Rabbitmq_03 Publish/Subscribe

　　发布订阅模式，一条消息可被多个接收者接收。注意在上一篇的tasks模式中，虽然有多个接收者，但每条消息还是只被一个接收者接收的。

发送者

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

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

# 指定了exchange的type
channel.exchange_declare(exchange='logs',
                         exchange_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()

接收者

#!/usr/bin/env python
import pika

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

channel.exchange_declare(exchange='logs',
                         exchange_type='fanout')

# 下面的队列声明语句，比上一篇的少了queue选项，多了exclusive选项。
# 没有queue选项，指明没有为创建的队列命名，由服务器创建一个现在还没有出现的随机名称。
# exclusive选项，指明接收者关闭之后，创建的这条队列页随之关闭
result = channel.queue_declare(exclusive=True)
queue_name = result.method.queue

# 绑定关系，下面详解
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()