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https://github.com/celery/kombu

Messaging library for Python.
https://github.com/celery/kombu

celery kombu message-queue messaging python python-3 python-library python3 rabbitmq redis sqs

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Messaging library for Python.

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README 

        
========================================

 kombu - Messaging library for Python

========================================



|build-status| |coverage| |license| |wheel| |pyversion| |pyimp| |downloads|



:Version: 5.5.0rc2

:Documentation: https://kombu.readthedocs.io/

:Download: https://pypi.org/project/kombu/

:Source: https://github.com/celery/kombu/

: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`_, or `qpid-python`_ libraries.



    * 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`_ and `Pyro`_.



    * 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://sldn.softlayer.com/reference/messagequeueapi

.. _`MongoDB`: https://www.mongodb.com/



.. _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                   |

+---------------+----------+------------+------------+---------------+--------------+-----------------------+

| *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 supported via storing routing tables in SimpleDB.

         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.delete()

    raise NotBoundError: Can't call delete on Exchange not bound to

        a channel.



Terminology

===========



There are some concepts you should be familiar with before starting:



    * Producers



        Producers sends messages to an exchange.



    * Exchanges



        Messages are sent to exchanges. Exchanges are named and can be

        configured to use one of several routing algorithms. The exchange

        routes the messages to consumers by matching the routing key in the

        message with the routing key the consumer provides when binding to

        the exchange.



    * Consumers



        Consumers declares a queue, binds it to a exchange and receives

        messages from it.



    * Queues



        Queues receive messages sent to exchanges. The queues are declared

        by consumers.



    * Routing keys



        Every message has a routing key. The interpretation of the routing

        key depends on the exchange type. There are four default exchange

        types defined by the AMQP standard, and vendors can define custom

        types (so see your vendors manual for details).



        These are the default exchange types defined by AMQP/0.8:



            * Direct exchange



                Matches if the routing key property of the message and

                the `routing_key` attribute of the consumer are identical.



            * Fan-out exchange



                Always matches, even if the binding does not have a routing

                key.



            * Topic exchange



                Matches the routing key property of the message by a primitive

                pattern matching scheme. The message routing key then consists

                of words separated by dots (`"."`, like domain names), and

                two special characters are available; star (`"*"`) and hash

                (`"#"`). The star matches any word, and the hash matches

                zero or more words. For example `"*.stock.#"` matches the

                routing keys `"usd.stock"` and `"eur.stock.db"` but not

                `"stock.nasdaq"`.



Installation

============



You can install `Kombu` either via the Python Package Index (PyPI)

or from source.



To install using `pip`,:



::



    $ pip install kombu



To install using `easy_install`,:



::



    $ easy_install kombu



If you have downloaded a source tarball you can install it

by doing the following,:



::



    $ python setup.py build

    # python setup.py install # as root



Getting Help

============



Mailing list

------------



Join the `celery-users`_ mailing list.



.. _`kombu forum`: https://github.com/celery/kombu/discussions



Bug tracker

===========



If you have any suggestions, bug reports or annoyances please report them

to our issue tracker at https://github.com/celery/kombu/issues/



Contributing

============



Development of `Kombu` happens at Github: https://github.com/celery/kombu



You are highly encouraged to participate in the development. If you don't

like Github (for some reason) you're welcome to send regular patches.



License

=======



This software is licensed under the `New BSD License`. See the `LICENSE`

file in the top distribution directory for the full license text.



.. |build-status| image:: https://github.com/celery/kombu/actions/workflows/ci.yaml/badge.svg

    :alt: Build status

    :target: https://github.com/celery/kombu/actions/workflows/ci.yml



.. |coverage| image:: https://codecov.io/github/celery/kombu/coverage.svg?branch=main

    :target: https://codecov.io/github/celery/kombu?branch=main



.. |license| image:: https://img.shields.io/pypi/l/kombu.svg

    :alt: BSD License

    :target: https://opensource.org/licenses/BSD-3-Clause



.. |wheel| image:: https://img.shields.io/pypi/wheel/kombu.svg

    :alt: Kombu can be installed via wheel

    :target: https://pypi.org/project/kombu/



.. |pyversion| image:: https://img.shields.io/pypi/pyversions/kombu.svg

    :alt: Supported Python versions.

    :target: https://pypi.org/project/kombu/



.. |pyimp| image:: https://img.shields.io/pypi/implementation/kombu.svg

     :alt: Support Python implementations.

     :target: https://pypi.org/project/kombu/

.. |downloads| image:: https://pepy.tech/badge/kombu

    :target: https://pepy.tech/project/kombu



kombu as part of the Tidelift Subscription

=======



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