一、

訊息的廣播需要exchange：exchange是一個轉發器，其實把訊息發給RabbitMQ裡的exchange

fanout: 所有bind到此exchange的queue都可以接收訊息，廣播

direct: 通過routingKey和exchange決定的那個唯一的queue可以接收訊息

topic:所有符合routingKey(此時可以是一個表示式)的routingKey所bind的queue可以接收訊息

headers：通過headers來決定把訊息發給哪些queue，用的比較少

原理：訊息釋出端分別傳送INFO，WARNING，ERROR型別的訊息，C1 C2 C3訂閱了不同型別的訊息

訊息傳送端：

'''
釋出者publisher
'''
import pika
import sys

connection = pika.BlockingConnection(pika.ConnectionParameters('localhost'))
channel = connection.channel()
channel.exchange_declare(exchange='direct_logs',
                         type='direct')  # 1、改成type='direct'
# 2、預設傳送的訊息級別為info，可以帶引數，warning error等
 

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, # 3、把上面的訊息發到這個queue中
                      body=message)
print("send :", message)
connection.close()
 

訊息訂閱者：

'''
訂閱者subscriber
'''
import pika
import sys

connection = pika.BlockingConnection(pika.ConnectionParameters('localhost'))
channel = connection.channel()
channel.exchange_declare(exchange='direct_logs',
                         type='direct')  # 4、改exchange的型別
result = channel.queue_declare(exclusive=True)
queue_name = result.method.queue

# 5、啟動訂閱端的時候，severities存放訂閱端訂閱了哪些級別
#    然後用routing_key把這些級別繫結到queue上，這些queue就放這些級別的訊息
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("Wait for logs...")
# 6、使用method.routing_key可以得到訊息的級別
def callback(ch, method, properties, body):
    print("received:", method.routing_key, body)
channel.basic_consume(callback,
                      queue=queue_name,
                      no_ack=True)
channel.start_consuming()

執行過程：

'''
啟動訂閱者1： python subscriber.py info
啟動訂閱者2：python subscriber.py info error
啟動釋出者1：python publisher.py info hello
啟動釋出者2：python publisher.py error  servicesdown
訂閱者1收到訊息：hello
訂閱者2收到訊息：hello servicesdown
'''