'Add a new member to a service group.
:param member: the joined member ID/name
:param group: the group ID/name, of the joined member
:param service: a `nova.service.Service` object'

def join(self, member, group, service=None):

    LOG.debug('DB_Driver:    join    new    ServiceGroup    member    %(member)s    to    the    %(group)s    group,    service    =    %(service)s', {'member': member, 'group': group, 'service': service})
    if (service is None):
        raise RuntimeError(_('service    is    a    mandatory    argument    for    DB    based    ServiceGroup    driver'))
    report_interval = service.report_interval
    if report_interval:
        service.tg.add_timer(report_interval, self._report_state, api.INITIAL_REPORTING_DELAY, service)
