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rabbitmq在centos7下安装

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知识预览

  • 一. RabbitMQ队列
  • 二. 事例
  • 三.基于RabbitMQ的RPC
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一. RabbitMQ队列

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#消息中间件 -消息队列
- 异步 提交的任务不需要实时得到结果或回应
python线程Q 实现了在同一个进程间不同线程间的交互
python线程Q 也可以实现进程间Q的通信

a. 安装

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#Centos7 安装
#注意/etc/hosts文件 ip和主机名对应
wget https: / / github.com / rabbitmq / rabbitmq - server / releases / download / rabbitmq_v3_6_10 / rabbitmq - server - 3.6 . 10 - 1.el7 .noarch.rpm
yum install epel - release - y
yum install rabbitmq - server - 3.6 . 10 - 1.el7 .noarch.rpm
rabbitmq - plugins enable rabbitmq_management
cp / usr / share / doc / rabbitmq - server - 3.6 . 10 / rabbitmq.config.example / etc / rabbitmq / rabbitmq.config
systemctl restart rabbitmq - server
systemctl status rabbitmq - server
#创建用户 授权
rabbitmqctl  add_user alex alex3714
rabbitmqctl set_permissions - p / alex ".*" ".*" ".*"

启动失败： 

[root@openstack ~]# systemctl start rabbitmq-server.service

Job for rabbitmq-server.service failed. See ‘systemctl status rabbitmq-server.service’ and ‘journalctl -xn’ for details. 

[root@openstack ~]# systemctl status rabbitmq-server.service

rabbitmq-server.service – RabbitMQ broker

Loaded: loaded (/usr/lib/systemd/system/rabbitmq-server.service; enabled)

Active: failed (Result: exit-code) since 六 2016-04-30 23:19:21 CST; 8s ago

Process: 3593 ExecStop=/usr/lib/rabbitmq/bin/rabbitmqctl stop (code=exited, status=2)

Process: 3563 ExecStart=/usr/lib/rabbitmq/bin/rabbitmq-server (code=exited, status=1/FAILURE)

Main PID: 3563 (code=exited, status=1/FAILURE)

4月 30 23:19:21 openstack rabbitmqctl[3593]: * epmd reports: node ‘rabbit’ not running at all

4月 30 23:19:21 openstack rabbitmqctl[3593]: no other nodes on openstack

4月 30 23:19:21 openstack rabbitmqctl[3593]: * suggestion: start the node

4月 30 23:19:21 openstack rabbitmqctl[3593]: current node details:

4月 30 23:19:21 openstack rabbitmqctl[3593]: – node name: rabbitmqctl3593@openstack

4月 30 23:19:21 openstack rabbitmqctl[3593]: – home dir: /var/lib/rabbitmq

4月 30 23:19:21 openstack rabbitmqctl[3593]: – cookie hash: DuHinHyRsf96Yx7NcAaAuQ==

4月 30 23:19:21 openstack systemd[1]: rabbitmq-server.service: control process exited, code=exited status=2

4月 30 23:19:21 openstack systemd[1]: Failed to start RabbitMQ broker.

4月 30 23:19:21 openstack systemd[1]: Unit rabbitmq-server.service entered failed state.

解决办法： 

firewall-cmd --permanent --add-port=5672/tcp

firewall-cmd --reload

setsebool -P nis_enabled 1

systemctl start rabbitmq-server再次启动: 

[root@oldboy_zny rabbitmq]# systemctl start rabbitmq-server

[root@oldboy_zny rabbitmq]# systemctl status rabbitmq-server

rabbitmq-server.service - RabbitMQ broker

   Loaded: loaded (/usr/lib/systemd/system/rabbitmq-server.service; enabled)

   Active: active (running) since 一 2018-03-05 10:33:48 CST; 8s ago

  Process: 22014 ExecStop=/usr/sbin/rabbitmqctl stop (code=exited, status=0/SUCCESS)

 Main PID: 22152 (beam)

   Status: "Initialized"

   CGroup: /system.slice/rabbitmq-server.service

           ├─22152 /usr/lib64/erlang/erts-5.10.4/bin/beam -W w -A 64 -P 1048576 -t 5000000 -stbt db -zdbbl 32000 -K true -- -root /usr/lib64/erlang...

           ├─22441 inet_gethost 4

           └─22442 inet_gethost 4

3月 05 10:33:47 oldboy_zny rabbitmq-server[22152]: ##  ##

3月 05 10:33:47 oldboy_zny rabbitmq-server[22152]: ##########  Logs: /var/log/rabbitmq/rabbit@oldboy_zny.log

3月 05 10:33:47 oldboy_zny rabbitmq-server[22152]: ######  ##        /var/log/rabbitmq/rabbit@oldboy_zny-sasl.log

3月 05 10:33:47 oldboy_zny rabbitmq-server[22152]: ##########

3月 05 10:33:47 oldboy_zny rabbitmq-server[22152]: Starting broker...

3月 05 10:33:48 oldboy_zny rabbitmq-server[22152]: systemd unit for activation check: "bin"

3月 05 10:33:48 oldboy_zny rabbitmq-server[22152]: 'systemctl' unavailable, falling back to sleep

3月 05 10:33:48 oldboy_zny systemd[1]: Started RabbitMQ broker.

3月 05 10:33:49 oldboy_zny python[22447]: SELinux is preventing /usr/bin/bash from getattr access on the file .

                                           *****  Plugin catchall (100. confidence) suggests   **************************...

3月 05 10:33:53 oldboy_zny rabbitmq-server[22152]: completed with 6 plugins.

Hint: Some lines were ellipsized, use -l to show in full.

b. 创建用户 授权 

#远程连接rabbitmq server的话,需要配置权限

#创建用户

rabbitmqctl  add_user alex alex3714

　

#同时还要配置权限，允许从外面访问

rabbitmqctl set_permissions -p / alex ".*" ".*" ".*"

  set_permissions [-p vhost] {user} {conf} {write} {read}

  vhost

  The name of the virtual host to which to grant the user access, defaulting to /.

  user

  The name of the user to grant access to the specified virtual host.

  conf

  A regular expression matching resource names for which the user is granted configure permissions.

  write

  A regular expression matching resource names for which the user is granted write permissions.

  read

  A regular expression matching resource names for which the user is granted read permissions.

c. python rabbitMQ module 安装

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

二. 事例

参考博客：http://www.cnblogs.com/yuanchenqi/articles/8507109.html

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注意: 一般申明队列(如下代码)只需要在服务端申明,但客户端也可以申明,是防止如果服务端没有启动,客户端先启动后没有队列会报错
此时服务端如果有相同代码,会检查,如果有相同队列就不创建
channel.queue_declare(queue = 'hello' )

a. 服务端和客户端一对一

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#查看队列
# rabbitmqctl list_queues
#客户端再次申明队列是因为客户端要清楚去哪里取数据
channel.queue_declare(queue = 'hello' ) 
import pika

credentials = pika.PlainCredentials("egon","egon123")                     #授权的账号 密码

connection = pika.BlockingConnection(

    pika.ConnectionParameters('192.168.11.106',credentials=credentials))  #建立socket

channel = connection.channel()            #创建rabbitmq协议通道

channel.queue_declare(queue='hello')      #通过通道生成一个队列

channel.basic_publish(exchange='',

                      routing_key='hello',      #队列

                      body='Hello World!')      #内容

print(" [x] Sent 'Hello World!'")

connection.close()

sender.py 

import pika

credentials = pika.PlainCredentials("egon","egon123")                     #授权的账号 密码

connection = pika.BlockingConnection(

    pika.ConnectionParameters('192.168.11.106',credentials=credentials))  #建立socket

channel = connection.channel()

channel.queue_declare(queue='hello')

def callback(ch, method, properties, body):

    print(ch)              #上面channel = connection.channel()对象

    print(method)          #除了服务端本身的数据，还带一些参数

    print(properties)      #属性

    print(body)            #byte数据

channel.basic_consume(callback,

                      queue='hello',

                      no_ack=True)

print(' Waiting for messages. To exit press CTRL+C')

channel.start_consuming()

receive.py

b. 消息持久化

1. 模拟客户端中断 观察服务端队列的数据会不会返回(不会)

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#- 开启一个服务端,两个客户端
#- 服务端向队列中存放一个值,一客户端从队列中取到数据,在睡20秒期间中断,表示出错,它不会报告给服务端
#- 这时队列中为零,另一客户端也不会取到值
# no_ack=True 表示客户端处理完了不需要向服务端确认消息 
import pika

credentials = pika.PlainCredentials("egon","egon123")                     #授权的账号 密码

connection = pika.BlockingConnection(

    pika.ConnectionParameters('192.168.11.106',credentials=credentials))  #建立socket

channel = connection.channel()            #创建rabbitmq协议通道

channel.queue_declare(queue='hello')      #通过通道生成一个队列

channel.basic_publish(exchange='',

                      routing_key='hello',      #队列

                      body='Hello World!')      #内容

print(" [x] Sent 'Hello World!'")

connection.close()

send.py 

import pika

import time

credentials = pika.PlainCredentials("egon","egon123")                     #授权的账号 密码

connection = pika.BlockingConnection(

    pika.ConnectionParameters('192.168.11.106',credentials=credentials))  #建立socket

channel = connection.channel()

channel.queue_declare(queue='hello')

def callback(ch, method, properties, body):

    print("received msg...start process",body)

    time.sleep(10)

    print("end process...")

channel.basic_consume(callback,

                      queue='hello',

                      no_ack=True)

print(' Waiting for messages. To exit press CTRL+C')

channel.start_consuming()

receive.py

2. 模拟客户端中断 观察服务端队列的数据会不会返回(会)

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#1. 生产者端发消息时，加参数 消息持久化
properties = pika.BasicProperties(
delivery_mode = 2 , # make message persistent
),
#2. 消费者端，消息处理完毕时，发送确认包
ch.basic_ack(delivery_tag = method.delivery_tag)
channel.basic_consume(callback, #取到消息后，调用callback 函数
queue = 'task1' ,)
#no_ack=True) #消息处理后，不向rabbit-server确认消息已消费完毕
#- 开启一个服务端,两个客户端
#- 服务端向队列中存放一个值,一客户端从队列中取到数据,在睡20秒期间中断,表示出错,它会报给服务端,服务端队列还有值
#- 这时启动另一客户端还可以取到值 
import pika

credentials = pika.PlainCredentials("egon","egon123")                     #授权的账号 密码

connection = pika.BlockingConnection(

    pika.ConnectionParameters('192.168.11.106',credentials=credentials))  #建立socket

channel = connection.channel()            #创建rabbitmq协议通道

channel.queue_declare(queue='hello')      #通过通道生成一个队列

channel.basic_publish(exchange='',

                      routing_key='hello',      #队列

                      properties=pika.BasicProperties(

                          delivery_mode=2,  # make message persistent

                      ),

                      body='Hello World!')      #内容

print(" [x] Sent 'Hello World!'")

connection.close()

sender.py 

import pika

import time

credentials = pika.PlainCredentials("egon","egon123")                     #授权的账号 密码

connection = pika.BlockingConnection(

    pika.ConnectionParameters('192.168.11.106',credentials=credentials))  #建立socket

channel = connection.channel()

channel.queue_declare(queue='hello')

def callback(ch, method, properties, body):

    print("received msg...start process",body)

    time.sleep(10)

    print("end process...")

    ch.basic_ack(delivery_tag=method.delivery_tag)

channel.basic_consume(callback,

                      queue='hello',

                      )

print(' Waiting for messages. To exit press CTRL+C')

channel.start_consuming()

receive.py

c. 队列持久化

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#队列持久化
channel.queue_declare(queue = 'hello' ,durable = True )
systemctl restart rabbitmq - server #重启服务发现hello队列还在,但是消息不在
rabbitmqctl list_queues
#hello
#队列和消息持久化
channel.queue_declare(queue = 'hello' ,durable = True )
properties = pika.BasicProperties(
delivery_mode = 2 , # make message persistent
),
systemctl restart rabbitmq - server #重启服务发现队列和消息都还在
rabbitmqctl list_queues
#hello 6 
import pika

credentials = pika.PlainCredentials("egon","egon123")                     #授权的账号 密码

connection = pika.BlockingConnection(

    pika.ConnectionParameters('192.168.11.106',credentials=credentials))  #建立socket

channel = connection.channel()            #创建rabbitmq协议通道

channel.queue_declare(queue='hello',durable=True)      #通过通道生成一个队列

channel.basic_publish(exchange='',

                      routing_key='hello',      #队列

                      properties=pika.BasicProperties(

                          delivery_mode=2,  # make message persistent

                      ),

                      body='Hello World!')      #内容

print(" [x] Sent 'Hello World!'")

connection.close()

sender.py

d. fanout 广播

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#服务端：
- 不需要申明队列
#客户端：
- 每个客户端都需要申明一个队列,自动设置队列名称,收听广播,当收听完后queue删除
- 把队列绑定到exchange上
#注意：客户端先打开,服务端再打开,客户端会收到消息
#应用：
- 微博粉丝在线,博主发消息,粉丝可以收到
#如果服务端先启动向exchange发消息,这时客户端没有启动,没有队列保存数据(exchange不负责保存数据)
#这时数据会丢,队列中没有数据
#exchange只负责转发 
import pika

import sys

import time

credentials = pika.PlainCredentials("egon","egon123")                     #授权的账号 密码

connection = pika.BlockingConnection(

    pika.ConnectionParameters('172.16.42.128',credentials=credentials))  #建立socket

channel = connection.channel()                             #创建rabbitmq协议通道

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(" Send %r" % message)

connection.close()

sender.py 

import pika

import time

credentials = pika.PlainCredentials("egon","egon123")                     #授权的账号 密码

connection = pika.BlockingConnection(

    pika.ConnectionParameters('172.16.42.128',credentials=credentials))  #建立socket

channel = connection.channel()

channel.exchange_declare(exchange='logs',

                         type='fanout')

queue_obj = channel.queue_declare(exclusive=True)  #随机创建一个队列对象 exclusive=True会在使用此queue的消费者断开后,自动将queue删除

queue_name = queue_obj.method.queue                #不指定queue名字,rabbit会随机分配一个名字,

channel.queue_bind(exchange='logs',queue=queue_name)    #把queue绑定到exchange

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()

receive.py

e. direct 组播

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#客户端一：
- python3 receive1.py info
#客户端二：
- python3 receive1.py  error
#客户端三：
- python3 receive1.py  warning
#客户端四：
- python3 receive1.py  warning error info
#服务端：
- python3 receive1.py  warning 
import pika

import sys

import time

credentials = pika.PlainCredentials("egon","egon123")                   #授权的账号 密码

connection = pika.BlockingConnection(

    pika.ConnectionParameters('172.16.42.128',credentials=credentials))  #建立socket

channel = connection.channel()                  #创建rabbitmq协议通道

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(" Send %r:%r" % (severity, message))

connection.close()

sender.py 

import pika

import time

import sys

credentials = pika.PlainCredentials("egon","egon123")                     #授权的账号 密码

connection = pika.BlockingConnection(

    pika.ConnectionParameters('172.16.42.128',credentials=credentials))  #建立socket

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()

receive.py

f. topic 规则传播

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#客户端一：
- python3 receive1.py * .django
#客户端二：
- python3 receive1.py mysql.error
#客户端三：
- python3 receive1.py mysql. *
#服务端：
- python3 receive1.py #匹配相应的客户端 
import pika

import time

import sys

credentials = pika.PlainCredentials("egon","egon123")                     #授权的账号 密码

connection = pika.BlockingConnection(

    pika.ConnectionParameters('172.16.42.128',credentials=credentials))  #建立socket

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:

    print(sys.argv[1:])

    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()

receive.py 

import pika

import sys

import time

credentials = pika.PlainCredentials("egon","egon123")                   #授权的账号 密码

connection = pika.BlockingConnection(

    pika.ConnectionParameters('172.16.42.128',credentials=credentials))  #建立socket

channel = connection.channel()                  #创建rabbitmq协议通道

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))

sender.py

以生产者消费者举例四种模式：

生产者： 

# ! /usr/bin/env python

# -*- coding: utf-8 -*-

#  Author :    张宁阳

#  date：      2018/3/6

# ######################### 简答模式生产者 #########################

import pika

connection = pika.BlockingConnection(pika.ConnectionParameters( host='192.168.20.56',port=5672,

        credentials=pika.credentials.PlainCredentials(

            username='alex',

            password='alex3714'

        )))

channel = connection.channel()

channel.queue_declare(queue='hello')

channel.basic_publish(exchange='',

                      routing_key='hello',

                      body='ssssssssssssss')

print(" 已经 发送 'ssssssssssssssssss'")

connection.close()

######################基于exchang分发模式的生产者###########################

import pika

connection = pika.BlockingConnection(pika.ConnectionParameters( host='192.168.20.56',port=5672,

        credentials=pika.credentials.PlainCredentials(

            username='alex',

            password='alex3714'

        )))

channel = connection.channel()

channel.exchange_declare(exchange='logs',

                         exchange_type='fanout')

message = "info: Hello World!"

channel.basic_publish(exchange='logs',

                      routing_key='',

                      body=message)

print(" [x] Sent %r" % message)

connection.close()

##########基于exchange关键字模式的生产者##############

import pika

connection = pika.BlockingConnection(pika.ConnectionParameters( host='192.168.20.56',port=5672,

        credentials=pika.credentials.PlainCredentials(

            username='alex',

            password='alex3714'

        )))

channel = connection.channel()

channel.exchange_declare(exchange='direct_logs',

                         exchange_type='direct')

message = "info: Hello World!"

channel.basic_publish(exchange='direct_logs',

                      routing_key='info',#关键字：info、error、warning

                      body=message)

print(" [x] Sent %r" % message)

connection.close()

##########基于exchange模糊匹配模式的生产者##############

import pika

connection = pika.BlockingConnection(pika.ConnectionParameters( host='192.168.20.56',port=5672,

        credentials=pika.credentials.PlainCredentials(

            username='alex',

            password='alex3714'

        )))

channel = connection.channel()

channel.exchange_declare(exchange='topic_logs',

                         exchange_type='topic')

message = "info: Hello World!"

#routing_key="模糊匹配字符"

routing_keys=["old.boy.python ","old.boy"]

for key in routing_keys:

    channel.basic_publish(exchange='topic_logs',

                          routing_key=key,

                          body=message)

    print(" [x] Sent %r" % message)

connection.close()

消费者 

# ! /usr/bin/env python

# -*- coding: utf-8 -*-

#  Author :    张宁阳

#  date：      2018/3/6

##########################基于简单模式的 消费者 ##########################

import pika

connection = pika.BlockingConnection(pika.ConnectionParameters(host='192.168.20.56',port=5672,

        credentials=pika.credentials.PlainCredentials(

            username='alex',

            password='alex3714'

        )))

channel = connection.channel()

channel.queue_declare(queue='hello')

def callback(ch, method, properties, body):

    print(" 已经 接受 %r" % body)

channel.basic_consume(callback,

                      queue='hello',

                      no_ack=True)

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

channel.start_consuming()

##############基于exchange分发模式消费者#####################

import pika

connection = pika.BlockingConnection(pika.ConnectionParameters( host='192.168.20.56',port=5672,

        credentials=pika.credentials.PlainCredentials(

            username='alex',

            password='alex3714'

        )))

channel = connection.channel()

channel.exchange_declare(exchange='logs',

                         exchange_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()

##########################基于exchange的关键字模式的 消费者 ##########################

import pika

connection = pika.BlockingConnection(pika.ConnectionParameters(host='192.168.20.56', port=5672,

                                                               credentials=pika.credentials.PlainCredentials(

                                                                   username='alex',

                                                                   password='alex3714'

                                                               )))

channel = connection.channel()

# 生成交换机

channel.exchange_declare(exchange='direct_logs',

                         exchange_type='direct')

# 创建的队列

result = channel.queue_declare(exclusive=True)

# 创建的队列的随机名称

queue_name = result.method.queue

# 给队列与direct_logs这个交换机绑定三个关键字

severities = ["info", "warning", "error"]

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()

##########################基于exchange的模糊匹配模式的 消费者 ##########################

import pika

import sys

connection = pika.BlockingConnection(pika.ConnectionParameters(host='192.168.20.56', port=5672,

                                                               credentials=pika.credentials.PlainCredentials(

                                                                   username='alex',

                                                                   password='alex3714'

                                                               )))

channel = connection.channel()

channel.exchange_declare(exchange='topic_logs',

                         exchange_type='topic')

result = channel.queue_declare(exclusive=True)

queue_name = result.method.queue

bind_keys=["old.*","old.#"]

for bind_key in bind_keys:

    channel.queue_bind(exchange='topic_logs',

                       queue=queue_name,

                       routing_key=bind_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()

基于RabbitMQ的RPC

回到顶部

Callback queue 回调队列

一个客户端向服务器发送请求，服务器端处理请求后，将其处理结果保存在一个存储体中。而客户端为了获得处理结果，那么客户在向服务器发送请求时，同时发送一个回调队列地址 reply_to 。

Correlation id 关联标识

一个客户端可能会发送多个请求给服务器，当服务器处理完后，客户端无法辨别在回调队列中的响应具体和那个请求时对应的。为了处理这种情况，客户端在发送每个请求时，同时会附带一个独有 correlation_id 属性，这样客户端在回调队列中根据 correlation_id 字段的值就可以分辨此响应属于哪个请求。 

客户端发送请求：某个应用将请求信息交给客户端，然后客户端发送RPC请求，在发送RPC请求到RPC请求队列时，客户端至少发送带有reply_to以及correlation_id两个属性的信息

服务器端工作流： 等待接受客户端发来RPC请求，当请求出现的时候，服务器从RPC请求队列中取出请求，然后处理后，将响应发送到reply_to指定的回调队列中

客户端接受处理结果： 客户端等待回调队列中出现响应，当响应出现时，它会根据响应中correlation_id字段的值，将其返回给对应的应用

服务器端 

#!/usr/bin/env python

import pika

# 建立连接，服务器地址为localhost，可指定ip地址

connection = pika.BlockingConnection(pika.ConnectionParameters(

        host='localhost'))

# 建立会话

channel = connection.channel()

# 声明RPC请求队列

channel.queue_declare(queue='rpc_queue')

# 数据处理方法

def fib(n):

    if n == 0:

        return 0

    elif n == 1:

        return 1

    else:

        return fib(n-1) + fib(n-2)

# 对RPC请求队列中的请求进行处理

def on_request(ch, method, props, body):

    n = int(body)

    print(" [.] fib(%s)" % n)

    # 调用数据处理方法

    response = fib(n)

    # 将处理结果(响应)发送到回调队列

    ch.basic_publish(exchange='',

                     routing_key=props.reply_to,

                     properties=pika.BasicProperties(correlation_id = \

                                                         props.correlation_id),

                     body=str(response))

    ch.basic_ack(delivery_tag = method.delivery_tag)

# 负载均衡，同一时刻发送给该服务器的请求不超过一个

channel.basic_qos(prefetch_count=1)

channel.basic_consume(on_request, queue='rpc_queue')

print(" [x] Awaiting RPC requests")

channel.start_consuming()

客户端 

#!/usr/bin/env python

import pika

import uuid

class FibonacciRpcClient(object):

    def __init__(self):

        ”“”

        客户端启动时，创建回调队列，会开启会话用于发送RPC请求以及接受响应

        “”“

        # 建立连接，指定服务器的ip地址

        self.connection = pika.BlockingConnection(pika.ConnectionParameters(

                host='localhost'))

        # 建立一个会话，每个channel代表一个会话任务

        self.channel = self.connection.channel()

        # 声明回调队列，再次声明的原因是，服务器和客户端可能先后开启，该声明是幂等的，多次声明，但只生效一次

        result = self.channel.queue_declare(exclusive=True)

        # 将次队列指定为当前客户端的回调队列

        self.callback_queue = result.method.queue

        # 客户端订阅回调队列，当回调队列中有响应时，调用`on_response`方法对响应进行处理;

        self.channel.basic_consume(self.on_response, no_ack=True,

                                   queue=self.callback_queue)

    # 对回调队列中的响应进行处理的函数

    def on_response(self, ch, method, props, body):

        if self.corr_id == props.correlation_id:

            self.response = body

    # 发出RPC请求

    def call(self, n):

        # 初始化 response

        self.response = None

        #生成correlation_id

        self.corr_id = str(uuid.uuid4())

        # 发送RPC请求内容到RPC请求队列`rpc_queue`，同时发送的还有`reply_to`和`correlation_id`

        self.channel.basic_publish(exchange='',

                                   routing_key='rpc_queue',

                                   properties=pika.BasicProperties(

                                         reply_to = self.callback_queue,

                                         correlation_id = self.corr_id,

                                         ),

                                   body=str(n))

        while self.response is None:

            self.connection.process_data_events()

        return int(self.response)

# 建立客户端

fibonacci_rpc = FibonacciRpcClient()

# 发送RPC请求

print(" [x] Requesting fib(30)")

response = fibonacci_rpc.call(30)

print(" [.] Got %r" % response)

Alex

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