I am diving into the world of node.js for the first time and seeking some guidance:
Here are the programs I have installed on my server:
- node.js v0.11.3-pre
- express v3.3.4
- socket.io v0.9.14
- connect-redis v1.4.5
- Redis server v=2.6.14
- redis-cli 2.6.14
To begin, I created an express app:
express testApplication
In the generated "package.json" file, I specified all the necessary dependencies.
Right from the start, I established a cluster for vertical scaling (multiple processes) in a file named "cluster.js":
var cluster = require('cluster');
if( cluster.isMaster ) {
var numOfWorkers = process.env.NODE_WORKERS || require('os').cpus().length;
console.log("Workers found: " + numOfWorkers);
for (var i = 0; i < numOfWorkers; i += 1) {
cluster.fork();
}
} else {
require('./app.js');
}
cluster.on('exit', function(worker, code, signal) {
var exitCode = worker.process.exitCode;
console.log('worker' + worker.process.pid + ' died (' + exitCode + '). restarting...');
if( typeof cluster.workers[worker.id] != "undefined" )
cluster.workers[worker.id].delete();
cluster.fork();
});
In my "app.js" file, I configured REDIS for storing socket.io information:
io.set('store', new RedisStore({
redisPub: pub,
redisSub: sub,
redisClient: client
}));
Everything is running smoothly so far.
When a client connects to the socket.io server, the cluster manages the connections with different workers.
My goal is to enable clients to send messages to particular individuals. This involves storing all socket ids for every user in an array, then selecting the relevant socket ids when sending a message by retrieving the sockets using those ids.
This method works well for a single-server socket.io application. Now, I aim to set up another server with identical programs, modules, and packages. Load balancing will likely be facilitated by HAProxy. Consequently, socket.io connections will be managed between Server A and Server B.
Illustrative scenario:
User A connects to Server A, while User B connects to Server B. User A's socket resides on Server A and User B's socket on Server B.
How can the application recognize that it needs to find User B's socket on Server B to dispatch the message? It won't locate the socket on Server A as it was created on Server B.
Thank you very much!