Patent ID: 7996360

Claim:
In a system comprised of a plurality of nodes, a method for storing consistent copies of objects across said plurality of nodes comprising steps of: processing a plurality of requests to update the objects; associating times with said plurality of requests; storing a copy of an object o 1 by at least two of said plurality of nodes; a first node n 0 receiving a request r 1 to update a copy of the object o 1 , wherein the request r 1 is associated with a time t 1 ; the node n 0 sending an invalidation message m 1 including the time t 1 to at least one of said plurality of nodes; a second node n 1 receiving the message m 1 ; in response to the node n 1 being aware of another update request r 2 to the object o 1 , wherein the request r 2 is associated with a time t 2 , the node n 1 processing the message m 1 based on the time t 1 and the time t 2 ; in response to the node n 0 receiving a negative reply to the message m 1 , the system aborting its attempt to update the object o 1 according to the request r 1 ; and in response to the node n 0 receiving positive replies from each node to which the node n 0 sent the message m 1 , the system updating the object o 1 according to the request r 1 .