@abc.abstractmethod<EOL><INDENT>def rollback_service(self, rollback_time):<DEDENT>
return<EOL>
Rolls back this service to a point in time.

        :param rollback_time: the requested time
        :type rollback_time: ``timestamp``
        :return: the journal entry corresponding to the actual state of this service
        :rtype: ``osid.journaling.JournalEntry``
        :raise: ``OperationFailed`` -- unable to complete request
        :raise: ``PermissionDenied`` -- authorization failure occurred
        :raise: ``Unimplemented`` -- ``supports_journal_rollback()`` is ``false``

        *compliance: mandatory -- This method must be implemented.*