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authorAsk Solem <ask@celeryproject.org>2016-10-26 18:01:55 -0700
committerAsk Solem <ask@celeryproject.org>2016-10-26 18:01:55 -0700
commit43efbdf5c5ce3bd52f0f3700f80693006b98fad0 (patch)
treede37bf7442bee7e4c56fa8231e82154608c9e12e /docs
parent719cd7b2afaef2d16ae913248f18cde985bf40db (diff)
downloadkombu-43efbdf5c5ce3bd52f0f3700f80693006b98fad0.tar.gz
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Basics
======
+You can create a producer using a :class:`~kombu.Connection`:
+
+.. code-block:: pycon
+
+ >>> producer = connection.Producer()
+
+You can also instantiate :class:`~kombu.Producer` directly,
+it takes a channel or a connection as an argument:
+
+.. code-block:: pycon
+
+ >>> with Connection('amqp://') as conn:
+ ... with conn.channel() as channel:
+ ... producer = Producer(channel)
+
+Having a producer instance you can publish messages:
+
+.. code-block:: pycon
+ >>> from kombu import Exchange
+
+ >>> exchange = Exchange('name', type='direct')
+
+ >>> producer.publish(
+ ... {'hello': 'world'}, # message to send
+ ... exchange=exchange, # destination exchange
+ ... routing_key='rk', # destination routing key,
+ ... decare=[exchange], # make sure exchange is declared,
+ ... )
+
+
+Mostly you will be getting a connection from a connection pool,
+and this connection can be stale, or you could lose the connection
+in the middle of sending the message. Using retries is a good
+way to handle these intermittent failures:
+
+.. code-block:: pycon
+
+ >>> producer.publish({'hello': 'world', ..., retry=True})
+
+In addition a retry policy can be specified, which is a dictionary
+of parameters supported by the :func:`~kombu.utils.functional.retry_over_time`
+function
+
+.. code-block:: pycon
+
+ >>> producer.publish(
+ ... {'hello': 'world'}, ...,
+ ... retry=True,
+ ... retry_policy={
+ ... 'interval_start': 0, # First retry immediately,
+ ... 'interval_step': 2, # then increase by 2s for every retry.
+ ... 'interval_max': 30, # but don't exceed 30s between retries.
+ ... 'max_retries': 30, # give up after 30 tries.
+ ... },
+ ... )
+
+The ``declare`` argument lets you pass a list of entities that must be
+declared before sending the message. This is especially important
+when using the ``retry`` flag, since the broker may actually restart
+during a retry in which case non-durable entities are removed.
+
+Say you are writing a task queue, and the workers may have not started yet
+so the queues aren't declared. In this case you need to define both the
+exchange, and the declare the queue so that the message is delivered to
+the queue while the workers are offline:
+
+.. code-block:: pycon
+
+ >>> from kombu import Exchange, Queue
+ >>> task_queue = Queue('tasks', Exchange('tasks'), routing_key='tasks')
+
+ >>> producer.publish(
+ ... {'hello': 'world'}, ...,
+ ... retry=True,
+ ... exchange=task_queue.exchange,
+ ... routing_key=task_queue.routing_key,
+ ... declare=[task_queue], # declares exchange, queue and binds.
+ ... )
+
+Bypassing routing by using the anon-exchange
+--------------------------------------------
+
+You may deliver to a queue directly, bypassing the brokers routing
+mechanisms, by using the "anon-exchange": set the exchange parameter to the
+empty string, and set the routing key to be the name of the queue:
+
+.. code-block:: pycon
+
+ >>> producer.publish(
+ ... {'hello': 'world'},
+ ... exchange='',
+ ... routing_key=task_queue.name,
+ ... )
Serialization
=============
-See :ref:`guide-serialization`.
+Json is the default serializer when a non-string object is passed
+to publish, but you can also specify a different serializer:
+
+.. code-block:: pycon
+
+ >>> producer.publish({'hello': 'world'}, serializer='pickle')
+
+See :ref:`guide-serialization` for more information.
Reference