retaining state within the server

greetings;

what is the "standard" approach to retaining state across connections.
i refer here to cached data within the server, rather than properties
which may be round-tripped through the user.

where users are authenticated, would it be appropriate to add such
things as properties to the authenticated user instance? releasing
resource and garbage collecting upon timeout?

i looked through the examples but found only the lisp listener which
used the method to which i alluded above. is anyone able to share some
experience on this?

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