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 kombu - AMQP Messaging Framework for Python
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:Version: 0.9.5

Introduction
------------

`Kombu` is an `AMQP`_ messaging queue framework. AMQP is the Advanced Message
Queuing Protocol, an open standard protocol for message orientation, queuing,
routing, reliability and security.

The aim of `Kombu` is to make messaging in Python as easy as possible by
providing a high-level interface for producing and consuming messages,
and provide tested and proven implementations of common messaging patterns.

`Kombu` has pluggable messaging transports, so it is possible to support
several messaging systems. Currently, there is support for `AMQP`_
(`py-amqplib`_, `pika`_), `Redis`_, and `Beanstalk`. Also there's an
in-memory transport for testing purposes.

There are also transports available as plug-ins, like `kombu-sqlalchemy`
(SQLAlchemy transport), or `django-kombu`_ (transport using the Django ORM).

Before you start playing with `Kombu`, you should probably read up on
AMQP, and you could start with the excellent article about using RabbitMQ
under Python, `Rabbits and warrens`_. For more detailed information, you can
refer to the `Wikipedia article about AMQP`_.

.. _`RabbitMQ`: http://www.rabbitmq.com/
.. _`AMQP`: http://amqp.org
.. _`Redis`: http://code.google.com/p/redis/
.. _`Python Queue module`: http://docs.python.org/library/queue.html
.. _`Apache ActiveMQ`: http://activemq.apache.org/
.. _`Rabbits and warrens`: http://blogs.digitar.com/jjww/2009/01/rabbits-and-warrens/
.. _`py-amqplib`: http://barryp.org/software/py-amqplib/
.. _`pika`: http://github.com/tonyg/pika
.. _`Wikipedia article about AMQP`: http://en.wikipedia.org/wiki/AMQP
.. _`kombu-sqlalchemy`: http://github.com/ask/kombu-sqlalchemy/
.. _`django-kombu`: http://github.com/ask/django-kombu/

Documentation
-------------

Kombu is using Sphinx, and the latest documentation is available at GitHub:

    http://ask.github.com/kombu

Quick overview
--------------

::

    from kombu.connection BrokerConnection
    from kombu.messaging import Exchange, Queue, Consumer, Producer

    media_exchange = Exchange("media", "direct", durable=True)
    video_queue = Queue("video", exchange=media_exchange, key="video")

    # connections/channels
    connection = BrokerConnection("localhost", "guest", "guest", "/")
    channel = connection.channel()

    # produce
    producer = Producer(channel, exchange=media_exchange, serializer="json")
    producer.publish({"name": "/tmp/lolcat1.avi", "size": 1301013})

    # consume
    consumer = Consumer(channel, video_queue)
    consumer.register_callback(process_media)
    consumer.consume()

    # Process messages on all channels
    while True:
        connection.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")

    consumer = Consumer(channel, [video_queue, image_queue])
    consumer.consume()

    while True:
        connection.drain_events()


`Exchange` and `Queue` are simply declarations that can be pickled
and used in configuaration files etc.

They also support operations, but to do so they need to be bound
to a channel:

::

    >>> exchange = Exchange("tasks", "direct")

    >>> connection = BrokerConnection()
    >>> channel = connection.channel()
    >>> bound_exchange = exchange(channel)
    >>> 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.

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


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"`.

Getting Help
============

Mailing list
------------

Join the `carrot-users`_ mailing list.

.. _`carrot-users`: http://groups.google.com/group/carrot-users/

Bug tracker
===========

If you have any suggestions, bug reports or annoyances please report them
to our issue tracker at http://github.com/ask/kombu/issues/

Contributing
============

Development of `Kombu` happens at Github: http://github.com/ask/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.