RabbitMQ

简介

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。

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。

安装

# 安装 rabbitMQ 程序
yum -y install rabbitmq-server

启动

# 启动 rabbitMQ
systemctl restart rabbitmq-server

# 启动管理插件，启动后访问 http://localhost:15672,默认用户名密码 guest/guest
rabbitmq-plugins enable rabbitmq-management

使用 API 操作 RabbitMQ

生产者消费者模型是通过队列来实现的

import time
import queue
import threading


q = queue.Queue(10)


def producer(msg):
    while True:
        time.sleep(1)
        q.put(msg)


def consumer():
    while True:
        time.sleep(0.5)
        msg = q.get()
        print(msg)


for i in range(5):
    t = threading.Thread(target=producer, args=(i,))
    t.start()

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

RabbitMQ 也是一个队列，也可以实现生产者消费者模型，区别在于对象并非存在内存的 queue 中，而是存在于一台服务器基于 RabbitMQ Server 实现的消息队列中

"""生产者: send.py"""

import pika

# 创建一个连接
connection = pika.BlockingConnection(pika.ConnectionParameters(host='10.211.55.5'))
channel = connection.channel()

# 创建一个队列，队列名为 hello
channel.queue_declare(queue='hello')

# 向 hello 队列中添加一条消息 'Hello World!'
channel.basic_publish(exchange='',
                      routing_key='hello',
                      body='Hello World!')

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

"""消费者: receive.py"""

import pika

connection = pika.BlockingConnection(pika.ConnectionParameters(host='10.211.55.5'))
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、Message acknowledgment 消息确认

no-ack=False 默认值，如果消费者由于故障(its channel is closed, connection is closed, or TCP connection is lost)为发送消息确认，生产者会将数据再重新添加到队列中

"""消费者: receive.py"""

import pika

connection = pika.BlockingConnection(pika.ConnectionParameters(host='10.211.55.5'))
channel = connection.channel()

channel.queue_declare(queue='hello')

def callback(ch, method, properties, body):
    print(" [x] Received %r" % body)
    # 消息确认，当未执行时，消息会重新添加回队列
    ch.basic_ack(delivery_tag=method.delivery_tag)

channel.basic_consume(callback, queue='hello', no_ack=False)  # no_ack=False 为默认值

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

2、Message durability 消息持久

当 RabbitMQ Server 因故重启，希望数据消息不丢失

"""生产者: send.py"""

import pika

connection = pika.BlockingConnection(pika.ConnectionParameters(host='10.211.55.5'))
channel = connection.channel()

# 为队列添加属性用于保持消息持久: durable=True
channel.queue_declare(queue='task_queue', durable=True)

channel.basic_publish(exchange='',
                      routing_key='task_queue',
                      body='Hello World!',
                      properties=pika.BasicProperties(
                          delivery_mode=2,  # 保持消息持久
                      ))

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

"""消费者"""

import pika

connection = pika.BlockingConnection(pika.ConnectionParameters(host='10.211.55.5'))
channel = connection.channel()

# durable=True
channel.queue_declare(queue='task_queue', durable=True)

def callback(ch, method, properties, body):
    print(" [x] Received %r" % body)
    ch.basic_ack(delivery_tag=method.delivery_tag)

channel.basic_consume(callback, queue='task_queue')

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

3、消息获取顺序

消费者在获取消息时默认为平均获取。当有两个消费者获取消息，消费者一处理消息需要2s，消费者二处理消息需要4s，RabbitMQ 按照默认的调度平均分配消息，会导致消费者一很闲，消费者二很忙。修改 basic.qos 为 prefetch_count=1，表示谁来谁去，不在按照顺序调度任务

"""消费者:receive.py"""

import pika

connection = pika.BlockingConnection(pika.ConnectionParameters(host='10.211.55.5'))
channel = connection.channel()

channel.queue_declare(queue='task_queue', durable=True)

def callback(ch, method, properties, body):
    print(" [x] Received %r" % body)
    ch.basic_ack(delivery_tag=method.delivery_tag)

# 修改调度顺序
channel.basic_qos(prefetch_count=1)

channel.basic_consume(callback, queue='task_queue')

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

4、发布与订阅

发布者发送消息，所有的订阅者都能收到消息。

但是队列中的消息消费一次之后就会消失，所有需要给每一个订阅者绑定一个队列，发布者将消息发布到所有的消费者绑定的队列中，所有的订阅者到自己绑定的队列中消费消息。

创建临时队列：

# 创建临时队列,队列名称类似：amq.gen-JzTY20BRgKO-HjmUJj0wLg
# exclusive=True 当消费者断开连接时，队列自动删除
result = channel.queue_declare(exclusive=True)

# 获取队列名称
queue_name = result.method.queue

exchange：

RabbitMQ 在发送消息时并不是直接发送给队列，而是通过 exchange 发送给队列

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

# exchange 绑定队列
channel.queue_bind(exchange='logs', queue=queue_name)

"""发布者: send.py"""

import pika

connection = pika.BlockingConnection(pika.ConnectionParameters(host='10.211.55.5'))
channel = connection.channel()

# 创建临时队列并获取队列名称
result = channel.queue_declare(exclusive=True)
queue_name = result.method.queue

channel.basic_publish(exchange='logs',
                      routing_key='',
                      body='Hello World!',
                      )

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

"""订阅者"""

import pika

connection = pika.BlockingConnection(pika.ConnectionParameters(host='10.211.55.5'))
channel = connection.channel()

# 创建临时队列并获取队列名称
result = channel.queue_declare(exclusive=True)
queue_name = result.method.queue

# 创建 exchange 并绑定临时队列到
channel.exchange_declare('logs', type='fanout')
channel.queue_bind(exchange='logs', queue=queue_name)


def callback(ch, method, properties, body):
    print(" [x] Received %r" % body)
    ch.basic_ack(delivery_tag = method.delivery_tag)

channel.basic_consume(callback, queue=queue_name)

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

RabbitMQ 的 绑定如图：

5、关键字发送(Routing)

为队列绑定关键字，进行路由

创建 exchange：

# 创建 exchange
channel.exchange_declare(exchange='logs',type='direct')

# 绑定队列
channel.queue_bind(exchange=exchange_name,
                   queue=queue_name,
                   routing_key='关键字')

 创建生产者与消费者：

"""生产者: send.py"""
import sys
import pika

connection = pika.BlockingConnection(pika.ConnectionParameters(host='10.211.55.5'))
channel = connection.channel()

# 创建 exchange
channel.exchange_declare('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,  # 定义关键字发送
                      body=message,
                      )

print(" [x] Sent %r:%r" % (severity, message))
connection.close()

"""消费者: receive.py"""

import sys
import pika

connection = pika.BlockingConnection(pika.ConnectionParameters(host='10.211.55.5'))
channel = connection.channel()

# 创建临时队列并获取队列名称
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)

# 为队列绑定 exchange 和 routing key
for severity in severities:
    print(severity)
    channel.queue_bind(exchange='direct_logs',
                       queue=queue_name,
                       routing_key=severity)

def callback(ch, method, properties, body):
    print(" [x] Received %r" % body)
    ch.basic_ack(delivery_tag = method.delivery_tag)

channel.basic_consume(callback, queue=queue_name)

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

RabbitMQ 的 绑定如图：

 

# 启动三个消费者，分别根据不同的关键字获取消息
python receive.py info
python receive.py error
python receive.py info error

# 发布关键字为 info 和 error 的消息
python send.py info info_message
python send.py error error_message

 

6、模糊匹配

当 exchange 的 type 为 topic 时，关键字允许模糊匹配

• * 表示匹配后面的一个单词
• # 表示匹配后面的一个或多个单词

"""生产者: send.py"""

import sys
import pika

connection = pika.BlockingConnection(pika.ConnectionParameters(host='10.211.55.5'))
channel = connection.channel()

# 创建 exchange
channel.exchange_declare('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,  # 定义关键字发送
                      body=message,
                      )

print(" [x] Sent %r:%r" % (routing_key, message))
connection.close()

"""消费者: receive.py"""

import sys
import pika

connection = pika.BlockingConnection(pika.ConnectionParameters(host='10.211.55.5'))
channel = connection.channel()

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

# 创建临时队列并获取队列名称
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)

# 为队列绑定 exchange 和 routing key
for binding_key in binding_keys:
    channel.queue_bind(exchange='topic_logs',
                       queue=queue_name,
                       routing_key=binding_key)

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

channel.basic_consume(callback, queue=queue_name)

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

观察运行命令：

# 消费者
python receive.py kern.*
python receive.py kern.#

# 生产者
python send.py kern.info "info message"
python send.py kern.error "error message"
python send.py kern.error.info "error message"

 7、RPC

"""rpc_server.py"""

import pika

connection = pika.BlockingConnection(pika.ConnectionParameters(host='10.211.55.5'))

channel = connection.channel()

channel.queue_declare(queue='rpc_queue')

def fib(n):
    if n == 0:
        return 0
    elif n == 1:
        return 1
    else:
        return fib(n-1) + fib(n-2)

def on_request(ch, method, props, body):
    n = int(body)

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

    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)

channel.basic_qos(prefetch_count=1)
channel.basic_consume(on_request, queue='rpc_queue')

print(" [x] Awaiting RPC requests")
channel.start_consuming()

"""rpc_client.py"""

import pika
import uuid


class FibonacciRpcClient(object):
    def __init__(self):
        self.connection = pika.BlockingConnection(pika.ConnectionParameters(host='10.211.55.5'))

        self.channel = self.connection.channel()

        result = self.channel.queue_declare(exclusive=True)
        self.callback_queue = result.method.queue

        self.channel.basic_consume(self.on_response, no_ack=True,
                                   queue=self.callback_queue)

    def on_response(self, ch, method, props, body):
        if self.corr_id == props.correlation_id:
            self.response = body

    def call(self, n):
        self.response = None
        self.corr_id = str(uuid.uuid4())
        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)

fibonacci_rpc = FibonacciRpcClient()

print(" [x] Requesting fib(30)")
response = fibonacci_rpc.call(30)
print(" [.] Got %r" % response)