Routing

In this example we us a direct exchange to route specific types of messages to specific queues. A direct exchange named “direct_logs” is created. When subscribers come oneline they register with the direct exchange for specific types of messages.

In this example, each subscriber to can register for one of the following severity levels: info, warning or error.

This allows subscribers to select which types of message they wish to process based on a routing key (info, warning, error).

This time when you start the subscriber, you will need to specify the routing key to bind to.

λ ruby lib/4-routing/subscribe.rb warning
 [*] Waiting for logs. To exit press CTRL+C
 [x] warning:blah

When you publish a message you will need to specify the routing key to use or else it will default to ‘info’.

λ ruby lib/4-routing/publish.rb error blah
 [x] Sent 'blah'

In the above example the routing key ’error’ was used. So that message will not be delivered to our subscriber that was bound the to ‘warning’ routing key.

To deliver a message to the subscriber of the ‘warning’ routing key we need to send a message using the ‘warning’ routing key.

λ ruby lib/4-routing/publish.rb warning 'no need for alarm'
 [x] Sent 'blah'