RABBITMQ EXCHANAGE --TOPIC

上一篇博文我们队exchange的direct type进行了测试，但是用户的需求总是在变化，上述在对消息进行路由的时候

通过message的basic_publish  routing_key参数是否匹配queue_bind的routing_key来决定消息到deliver到

那一个queue。

但是当用户的两个key不能够完全枚举的时候我们该怎么办呢，

dev1_info

dev2_info

...

dev1_warning

dev2_warning

...

dev1_error

dev1_error

...

这时候，通过直接bind，

看起来就不在可行？那该怎么办？这时候topic就要隆重出场了

exchange是通过支持模式来实现功能增强的。其中

* (star) can substitute for exactly one word.

# (hash) can substitute for zero or more words.

这样在bind的时候我们可以有更多的选择

如下的消息模式".."

Q1 is bound with binding key "*.orange.*" 

and Q2 with "*.*.rabbit" 

Q1 is interested in all the orange animals.

Q2 wants to hear everything about rabbits, and everything about lazy animals.

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

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

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)
connection.close()

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

connection = pika.BlockingConnection(pika.ConnectionParameters(
        host='localhost'))
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.stderr, "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()

CONSOLE 1

H:\mq>topic_send.py  "kern.critical" "A critical kernel error"

 [x] Sent 'kern.critical':'A critical kernel error'

CONSOLE2

H:\mq>topic_receiver.py "#"

 [*] Waiting for logs. To exit press CTRL+C

 [x] 'kern.critical':'A critical kernel error'

CONSOLE3

H:\mq>topic_receiver.py   "*.critical"

 [*] Waiting for logs. To exit press CTRL+C

 [x] 'kern.critical':'A critical kernel error'

CONSOLE 4 

H:\mq>topic_receiver.py  "kern.*"

 [*] Waiting for logs. To exit press CTRL+C

 [x] 'kern.critical':'A critical kernel error'

 可以看到的通过不同的bind方式，我们可以对自己感兴趣的消息进行bind，并rout到不同的message  queue。

 REF: