RabbitMQ---广播模式

Posted 2021-03-03 lzq930

广播模式：1对多，produce发送一则消息多个consumer同时收到。

注意：广播是实时的，produce只负责发出去，不会管对端是否收到，若发送的时刻没有对端接收，那消息就没了，因此在广播模式下设置消息持久化是无效的。

三种广播模式：

fanout: 所有bind到此exchange的queue都可以接收消息（纯广播，绑定到RabbitMQ的接受者都能收到消息）；
direct: 通过routingKey和exchange决定的那个唯一的queue可以接收消息；
topic:所有符合routingKey(此时可以是一个表达式)的routingKey所bind的queue可以接收消息；

原理：

fanout：接受者会在RabbitMQ中创建一个queue用来接收消息，发送者往queue中发送消息。（发送给全员）

direct：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。（发送给指定人）

topic：接受者可以收取指定内容的消息

代码饭粒1：fanout广播模式

# publisher发送者

import pika
connection = pika.BlockingConnection(pika.ConnectionParameters(host=‘localhost‘))
channel = connection.channel()
channel.exchange_declare(exchange=‘broadcast‘, exchange_type=‘fanout‘)
message = ‘big bang!‘
channel.basic_publish(
    exchange=‘broadcast‘,
    routing_key=‘‘,
    body=message,
)
print("[v] Send %r" % message)
connection.close()

 # subscriber接收者

import pika
connection = pika.BlockingConnection(pika.ConnectionParameters(host=‘localhost‘))
channel = connection.channel()
channel.exchange_declare(exchange=‘broadcast‘, exchange_type=‘fanout‘)

result = channel.queue_declare(exclusive=True)
# 不指定queue名字，Rabbit会随机分配一个名字，并在使用此queue的消费者断开后,自动将queue删除
queue_name = result.method.queue
channel.queue_bind(exchange=‘broadcast‘,queue=queue_name)
print(" [*] Waiting for broadcast. To exit press Ctrl+C")

def callback(ch, method, properties, body):
    print(" [v] Get broadcast:",body)

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

 

代码饭粒2：direct广播模式

# publisher发送者

import pika
import sys
connection = pika.BlockingConnection(pika.ConnectionParameters(host=‘localhost‘))
channel = connection.channel()

channel.exchange_declare(exchange=‘direct_logs‘, exchange_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()

# subscriber接收者

import pika
import sys
connection = pika.BlockingConnection(pika.ConnectionParameters(host=‘localhost‘))
channel = connection.channel()

channel.exchange_declare(exchange=‘direct_logs‘, exchange_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]
" % 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()

 

代码饭粒3：topic广播模式

# publisher发送者

import pika
import sys
connection = pika.BlockingConnection(pika.ConnectionParameters(host=‘localhost‘))
channel = connection.channel()
channel.exchange_declare(exchange=‘topic_logs‘, exchange_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()

# subscriber接收者

import pika
import sys

connection = pika.BlockingConnection(pika.ConnectionParameters(host=‘localhost‘))
channel = connection.channel()
channel.exchange_declare(exchange=‘topic_logs‘, exchange_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]...
" % 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()