text: # Licensed under the Apache License, Version 2.0 (the "License"); you may
  # not use this file except in compliance with the License. You may obtain
  # a copy of the License at
  #
  #      http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  # WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
  # License for the specific language governing permissions and limitations
  # under the License.
  
  from oslo_utils import timeutils
  
  from keystone.common import controller
  from keystone.common import dependency
  from keystone import exception
  from keystone.i18n import _
  
  
  @dependency.requires('revoke_api')
  class RevokeController(controller.V3Controller):
      @controller.protected()
      def list_revoke_events(self, context):
          since = context['query_string'].get('since')
          last_fetch = None
          if since:
              try:
                  last_fetch = timeutils.normalize_time(
                      timeutils.parse_isotime(since))
              except ValueError:
                  raise exception.ValidationError(
                      message=_('invalid date format %s') % since)
          events = self.revoke_api.list_events(last_fetch=last_fetch)
          # Build the links by hand as the standard controller calls require ids
          response = {'events': [event.to_dict() for event in events],
                      'links': {
                          'next': None,
                          'self': RevokeController.base_url(
                              context,
                              path=context['path']),
                          'previous': None}
                      }
          return response
  