AMQP: Use exchange instead of queue for discovery

References msgflo/msgflo#13

src/amqp.coffee

@@ -2,6 +2,7 @@
 debug = require('debug')('msgflo:amqp')
 async = require 'async'
 interfaces = require './interfaces'
+uuid = require 'uuid'
 
 try
   amqp = require 'amqplib/callback_api'
@@ -144,10 +145,12 @@ class Client extends interfaces.MessagingClient
       protocol: 'discovery'
       command: 'participant'
       payload: part
-    @channel.assertQueue 'fbp'
-    data = new Buffer JSON.stringify msg
-    @channel.sendToQueue 'fbp', data
-    return callback null
+    topic = 'fbp'
+    @channel.assertExchange topic, 'fanout', (err) ->
+      return callback err if err
+      data = new Buffer JSON.stringify msg
+      @channel.publish topic, data
+      return callback null
 
 class MessageBroker extends Client
   constructor: (address, options) ->
@@ -221,9 +224,13 @@ class MessageBroker extends Client
         data: data
       return handler out
 
-    @channel.assertQueue 'fbp'
-    @channel.consume 'fbp', deserialize
-    return callback null
+    @channel.assertExchange 'fbp', 'fanout', {}, (err) =>
+      return callback err if err
+      subscribeQueue = '.fbp-subscribe-' + uuid.v4()
+      @channel.assertQueue subscribeQueue, { persistent: false }, (err) =>
+        return callback err if err
+        @channel.consume subscribeQueue, deserialize
+        return callback null
 
 exports.Client = Client
 exports.MessageBroker = MessageBroker