiating a request to ascertain obsolescence of at least one data object from the source location; and upon receiving one or more messages from the source location, rendering inaccessible those versions of data objects identified by any one of the messages so received. - View Dependent Claims (4, 5)
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6. In a distributed processing system having a network of nodes connected by communication links in which at least one node of the system operates as a source location having access to a source database containing source data objects and at least one other node operates as a replica location having a means for storing replicas of source data objects received from a source location, an apparatus for managing obsolescence of replicas comprising:
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manager means, in communication with a source location, for maintaining obsolescence data identifying obsolete replicas; means at a requesting replica location for generating an invalidation request for at least a portion of the obsolescence data; and server means, in communication with the manager means and the requesting replica location and responsive to the invalidation request, for supplying the portion of the obsolescence data to the requesting replica location. - View Dependent Claims (7, 8, 9, 10)
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Specification