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# RabbitMQ Random Exchange Type
This exchange type is for load-balancing among consumers. It's basically
a direct exchange, with the exception that, instead of each consumer bound
to that exchange with the same routing key getting a copy of the message,
the exchange type randomly selects a queue to route to.
There is no weighting or anything, so maybe load "balancing" might be a bit
of a misnomer. It uses Erlang's crypto:rand_uniform/2 function, if you're
interested.
## Installation
This plugin ships with RabbitMQ. Like all other plugins, it must be enabled
before it can be used:
```bash
[sudo] rabbitmq-plugins enable rabbitmq_random_exchange
```
## Usage
To create a _random_, just declare an exchange providing the type `"x-random"`.
```java
channel.exchangeDeclare("logs", "x-random");
```
and bind several queues to it. Routing keys will be ignored by modern releases
of this exchange plugin: the binding and its target queue (exchange) are picked
entirely randomly.
### Extended Example
This example uses [Bunny](http://rubybunny.info) and demonstrates
how the plugin is mean to be used with 3 queues:
``` ruby
#!/usr/bin/env ruby
require 'bundler'
Bundler.setup(:default)
require 'bunny'
c = Bunny.new; c.start
ch = c.create_channel
rx = ch.exchange("x.rnd", durable: true, type: "x-random")
q1 = ch.queue("r1").bind(rx)
q2 = ch.queue("r2").bind(rx)
q3 = ch.queue("r3").bind(rx)
ch.confirm_select
100.times do
rx.publish(rand.to_s, routing_key: rand.to_s)
end
ch.wait_for_confirms
# the consumer part is left out: see
# management UI
puts "Done"
```
## License
See [LICENSE](./LICENSE).
|
