Distributed state recovery in a system having dynamic reconfiguration of participating nodes

A method for resuming a prior session that has been interrupted between a system having a plurality of nodes and a client device, the prior session having associated session state data, the method comprising:

• subsequent to interruption of service in the prior session between a first node and a client device in which the first node delivers a service to the client device, receiving a session resume request from the client device at a second node in the system, the session resume request including information allowing the second node to obtain a session identifier specifying the prior session;
• hashing the session identifier;
• searching a currently valid hash map that maps a hash of the session identifier to the nodes in the system for a current system configuration, the search being performed to identify a system node on which the session state data for the prior session is stored;
• if the session state data is not located using the currently valid hash map, searching at least one earlier generation hash map that is valid for a previous configuration of the system;
• upon identifying the system node on which the session state data is stored, retrieving the session state data from the system node;
• and
• using the session state data so that the second node is able to resume delivery of the service to the client device.