======================================== kombu - Messaging library for Python
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:Version: 5.6.2 :Documentation: https://kombu.readthedocs.io/ :Download: https://pypi.org/project/kombu/ :Source: https://github.com/celery/kombu/ :DeepWiki: |deepwiki| :Keywords: messaging, amqp, rabbitmq, redis, mongodb, python, queue
About
Kombu is a messaging library for Python.
The aim of Kombu is to make messaging in Python as easy as possible by
providing an idiomatic high-level interface for the AMQ protocol, and also
provide proven and tested solutions to common messaging problems.
AMQP_ is the Advanced Message Queuing Protocol, an open standard protocol
for message orientation, queuing, routing, reliability and security,
for which the RabbitMQ_ messaging server is the most popular implementation.
Features
Allows application authors to support several message server solutions by using pluggable transports.
AMQP transport using the
py-amqp, orqpid-pythonlibraries.Virtual transports makes it really easy to add support for non-AMQP transports. There is already built-in support for
Redis,Amazon SQS,ZooKeeper,SoftLayer MQ,MongoDB,PGMQandPyro_.In-memory transport for unit testing.
Supports automatic encoding, serialization and compression of message payloads.
Consistent exception handling across transports.
The ability to ensure that an operation is performed by gracefully handling connection and channel errors.
Several annoyances with
amqplib_ has been fixed, like supporting timeouts and the ability to wait for events on more than one channel.Projects already using
carrot_ can easily be ported by using a compatibility layer.
For an introduction to AMQP you should read the article Rabbits and warrens,
and the Wikipedia article about AMQP.
.. _RabbitMQ: https://www.rabbitmq.com/
.. _AMQP: https://amqp.org
.. _py-amqp: https://pypi.org/project/amqp/
.. _qpid-python: https://pypi.org/project/qpid-python/
.. _Redis: https://redis.io
.. _Amazon SQS: https://aws.amazon.com/sqs/
.. _Zookeeper: https://zookeeper.apache.org/
.. _Rabbits and warrens: http://web.archive.org/web/20160323134044/http://blogs.digitar.com/jjww/2009/01/rabbits-and-warrens/
.. _amqplib: https://barryp.org/software/py-amqplib/
.. _Wikipedia article about AMQP: https://en.wikipedia.org/wiki/AMQP
.. _carrot: https://pypi.org/project/carrot/
.. _librabbitmq: https://pypi.org/project/librabbitmq/
.. _Pyro: https://pyro4.readthedocs.io/
.. _SoftLayer MQ: https://web.archive.org/web/20180313081320/http://sldn.softlayer.com/reference/messagequeueapi
.. _MongoDB: https://www.mongodb.com/
.. _PGMQ: https://pgmq.github.io/pgmq/
.. _AWS SNS: https://aws.amazon.com/sns/
.. _transport-comparison:
Transport Comparison
+---------------+----------+------------+------------+---------------+--------------+-----------------------+ | Client | Type | Direct | Topic | Fanout | Priority | TTL | +---------------+----------+------------+------------+---------------+--------------+-----------------------+ | amqp | Native | Yes | Yes | Yes | Yes [#f3]_ | Yes [#f4]_ | +---------------+----------+------------+------------+---------------+--------------+-----------------------+ | qpid | Native | Yes | Yes | Yes | No | No | +---------------+----------+------------+------------+---------------+--------------+-----------------------+ | redis | Virtual | Yes | Yes | Yes (PUB/SUB) | Yes | No | +---------------+----------+------------+------------+---------------+--------------+-----------------------+ | mongodb | Virtual | Yes | Yes | Yes | Yes | Yes | +---------------+----------+------------+------------+---------------+--------------+-----------------------+ | pgmq | Virtual | Yes | Yes | Yes | No | No | +---------------+----------+------------+------------+---------------+--------------+-----------------------+ | SQS | Virtual | Yes | Yes [#f1]_ | Yes [#f2]_ | No | No | +---------------+----------+------------+------------+---------------+--------------+-----------------------+ | zookeeper | Virtual | Yes | Yes [#f1]_ | No | Yes | No | +---------------+----------+------------+------------+---------------+--------------+-----------------------+ | in-memory | Virtual | Yes | Yes [#f1]_ | No | No | No | +---------------+----------+------------+------------+---------------+--------------+-----------------------+ | SLMQ | Virtual | Yes | Yes [#f1]_ | No | No | No | +---------------+----------+------------+------------+---------------+--------------+-----------------------+ | Pyro | Virtual | Yes | Yes [#f1]_ | No | No | No | +---------------+----------+------------+------------+---------------+--------------+-----------------------+
.. [#f1] Declarations only kept in memory, so exchanges/queues must be declared by all clients that needs them.
.. [#f2] Fanout is supported via AWS SNS. A notification is sent to SNS, and a copy is set to all subscribed
Amazon SQS queues. Please consult the AWS SNS and SQS pricing pages to see how this will affect your usage
costs. Disabled by default, but can be enabled by using the supports_fanout transport option.
.. [#f3] AMQP Message priority support depends on broker implementation.
.. [#f4] AMQP Message/Queue TTL support depends on broker implementation.
Documentation
Kombu is using Sphinx, and the latest documentation can be found here:
https://kombu.readthedocs.io/
Quick overview
.. code:: python
from kombu import Connection, Exchange, Queue
media_exchange = Exchange('media', 'direct', durable=True)
video_queue = Queue('video', exchange=media_exchange, routing_key='video')
def process_media(body, message):
print(body)
message.ack()
# connections
with Connection('amqp://guest:guest@localhost//') as conn:
# produce
producer = conn.Producer(serializer='json')
producer.publish({'name': '/tmp/lolcat1.avi', 'size': 1301013},
exchange=media_exchange, routing_key='video',
declare=[video_queue])
# the declare above, makes sure the video queue is declared
# so that the messages can be delivered.
# It's a best practice in Kombu to have both publishers and
# consumers declare the queue. You can also declare the
# queue manually using:
# video_queue(conn).declare()
# consume
with conn.Consumer(video_queue, callbacks=[process_media]) as consumer:
# Process messages and handle events on all channels
while True:
conn.drain_events()
# Consume from several queues on the same channel:
video_queue = Queue('video', exchange=media_exchange, key='video')
image_queue = Queue('image', exchange=media_exchange, key='image')
with connection.Consumer([video_queue, image_queue],
callbacks=[process_media]) as consumer:
while True:
connection.drain_events()
Or handle channels manually:
.. code:: python
with connection.channel() as channel:
producer = Producer(channel, ...)
consumer = Consumer(channel)
All objects can be used outside of with statements too, just remember to close the objects after use:
.. code:: python
from kombu import Connection, Consumer, Producer
connection = Connection()
# ...
connection.release()
consumer = Consumer(channel_or_connection, ...)
consumer.register_callback(my_callback)
consumer.consume()
# ....
consumer.cancel()
Exchange and Queue are simply declarations that can be pickled
and used in configuration files etc.
They also support operations, but to do so they need to be bound to a channel.
Binding exchanges and queues to a connection will make it use that connections default channel.
::
>>> exchange = Exchange('tasks', 'direct')
>>> connection = Connection()
>>> bound_exchange = exchange(connection)
>>> bound_exchange.delete()
# the original exchange is not affected, and stays unbound.
>>> exchange.dele