Metadata-Version: 1.0
Name: kombu
Version: 0.2.0
Summary: AMQP Messaging Framework for Python
Home-page: http://github.com/ask/kombu/
Author: Ask Solem
Author-email: ask@celeryproject.org
License: UNKNOWN
Description: #############################################
        kombu - AMQP Messaging Framework for Python
        #############################################
        
        :Version: 0.2.0
        
        **THIS IS A REWRITE OF CARROT**
        
        Carrot will be discontinued in favor of Kombu.
        
        Proposed API::
        
        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()
        
        while True:
        connection.drain_events()
        
        
        # consumerset:
        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()
        
        
        
        Exchanges/Queue can 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.
        
        **ORIGINAL CARROT README BELOW**
        
        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. At the
        same time it is a goal to re-use what is already available as much as possible.
        
        `kombu` has pluggable messaging transports, so it is possible to support
        several messaging systems. Currently, there is support for `AMQP`_
        (`py-amqplib`_, `pika`_), `STOMP`_ (`stompy`_). There's also an
        in-memory transport for testing purposes, using the `Python queue module`_.
        
        Several AMQP message broker implementations exists, including `RabbitMQ`_,
        `Apache ActiveMQ`_. You'll need to have one of these installed,
        personally we've been using `RabbitMQ`_.
        
        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
        .. _`STOMP`: http://stomp.codehaus.org
        .. _`stompy`: http://pypi.python.org/stompy
        .. _`Python Queue module`: http://docs.python.org/library/queue.html
        .. _`Apache ActiveMQ`: http://activemq.apache.org/
        .. _`Django`: http://www.djangoproject.com/
        .. _`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
        
        Documentation
        -------------
        
        Kombu is using Sphinx, and the latest documentation is available at GitHub:
        
        http://ask.github.com/kombu
        
        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"``.
        
        
        Examples
        ========
        
        Creating a connection
        ---------------------
        
        You can set up a connection by creating an instance of
        ``kombu.BrokerConnection``, with the appropriate options for
        your broker:
        
        >>> from kombu import BrokerConnection
        >>> conn = BrokerConnection(hostname="localhost", port=5672,
        ...                         userid="guest", password="guest",
        ...                         virtual_host="/")
        
        
        Receiving messages using a Consumer
        -----------------------------------
        
        First we open up a Python shell and start a message consumer.
        
        This consumer declares a queue named ``"feed"``, receiving messages with
        the routing key ``"importer"`` from the ``"feed"`` exchange.
        
        >>> from kombu import Exchange, Queue, Consumer
        
        >>> feed_exchange = Exchange("feed", type="direct")
        >>> feed_queue = Queue("feed", feed_exchange, "importer")
        
        >>> channel = connection.channel()
        >>> consumer = Consumer(channel, [feed_queue])
        
        >>> def import_feed_callback(message_data, message)
        ...     feed_url = message_data["import_feed"]
        ...     print("Got feed import message for: %s" % feed_url)
        ...     # something importing this feed url
        ...     # import_feed(feed_url)
        ...     message.ack()
        
        >>> consumer.register_callback(import_feed_callback)
        
        >>> # Consume messages in a loop
        >>> while True:
        ...     connection.drain_events(timeout=...)
        
        Sending messages using a Producer
        ---------------------------------
        
        Then we open up another Python shell to send some messages to the consumer
        defined in the last section.
        
        >>> from kombu import Exchange, Producer
        >>> feed_exchange = Exchange("feed", type="direct")
        
        >>> channel = connection.channel()
        >>> producer = Producer(channel, feed_exchange)
        >>> producer.publish({"import_feed": "http://cnn.com/rss/edition.rss"},
        ...                  routing_key="importer")
        >>> producer.close()
        
        
        Look in the first Python shell again (where consumer loop is running),
        where the following text has been printed to the screen::
        
        Got feed import message for: http://cnn.com/rss/edition.rss
        
        
        Serialization of Data
        -----------------------
        
        By default every message is encoded using `JSON`_, so sending
        Python data structures like dictionaries and lists works.
        `YAML`_, `msgpack`_ and Python's built-in ``pickle`` module is also supported,
        and if needed you can register any custom serialization scheme you
        want to use.
        
        .. _`JSON`: http://www.json.org/
        .. _`YAML`: http://yaml.org/
        .. _`msgpack`: http://msgpack.sourceforge.net/
        
        Each option has its advantages and disadvantages.
        
        ``json`` -- JSON is supported in many programming languages, is now
        a standard part of Python (since 2.6), and is fairly fast to
        decode using the modern Python libraries such as ``cjson or
        ``simplejson``.
        
        The primary disadvantage to ``JSON`` is that it limits you to
        the following data types: strings, unicode, floats, boolean,
        dictionaries, and lists.  Decimals and dates are notably missing.
        
        Also, binary data will be transferred using base64 encoding, which
        will cause the transferred data to be around 34% larger than an
        encoding which supports native binary types.
        
        However, if your data fits inside the above constraints and
        you need cross-language support, the default setting of ``JSON``
        is probably your best choice.
        
        ``pickle`` -- If you have no desire to support any language other than
        Python, then using the ``pickle`` encoding will gain you
        the support of all built-in Python data types (except class instances),
        smaller messages when sending binary files, and a slight speedup
        over ``JSON`` processing.
        
        ``yaml`` -- YAML has many of the same characteristics as ``json``,
        except that it natively supports more data types (including dates,
        recursive references, etc.)
        
        However, the Python libraries for YAML are a good bit slower
        than the libraries for JSON.
        
        If you need a more expressive set of data types and need to maintain
        cross-language compatibility, then ``YAML`` may be a better fit
        than the above.
        
        To instruct carrot to use an alternate serialization method,
        use one of the following options.
        
        1.  Set the serialization option on a per-producer basis::
        
        >>> producer = Producer(channel,
        ...                     exchange=exchange,
        ...                     serializer="yaml")
        
        2.  Set the serialization option per message::
        
        >>> producer.publish(message, routing_key=rkey,
        ...                  serializer="pickle")
        
        Note that a ``Consumer`` do not need the serialization method specified.
        They can auto-detect the serialization method as the
        content-type is sent as a message header.
        
        Sending raw data without Serialization
        ---------------------------------------
        
        In some cases, you don't need your message data to be serialized. If you
        pass in a plain string or unicode object as your message, then carrot will
        not waste cycles serializing/deserializing the data.
        
        You can optionally specify a ``content_type`` and ``content_encoding``
        for the raw data:
        
        >>> producer.send(open('~/my_picture.jpg','rb').read(),
        content_type="image/jpeg",
        content_encoding="binary",
        routing_key=rkey)
        
        The ``Message`` object returned by the ``Consumer`` class will have a
        ``content_type`` and ``content_encoding`` attribute.
        
        
        Receiving messages without a callback
        --------------------------------------
        
        You can also poll the queue manually, by using the ``get`` method.
        This method returns a ``Message`` object, from where you can get the
        message body, de-serialize the body to get the data, acknowledge, reject or
        re-queue the message.
        
        >>> consumer = Consumer(channel, queues)
        >>> message = consumer.get()
        >>> if message:
        ...    message_data = message.payload
        ...    message.ack()
        ... else:
        ...     # No messages waiting on the queue.
        >>> consumer.close()
        
        Sub-classing the messaging classes
        ----------------------------------
        
        The ``Consumer``, and ``Producer`` classes can also be sub classed. Thus you
        can define the above producer and consumer like so:
        
        >>> class FeedProducer(Producer):
        ...     exchange = exchange
        ...     routing_key = "importer"
        ...
        ...     def import_feed(self, feed_url):
        ...         return self.publish({"action": "import_feed",
        ...                              "feed_url": feed_url})
        
        >>> class FeedConsumer(Consumer):
        ...     queues = queues
        ...
        ...     def receive(self, message_data, message):
        ...         action = message_data["action"]
        ...         if action == "import_feed":
        ...             # something importing this feed
        ...             # import_feed(message_data["feed_url"])
        message.ack()
        ...         else:
        ...             raise Exception("Unknown action: %s" % action)
        
        >>> producer = FeedProducer(channel)
        >>> producer.import_feed("http://cnn.com/rss/edition.rss")
        >>> producer.close()
        
        >>> consumer = FeedConsumer(channel)
        >>> while True:
        ...     connection.drain_events()
        
        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.
        
Platform: any
Classifier: Development Status :: 4 - Beta
Classifier: Framework :: Django
Classifier: Operating System :: OS Independent
Classifier: Programming Language :: Python
Classifier: License :: OSI Approved :: BSD License
Classifier: Intended Audience :: Developers
Classifier: Topic :: Communications
Classifier: Topic :: System :: Distributed Computing
Classifier: Topic :: Software Development :: Libraries :: Python Modules
