Connecting to RabbitMQ with Callback-Passing Style
使用被动回调的方式创建与RabbitMQ的连接
When you connect to RabbitMQ with an asynchronous adapter, you are writing event oriented code. The connection adapter will block on the IOLoop that is watching to see when pika should read data from and write data to RabbitMQ. Because you’re now blocking on the IOLoop, you will receive callback notifications when specific events happen.
当你以异步适配器(asynchronous adapter)的方式连接RabbitMQ，就需要以面向事件的方式编写代码。当pika从RabbitMQ中读写数据时，连接适配器会在IO循环上阻塞。因为你阻塞在IO循环上，所以当特殊的事件发生时你会接收到回调提示（callback notifications）
import pika
# Step #3
def on_open(connection):
connection.channel(on_channel_open)
# Step #4
def on_channel_open(channel):
channel.basic_publish('exchange_name',
'routing_key',
'Test Message',
pika.BasicProperties(content_type='text/plain',
type='example'))
# Step #1: Connect to RabbitMQ
connection = pika.SelectConnection(on_open_callback=on_open)
try:
# Step #2 - Block on the IOLoop
connection.ioloop.start()
# Catch a Keyboard Interrupt to make sure that the connection is closed cleanly
except KeyboardInterrupt:
# Gracefully close the connection
connection.close()
# Start the IOLoop again so Pika can communicate, it will stop on its own when the connection is closed
connection.ioloop.start()
Step1 创建与RabbitMQ的连接
Step2 开始IO循环
Step3 一旦连接被创建，on_open方法就会被Pika调用（伴随对连接的处理方法）。以这种方式，连接中会打开一个新的管道（a new channel）
Step4 当管道打开后，你就可以执行你的其他操作。可以是发布消息，消费消息或其他与RabbitMQ相关的操作。
Using the Blocking Connection to get a message from RabbitMQ
使用阻塞连接从RabbitMQ中获取单条消息
The BlockingChannel.basic_get method will return a tuple with the members.
这种方法会返回一个含有成员（members）的元组
If the server returns a message, the first item in the tuple will be a pika.spec.Basic.GetOk object with the current message count, the redelivered flag, the routing key that was used to put the message in the queue, and the exchange the message was published to. The second item will be a BasicProperties object and the third will be the message body.
如果服务器返回了一条信息，元组中的第一个元素是携带当前消息数目、重传递标识（redelivered flag）、用于将消息传送给序列的路由键（routing key）和已经被发布的交换信息（exchange the message）的pika.spec.Basic.GetOk对象。第二个元素会是BasicProperties对象，第三个元素将会是消息本体。
If the server did not return a message a tuple of None, None, None will be returned.
如果服务器没有返回消息，那么这个元组返回的三个元素都将是None
Example of getting a message and acknowledging it:
以下是代码示例
import pika
connection = pika.BlockingConnection()
# 一般BlockingConnection中会添加Parameter对象来携带连接信息
channel = connection.channel()
method_frame, header_frame, body = channel.basic_get('test')
# basic_get相当于一次仅获取一条日志
if method_frame:
# 如果没有日志，则返回元组的对象会是None
print(method_frame, header_frame, body)
channel.basic_ack(method_frame.delivery_tag)
else:
print('No message returned')
Using the Blocking Connection to consume messages from RabbitMQ
使用阻塞连接从RabbitMQ消费信息
The BlockingChannel.basic_consume method assign a callback method to be called every time that RabbitMQ delivers messages to your consuming application.
BlockingChannel.basic_consume方法会在RabbitMQ每次给你的消费程序传送信息时候调用你所分配的回调函数。
When pika calls your method, it will pass in the channel, a pika.spec.Basic.Deliver object with the delivery tag, the redelivered flag, the routing key that was used to put the message in the queue, and the exchange the message was published to. The third argument will be a pika.spec.BasicProperties object and the last will be the message body.
当pika调用你的函数时，会有以下内容传递到管道中：传递标签（delivery tag）、重传递标签、用于将信息放进队列的路由键、被分开的交换消息。第三个参数将会是pika.spec.BasicProperties对象，最后一个对象将是消息本身。
Example of consuming messages and acknowledging them:
import pika
def on_message(channel, method_frame, header_frame, body):
print(method_frame.delivery_tag)
print(body)
print(header_frame)
channel.basic_ack(delivery_tag=method_frame.delivery_tag)
# 创建回调函数
connection = pika.BlockingConnection()
channel = connection.channel()
channel.basic_consume(on_message, 'test')
# 这里的test是路由key，或生产者声明的queue name
try:
channel.start_consuming()
# 以阻塞的方法持续监听队列
except KeyboardInterrupt:
channel.stop_consuming()
connection.close()
Using the BlockingChannel.consume generator to consume messages
使用阻塞通道消费生成器来消费日志
The BlockingChannel.consume method is a generator that will return a tuple of method, properties and body.
BlockingChannel.consume方法是一个生产期，可以返回method、properties、body三者组成元组的生成器。
When you escape out of the loop, be sure to call consumer.cancel() to return any unprocessed messages.
当你退出循环后，请确保调用consumer.cancel()方法来返回任何未被处理的消息
Example of consuming messages and acknowledging them:
import pika
connection = pika.BlockingConnection()
channel = connection.channel()
# Get ten messages and break out
for method_frame, properties, body in channel.consume('test'):
# Display the message parts
print(method_frame)
print(properties)
print(body)
# Acknowledge the message
channel.basic_ack(method_frame.delivery_tag)
# Escape out of the loop after 10 messages
if method_frame.delivery_tag == 10:
break
# Cancel the consumer and return any pending messages
requeued_messages = channel.cancel()
print('Requeued %i messages' % requeued_messages)
# Close the channel and the connection
channel.close()
connection.close()
如果在test队列中存在挂起的消息，那么你应该会得到类似下文的输出：
(pika)gmr-0x02:pika gmr$ python blocking_nack.py
Hello World!
Hello World!
Hello World!
Hello World!
Hello World!
Hello World!
Hello World!
Hello World!
Hello World!
Hello World!
Requeued 1894 messages
Comparing Message Publishing with BlockingConnection and SelectConnection
对比阻塞连接与选择连接的消息发布
For those doing simple, non-asynchronous programing, pika.adapters.blocking_connection.BlockingConnection() proves to be the easiest way to get up and running with Pika to publish messages.
In the following example, a connection is made to RabbitMQ listening to port 5672 on localhostusing the username guest and password guest and virtual host /. Once connected, a channel is opened and a message is published to the test_exchange exchange using the test_routing_keyrouting key. The BasicProperties value passed in sets the message to delivery mode 1 (non-persisted) with a content-type of text/plain. Once the message is published, the connection is closed:
如果要完成简单、非异步的编程，BlockingConnection()被证明是pika中最便于启动与发布消息的方法。在下面的例子中，将会创建一个使用guest账号密码、虚拟机地址为/、监听端口为5672的本地RabbitMQ。一旦连接完成，将会打开一个管道并且一条信息会以使用test_routing_key作为路由键并发布给test_exchange。而这条信息中传递的BasicProperties会被设置为传送模式1——非持续（delivery mode 1 non-persisted）、内容类型为text/plain。一旦消息被发布，连接就会被关闭
import pika
parameters = pika.URLParameters('amqp://guest:guest@localhost:5672/%2F')
connection = pika.BlockingConnection(parameters)
channel = connection.channel()
channel.basic_publish('test_exchange',
'test_routing_key',
'message body value',
pika.BasicProperties(content_type='text/plain',
delivery_mode=1))
connection.close()
In contrast, using pika.adapters.select_connection.SelectConnection() and the other asynchronous adapters is more complicated and less pythonic, but when used with other asynchronous services can have tremendous performance improvements. In the following code example, all of the same parameters and values are used as were used in the previous example:
相比而言，使用SelectConnection()这种方法或其他异步适配器就要复杂得多而且代码风格也不会那么pythonic（简介明了），但是使用异步的方式可以获得巨大的性能提升。在下面的实例代码，使用的参数和值和上面的例子都是一致的。
import pika
# 第三步
def on_open(connection):
connection.channel(on_open_callback=on_channel_open)
# 第四步
def on_channel_open(channel):
channel.basic_publish('test_exchange',
'test_routing_key',
'message body value',
pika.BasicProperties(content_type='text/plain',
delivery_mode=1))
connection.close()
# 第一步，连接至rabbitmq
parameters = pika.URLParameters('amqp://guest:guest@localhost:5672/%2F')
connection = pika.SelectConnection(parameters=parameters,
on_open_callback=on_open)
try:
# 第二步，阻塞IO循环
connection.ioloop.start()
# Catch a Keyboard Interrupt to make sure that the connection is closed cleanly
except KeyboardInterrupt:
# 优雅地关闭连接
connection.close()
# Start the IOLoop again so Pika can communicate, it will stop on its own when the connection is closed
# 再次打开IO循环让Pika能与服务器进行交互，当连接关闭时候这个循环就会关闭
connection.ioloop.start()
Using Delivery Confirmations with the BlockingConnection
在阻塞连接中使用（消息）传达确认
The following code demonstrates how to turn on delivery confirmations with the BlockingConnection and how to check for confirmation from RabbitMQ:
下面的代码将会展示如何打开消息传达确认并如何从rabbitmq中检查确认状况。
import pika
# Open a connection to RabbitMQ on localhost using all default parameters
connection = pika.BlockingConnection()
# Open the channel
channel = connection.channel()
# Declare the queue
channel.queue_declare(queue="test", durable=True, exclusive=False, auto_delete=False)
# Turn on delivery confirmations
channel.confirm_delivery()
# Send a message
if channel.basic_publish(exchange='test',
routing_key='test',
body='Hello World!',
properties=pika.BasicProperties(content_type='text/plain',
delivery_mode=1)):
print('Message publish was confirmed')
else:
print('Message could not be confirmed')
Ensuring message delivery with the mandatory flag
使用强制标识确保消息传递
The following example demonstrates how to check if a message is delivered by setting the mandatory flag and checking the return result when using the BlockingConnection:
下面的实例将展示如何通过BlockingConnection设置强制标识与检查返回信息来确认生产的消息是否送达消费者。
import pika
# Open a connection to RabbitMQ on localhost using all default parameters
connection = pika.BlockingConnection()
# Open the channel
channel = connection.channel()
# Declare the queue
channel.queue_declare(queue="test", durable=True, exclusive=False, auto_delete=False)
# Enabled delivery confirmations
channel.confirm_delivery()
# Send a message
if channel.basic_publish(exchange='test',
routing_key='test',
body='Hello World!',
properties=pika.BasicProperties(content_type='text/plain',
delivery_mode=1),
mandatory=True):
print('Message was published')
else:
print('Message was returned')
Asynchronous consumer example
异步消费者实例
The following example implements a consumer that will respond to RPC commands sent from RabbitMQ. For example, it will reconnect if RabbitMQ closes the connection and will shutdown if RabbitMQ cancels the consumer or closes the channel. While it may look intimidating, each method is very short and represents a individual actions that a consumer can do.
下面的实例将展示可以回复RabbitMQ发送的RPC命令的消费者应用。例如，当rabbitMQ关闭连接消费者将会尝试重新连接，当rabbitMQ取消了消费者或者关闭了信息通道则代码则会关闭与rabbitMQ的连接。涉及的每个方法都非常简单并能执行一个独立的消费者动作。
# -*- coding: utf-8 -*-
import logging
import pika
LOG_FORMAT = ('%(levelname) -10s %(asctime)s %(name) -30s %(funcName) '
'-35s %(lineno) -5d: %(message)s')
LOGGER = logging.getLogger(__name__)
class ExampleConsumer(object):
# 这个消费者示例将会处理一些消费过程中可能和rabbitMQ发生的意外交互情况，包括管道与连接中断
# 如果RabbitMQ关闭了连接，消费者会重新创建。你应该观察输出，连接被关闭的可能是有限的，一般都与权限或socket超时有关。
If the channel is closed, it will indicate a problem with one of the
commands that were issued and that should surface in the output as well.
"""
EXCHANGE = 'message'
EXCHANGE_TYPE = 'topic'
QUEUE = 'text'
ROUTING_KEY = 'example.text'
def __init__(self, amqp_url):
# 通过传递一个用于连接RabbitMQ的AMQP URL来创建一个消费者类新的实例
self._connection = None
self._channel = None
self._closing = False
self._consumer_tag = None
self._url = amqp_url
def connect(self):
# 这个方法将会返回创建的连接，一旦连接创建完成，on_connection_open的方法就会被pika调用。返回内容为pika.SelectConnection
LOGGER.info('Connecting to %s', self._url)
return pika.SelectConnection(pika.URLParameters(self._url),
self.on_connection_open)
def on_connection_open(self, unused_connection):
# 当pika对RabbitMQ的连接创建完成后，该方法将会被调用。它可以传递创建的连接handle，但在这个例子中，我们将其标记为未使用
# 返回的内容未 未连接的 pika.SelectConnection
LOGGER.info('Connection opened')
self.add_on_connection_close_callback()
self.open_channel()
def add_on_connection_close_callback(self):
# 这个方法将会添加一个关闭回调函数用于当与RabbitMQ与消息发布者的连接意外关闭时让pika进行调用
LOGGER.info('Adding connection close callback')
self._connection.add_on_close_callback(self.on_connection_closed)
def on_connection_closed(self, connection, reply_code, reply_text):
# 这个方法将会pika在与RabbitMQ的连接意外关闭时调用，既然是意外地，我们将会在与RabbitMQ断开连接后重新连接。
#:param pika.connection.Connection connection: The closed connection obj
#:param int reply_code: The server provided reply_code if given
#:param str reply_text: The server provided reply_text if given
self._channel = None
if self._closing:
self._connection.ioloop.stop()
else:
LOGGER.warning('Connection closed, reopening in 5 seconds: (%s) %s',
reply_code, reply_text)
self._connection.add_timeout(5, self.reconnect)
def reconnect(self):
# 当连接关闭时将会被IO循环计时器所调用
# 这是一个老的连接IO循环实例，关闭循环的方法是
self._connection.ioloop.stop()
if not self._closing:
# Create a new connection
self._connection = self.connect()
# There is now a new connection, needs a new ioloop to run
self._connection.ioloop.start()
def open_channel(self):
"""Open a new channel with RabbitMQ by issuing the Channel.Open RPC
command. When RabbitMQ responds that the channel is open, the
on_channel_open callback will be invoked by pika.
"""
LOGGER.info('Creating a new channel')
self._connection.channel(on_open_callback=self.on_channel_open)
def on_channel_open(self, channel):
"""This method is invoked by pika when the channel has been opened.
The channel object is passed in so we can make use of it.
Since the channel is now open, we'll declare the exchange to use.
:param pika.channel.Channel channel: The channel object
"""
LOGGER.info('Channel opened')
self._channel = channel
self.add_on_channel_close_callback()
self.setup_exchange(self.EXCHANGE)
def add_on_channel_close_callback(self):
"""This method tells pika to call the on_channel_closed method if
RabbitMQ unexpectedly closes the channel.
"""
LOGGER.info('Adding channel close callback')
self._channel.add_on_close_callback(self.on_channel_closed)
def on_channel_closed(self, channel, reply_code, reply_text):
"""Invoked by pika when RabbitMQ unexpectedly closes the channel.
Channels are usually closed if you attempt to do something that
violates the protocol, such as re-declare an exchange or queue with
different parameters. In this case, we'll close the connection
to shutdown the object.
:param pika.channel.Channel: The closed channel
:param int reply_code: The numeric reason the channel was closed
:param str reply_text: The text reason the channel was closed
"""
LOGGER.warning('Channel %i was closed: (%s) %s',
channel, reply_code, reply_text)
self._connection.close()
def setup_exchange(self, exchange_name):
"""Setup the exchange on RabbitMQ by invoking the Exchange.Declare RPC
command. When it is complete, the on_exchange_declareok method will
be invoked by pika.
:param str|unicode exchange_name: The name of the exchange to declare
"""
LOGGER.info('Declaring exchange %s', exchange_name)
self._channel.exchange_declare(self.on_exchange_declareok,
exchange_name,
self.EXCHANGE_TYPE)
def on_exchange_declareok(self, unused_frame):
"""Invoked by pika when RabbitMQ has finished the Exchange.Declare RPC
command.
:param pika.Frame.Method unused_frame: Exchange.DeclareOk response frame
"""
LOGGER.info('Exchange declared')
self.setup_queue(self.QUEUE)
def setup_queue(self, queue_name):
"""Setup the queue on RabbitMQ by invoking the Queue.Declare RPC
command. When it is complete, the on_queue_declareok method will
be invoked by pika.
:param str|unicode queue_name: The name of the queue to declare.
"""
LOGGER.info('Declaring queue %s', queue_name)
self._channel.queue_declare(queue_name, self.on_queue_declareok)
def on_queue_declareok(self, method_frame):
"""Method invoked by pika when the Queue.Declare RPC call made in
setup_queue has completed. In this method we will bind the queue
and exchange together with the routing key by issuing the Queue.Bind
RPC command. When this command is complete, the on_bindok method will
be invoked by pika.
:param pika.frame.Method method_frame: The Queue.DeclareOk frame
"""
LOGGER.info('Binding %s to %s with %s',
self.EXCHANGE, self.QUEUE, self.ROUTING_KEY)
self._channel.queue_bind(self.on_bindok, self.QUEUE,
self.EXCHANGE, self.ROUTING_KEY)
def on_bindok(self, unused_frame):
"""Invoked by pika when the Queue.Bind method has completed. At this
point we will start consuming messages by calling start_consuming
which will invoke the needed RPC commands to start the process.
:param pika.frame.Method unused_frame: The Queue.BindOk response frame
"""
LOGGER.info('Queue bound')
self.start_consuming()
def start_consuming(self):
"""This method sets up the consumer by first calling
add_on_cancel_callback so that the object is notified if RabbitMQ
cancels the consumer. It then issues the Basic.Consume RPC command
which returns the consumer tag that is used to uniquely identify the
consumer with RabbitMQ. We keep the value to use it when we want to
cancel consuming. The on_message method is passed in as a callback pika
will invoke when a message is fully received.
"""
LOGGER.info('Issuing consumer related RPC commands')
self.add_on_cancel_callback()
self._consumer_tag = self._channel.basic_consume(self.QUEUE,
self.on_message)
def add_on_cancel_callback(self):
"""Add a callback that will be invoked if RabbitMQ cancels the consumer
for some reason. If RabbitMQ does cancel the consumer,
on_consumer_cancelled will be invoked by pika.
"""
LOGGER.info('Adding consumer cancellation callback')
self._channel.add_on_cancel_callback(self.on_consumer_cancelled)
def on_consumer_cancelled(self, method_frame):
"""Invoked by pika when RabbitMQ sends a Basic.Cancel for a consumer
receiving messages.
:param pika.frame.Method method_frame: The Basic.Cancel frame
"""
LOGGER.info('Consumer was cancelled remotely, shutting down: %r',
method_frame)
if self._channel:
self._channel.close()
def on_message(self, unused_channel, basic_deliver, properties, body):
"""Invoked by pika when a message is delivered from RabbitMQ. The
channel is passed for your convenience. The basic_deliver object that
is passed in carries the exchange, routing key, delivery tag and
a redelivered flag for the message. The properties passed in is an
instance of BasicProperties with the message properties and the body
is the message that was sent.
:param pika.channel.Channel unused_channel: The channel object
:param pika.Spec.Basic.Deliver: basic_deliver method
:param pika.Spec.BasicProperties: properties
:param str|unicode body: The message body
"""
LOGGER.info('Received message # %s from %s: %s',
basic_deliver.delivery_tag, properties.app_id, body)
self.acknowledge_message(basic_deliver.delivery_tag)
def acknowledge_message(self, delivery_tag):
"""Acknowledge the message delivery from RabbitMQ by sending a
Basic.Ack RPC method for the delivery tag.
:param int delivery_tag: The delivery tag from the Basic.Deliver frame
"""
LOGGER.info('Acknowledging message %s', delivery_tag)
self._channel.basic_ack(delivery_tag)
def stop_consuming(self):
"""Tell RabbitMQ that you would like to stop consuming by sending the
Basic.Cancel RPC command.
"""
if self._channel:
LOGGER.info('Sending a Basic.Cancel RPC command to RabbitMQ')
self._channel.basic_cancel(self.on_cancelok, self._consumer_tag)
def on_cancelok(self, unused_frame):
"""This method is invoked by pika when RabbitMQ acknowledges the
cancellation of a consumer. At this point we will close the channel.
This will invoke the on_channel_closed method once the channel has been
closed, which will in-turn close the connection.
:param pika.frame.Method unused_frame: The Basic.CancelOk frame
"""
LOGGER.info('RabbitMQ acknowledged the cancellation of the consumer')
self.close_channel()
def close_channel(self):
"""Call to close the channel with RabbitMQ cleanly by issuing the
Channel.Close RPC command.
"""
LOGGER.info('Closing the channel')
self._channel.close()
def run(self):
"""Run the example consumer by connecting to RabbitMQ and then
starting the IOLoop to block and allow the SelectConnection to operate.
"""
self._connection = self.connect()
self._connection.ioloop.start()
def stop(self):
"""Cleanly shutdown the connection to RabbitMQ by stopping the consumer
with RabbitMQ. When RabbitMQ confirms the cancellation, on_cancelok
will be invoked by pika, which will then closing the channel and
connection. The IOLoop is started again because this method is invoked
when CTRL-C is pressed raising a KeyboardInterrupt exception. This
exception stops the IOLoop which needs to be running for pika to
communicate with RabbitMQ. All of the commands issued prior to starting
the IOLoop will be buffered but not processed.
"""
LOGGER.info('Stopping')
self._closing = True
self.stop_consuming()
self._connection.ioloop.start()
LOGGER.info('Stopped')
def close_connection(self):
"""This method closes the connection to RabbitMQ."""
LOGGER.info('Closing connection')
self._connection.close()
def main():
logging.basicConfig(level=logging.INFO, format=LOG_FORMAT)
example = ExampleConsumer('amqp://guest:guest@localhost:5672/%2F')
try:
example.run()
except KeyboardInterrupt:
example.stop()
if __name__ == '__main__':
main()
Asynchronous publisher example
异步生产者实例
The following example implements a publisher that will respond to RPC commands sent from RabbitMQ and uses delivery confirmations. It will reconnect if RabbitMQ closes the connection and will shutdown if RabbitMQ closes the channel. While it may look intimidating, each method is very short and represents a individual actions that a publisher can do.
下面这个消息生产者实例可以响应RabbitMQ发送的RPC命令，并使用了消息传达确认。同样的，当RabbitMQ关闭连接实例将重连，RabbitMQ关闭管道实例将关闭。这个实例看起来可能有点复杂，但实际上每个方法都非常简介而且代表一个生产者可以执行的动作。
import logging
import pika
import json
LOG_FORMAT = ('%(levelname) -10s %(asctime)s %(name) -30s %(funcName) '
'-35s %(lineno) -5d: %(message)s')
LOGGER = logging.getLogger(__name__)
class ExamplePublisher(object):
"""This is an example publisher that will handle unexpected interactions
with RabbitMQ such as channel and connection closures.
If RabbitMQ closes the connection, it will reopen it. You should
look at the output, as there are limited reasons why the connection may
be closed, which usually are tied to permission related issues or
socket timeouts.
It uses delivery confirmations and illustrates one way to keep track of
messages that have been sent and if they've been confirmed by RabbitMQ.
"""
EXCHANGE = 'message'
EXCHANGE_TYPE = 'topic'
PUBLISH_INTERVAL = 1
QUEUE = 'text'
ROUTING_KEY = 'example.text'
def __init__(self, amqp_url):
"""Setup the example publisher object, passing in the URL we will use
to connect to RabbitMQ.
:param str amqp_url: The URL for connecting to RabbitMQ
"""
self._connection = None
self._channel = None
self._deliveries = None
self._acked = None
self._nacked = None
self._message_number = None
self._stopping = False
self._url = amqp_url
def connect(self):
"""This method connects to RabbitMQ, returning the connection handle.
When the connection is established, the on_connection_open method
will be invoked by pika.
:rtype: pika.SelectConnection
"""
LOGGER.info('Connecting to %s', self._url)
return pika.SelectConnection(pika.URLParameters(self._url),
on_open_callback=self.on_connection_open,
on_close_callback=self.on_connection_closed)
def on_connection_open(self, unused_connection):
"""This method is called by pika once the connection to RabbitMQ has
been established. It passes the handle to the connection object in
case we need it, but in this case, we'll just mark it unused.
:type unused_connection: pika.SelectConnection
"""
LOGGER.info('Connection opened')
self.open_channel()
def on_connection_closed(self, connection, reply_code, reply_text):
"""This method is invoked by pika when the connection to RabbitMQ is
closed unexpectedly. Since it is unexpected, we will reconnect to
RabbitMQ if it disconnects.
:param pika.connection.Connection connection: The closed connection obj
:param int reply_code: The server provided reply_code if given
:param str reply_text: The server provided reply_text if given
"""
self._channel = None
if self._stopping:
self._connection.ioloop.stop()
else:
LOGGER.warning('Connection closed, reopening in 5 seconds: (%s) %s',
reply_code, reply_text)
self._connection.add_timeout(5, self._connection.ioloop.stop)
def open_channel(self):
"""This method will open a new channel with RabbitMQ by issuing the
Channel.Open RPC command. When RabbitMQ confirms the channel is open
by sending the Channel.OpenOK RPC reply, the on_channel_open method
will be invoked.
"""
LOGGER.info('Creating a new channel')
self._connection.channel(on_open_callback=self.on_channel_open)
def on_channel_open(self, channel):
"""This method is invoked by pika when the channel has been opened.
The channel object is passed in so we can make use of it.
Since the channel is now open, we'll declare the exchange to use.
:param pika.channel.Channel channel: The channel object
"""
LOGGER.info('Channel opened')
self._channel = channel
self.add_on_channel_close_callback()
self.setup_exchange(self.EXCHANGE)
def add_on_channel_close_callback(self):
"""This method tells pika to call the on_channel_closed method if
RabbitMQ unexpectedly closes the channel.
"""
LOGGER.info('Adding channel close callback')
self._channel.add_on_close_callback(self.on_channel_closed)
def on_channel_closed(self, channel, reply_code, reply_text):
"""Invoked by pika when RabbitMQ unexpectedly closes the channel.
Channels are usually closed if you attempt to do something that
violates the protocol, such as re-declare an exchange or queue with
different parameters. In this case, we'll close the connection
to shutdown the object.
:param pika.channel.Channel channel: The closed channel
:param int reply_code: The numeric reason the channel was closed
:param str reply_text: The text reason the channel was closed
"""
LOGGER.warning('Channel was closed: (%s) %s', reply_code, reply_text)
self._channel = None
if not self._stopping:
self._connection.close()
def setup_exchange(self, exchange_name):
"""Setup the exchange on RabbitMQ by invoking the Exchange.Declare RPC
command. When it is complete, the on_exchange_declareok method will
be invoked by pika.
:param str|unicode exchange_name: The name of the exchange to declare
"""
LOGGER.info('Declaring exchange %s', exchange_name)
self._channel.exchange_declare(self.on_exchange_declareok,
exchange_name,
self.EXCHANGE_TYPE)
def on_exchange_declareok(self, unused_frame):
"""Invoked by pika when RabbitMQ has finished the Exchange.Declare RPC
command.
:param pika.Frame.Method unused_frame: Exchange.DeclareOk response frame
"""
LOGGER.info('Exchange declared')
self.setup_queue(self.QUEUE)
def setup_queue(self, queue_name):
"""Setup the queue on RabbitMQ by invoking the Queue.Declare RPC
command. When it is complete, the on_queue_declareok method will
be invoked by pika.
:param str|unicode queue_name: The name of the queue to declare.
"""
LOGGER.info('Declaring queue %s', queue_name)
self._channel.queue_declare(queue_name, self.on_queue_declareok)
def on_queue_declareok(self, method_frame):
"""Method invoked by pika when the Queue.Declare RPC call made in
setup_queue has completed. In this method we will bind the queue
and exchange together with the routing key by issuing the Queue.Bind
RPC command. When this command is complete, the on_bindok method will
be invoked by pika.
:param pika.frame.Method method_frame: The Queue.DeclareOk frame
"""
LOGGER.info('Binding %s to %s with %s',
self.EXCHANGE, self.QUEUE, self.ROUTING_KEY)
self._channel.queue_bind(self.on_bindok, self.QUEUE,
self.EXCHANGE, self.ROUTING_KEY)
def on_bindok(self, unused_frame):
"""This method is invoked by pika when it receives the Queue.BindOk
response from RabbitMQ. Since we know we're now setup and bound, it's
time to start publishing."""
LOGGER.info('Queue bound')
self.start_publishing()
def start_publishing(self):
"""This method will enable delivery confirmations and schedule the
first message to be sent to RabbitMQ
"""
LOGGER.info('Issuing consumer related RPC commands')
self.enable_delivery_confirmations()
self.schedule_next_message()
def enable_delivery_confirmations(self):
"""Send the Confirm.Select RPC method to RabbitMQ to enable delivery
confirmations on the channel. The only way to turn this off is to close
the channel and create a new one.
When the message is confirmed from RabbitMQ, the
on_delivery_confirmation method will be invoked passing in a Basic.Ack
or Basic.Nack method from RabbitMQ that will indicate which messages it
is confirming or rejecting.
"""
LOGGER.info('Issuing Confirm.Select RPC command')
self._channel.confirm_delivery(self.on_delivery_confirmation)
def on_delivery_confirmation(self, method_frame):
"""Invoked by pika when RabbitMQ responds to a Basic.Publish RPC
command, passing in either a Basic.Ack or Basic.Nack frame with
the delivery tag of the message that was published. The delivery tag
is an integer counter indicating the message number that was sent
on the channel via Basic.Publish. Here we're just doing house keeping
to keep track of stats and remove message numbers that we expect
a delivery confirmation of from the list used to keep track of messages
that are pending confirmation.
:param pika.frame.Method method_frame: Basic.Ack or Basic.Nack frame
"""
confirmation_type = method_frame.method.NAME.split('.')[1].lower()
LOGGER.info('Received %s for delivery tag: %i',
confirmation_type,
method_frame.method.delivery_tag)
if confirmation_type == 'ack':
self._acked += 1
elif confirmation_type == 'nack':
self._nacked += 1
self._deliveries.remove(method_frame.method.delivery_tag)
LOGGER.info('Published %i messages, %i have yet to be confirmed, '
'%i were acked and %i were nacked',
self._message_number, len(self._deliveries),
self._acked, self._nacked)
def schedule_next_message(self):
"""If we are not closing our connection to RabbitMQ, schedule another
message to be delivered in PUBLISH_INTERVAL seconds.
"""
LOGGER.info('Scheduling next message for %0.1f seconds',
self.PUBLISH_INTERVAL)
self._connection.add_timeout(self.PUBLISH_INTERVAL,
self.publish_message)
def publish_message(self):
"""If the class is not stopping, publish a message to RabbitMQ,
appending a list of deliveries with the message number that was sent.
This list will be used to check for delivery confirmations in the
on_delivery_confirmations method.
Once the message has been sent, schedule another message to be sent.
The main reason I put scheduling in was just so you can get a good idea
of how the process is flowing by slowing down and speeding up the
delivery intervals by changing the PUBLISH_INTERVAL constant in the
class.
"""
if self._channel is None or not self._channel.is_open:
return
hdrs = {u'مفتاح': u' قيمة',
u'键': u'值',
u'キー': u'値'}
properties = pika.BasicProperties(app_id='example-publisher',
content_type='application/json',
headers=hdrs)
message = u'مفتاح قيمة 键 值 キー 値'
self._channel.basic_publish(self.EXCHANGE, self.ROUTING_KEY,
json.dumps(message, ensure_ascii=False),
properties)
self._message_number += 1
self._deliveries.append(self._message_number)
LOGGER.info('Published message # %i', self._message_number)
self.schedule_next_message()
def run(self):
"""Run the example code by connecting and then starting the IOLoop.
"""
while not self._stopping:
self._connection = None
self._deliveries = []
self._acked = 0
self._nacked = 0
self._message_number = 0
try:
self._connection = self.connect()
self._connection.ioloop.start()
except KeyboardInterrupt:
self.stop()
if (self._connection is not None and
not self._connection.is_closed):
# Finish closing
self._connection.ioloop.start()
LOGGER.info('Stopped')
def stop(self):
"""Stop the example by closing the channel and connection. We
set a flag here so that we stop scheduling new messages to be
published. The IOLoop is started because this method is
invoked by the Try/Catch below when KeyboardInterrupt is caught.
Starting the IOLoop again will allow the publisher to cleanly
disconnect from RabbitMQ.
"""
LOGGER.info('Stopping')
self._stopping = True
self.close_channel()
self.close_connection()
def close_channel(self):
"""Invoke this command to close the channel with RabbitMQ by sending
the Channel.Close RPC command.
"""
if self._channel is not None:
LOGGER.info('Closing the channel')
self._channel.close()
def close_connection(self):
"""This method closes the connection to RabbitMQ."""
if self._connection is not None:
LOGGER.info('Closing connection')
self._connection.close()
def main():
logging.basicConfig(level=logging.DEBUG, format=LOG_FORMAT)
# Connect to localhost:5672 as guest with the password guest and virtual host "/" (%2F)
example = ExamplePublisher('amqp://guest:guest@localhost:5672/%2F?connection_attempts=3&heartbeat_interval=3600')
example.run()
if __name__ == '__main__':
main()
Twisted Consumer Example
混合消费者实例
Example of writing a consumer using the Twisted connection adapter
使用Twisted connection adapter的消费者实例。
import pika
from pika import exceptions
from pika.adapters import twisted_connection
from twisted.internet import defer, reactor, protocol,task
@defer.inlineCallbacks
def run(connection):
channel = yield connection.channel()
exchange = yield channel.exchange_declare(exchange='topic_link', exchange_type='topic')
queue = yield channel.queue_declare(queue='hello', auto_delete=False, exclusive=False)
yield channel.queue_bind(exchange='topic_link',queue='hello',routing_key='hello.world')
yield channel.basic_qos(prefetch_count=1)
queue_object, consumer_tag = yield channel.basic_consume('hello', auto_ack=False)
l = task.LoopingCall(read, queue_object)
l.start(0.01)
@defer.inlineCallbacks
def read(queue_object):
ch,method,properties,body = yield queue_object.get()
if body:
print(body)
yield ch.basic_ack(delivery_tag=method.delivery_tag)
parameters = pika.ConnectionParameters()
cc = protocol.ClientCreator(reactor, twisted_connection.TwistedProtocolConnection, parameters)
d = cc.connectTCP('hostname', 5672)
d.addCallback(lambda protocol: protocol.ready)
d.addCallback(run)
reactor.run()
Tornado Consumer
在Tornado框架中实现消费者
The following example implements a consumer using the Tornado adapter for the Tornado framework that will respond to RPC commands sent from RabbitMQ. For example, it will reconnect if RabbitMQ closes the connection and will shutdown if RabbitMQ cancels the consumer or closes the channel. While it may look intimidating, each method is very short and represents a individual actions that a consumer can do.
from pika import adapters
import pika
import logging
LOG_FORMAT = ('%(levelname) -10s %(asctime)s %(name) -30s %(funcName) '
'-35s %(lineno) -5d: %(message)s')
LOGGER = logging.getLogger(__name__)
class ExampleConsumer(object):
"""This is an example consumer that will handle unexpected interactions
with RabbitMQ such as channel and connection closures.
If RabbitMQ closes the connection, it will reopen it. You should
look at the output, as there are limited reasons why the connection may
be closed, which usually are tied to permission related issues or
socket timeouts.
If the channel is closed, it will indicate a problem with one of the
commands that were issued and that should surface in the output as well.
"""
EXCHANGE = 'message'
EXCHANGE_TYPE = 'topic'
QUEUE = 'text'
ROUTING_KEY = 'example.text'
def __init__(self, amqp_url):
"""Create a new instance of the consumer class, passing in the AMQP
URL used to connect to RabbitMQ.
:param str amqp_url: The AMQP url to connect with
"""
self._connection = None
self._channel = None
self._closing = False
self._consumer_tag = None
self._url = amqp_url
def connect(self):
"""This method connects to RabbitMQ, returning the connection handle.
When the connection is established, the on_connection_open method
will be invoked by pika.
:rtype: pika.SelectConnection
"""
LOGGER.info('Connecting to %s', self._url)
return adapters.TornadoConnection(pika.URLParameters(self._url),
self.on_connection_open)
def close_connection(self):
"""This method closes the connection to RabbitMQ."""
LOGGER.info('Closing connection')
self._connection.close()
def add_on_connection_close_callback(self):
"""This method adds an on close callback that will be invoked by pika
when RabbitMQ closes the connection to the publisher unexpectedly.
"""
LOGGER.info('Adding connection close callback')
self._connection.add_on_close_callback(self.on_connection_closed)
def on_connection_closed(self, connection, reply_code, reply_text):
"""This method is invoked by pika when the connection to RabbitMQ is
closed unexpectedly. Since it is unexpected, we will reconnect to
RabbitMQ if it disconnects.
:param pika.connection.Connection connection: The closed connection obj
:param int reply_code: The server provided reply_code if given
:param str reply_text: The server provided reply_text if given
"""
self._channel = None
if self._closing:
self._connection.ioloop.stop()
else:
LOGGER.warning('Connection closed, reopening in 5 seconds: (%s) %s',
reply_code, reply_text)
self._connection.add_timeout(5, self.reconnect)
def on_connection_open(self, unused_connection):
"""This method is called by pika once the connection to RabbitMQ has
been established. It passes the handle to the connection object in
case we need it, but in this case, we'll just mark it unused.
:type unused_connection: pika.SelectConnection
"""
LOGGER.info('Connection opened')
self.add_on_connection_close_callback()
self.open_channel()
def reconnect(self):
"""Will be invoked by the IOLoop timer if the connection is
closed. See the on_connection_closed method.
"""
if not self._closing:
# Create a new connection
self._connection = self.connect()
def add_on_channel_close_callback(self):
"""This method tells pika to call the on_channel_closed method if
RabbitMQ unexpectedly closes the channel.
"""
LOGGER.info('Adding channel close callback')
self._channel.add_on_close_callback(self.on_channel_closed)
def on_channel_closed(self, channel, reply_code, reply_text):
"""Invoked by pika when RabbitMQ unexpectedly closes the channel.
Channels are usually closed if you attempt to do something that
violates the protocol, such as re-declare an exchange or queue with
different parameters. In this case, we'll close the connection
to shutdown the object.
:param pika.channel.Channel: The closed channel
:param int reply_code: The numeric reason the channel was closed
:param str reply_text: The text reason the channel was closed
"""
LOGGER.warning('Channel %i was closed: (%s) %s',
channel, reply_code, reply_text)
self._connection.close()
def on_channel_open(self, channel):
"""This method is invoked by pika when the channel has been opened.
The channel object is passed in so we can make use of it.
Since the channel is now open, we'll declare the exchange to use.
:param pika.channel.Channel channel: The channel object
"""
LOGGER.info('Channel opened')
self._channel = channel
self.add_on_channel_close_callback()
self.setup_exchange(self.EXCHANGE)
def setup_exchange(self, exchange_name):
"""Setup the exchange on RabbitMQ by invoking the Exchange.Declare RPC
command. When it is complete, the on_exchange_declareok method will
be invoked by pika.
:param str|unicode exchange_name: The name of the exchange to declare
"""
LOGGER.info('Declaring exchange %s', exchange_name)
self._channel.exchange_declare(self.on_exchange_declareok,
exchange_name,
self.EXCHANGE_TYPE)
def on_exchange_declareok(self, unused_frame):
"""Invoked by pika when RabbitMQ has finished the Exchange.Declare RPC
command.
:param pika.Frame.Method unused_frame: Exchange.DeclareOk response frame
"""
LOGGER.info('Exchange declared')
self.setup_queue(self.QUEUE)
def setup_queue(self, queue_name):
"""Setup the queue on RabbitMQ by invoking the Queue.Declare RPC
command. When it is complete, the on_queue_declareok method will
be invoked by pika.
:param str|unicode queue_name: The name of the queue to declare.
"""
LOGGER.info('Declaring queue %s', queue_name)
self._channel.queue_declare(self.on_queue_declareok,
queue_name)
def on_queue_declareok(self, method_frame):
"""Method invoked by pika when the Queue.Declare RPC call made in
setup_queue has completed. In this method we will bind the queue
and exchange together with the routing key by issuing the Queue.Bind
RPC command. When this command is complete, the on_bindok method will
be invoked by pika.
:param pika.frame.Method method_frame: The Queue.DeclareOk frame
"""
LOGGER.info('Binding %s to %s with %s',
self.EXCHANGE, self.QUEUE, self.ROUTING_KEY)
self._channel.queue_bind(self.on_bindok, self.QUEUE,
self.EXCHANGE, self.ROUTING_KEY)
def add_on_cancel_callback(self):
"""Add a callback that will be invoked if RabbitMQ cancels the consumer
for some reason. If RabbitMQ does cancel the consumer,
on_consumer_cancelled will be invoked by pika.
"""
LOGGER.info('Adding consumer cancellation callback')
self._channel.add_on_cancel_callback(self.on_consumer_cancelled)
def on_consumer_cancelled(self, method_frame):
"""Invoked by pika when RabbitMQ sends a Basic.Cancel for a consumer
receiving messages.
:param pika.frame.Method method_frame: The Basic.Cancel frame
"""
LOGGER.info('Consumer was cancelled remotely, shutting down: %r',
method_frame)
if self._channel:
self._channel.close()
def acknowledge_message(self, delivery_tag):
"""Acknowledge the message delivery from RabbitMQ by sending a
Basic.Ack RPC method for the delivery tag.
:param int delivery_tag: The delivery tag from the Basic.Deliver frame
"""
LOGGER.info('Acknowledging message %s', delivery_tag)
self._channel.basic_ack(delivery_tag)
def on_message(self, unused_channel, basic_deliver, properties, body):
"""Invoked by pika when a message is delivered from RabbitMQ. The
channel is passed for your convenience. The basic_deliver object that
is passed in carries the exchange, routing key, delivery tag and
a redelivered flag for the message. The properties passed in is an
instance of BasicProperties with the message properties and the body
is the message that was sent.
:param pika.channel.Channel unused_channel: The channel object
:param pika.Spec.Basic.Deliver: basic_deliver method
:param pika.Spec.BasicProperties: properties
:param str|unicode body: The message body
"""
LOGGER.info('Received message # %s from %s: %s',
basic_deliver.delivery_tag, properties.app_id, body)
self.acknowledge_message(basic_deliver.delivery_tag)
def on_cancelok(self, unused_frame):
"""This method is invoked by pika when RabbitMQ acknowledges the
cancellation of a consumer. At this point we will close the channel.
This will invoke the on_channel_closed method once the channel has been
closed, which will in-turn close the connection.
:param pika.frame.Method unused_frame: The Basic.CancelOk frame
"""
LOGGER.info('RabbitMQ acknowledged the cancellation of the consumer')
self.close_channel()
def stop_consuming(self):
"""Tell RabbitMQ that you would like to stop consuming by sending the
Basic.Cancel RPC command.
"""
if self._channel:
LOGGER.info('Sending a Basic.Cancel RPC command to RabbitMQ')
self._channel.basic_cancel(self.on_cancelok, self._consumer_tag)
def start_consuming(self):
"""This method sets up the consumer by first calling
add_on_cancel_callback so that the object is notified if RabbitMQ
cancels the consumer. It then issues the Basic.Consume RPC command
which returns the consumer tag that is used to uniquely identify the
consumer with RabbitMQ. We keep the value to use it when we want to
cancel consuming. The on_message method is passed in as a callback pika
will invoke when a message is fully received.
"""
LOGGER.info('Issuing consumer related RPC commands')
self.add_on_cancel_callback()
self._consumer_tag = self._channel.basic_consume(self.on_message,
self.QUEUE)
def on_bindok(self, unused_frame):
"""Invoked by pika when the Queue.Bind method has completed. At this
point we will start consuming messages by calling start_consuming
which will invoke the needed RPC commands to start the process.
:param pika.frame.Method unused_frame: The Queue.BindOk response frame
"""
LOGGER.info('Queue bound')
self.start_consuming()
def close_channel(self):
"""Call to close the channel with RabbitMQ cleanly by issuing the
Channel.Close RPC command.
"""
LOGGER.info('Closing the channel')
self._channel.close()
def open_channel(self):
"""Open a new channel with RabbitMQ by issuing the Channel.Open RPC
command. When RabbitMQ responds that the channel is open, the
on_channel_open callback will be invoked by pika.
"""
LOGGER.info('Creating a new channel')
self._connection.channel(on_open_callback=self.on_channel_open)
def run(self):
"""Run the example consumer by connecting to RabbitMQ and then
starting the IOLoop to block and allow the SelectConnection to operate.
"""
self._connection = self.connect()
self._connection.ioloop.start()
def stop(self):
"""Cleanly shutdown the connection to RabbitMQ by stopping the consumer
with RabbitMQ. When RabbitMQ confirms the cancellation, on_cancelok
will be invoked by pika, which will then closing the channel and
connection. The IOLoop is started again because this method is invoked
when CTRL-C is pressed raising a KeyboardInterrupt exception. This
exception stops the IOLoop which needs to be running for pika to
communicate with RabbitMQ. All of the commands issued prior to starting
the IOLoop will be buffered but not processed.
"""
LOGGER.info('Stopping')
self._closing = True
self.stop_consuming()
self._connection.ioloop.start()
LOGGER.info('Stopped')
def main():
logging.basicConfig(level=logging.INFO, format=LOG_FORMAT)
example = ExampleConsumer('amqp://guest:guest@localhost:5672/%2F')
try:
example.run()
except KeyboardInterrupt:
example.stop()
if __name__ == '__main__':
main()
TLS parameters example
TLS参数实例
This examples demonstrates a TLS session with RabbitMQ using mutual authentication.
It was tested against RabbitMQ 3.6.10, using Python 3.6.1 and pre-release Pika 0.11.0
Note the use of ssl_version=ssl.PROTOCOL_TLSv1. The recent verions of RabbitMQ disable older versions of SSL due to security vulnerabilities.
See https://www.rabbitmq.com/ssl.html for certificate creation and rabbitmq SSL configuration instructions.
tls_example.py
import ssl
import pika
import logging
logging.basicConfig(level=logging.INFO)
context = ssl.SSLContext(ssl.PROTOCOL_TLSv1)
context.verify_mode = ssl.CERT_REQUIRED
context.load_verify_locations('/Users/me/tls-gen/basic/testca/cacert.pem')
context.load_cert_chain('/Users/me/tls-gen/basic/client/cert.pem',
'/Users/me/tls-gen/basic/client/key.pem')
cp = pika.ConnectionParameters(ssl_options=pika.SSLOptions(context))
conn = pika.BlockingConnection(cp)
ch = conn.channel()
print(ch.queue_declare("sslq"))
ch.publish("", "sslq", "abc")
print(ch.basic_get("sslq"))
rabbitmq.config
%% Both the client and rabbitmq server were running on the same machine, a MacBookPro laptop.
%%
%% rabbitmq.config was created in its default location for OS X: /usr/local/etc/rabbitmq/rabbitmq.config.
%%
%% The contents of the example rabbitmq.config are for demonstration purposes only. See https://www.rabbitmq.com/ssl.html for instructions about creating the test certificates and the contents of rabbitmq.config.
[
{rabbit,
[
{ssl_listeners, [{"127.0.0.1", 5671}]},
%% Configuring SSL.
%% See http://www.rabbitmq.com/ssl.html for full documentation.
%%
{ssl_options, [{cacertfile, "/Users/me/tls-gen/basic/testca/cacert.pem"},
{certfile, "/Users/me/tls-gen/basic/server/cert.pem"},
{keyfile, "/Users/me/tls-gen/basic/server/key.pem"},
{verify, verify_peer},
{fail_if_no_peer_cert, true}]}
]
}
].