Node.js + socket.io + node-amqp and queue binginds when "re" connecting thru socket.io - rabbitmq

Question

I have one scenario which is very close to this sample:
One main screen:
this screen (client side) will connect to the socket.io server thru server:9090/scope (io.connect("http://server:9090/scope)) and will send one event "userBindOk" (socket.emit("userBindOk", message)) to the socket.io server;
the server receives the connection and the "userBindOk". At this moment, the server should get the active connection to rabbitmq server and bind the queue to the respective user that just connected to the application thru socket.io. sample:
socket.on("connection", function(client){
//client id is 1234
// bind rabbitmq exchange, queue, and:
queue.subscribe(//receive callback);
})
So far, no problem - I can send/receive messages thru socket.io without problems.
BUT, If I refresh the page, all those steps will be done again. As consequence, the binding to the queue will occur, but this time related to another session of the socket.io client. This means that if I send a message to the queue which is related to the first socket.io session (before the page refresh), that bind should (I think) receive the message and send it to a invalid socket.io client (page refresh = new client.id on the socket.io context). I can prove this behaviour because every time I refresh the page I need to send x times more messages. For instance: I`ve connected for the first time: - so, 1 message - one screen update; refresh the page: I need to send 2 messages to the queue and only the second message will be received from the "actual" socket.io client session - this behaviour will occur as many as I refresh the page (20 page refreshs, 20 messages to be sent to a queue and the server socket.io "last" client will send the message to the client socket.io to render into the screen).
The solutions I believe are:
Find a way to "unbind" the queue when disconnecting from the socket.io server - I didn`t see this option at the node-amqp api yet (waiting for it :D)
find a way to reconnect the socket.io client using the same client.id. This way I can identify the client that is coming and apply some logic to cache the socket.
Any ideas? I tried to be very clear... But, as you know, it`s not so eaey to expose your problem when trying to clarify something that is very specific to some context...
tks

Answer 1

I solved it like this:
I used to declare the rabbitMq queue as durable=true,autoDelete=false,exclusive=false and in my app there was 1 queue/user and 1 exchange(type=direct) with the routing_key name=queueName, my app also used the queue for other client diffent to browsers like android app or iphone app as push fallback, so i use to crear 1 queue for earch user.
The solution to this problem was to change my rabbitMQ queue and exchange declaration. Now i declare the exchange/user as fanout and autoDelete=True, and the user is going to have N queues with durable=true, autoDelete=true, exclusive=true (No. queue = No. clients) and all the queues are bind to the user-exchange(multicast).
NOTE: my app is wirten in django, and i use node+socket+amqp to be able to comunicate with the browser using web.scokets, so i use node-restler to query my app api to get the user-queue info.
thats the rabbitMQ side, for the node+amqp+socket i did this:
server-side:
onConnect: the declaration of the user exchange as fanout, autoDelete, durable. then declaration of the queue as durable, autodelete and exclusive, then the queue.bind to the user-exchange and finaly the queue.subscribe and the socket.disconnect will destroy the queue so there are going to exist queue as client connected the app and this solve the problem of the refresh and allow the user to have more than 1 window-tab with the app:
Server-side:
/*
* unCaught exception handler
*/
process.on('uncaughtException', function (err) {
sys.p('Caught exception: ' + err);
global.connection.end();
});
/*
* Requiere libraries
*/
global.sys = require('sys');
global.amqp = require('amqp');
var rest = require('restler');
var io = require('socket.io').listen(8080);
/*
* Module global variables
*/
global.amqpReady = 0;
/*
* RabbitMQ connection
*/
global.connection = global.amqp.createConnection({
host: host,
login: adminuser,
password: adminpassword,
vhost: vhost
});
global.connection.addListener('ready',
function () {
sys.p("RabbitMQ connection stablished");
global.amqpReady = 1;
}
);
/*
* Web-Socket declaration
*/
io.sockets.on('connection', function (socket) {
socket.on('message', function (data) {
sys.p(data);
try{
var message = JSON.parse(data);
}catch(error){
socket.emit("message", JSON.stringify({"error": "invalid_params", "code": 400}));
var message = {};
}
var message = JSON.parse(data);
if(message.token != undefined) {
rest.get("http://dev.kinkajougames.com/api/push",
{headers:
{
"x-geochat-auth-token": message.token
}
}).on('complete',
function(data) {
a = data;
}).on('success',
function (data){
sys.p(data);
try{
sys.p("---- creating exchange");
socket.exchange = global.connection.exchange(data.data.bind, {type: 'fanout', durable: true, autoDelete: true});
sys.p("---- declarando queue");
socket.q = global.connection.queue(data.data.queue, {durable: true, autoDelete: true, exclusive: false},
function (){
sys.p("---- bind queue to exchange");
//socket.q.bind(socket.exchange, "*");
socket.q.bind(socket.exchange, "*");
sys.p("---- subscribing queue exchange");
socket.q.subscribe(function (message) {
socket.emit("message", message.data.toString());
});
}
);
}catch(err){
sys.p("Imposible to connection to rabbitMQ-server");
}
}).on('error', function (data){
a = {
data: data,
};
}).on('400', function() {
socket.emit("message", JSON.stringify({"error": "connection_error", "code": 400}));
}).on('401', function() {
socket.emit("message", JSON.stringify({"error": "invalid_token", "code": 401}));
});
}
else {
socket.emit("message", JSON.stringify({"error": "invalid_token", "code": 401}));
}
});
socket.on('disconnect', function () {
socket.q.destroy();
sys.p("closing socket");
});
});
client-side:
The socket intance with options 'force new connection'=true and 'sync disconnect on unload'= false.
The client side use the onbeforeunload and onunload windows object events to send socket.disconnect
The client on socket.connect event send the user token to node.
proces message from socket
var socket;
function webSocket(){
//var socket = new io.Socket();
socket = io.connect("ws.dev.kinkajougames.com", {'force new connection':true, 'sync disconnect on unload': false});
//socket.connect();
onSocketConnect = function(){
alert('Connected');
socket.send(JSON.stringify({
token: Get_Cookie('liveScoopToken')
}));
};
socket.on('connect', onSocketConnect);
socket.on('message', function(data){
message = JSON.parse(data);
if (message.action == "chat") {
if (idList[message.data.sender] != undefined) {
chatboxManager.dispatch(message.data.sender, {
first_name: message.data.sender
}, message.data.message);
}
else {
var username = message.data.sender;
Data.Collections.Chats.add({
id: username,
title: username,
user: username,
desc: "Chat",
first_name: username,
last_name: ""
});
idList[message.data.sender] = message.data.sender;
chatboxManager.addBox(message.data.sender, {
title: username,
user: username,
desc: "Chat",
first_name: username,
last_name: "",
boxClosed: function(id){
alert("closing");
}
});
chatboxManager.dispatch(message.data.sender, {
first_name: message.data.sender
}, message.data.message);
}
}
});
}
webSocket();
window.onbeforeunload = function() {
return "You have made unsaved changes. Would you still like to leave this page?";
}
window.onunload = function (){
socket.disconnect();
}
And that's it, so no more round-robing of the message.