text: # Copyright 2013 Red Hat, Inc.
  #
  #    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.
  
  """
  Client side of the console RPC API.
  """
  
  from oslo_config import cfg
  import oslo_messaging as messaging
  
  from nova import rpc
  
  rpcapi_opts = [
      cfg.StrOpt('console_topic',
                 default='console',
                 help='The topic console proxy nodes listen on'),
  ]
  
  CONF = cfg.CONF
  CONF.register_opts(rpcapi_opts)
  
  rpcapi_cap_opt = cfg.StrOpt('console',
          help='Set a version cap for messages sent to console services')
  CONF.register_opt(rpcapi_cap_opt, 'upgrade_levels')
  
  
  class ConsoleAPI(object):
      '''Client side of the console rpc API.
  
      API version history:
  
          1.0 - Initial version.
          1.1 - Added get_backdoor_port()
  
          ... Grizzly and Havana support message version 1.1.  So, any changes to
          existing methods in 1.x after that point should be done such that they
          can handle the version_cap being set to 1.1.
  
          2.0 - Major API rev for Icehouse
  
          ... Icehouse and Juno support message version 2.0.  So, any changes to
          existing methods in 2.x after that point should be done such that they
          can handle the version_cap being set to 2.0.
      '''
  
      VERSION_ALIASES = {
          'grizzly': '1.1',
          'havana': '1.1',
          'icehouse': '2.0',
          'juno': '2.0',
      }
  
      def __init__(self, topic=None, server=None):
          super(ConsoleAPI, self).__init__()
          topic = topic if topic else CONF.console_topic
          target = messaging.Target(topic=topic, server=server, version='2.0')
          version_cap = self.VERSION_ALIASES.get(CONF.upgrade_levels.console,
                                                 CONF.upgrade_levels.console)
          self.client = rpc.get_client(target, version_cap=version_cap)
  
      def add_console(self, ctxt, instance_id):
          cctxt = self.client.prepare()
          cctxt.cast(ctxt, 'add_console', instance_id=instance_id)
  
      def remove_console(self, ctxt, console_id):
          cctxt = self.client.prepare()
          cctxt.cast(ctxt, 'remove_console', console_id=console_id)
  