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+# [Publish/Subscribe](http://www.rabbitmq.com/tutorials/tutorial-three-ruby.html)
+
+In this example we use a fanout exchange to deliver a single message to
+multiple queues. This allows multiple services to subscribe to a single
+fanout exchange and all receive the same message. This type of setup can be very useful for a
+[CQRS](http://martinfowler.com/bliki/CQRS.html) style architecture.
+
+This example uses a named fanout exchange called "logs". The queue that
+is used to bind to the exchange does not have a name so RabbitMQ will
+generate a unique name for the queue.
+
+When a message is published to the exchange. The message will be
+delivered to each subscriber queue. In this example the subscriber
+queues are not durable, so the messages will be available in memory
+until they are either processed or the server is restarted.
+
+This allows subscribers to come online and "subscribe" to live messages
+from the fanout exchange, then disconnect whenever they like without
+affecting other services.
+
+You can run as many subscribers as you like by starting a new shell and
+running:
+
+```bash
+λ ruby lib/3-pubsub/subscriber.rb 
+ [*] Waiting for logs. To exit press CTRL+C
+```
+
+When you send a message using the publisher. That message will be
+delivered to all subscribers at once.
+
+```bash
+λ ruby lib/3-pubsub/publish.rb 
+ [x] Sent Hello World!
+```