python与RabbitMQ

Posted 2021-02-07 YC的技术笔记

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RabbitMQ

前言

什么是MQ？

MQ全称为Message Queue, 消息队列（MQ）是一种应用程序对应用程序的通信方法。应用程序通过读写出入队列的消息（针对应用程序的数据）来通信，而无需专用连接来链接它们。消息传递指的是程序之间通过在消息中发送数据进行通信，而不是通过直接调用彼此来通信，直接调用通常是用于诸如远程过程调用的技术。排队指的是应用程序通过队列来通信。队列的使用除去了接收和发送应用程序同时执行的要求。

什么是RabbitMQ？

RabbitMQ是一个在AMQP基础上完整的，可复用的企业消息系统。他遵循Mozilla Public License开源协议

RabbitMQ是一个消息代理：它接受和转发消息。您可以将其视为顺丰快递：当您将要发布的消息快件给到顺丰快递手上，您可以确定顺丰以及快递小哥最终会将邮件发送给您的收件人。在这个类比中，RabbitMQ是一个顺丰快递、快递小哥、丰巢。

RabbitMQ和顺丰之间的主要区别在于它不处理实体货物信件，而是接受，存储和转发二进制数据——消息。

RabbitMQ和一般的消息传递使用了一些术语：

生产（Producing）就是发送（消息）。发送消息的程序就所谓的生产者（producer ）
队列（queue ）是RabbitMQ中的邮箱的名称。虽然消息流经RabbitMQ和您的应用程序，但它们只能存储在队列中。队列只受主机的内存和磁盘限制的约束，它本质上是一个大的消息缓冲区。许多生产者可以发送到一个队列的消息，并且许多消费者可以尝试从一个队列接收数据。这就是我们代表队列的方式：
消费（Consuming ）与接受（receiving）有类似的意义。消费者（consumer ）是一个主要等待接收消息的程序：

请注意，生产者，消费者和代理不必驻留在同一主机上; 实际上在大多数应用中他们没有。应用程序也可以是生产者和消费者。

RabbitMQ安装

安装配置epel源
   $ rpm -ivh http://dl.fedoraproject.org/pub/epel/6/i386/epel-release-6-8.noarch.rpm
 
安装erlang
   $ yum -y install erlang
 
安装RabbitMQ
   $ yum -y install rabbitmq-server

注意：service rabbitmq-server start/stop

安装API

pip install pika
or
easy_install pika
or
源码
 
https://pypi.python.org/pypi/pika

使用API操作RabbitMQ

回顾基于Queue实现生产者消费者模型

#!/usr/bin/env python
# -*- coding:utf-8 -*-
import Queue
import threading


message = Queue.Queue(10)


def producer(i):
    while True:
        message.put(i)


def consumer(i):
    while True:
        msg = message.get()


for i in range(12):
    t = threading.Thread(target=producer, args=(i,))
    t.start()

for i in range(10):
    t = threading.Thread(target=consumer, args=(i,))
    t.start()

对于RabbitMQ来说，生产和消费不再针对内存里的一个Queue对象，而是某台服务器上的RabbitMQ Server实现的消息队列

生产者：

#!/usr/bin/env python
import pika
 
# ######################### 生产者 #########################
 
connection = pika.BlockingConnection(pika.ConnectionParameters(
        host=\'localhost\'))
channel = connection.channel()
 
channel.queue_declare(queue=\'hello\')
 
channel.basic_publish(exchange=\'\',
                      routing_key=\'hello\',
                      body=\'Hello World!\')
print(" [x] Sent \'Hello World!\'")
connection.close()

消费者：

#!/usr/bin/env python
import pika
 
# ########################## 消费者 ##########################
 
connection = pika.BlockingConnection(pika.ConnectionParameters(
        host=\'localhost\'))
channel = connection.channel()
 
channel.queue_declare(queue=\'hello\')
 
def callback(ch, method, properties, body):
    print(" [x] Received %r" % body)
 
channel.basic_consume(callback,
                      queue=\'hello\',
                      no_ack=True)
 
print(\' [*] Waiting for messages. To exit press CTRL+C\')
channel.start_consuming()

1、acknowledgment 消息不丢失

no-ack ＝ False，如果消费者遇到情况(its channel is closed, connection is closed, or TCP connection is lost)挂掉了，那么，RabbitMQ会重新将该任务添加到队列中。

import pika

connection = pika.BlockingConnection(pika.ConnectionParameters(
        host=\'10.211.55.4\'))
channel = connection.channel()

channel.queue_declare(queue=\'hello\')

def callback(ch, method, properties, body):
    print(" [x] Received %r" % body)
    import time
    time.sleep(10)
    print \'ok\'
    ch.basic_ack(delivery_tag = method.delivery_tag)

channel.basic_consume(callback,
                      queue=\'hello\',
                      no_ack=False)

print(\' [*] Waiting for messages. To exit press CTRL+C\')
channel.start_consuming()

2、durable 消息不丢失

生产者：

#!/usr/bin/env python
import pika

connection = pika.BlockingConnection(pika.ConnectionParameters(host=\'10.211.55.4\'))
channel = connection.channel()

# make message persistent
channel.queue_declare(queue=\'hello\', durable=True)

channel.basic_publish(exchange=\'\',
                      routing_key=\'hello\',
                      body=\'Hello World!\',
                      properties=pika.BasicProperties(
                          delivery_mode=2, # make message persistent
                      ))
print(" [x] Sent \'Hello World!\'")
connection.close()

消费者：

#!/usr/bin/env python
# -*- coding:utf-8 -*-
import pika

connection = pika.BlockingConnection(pika.ConnectionParameters(host=\'10.211.55.4\'))
channel = connection.channel()

# make message persistent
channel.queue_declare(queue=\'hello\', durable=True)


def callback(ch, method, properties, body):
    print(" [x] Received %r" % body)
    import time
    time.sleep(10)
    print \'ok\'
    ch.basic_ack(delivery_tag = method.delivery_tag)

channel.basic_consume(callback,
                      queue=\'hello\',
                      no_ack=False)

print(\' [*] Waiting for messages. To exit press CTRL+C\')
channel.start_consuming()

3、消息获取顺序

默认消息队列里的数据是按照顺序被消费者拿走，例如：消费者1 去队列中获取奇数序列的任务，消费者1去队列中获取偶数序列的任务。

channel.basic_qos(prefetch_count=1) 表示谁来谁取，不再按照奇偶数排列

消费者：

#!/usr/bin/env python
# -*- coding:utf-8 -*-
import pika

connection = pika.BlockingConnection(pika.ConnectionParameters(host=\'10.211.55.4\'))
channel = connection.channel()

# make message persistent
channel.queue_declare(queue=\'hello\')


def callback(ch, method, properties, body):
    print(" [x] Received %r" % body)
    import time
    time.sleep(10)
    print \'ok\'
    ch.basic_ack(delivery_tag = method.delivery_tag)

channel.basic_qos(prefetch_count=1)

channel.basic_consume(callback,
                      queue=\'hello\',
                      no_ack=False)

print(\' [*] Waiting for messages. To exit press CTRL+C\')
channel.start_consuming()

4、发布订阅

发布订阅和简单的消息队列区别在于，发布订阅会将消息发送给所有的订阅者，而消息队列中的数据被消费一次便消失。所以，RabbitMQ实现发布和订阅时，会为每一个订阅者创建一个队列，而发布者发布消息时，会将消息放置在所有相关队列中。

exchange type = fanout

#!/usr/bin/env python
import pika
import sys

connection = pika.BlockingConnection(pika.ConnectionParameters(
        host=\'localhost\'))
channel = connection.channel()

channel.exchange_declare(exchange=\'logs\',
                         type=\'fanout\')

message = \' \'.join(sys.argv[1:]) or "info: Hello World!"
channel.basic_publish(exchange=\'logs\',
                      routing_key=\'\',
                      body=message)
print(" [x] Sent %r" % message)
connection.close()

#!/usr/bin/env python
import pika

connection = pika.BlockingConnection(pika.ConnectionParameters(
        host=\'localhost\'))
channel = connection.channel()

channel.exchange_declare(exchange=\'logs\',
                         type=\'fanout\')

result = channel.queue_declare(exclusive=True)
queue_name = result.method.queue

channel.queue_bind(exchange=\'logs\',
                   queue=queue_name)

print(\' [*] Waiting for logs. To exit press CTRL+C\')

def callback(ch, method, properties, body):
    print(" [x] %r" % body)

channel.basic_consume(callback,
                      queue=queue_name,
                      no_ack=True)

channel.start_consuming()

5、关键字发送

exchange type = direct

之前事例，发送消息时明确指定某个队列并向其中发送消息，RabbitMQ还支持根据关键字发送，即：队列绑定关键字，发送者将数据根据关键字发送到消息exchange，exchange根据关键字判定应该将数据发送至指定队列。

#!/usr/bin/env python
import pika
import sys

connection = pika.BlockingConnection(pika.ConnectionParameters(
        host=\'localhost\'))
channel = connection.channel()

channel.exchange_declare(exchange=\'direct_logs\',
                         type=\'direct\')

result = channel.queue_declare(exclusive=True)
queue_name = result.method.queue

severities = sys.argv[1:]
if not severities:
    sys.stderr.write("Usage: %s [info] [warning] [error]\\n" % sys.argv[0])
    sys.exit(1)

for severity in severities:
    channel.queue_bind(exchange=\'direct_logs\',
                       queue=queue_name,
                       routing_key=severity)

print(\' [*] Waiting for logs. To exit press CTRL+C\')

def callback(ch, method, properties, body):
    print(" [x] %r:%r" % (method.routing_key, body))

channel.basic_consume(callback,
                      queue=queue_name,
                      no_ack=True)

channel.start_consuming()

#!/usr/bin/env python
import pika
import sys

connection = pika.BlockingConnection(pika.ConnectionParameters(
        host=\'localhost\'))
channel = connection.channel()

channel.exchange_declare(exchange=\'direct_logs\',
                         type=\'direct\')

severity = sys.argv[1] if len(sys.argv) > 1 else \'info\'
message = \' \'.join(sys.argv[2:]) or \'Hello World!\'
channel.basic_publish(exchange=\'direct_logs\',
                      routing_key=severity,
                      body=message)
print(" [x] Sent %r:%r" % (severity, message))
connection.close()

6、模糊匹配

exchange type = topic

在topic类型下，可以让队列绑定几个模糊的关键字，之后发送者将数据发送到exchange，exchange将传入”路由值“和 ”关键字“进行匹配，匹配成功，则将数据发送到指定队列。

# 表示可以匹配 0 个或多个单词
* 表示只能匹配一个单词

发送者路由值              队列中
old.boy.python          old.*  -- 不匹配
old.boy.python          old.#  -- 匹配

#!/usr/bin/env python
import pika
import sys

connection = pika.BlockingConnection(pika.ConnectionParameters(
        host=\'localhost\'))
channel = connection.channel()

channel.exchange_declare(exchange=\'topic_logs\',
                         type=\'topic\')

result = channel.queue_declare(exclusive=True)
queue_name = result.method.queue

binding_keys = sys.argv[1:]
if not binding_keys:
    sys.stderr.write("Usage: %s [binding_key]...\\n" % sys.argv[0])
    sys.exit(1)

for binding_key in binding_keys:
    channel.queue_bind(exchange=\'topic_logs\',
                       queue=queue_name,
                       routing_key=binding_key)

print(\' [*] Waiting for logs. To exit press CTRL+C\')

def callback(ch, method, properties, body):
    print(" [x] %r:%r" % (method.routing_key, body))

channel.basic_consume(callback,
                      queue=queue_name,
                      no_ack=True)

channel.start_consuming()

#!/usr/bin/env python
import pika
import sys

connection = pika.BlockingConnection(pika.ConnectionParameters(
        host=\'localhost\'))
channel = connection.channel()

channel.exchange_declare(exchange=\'topic_logs\',
                         type=\'topic\')

routing_key = sys.argv[1] if len(sys.argv) > 1 else \'anonymous.info\'
message = \' \'.join(sys.argv[2:]) or \'Hello World!\'
channel.basic_publish(exchange=\'topic_logs\',
                      routing_key=routing_key,
                      body=message)
print(" [x] Sent %r:%r" % (routing_key, message))
connection.close()

注意：

sudo rabbitmqctl add_user wupeiqi 123
# 设置用户为administrator角色
sudo rabbitmqctl set_user_tags wupeiqi administrator
# 设置权限
sudo rabbitmqctl set_permissions -p "/" root ".*" ".*" ".*"

# 然后重启rabbiMQ服务
sudo /etc/init.d/rabbitmq-server restart
 
# 然后可以使用刚才的用户远程连接rabbitmq server了。


------------------------------
credentials = pika.PlainCredentials("wupeiqi","123")

connection = pika.BlockingConnection(pika.ConnectionParameters(\'192.168.14.47\',credentials=credentials))

#!/usr/bin/env python
# -*- coding:utf-8 -*-
import pika
from pika.adapters.blocking_connection import BlockingChannel

credentials = pika.PlainCredentials("root", "123")

conn = pika.BlockingConnection(pika.ConnectionParameters(host=\'10.211.55.20\', credentials=credentials))
# 超时时间
conn.add_timeout(5, lambda: channel.stop_consuming())

channel = conn.channel()

channel.queue_declare(queue=\'hello\')


def callback(ch, method, properties, body):
    print(" [x] Received %r" % body)
    channel.stop_consuming()


channel.basic_consume(callback,
                      queue=\'hello\',
                      no_ack=True)

print(\' [*] Waiting for messages. To exit press CTRL+C\')
channel.start_consuming()

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