Synchronization and replication of object databases
First Claim
1. In a distributed database system, a method of synchronizing information between a plurality of sites and a central location, comprising the steps of, for each of said plurality of sites:
- establishing a first database portion at the central location and a second data base portion at the site, where the second database portion is a substantial replica of the first database portion, wherein each of the first and second database portions comprise a plurality of named information items including information items to be output in such a way as to be perceived by a user, and wherein said plurality of named information items are managed at the central location by a database engine;
changing the second database portion at the site;
reporting changes in the second database portion to the central location;
at the central location, sending one or more messages describing changes in the second database portion to one or more named information items of the first database portion affected by the changes, without the database engine itself effecting the changes; and
the one or more named information items of the first database portion affected by the changes responding to the one or more messages describing changes in the second database portion by updating themselves to reflect the changes to the second database portion reported to the central location.
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Accused Products
Abstract
The present invention, generally speaking, provides a method of synchronizing information between a plurality of sites and a central location that solves number of potentially "thorny" problems of distributed database systems in an elegant and efficient manner. The first issue involves sychronizing different copies of an item on machines that are not continuously linked at which each copy may be changed independently. Rather than attempting to formulate a set of synchronization policies generally applicable to all items in all instances, synchronization policies are moved from the database engine to the items themselves. The second issue involves lifetime--knowing, given a complex set of interrelationship of items, when an item may be safely deleted. This problem is addressed by providing an interested party mechanism whereby items may "express interest" in each other. When no item is interested in a particular item, that item may safely "go away".
268 Citations
11 Claims
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1. In a distributed database system, a method of synchronizing information between a plurality of sites and a central location, comprising the steps of, for each of said plurality of sites:
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establishing a first database portion at the central location and a second data base portion at the site, where the second database portion is a substantial replica of the first database portion, wherein each of the first and second database portions comprise a plurality of named information items including information items to be output in such a way as to be perceived by a user, and wherein said plurality of named information items are managed at the central location by a database engine; changing the second database portion at the site; reporting changes in the second database portion to the central location; at the central location, sending one or more messages describing changes in the second database portion to one or more named information items of the first database portion affected by the changes, without the database engine itself effecting the changes; and the one or more named information items of the first database portion affected by the changes responding to the one or more messages describing changes in the second database portion by updating themselves to reflect the changes to the second database portion reported to the central location. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification