RabbitMQ Routing 消息路由

  上篇文章中，我们构建了一个简单的日志系统。接下来，我们将丰富它：能够使用不同的severity来监听不同等级的log。比如我们希望只有error的log才保存到磁盘上。

1. Bindings绑定

    上篇文章中我们是这么做的绑定：

 

[python] view plain copy
 
print?
  1. channel.queue_bind(exchange=exchange_name,  
  2.                    queue=queue_name)  
channel.queue_bind(exchange=exchange_name,
                   queue=queue_name)

    绑定其实就是关联了exchange和queue。或者这么说：queue对exchagne的内容感兴趣，exchange要把它的Message deliver到queue中。

 

    实际上，绑定可以带routing_key 这个参数。其实这个参数的名称和basic_publish 的参数名是相同了。为了避免混淆，我们把它成为binding key。
    使用一个key来创建binding :

[python] view plain copy
 
print?
  1. channel.queue_bind(exchange=exchange_name,  
  2.                    queue=queue_name,  
  3.                    routing_key='black')  
channel.queue_bind(exchange=exchange_name,
                   queue=queue_name,
                   routing_key='black')

对于fanout的exchange来说，这个参数是被忽略的。

2. Direct exchange

  Direct exchange的路由算法非常简单：通过binding key的完全匹配，可以通过下图来说明。


    exchange X和两个queue绑定在一起。Q1的binding key是orange。Q2的binding key是black和green。
    当P publish key是orange时，exchange会把它放到Q1。如果是black或者green那么就会到Q2。其余的Message都会被丢弃。


3. Multiple bindings

      多个queue绑定同一个key是可以的。对于下图的例子，Q1和Q2都绑定了black。也就是说，对于routing key是black的Message，会被deliver到Q1和Q2。其余的Message都会被丢弃。

  

4. Emitting logs

首先是我们要创建一个direct的exchange：

 

[python] view plain copy
 
print?
  1. channel.exchange_declare(exchange='direct_logs',  
  2.                          type='direct')  
channel.exchange_declare(exchange='direct_logs',
                         type='direct')

我们将使用log的severity作为routing key，这样Consumer可以针对不同severity的log进行不同的处理。
publish：

 

 

[python] view plain copy
 
print?
  1. channel.basic_publish(exchange='direct_logs',  
  2.                       routing_key=severity,  
  3.                       body=message)  
channel.basic_publish(exchange='direct_logs',
                      routing_key=severity,
                      body=message)

我们使用三种severity：'info', 'warning', 'error'.

 

 

5. Subscribing

对于queue，我们需要绑定severity：

 

[python] view plain copy
 
print?
  1. result = channel.queue_declare(exclusive=True)  
  2. queue_name = result.method.queue  
  3.   
  4. for severity in severities:  
  5.     channel.queue_bind(exchange='direct_logs',  
  6.                        queue=queue_name,  
  7.                        routing_key=severity)  
result = channel.queue_declare(exclusive=True)
queue_name = result.method.queue

for severity in severities:
    channel.queue_bind(exchange='direct_logs',
                       queue=queue_name,
                       routing_key=severity)

 

 

6. 最终版本

The code for emit_log_direct.py:

 

[python] view plain copy
 
print?
  1. #!/usr/bin/env python  
  2. import pika  
  3. import sys  
  4.   
  5. connection = pika.BlockingConnection(pika.ConnectionParameters(  
  6.         host='localhost'))  
  7. channel = connection.channel()  
  8.   
  9. channel.exchange_declare(exchange='direct_logs',  
  10.                          type='direct')  
  11.   
  12. severity = sys.argv[1] if len(sys.argv) > 1 else 'info'  
  13. message = ' '.join(sys.argv[2:]) or 'Hello World!'  
  14. channel.basic_publish(exchange='direct_logs',  
  15.                       routing_key=severity,  
  16.                       body=message)  
  17. print " [x] Sent %r:%r" % (severity, message)  
  18. connection.close()  
#!/usr/bin/env python
import pika
import sys

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

channel.exchange_declare(exchange='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,
                      body=message)
print " [x] Sent %r:%r" % (severity, message)
connection.close()


The code for receive_logs_direct.py:

 

 

[python] view plain copy
 
print?
  1. #!/usr/bin/env python  
  2. import pika  
  3. import sys  
  4.   
  5. connection = pika.BlockingConnection(pika.ConnectionParameters(  
  6.         host='localhost'))  
  7. channel = connection.channel()  
  8.   
  9. channel.exchange_declare(exchange='direct_logs',  
  10.                          type='direct')  
  11.   
  12. result = channel.queue_declare(exclusive=True)  
  13. queue_name = result.method.queue  
  14.   
  15. severities = sys.argv[1:]  
  16. if not severities:  
  17.     print >> sys.stderr, "Usage: %s [info] [warning] [error]" % \  
  18.                          (sys.argv[0],)  
  19.     sys.exit(1)  
  20.   
  21. for severity in severities:  
  22.     channel.queue_bind(exchange='direct_logs',  
  23.                        queue=queue_name,  
  24.                        routing_key=severity)  
  25.   
  26. print ' [*] Waiting for logs. To exit press CTRL+C'  
  27.   
  28. def callback(ch, method, properties, body):  
  29.     print " [x] %r:%r" % (method.routing_key, body,)  
  30.   
  31. channel.basic_consume(callback,  
  32.                       queue=queue_name,  
  33.                       no_ack=True)  
  34.   
  35. channel.start_consuming()  
#!/usr/bin/env python
import pika
import sys

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

channel.exchange_declare(exchange='direct_logs',
                         type='direct')

result = channel.queue_declare(exclusive=True)
queue_name = result.method.queue

severities = sys.argv[1:]
if not severities:
    print >> sys.stderr, "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()

我们想把warning和error的log记录到一个文件中：

 

 

[python] view plain copy
 
print?
  1. $ python receive_logs_direct.py warning error > logs_from_rabbit.log  
$ python receive_logs_direct.py warning error > logs_from_rabbit.log

打印所有log到屏幕：

 

 

[python] view plain copy
 
print?
  1. $ python receive_logs_direct.py info warning error  
  2.  [*] Waiting for logs. To exit press CTRL+C  
$ python receive_logs_direct.py info warning error
 [*] Waiting for logs. To exit press CTRL+C

 

 

转载自： anzhsoft: http://blog.csdn.net/anzhsoft/article/details/19630147

参考资料：

1. http://www.rabbitmq.com/tutorials/tutorial-four-python.html

 
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posted on 2018-01-04 14:33  哎呦！不得了了  阅读(1096)  评论(0)  编辑  收藏  举报