RabbitMQ

Direct exchange

在此设置中，我们可以看到绑定了两个队列的直接交换X。第一个队列由绑定键orange绑定，第二个队列有两个绑定，一个绑定键为black，另一个绑定为green。

在这样的设置中，使用路由键orange发布到交换机的消息 将被路由到队列Q1。路由键为black 或green的消息将转到Q2。所有其他消息将被丢弃。

Multiple bindings

 用相同的routing_key绑定多个队列是完全合法的。在我们的示例中，我们可以使用绑定键black在X和Q1之间添加绑定。

在这种情况下，直接交换的行为将类似于fanout，并将消息广播到所有匹配的队列。带有black路由键的消息将同时传递到 Q1和Q2。

Putting it all together

send.py

#!/usr/bin/env python
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()

receive.py

#!/usr/bin/env python
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(queue='', 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(
    queue=queue_name, on_message_callback=callback, auto_ack=True)

channel.start_consuming()