'Authenticate with Dell REST interface.
:raises VolumeBackendAPIException.:'

def open_connection(self):

    self.failed_over = (self.primaryssn != self.ssn)
    payload = {}
    payload['Application'] = 'Cinder    REST    Driver'
    payload['ApplicationVersion'] = self.APIDRIVERVERSION
    r = self.client.post('ApiConnection/Login', payload)
    if (not self._check_result(r)):
        r = self._check_version_fail(payload, r)
        if (not self._check_result(r)):
            raise exception.VolumeBackendAPIException(data=_('Failed    to    connect    to    Dell    REST    API'))
    try:
        apidict = self._get_json(r)
        version = apidict['apiVersion']
        self.is_direct_connect = (apidict['provider'] == 'StorageCenter')
        splitver = version.split('.')
        if (splitver[0] == '2'):
            if (splitver[1] == '0'):
                self.consisgroups = False
                self.legacypayloadfilters = True
            elif (splitver[1] == '1'):
                self.legacypayloadfilters = True
        return
    except Exception:
        LOG.error('Unrecognized    Login    Response:    %s', r)
