255 lines
8.2 KiB
Python
255 lines
8.2 KiB
Python
# vim: tabstop=4 shiftwidth=4 softtabstop=4
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# Copyright 2010 United States Government as represented by the
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# Administrator of the National Aeronautics and Space Administration.
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# All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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"""
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AMQP-based RPC. Queues have consumers and publishers.
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No fan-out support yet.
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"""
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import json
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import logging
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import sys
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import uuid
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from carrot import connection
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from carrot import messaging
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from twisted.internet import defer
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from twisted.internet import reactor
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from twisted.internet import task
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from nova import exception
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from nova import fakerabbit
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from nova import flags
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FLAGS = flags.FLAGS
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_log = logging.getLogger('amqplib')
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_log.setLevel(logging.WARN)
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class Connection(connection.BrokerConnection):
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@classmethod
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def instance(cls):
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if not hasattr(cls, '_instance'):
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params = dict(hostname=FLAGS.rabbit_host,
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port=FLAGS.rabbit_port,
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userid=FLAGS.rabbit_userid,
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password=FLAGS.rabbit_password,
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virtual_host=FLAGS.rabbit_virtual_host)
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if FLAGS.fake_rabbit:
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params['backend_cls'] = fakerabbit.Backend
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cls._instance = cls(**params)
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return cls._instance
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@classmethod
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def recreate(cls):
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del cls._instance
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return cls.instance()
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class Consumer(messaging.Consumer):
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# TODO(termie): it would be nice to give these some way of automatically
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# cleaning up after themselves
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def attach_to_tornado(self, io_inst=None):
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from tornado import ioloop
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if io_inst is None:
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io_inst = ioloop.IOLoop.instance()
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injected = ioloop.PeriodicCallback(
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lambda: self.fetch(enable_callbacks=True), 100, io_loop=io_inst)
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injected.start()
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return injected
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attachToTornado = attach_to_tornado
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def fetch(self, *args, **kwargs):
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# TODO(vish): the logic for failed connections and logging should be
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# refactored into some sort of connection manager object
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try:
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if getattr(self, 'failed_connection', False):
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# attempt to reconnect
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self.conn = Connection.recreate()
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self.backend = self.conn.create_backend()
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super(Consumer, self).fetch(*args, **kwargs)
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if getattr(self, 'failed_connection', False):
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logging.error("Reconnected to queue")
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self.failed_connection = False
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except Exception, ex:
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if not getattr(self, 'failed_connection', False):
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logging.exception("Failed to fetch message from queue")
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self.failed_connection = True
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def attach_to_twisted(self):
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loop = task.LoopingCall(self.fetch, enable_callbacks=True)
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loop.start(interval=0.1)
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class Publisher(messaging.Publisher):
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pass
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class TopicConsumer(Consumer):
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exchange_type = "topic"
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def __init__(self, connection=None, topic="broadcast"):
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self.queue = topic
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self.routing_key = topic
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self.exchange = FLAGS.control_exchange
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super(TopicConsumer, self).__init__(connection=connection)
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class AdapterConsumer(TopicConsumer):
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def __init__(self, connection=None, topic="broadcast", proxy=None):
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_log.debug('Initing the Adapter Consumer for %s' % (topic))
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self.proxy = proxy
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super(AdapterConsumer, self).__init__(connection=connection, topic=topic)
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@exception.wrap_exception
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def receive(self, message_data, message):
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_log.debug('received %s' % (message_data))
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msg_id = message_data.pop('_msg_id', None)
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method = message_data.get('method')
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args = message_data.get('args', {})
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message.ack()
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if not method:
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# NOTE(vish): we may not want to ack here, but that means that bad
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# messages stay in the queue indefinitely, so for now
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# we just log the message and send an error string
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# back to the caller
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_log.warn('no method for message: %s' % (message_data))
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msg_reply(msg_id, 'No method for message: %s' % message_data)
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return
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node_func = getattr(self.proxy, str(method))
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node_args = dict((str(k), v) for k, v in args.iteritems())
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d = defer.maybeDeferred(node_func, **node_args)
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if msg_id:
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d.addCallback(lambda rval: msg_reply(msg_id, rval))
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d.addErrback(lambda e: msg_reply(msg_id, str(e)))
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return
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class TopicPublisher(Publisher):
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exchange_type = "topic"
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def __init__(self, connection=None, topic="broadcast"):
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self.routing_key = topic
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self.exchange = FLAGS.control_exchange
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super(TopicPublisher, self).__init__(connection=connection)
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class DirectConsumer(Consumer):
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exchange_type = "direct"
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def __init__(self, connection=None, msg_id=None):
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self.queue = msg_id
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self.routing_key = msg_id
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self.exchange = msg_id
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self.auto_delete = True
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super(DirectConsumer, self).__init__(connection=connection)
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class DirectPublisher(Publisher):
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exchange_type = "direct"
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def __init__(self, connection=None, msg_id=None):
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self.routing_key = msg_id
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self.exchange = msg_id
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self.auto_delete = True
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super(DirectPublisher, self).__init__(connection=connection)
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def msg_reply(msg_id, reply):
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conn = Connection.instance()
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publisher = DirectPublisher(connection=conn, msg_id=msg_id)
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try:
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publisher.send({'result': reply})
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except TypeError:
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publisher.send(
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{'result': dict((k, repr(v))
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for k, v in reply.__dict__.iteritems())
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})
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publisher.close()
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def call(topic, msg):
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_log.debug("Making asynchronous call...")
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msg_id = uuid.uuid4().hex
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msg.update({'_msg_id': msg_id})
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_log.debug("MSG_ID is %s" % (msg_id))
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conn = Connection.instance()
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d = defer.Deferred()
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consumer = DirectConsumer(connection=conn, msg_id=msg_id)
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consumer.register_callback(lambda data, message: d.callback(data))
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injected = consumer.attach_to_tornado()
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# clean up after the injected listened and return x
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d.addCallback(lambda x: injected.stop() and x or x)
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publisher = TopicPublisher(connection=conn, topic=topic)
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publisher.send(msg)
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publisher.close()
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return d
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def cast(topic, msg):
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_log.debug("Making asynchronous cast...")
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conn = Connection.instance()
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publisher = TopicPublisher(connection=conn, topic=topic)
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publisher.send(msg)
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publisher.close()
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def generic_response(message_data, message):
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_log.debug('response %s', message_data)
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message.ack()
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sys.exit(0)
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def send_message(topic, message, wait=True):
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msg_id = uuid.uuid4().hex
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message.update({'_msg_id': msg_id})
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_log.debug('topic is %s', topic)
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_log.debug('message %s', message)
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if wait:
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consumer = messaging.Consumer(connection=Connection.instance(),
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queue=msg_id,
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exchange=msg_id,
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auto_delete=True,
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exchange_type="direct",
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routing_key=msg_id)
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consumer.register_callback(generic_response)
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publisher = messaging.Publisher(connection=Connection.instance(),
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exchange="nova",
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exchange_type="topic",
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routing_key=topic)
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publisher.send(message)
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publisher.close()
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if wait:
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consumer.wait()
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# TODO: Replace with a docstring test
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if __name__ == "__main__":
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send_message(sys.argv[1], json.loads(sys.argv[2]))
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