The Virtuoso HTTP session management consists of functions for
session variables manipulation and an ability to define a pre- and
post-processing function. The pre and post-processing functions are
used to save and restore session data between HTTP posts, usually
to and from a session table.
Session management must be enable by settings the flag for
persistent session variables in virtual directory mapping. Virtual
directory mappings use the persistent_session_variables flag, which
when specified, session variables can be used in a post-process
function to determine if the session variables content must be
stored on to the session table or not.
The post-processing function hook can be any user-defined
Virtuoso/PL procedure, it will be executed every time after
processing of the active page.