def do_get_session(self, session_key):
        """
        :type session_key: SessionKey
        :returns: SimpleSession
        """
        session_id = session_key.session_id
        msg = ("do_get_session: Attempting to retrieve session with key " +
               str(session_id))
        logger.debug(msg)

        session = self._retrieve_session(session_key)

        if (session is not None):
            self.validate(session, session_key)

        return session
:type session_key: SessionKey
        :returns: SimpleSession