python隊(duì)列通信:rabbitMQ的使用(實(shí)例講解)

更新時(shí)間：2017年12月22日 15:55:19 作者：ywq935

下面小編就為大家分享一篇python隊(duì)列通信:rabbitMQ的使用(實(shí)例講解)，具有很好的參考價(jià)值，希望對(duì)大家有所幫助。一起跟隨小編過(guò)來(lái)看看吧

（一）、前言

為什么引入消息隊(duì)列？

1.程序解耦

2.提升性能

3.降低多業(yè)務(wù)邏輯復(fù)雜度

（二）、python操作rabbit mq

rabbitmq配置安裝基本使用參見上節(jié)文章，不再?gòu)?fù)述。

若想使用python操作rabbitmq，需安裝pika模塊，直接pip安裝：

pip install pika

1.最簡(jiǎn)單的rabbitmq producer端與consumer端對(duì)話：

producer：

#Author :ywq
import pika
auth=pika.PlainCredentials('ywq','qwe') #save auth indo
connection = pika.BlockingConnection(pika.ConnectionParameters(
  '192.168.0.158',5672,'/',auth)) #connect to rabbit
channel = connection.channel() #create channel
channel.queue_declare(queue='hello') #declare queue
#n RabbitMQ a message can never be sent directly to the queue, it always needs to go through an exchange.
channel.basic_publish(exchange='',
   routing_key='hello',
   body='Hello World!') #the body is the msg content
print(" [x] Sent 'Hello World!'")
connection.close()

consumer：

#Author :ywq
import pika
auth=pika.PlainCredentials('ywq','qwe') #auth info
connection = pika.BlockingConnection(pika.ConnectionParameters(
  '192.168.0.158',5672,'/',auth)) #connect to rabbit
channel = connection.channel()  #create channel

channel.queue_declare(queue='hello') #decalre queue
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()

消息傳遞消費(fèi)過(guò)程中，可以在rabbit web管理頁(yè)面實(shí)時(shí)查看隊(duì)列消息信息。

2.持久化的消息隊(duì)列，避免宕機(jī)等意外情況造成消息隊(duì)列丟失。

consumer端無(wú)需改變，在producer端代碼內(nèi)加上兩個(gè)屬性，分別使消息持久化、隊(duì)列持久化，只選其一還是會(huì)出現(xiàn)消息丟失，必須同時(shí)開啟：

delivery_mode=2 #make msg persisdent
durable=True

屬性插入位置見如下代碼（producer端）：

#Author :ywq
import pika,sys
auth_info=pika.PlainCredentials('ywq','qwe')
connection=pika.BlockingConnection(pika.ConnectionParameters(
  '192.168.0.158',5672,'/',auth_info
 ))
channel=connection.channel()
channel.queue_declare(queue='test1',durable=True) #durable=Ture, make queue persistent

msg=''.join(sys.argv[1:]) or 'Hello'
channel.basic_publish(
 exchange='',
 routing_key='test1',
 body=msg,
 properties=pika.BasicProperties(
  delivery_mode=2 #make msg persisdent
 )
)

print('Send done:',msg)
connection.close()

3.公平分發(fā)

在多consumer的情況下，默認(rèn)rabbit是輪詢發(fā)送消息的，但有的consumer消費(fèi)速度快，有的消費(fèi)速度慢，為了資源使用更平衡，引入ack確認(rèn)機(jī)制。consumer消費(fèi)完消息后會(huì)給rabbit發(fā)送ack，一旦未ack的消息數(shù)量超過(guò)指定允許的數(shù)量，則不再往該consumer發(fā)送，改為發(fā)送給其他consumer。

producer端代碼不用改變，需要給consumer端代碼插入兩個(gè)屬性：

channel.basic_qos(prefetch_count= *) #define the max non_ack_count
channel.basic_ack(delivery_tag=deliver.delivery_tag) #send ack to rabbitmq

屬性插入位置見如下代碼（consumer端）：

#Author :ywq
import pika,time
auth_info=pika.PlainCredentials('ywq','qwe')
connection=pika.BlockingConnection(pika.ConnectionParameters(
 '192.168.0.158',5672,'/',auth_info
 )
)
channel=connection.channel()
channel.queue_declare(queue='test2',durable=True)
def callback(chann,deliver,properties,body):
 print('Recv:',body)
 time.sleep(5)
 chann.basic_ack(delivery_tag=deliver.delivery_tag) #send ack to rabbit
channel.basic_qos(prefetch_count=1)
'''
注意，no_ack=False 注意，這里的no_ack類型僅僅是告訴rabbit該消費(fèi)者隊(duì)列是否返回ack，若要返回ack，需要在callback內(nèi)定義
prefetch_count=1,未ack的msg數(shù)量超過(guò)1個(gè)，則此consumer不再接受msg，此配置需寫在channel.basic_consume上方，否則會(huì)造成non_ack情況出現(xiàn)。
'''
channel.basic_consume(
 callback,
 queue='test2'
)

channel.start_consuming()

三、消息發(fā)布/訂閱

上方的幾種模式都是producer端發(fā)送一次，則consumer端接收一次，能不能實(shí)現(xiàn)一個(gè)producer發(fā)送，多個(gè)關(guān)聯(lián)的consumer同時(shí)接收呢？of course，rabbit支持消息發(fā)布訂閱，共支持三種模式，通過(guò)組件exchange轉(zhuǎn)發(fā)器，實(shí)現(xiàn)3種模式：

fanout: 所有bind到此exchange的queue都可以接收消息，類似廣播。

direct: 通過(guò)routingKey和exchange決定的哪個(gè)唯一的queue可以接收消息，推送給綁定了該queue的consumer，類似組播。

topic:所有符合routingKey(此時(shí)可以是一個(gè)表達(dá)式)的routingKey所bind的queue可以接收消息，類似前綴列表匹配路由。

1.fanout

publish端（producer）：

#Author :ywq
import pika,sys,time
auth_info=pika.PlainCredentials('ywq','qwe')
connection=pika.BlockingConnection(pika.ConnectionParameters(
 '192.168.0.158',5672,'/',auth_info
 )
)
channel=connection.channel()
channel.exchange_declare(exchange='hello',
    exchange_type='fanout'
    )
msg=''.join(sys.argv[1:]) or 'Hello world %s' %time.time()
channel.basic_publish(
 exchange='hello',
 routing_key='',
 body=msg,
 properties=pika.BasicProperties(
 delivery_mode=2
 )
)
print('send done')
connection.close()

subscribe端（consumer）：

#Author :ywq
import pika
auth_info=pika.PlainCredentials('ywq','qwe')
connection=pika.BlockingConnection(pika.ConnectionParameters(
 '192.168.0.158',5672,'/',auth_info
 )
)
channel=connection.channel()
channel.exchange_declare(
 exchange='hello',
 exchange_type='fanout'
)
random_num=channel.queue_declare(exclusive=True) #隨機(jī)與rabbit建立一個(gè)queue，comsumer斷開后，該queue立即刪除釋放
queue_name=random_num.method.queue
channel.basic_qos(prefetch_count=1)
channel.queue_bind(
 queue=queue_name,
 exchange='hello'
)
def callback(chann,deliver,properties,body):
 print('Recv:',body)
 chann.basic_ack(delivery_tag=deliver.delivery_tag) #send ack to rabbit

channel.basic_consume(
 callback,
 queue=queue_name,
)
channel.start_consuming()

實(shí)現(xiàn)producer一次發(fā)送，多個(gè)關(guān)聯(lián)consumer接收。

使用exchange模式時(shí)：

1.producer端不再申明queue，直接申明exchange

2.consumer端仍需綁定隊(duì)列并指定exchange來(lái)接收message

3.consumer最好創(chuàng)建隨機(jī)queue，使用完后立即釋放。

隨機(jī)隊(duì)列名在web下可以檢測(cè)到：

2.direct

使用exchange同時(shí)consumer有選擇性的接收消息。隊(duì)列綁定關(guān)鍵字，producer將數(shù)據(jù)根據(jù)關(guān)鍵字發(fā)送到消息exchange，exchange根據(jù) 關(guān)鍵字判定應(yīng)該將數(shù)據(jù)發(fā)送至指定隊(duì)列，consumer相應(yīng)接收。即在fanout基礎(chǔ)上增加了routing key.

producer：

#Author :ywq
import pika,sys
auth_info=pika.PlainCredentials('ywq','qwe')
connection=pika.BlockingConnection(pika.ConnectionParameters(
 '192.168.0.158',5672,'/',auth_info
 )
)
channel=connection.channel()
channel.exchange_declare(exchange='direct_log',
   exchange_type='direct',
   )
while True:
 route_key=input('Input routing key:')
 msg=''.join(sys.argv[1:]) or 'Hello'
 channel.basic_publish(
 exchange='direct_log',
 routing_key=route_key,
 body=msg,
 properties=pika.BasicProperties(
  delivery_mode=2
 )
 )
connection.close()

consumer：

#Author :ywq
import pika,sys
auth_info=pika.PlainCredentials('ywq','qwe')
connection=pika.BlockingConnection(pika.ConnectionParameters(
 '192.168.0.158',5672,'/',auth_info
))
channel=connection.channel()
channel.exchange_declare(
 exchange='direct_log',
 exchange_type='direct'
)
queue_num=channel.queue_declare(exclusive=True)
queue_name=queue_num.method.queue
route_key=input('Input routing key:')

channel.queue_bind(
 queue=queue_name,
 exchange='direct_log',
 routing_key=route_key
)
def callback(chann,deliver,property,body):
 print('Recv:[level:%s],[msg:%s]' %(route_key,body))
 chann.basic_ack(delivery_tag=deliver.delivery_tag)

channel.basic_qos(prefetch_count=1)
channel.basic_consume(
 callback,
 queue=queue_name
)
channel.start_consuming()

同時(shí)開啟多個(gè)consumer，其中兩個(gè)接收notice，兩個(gè)接收warning，運(yùn)行效果如下：

3.topic

相較于direct，topic能實(shí)現(xiàn)模糊匹配式工作方式（在consumer端指定匹配方式），只要routing key包含指定的關(guān)鍵字，則將該msg發(fā)往綁定的queue上。

rabbitmq通配符規(guī)則：

符號(hào)“#”匹配一個(gè)或多個(gè)詞，符號(hào)“”匹配一個(gè)詞。因此“abc.#”能夠匹配到“abc.m.n”，但是“abc.*‘' 只會(huì)匹配到“abc.m”?！?'號(hào)為分割符。使用通配符匹配時(shí)必須使用‘.'號(hào)分割。

producer：

#Author :ywq
import pika,sys
auth_info=pika.PlainCredentials('ywq','qwe')
connection=pika.BlockingConnection(pika.ConnectionParameters(
 '192.168.0.158',5672,'/',auth_info
 )
)
channel=connection.channel()
channel.exchange_declare(exchange='topic_log',
   exchange_type='topic',
   )
while True:
 route_key=input('Input routing key:')
 msg=''.join(sys.argv[1:]) or 'Hello'
 channel.basic_publish(
 exchange='topic_log',
 routing_key=route_key,
 body=msg,
 properties=pika.BasicProperties(
  delivery_mode=2
 )
 )
connection.close()

consumer：

#Author :ywq
import pika,sys
auth_info=pika.PlainCredentials('ywq','qwe')
connection=pika.BlockingConnection(pika.ConnectionParameters(
 '192.168.0.158',5672,'/',auth_info
))
channel=connection.channel()
channel.exchange_declare(
 exchange='topic_log',
 exchange_type='topic'
)
queue_num=channel.queue_declare(exclusive=True)
queue_name=queue_num.method.queue
route_key=input('Input routing key:')

channel.queue_bind(
 queue=queue_name,
 exchange='topic_log',
 routing_key=route_key
)
def callback(chann,deliver,property,body):
 print('Recv:[type:%s],[msg:%s]' %(route_key,body))
 chann.basic_ack(delivery_tag=deliver.delivery_tag)

channel.basic_qos(prefetch_count=1)
channel.basic_consume(
 callback,
 queue=queue_name
)
channel.start_consuming()

運(yùn)行效果：