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POAMQP creating subscribing to queues dynamically
 

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    <p>I am trying to build a simple chat application using AMQP, Websockets and Ruby. I understand that this may not be the best use-case to understand AMQP but I would like to understand where i am going wrong. </p> <p>The following is my amqp-server code</p> <pre><code>require 'rubygems' require 'amqp' require 'mongo' require 'em-websocket' require 'json' class MessageParser # message format =&gt; "room:harry_potter, nickname:siddharth, room:members" def self.parse(message) parsed_message = JSON.parse(message) response = {} if parsed_message['status'] == 'status' response[:status] = 'STATUS' response[:username] = parsed_message['username'] response[:roomname] = parsed_message['roomname'] elsif parsed_message['status'] == 'message' response[:status] = 'MESSAGE' response[:message] = parsed_message['message'] response[:roomname] = parsed_message['roomname'].split().join('_') end response end end class MongoManager def self.establish_connection(database) @db ||= Mongo::Connection.new('localhost', 27017).db(database) @db.collection('rooms') @db end end @sockets = [] EventMachine.run do connection = AMQP.connect(:host =&gt; '127.0.0.1') channel = AMQP::Channel.new(connection) puts "Connected to AMQP broker. #{AMQP::VERSION} " mongo = MongoManager.establish_connection("trackertalk_development") EventMachine::WebSocket.start(:host =&gt; '127.0.0.1', :port =&gt; 8080) do |ws| socket_detail = {:socket =&gt; ws} ws.onopen do @sockets &lt;&lt; socket_detail end ws.onmessage do |message| status = MessageParser.parse(message) exchange = channel.fanout(status[:roomname].split().join('_')) if status[:status] == 'STATUS' queue = channel.queue(status[:username], :durable =&gt; true) unless queue.subscribed? puts "--------- SUBSCRIBED --------------" queue.bind(exchange).subscribe do |payload| puts "PAYLOAD : #{payload}" ws.send(payload) end else puts "----ALREADY SUBSCRIBED" end # only after 0.8.0rc14 #queue = channel.queue(status[:username], :durable =&gt; true) #AMQP::Consumer.new(channel, queue) elsif status[:status] == 'MESSAGE' puts "********************* Message- published ******************************" exchange.publish(status[:message) end end ws.onclose do @sockets.delete ws end end end </code></pre> <p>I use the status to indicate whether the incoming message is a message for ongoing chat or for a status message requiring me to handle chores like subscribing to the queue. </p> <p>The problem i face is that when I send a message like <code>socket.send(JSON.stringify({status:'message', message:'test', roomname:'Harry Potter'}))</code></p> <p>The <code>exchange.publish' is called but it still doesn't get pushed via the</code>ws.send` to the browser.</p> <p>Is there something fundamentally wrong with my understanding of EventMachine and AMQP? </p> <p>Here is the pastie for the same code <a href="http://pastie.org/private/xosgb8tw1w5vuroa4w7a" rel="nofollow">http://pastie.org/private/xosgb8tw1w5vuroa4w7a</a></p> <p>My code seems to work as desired when i remove the <code>durable =&gt; true</code> from <code>queue = channel.queue(status[:username], :durable =&gt; true)</code></p> <p>The following is a snippet of my Rails view which identifies the user's username and the roomname and sends it as part of message via Websockets.</p> <p>Though the code seems to work when i remove the <code>durable =&gt; true</code> I fail to understand why that affects the message being delivered. Please Ignore the mongo part of as it does not play any part yet.</p> <p>I would also like to know if my approach to AMQP and its usage is correct</p> <pre><code>&lt;script&gt; $(document).ready(function(){ var username = '&lt;%= @user.email %&gt;'; var roomname = 'Bazingaa'; socket = new WebSocket('ws://127.0.0.1:8080/'); socket.onopen = function(msg){ console.log('connected'); socket.send(JSON.stringify({status:'status', username:username, roomname:roomname})); } socket.onmessage = function(msg){ $('#chat-log').append(msg.data); } }); &lt;/script&gt; &lt;div class='block'&gt; &lt;div class='content'&gt; &lt;h2 class='title'&gt;&lt;%= @room.name %&gt;&lt;/h2&gt; &lt;div class='inner'&gt; &lt;div id="chat-log"&gt; &lt;/div&gt; &lt;div id="chat-console"&gt; &lt;textarea rows="5" cols="40"&gt;&lt;/textarea&gt; &lt;/div&gt; &lt;/div&gt; &lt;/div&gt; &lt;/div&gt; &lt;style&gt; #chat-log{ color:#000; font-weight:bold; margin-top:1em; width:900px; overflow:auto; height:300px; } #chat-console{ bottom:10px; } textarea{ width:100%; height:60px; } &lt;/style&gt; </code></pre>
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    1. COCould someone also tell me how to organize my code in the production environment if I were to run my amqp code as a daemon. Any sample code that'll help me organize my code will be of great help.
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