ZeroMQ: How to notify a Publisher from a Subscriber - node.js

Question

I use PUB/SUB ZeroMQ pattern.
System consists from Web Server ( Publisher ), clustered TCP servers ( Subscribers ) and external applications ( clients, which connect to TCP servers ).
Huge amount of external clients connect to every TCP server. Every external client has unique peerId which I use as topic in Publisher. For some management purposes I send messages to TCP servers ( like remove peer, change, etc. ). But also I need to send messages from TCP server to Web Server ( connect, disconnect, error ). I didn't find right way how to do it. Can anybody suggest how to do it correctly?
Update 1
It looks like using ROUTER/DEALER pattern is the most convenient for that.
Some comments about scripts.
External clients connect to tcp servers ( cluster ) and send unique peerId, on tcp server side tcp socket cached by unique peerId. Then tcp server sends peerId message by ZeroMQ socket to Web Server. Web Server caches envelope by peerId. Every n milliseconds Web Server sends messages to random peer ( generate 'peerId' ). TCP Server receives these messages, gets correct tcp socket from cache and sends theirs to clients. Clients calculate count of messages and every n milliseconds send their to TCP server, which sends count to WEB Server by ZeroMQ socket. On Web Server every n milliseconds count of sended and received messages are printed on console.
Test js script of server part:
var cluster = require('cluster'),
zmq = require('zmq'),
net = require('net'),
zmqport = 'tcp://127.0.0.1:12345';
var count = 10;
var countPeers = 10000;
var interval = 1;
if (cluster.isMaster) {
for (var i = 0; i < count; i++) cluster.fork({
TCP_SERVER: 1
});
cluster.fork({
WEB_SERVER: 1
});
cluster.on('death', function (worker) {
console.log('worker ' + worker.pid + ' died');
});
} else {
if (process.env.TCP_SERVER) {
var sockets = Object.create(null);
var socket = zmq.socket('dealer');
socket.identity = 'process-' + process.pid;
socket.connect(zmqport);
socket.on('message', function (peerIdBuffer) {
var peerId = peerIdBuffer.toString();
if (typeof sockets[peerId] !== 'undefined') {
var buffer = new Buffer(4);
buffer.writeUInt32BE(1, 0);
sockets[peerId].write(buffer);
}
});
var server = net.createServer(function (tcpsocket) {
tcpsocket.on('data', function (data) {
if (!tcpsocket.peerId) {
var peerId = data.toString();
sockets[peerId] = tcpsocket;
tcpsocket.peerId = peerId;
return socket.send(['id', data]);
}
return socket.send(['count', data]);
});
});
server.listen('13333', '0.0.0.0');
} else {
var countMessagesSended = 0;
var countMessagesReceived = 0;
var socket = zmq.socket('router');
var clients = Object.create(null);
socket.bind(zmqport, function (err) {
if (err) throw err;
setInterval(function () {
for (var i = 0; i < countPeers; i++) {
var topic = Math.floor(Math.random() * countPeers) + '-peer';
if (typeof clients[topic] !== 'undefined') {
countMessagesSended++;
socket.send([clients[topic], topic]);
}
}
}, interval);
});
socket.on('message', function (envelope, messageId, data) {
switch (messageId.toString()) {
case "id":
clients[data.toString()] = envelope.toString();
break;
case "count":
countMessagesReceived += data.readUInt32BE(0);
break;
}
});
setInterval(function () {
console.log('%s messages have been sended, %s - received', countMessagesSended, countMessagesReceived);
countMessagesSended = 0;
countMessagesReceived = 0;
}, 5000);
}
}
Test js script for clients:
var cluster = require('cluster'),
net = require('net');
var count = 10;
if (cluster.isMaster) {
for (var i = 0; i < count; i++) cluster.fork({
CLUSTER: i
});
cluster.on('death', function (worker) {
console.log('worker ' + worker.pid + ' died');
});
} else {
var clientspernode = 1000;
var offset = parseInt(process.env.CLUSTER, 10);
for (var j = (offset) * clientspernode; j < (offset + 1) * clientspernode; j++) {
(function (j) {
var countMessages = 0;
var client = net.connect({
port: 13333,
host: '127.0.0.1'
}, function () {
client.write(j + '-peer');
});
client.on('data', function (buffer) {
countMessages += Math.ceil(buffer.length / 8);
});
client.on('error', function () {
});
setInterval(function () {
var buf = new Buffer(4);
buf.writeUInt32BE(countMessages, 0);
client.write(buf);
countMessages = 0;
}, 5000);
})(j);
}
}