Routing : Receiving messages selectively¶
Routing is an interesting concept in RabbitMQ/AMQP: in this tutorial, messages are published to a direct exchange with a specific routing_key (the log severity The consumer create a queue, binds the queue to the exchange and specifies the severity he wants to receive.
The publisher creater the direct exchange:
await channel.exchange(exchange_name='direct_logs', type_name='direct')
Message are published into that exchange and routed using the severity for instance:
await channel.publish(message, exchange_name='direct_logs', routing_key='info')
The consumer may subscribe to multiple severities. To accomplish this purpose, it create a queue bind this queue multiple time using the (exchange_name, routing_key) configuration:
result = await channel.queue(queue_name='', durable=False, auto_delete=True) queue_name = result['queue'] severities = sys.argv[1:] if not severities: print("Usage: %s [info] [warning] [error]" % (sys.argv,)) sys.exit(1) for severity in severities: await channel.queue_bind( exchange_name='direct_logs', queue_name=queue_name, routing_key=severity, )