Patent ID: 7788346

Claim:
A system, comprising: a plurality of computer systems, each comprising a non-transitory computer readable storage medium; a first node of a distributed store provided from one of the plurality of computer systems, wherein the first node stores a primary state of session data configured for access by a plurality of application servers, wherein the session data provides state information for each of a plurality of sessions, wherein each session involves a plurality of application level interactions between a client and one or more of the plurality of application servers, wherein for each session the session data indicates the state of the application level interactions between the client and the one or more application servers for that session, and wherein the session data comprises a current version of a plurality of attributes; another node provided from another one of the plurality of computer systems, wherein the another node stores a back-up instance of the primary state, wherein the back-up instance of the primary state comprises a back-up version of the plurality of attributes in the session data of the primary state; wherein during operation one or more of the plurality of computer systems: compares the primary state to a benchmark version of the primary state to determine one or more of the attributes of the session data that have been modified in the current version of the plurality of attributes in the primary state, wherein the benchmark version of the primary state comprises a previous version of the plurality of attributes in the session data of the primary state, and wherein the benchmark version is separate from the back-up instance; and synchronizes the back-up version of the plurality of attributes in the back-up instance of the primary state on the other node with the current version of the plurality of attributes in the primary state, wherein, to synchronize the back-up version of the plurality of attributes in the back-up instance of the primary state on the other node with the current version of the plurality of attributes in the primary state, one or more of the computer systems: sends the determined one or more of the attributes of the session data that have been modified to the other node as modified attributes of the session data, wherein unmodified attributes of the session data are not sent to the other node; and updates respective attributes in the plurality of attributes in the back-up instance of the primary state according to the modified attributes.