A Pool User (PU) is a client in the Reliable Server Pooling (RSerPool) framework.
In order to use the service provided by a pool, a PU has to proceed the following steps:
Ask a Pool Registrar for server selection (the Pool Registrar will return a list of servers, called Pool Elements),
Select one Pool Element, establish a connection and use the actual service,
Repeat the server selection and connection establishment procedure in case of server failures,
Perform an application-specific session failover to a new server to resume an interrupted session,
Report failed servers to the Pool Registrar.
