In a network having a plurality of routers and also an application running
at a plurality of replicas, a system for maintaining a client session
between a client and a particular replica includes providing a database
of bindings of client request identifiers to replicas. The system further
includes a change log of changes made to the database where each entry
has an event number. A version vector associated with the database and
the change log holds a most recent event number for each router in the
network. The system receives updates of change events made at the routers
in the network and reconciles the updates with the database and current
version vector. The system has data to maintain a client session between
the client and the particular replica through repeated requests. Also the
system and routers share data so that the client session can be
maintained no matter which router handles subsequent client requests.