I'm building a website that requires real-time communication and am using socket.io for that but am trying to make socket.io global. Have actually tried global.io (though it's not secure, just for testing purpose) but when I use this, I noticed I can't listen for event's using socket.emit maybe because it's a callback
const io = require('socket.io')(server);
io.on('connection', socket => {
console.log('connected')
})
Related
I want to build a microservice infrastructure with nodejs services and a master service, the communication between these services should happen via socket.io, i've setup my socket.io server, but their browser client (socket.io-client) is not working in nodejs (i guess it uses some browser only APIs). Is there a way to create a nodejs socket.io (NOT WEBSOCKETS) client?
EDIT
My client side code:
import { io } from "socket.io-client";
const socket = io("127.0.0.1:3000");
socket.on("connect", () => {
console.log(socket.id);
});
socket.on("disconnect", () => {
console.log(socket.id);
});
My server side code:
import { Server } from "socket.io";
const io = new Server();
io.on("connection", (socket) => {
console.log(socket)
});
io.listen(3000);
Both are written in typescript, the package versions are:
socket.io: ^4.4.0
socket.io-client: ^4.4.0
The Problem is, that i don't get any logs in my console, so i think there is something wrong with client, because socket.io does not mention node in there client side compatiblity graph.
The problem is that you have to pass a valid URL here:
const socket = io("127.0.0.1:3000");
I have no idea why socket.io doesn't give you an error, but if you change that to:
const socket = io("http://127.0.0.1:3000");
Then, it will work.
If you set DEBUG=socket.io-client in your environment, it won't show you an error, but it will show you that it's trying to connect to:
undefined//127.0.0.1:3000
which would give you a clue, I guess.
If you set DEBUG=* in your environment, you will get a lot more debug info (so much that it's a bit hard to sort through).
Set Logging and Debugging Socket.io for more info.
On another terminal,
$curl localhost:3001
However, on nodejs server side,
I never saw
"sdfsdf" for
console.log("sdfsdf");
Questions
1 Can some expert explain why?
2 How to fix it to make 'connect' callback triggered?
Thank you.
var express = require('express'),
http = require('http')
var app = express();
var server = http.createServer(app);
//var server = http.Server(app);
//server.listen(app.get('port'), function () {
server.listen(3001, function () {
//logger.info('openHAB-cloud: express server listening on port ' + app.get('port'));
console.log("3001");
});
app.get('/', function(req, res){
//res.sendfile('index.html');
res.send("xxx");
});
io = require('socket.io').listen(server);
io.on('connection', function(socket) {
console.log("sdfsdf");
});
To connect to a socket.io server, you must use a socket.io client - you cannot just use a regular curl or http request.
A socket.io client must be specifically designed to connect to a socket.io server. That means it uses the socket.io message format on top of webSocket and it follows the proper convention that socket.io and webSocket use for connecting.
Here are some client-side examples: https://socket.io/docs/client-api/
The connection can be made either from browser Javascript with the appropriate socket.io library included or using any socket.io client-side library from some other Javascript environment.
To see a bit how webSocket connections (which socket.io uses), you may want to read this: How does WebSockets server architecture work?. And then, socket.io adds its own message layer on top of webSockets.
const io = require('socket.io-client');
const socket = io('http://localhost:3001');
I made a basic chat app using node.js, express and socket.io. It's not too different from the tutorial chat app for socket.io, it simply emits events between connected clients. When I ran it on port 3001 on my server, it worked fine.
Then I made a proxy server app using node-http-proxy which listens on port 80 and redirects traffic based on the requested url to various independent node apps I have running on different ports. Pretty straightforward. But something is breaking. Whenever anyone disconnects, every single socket dis- and re-connects. This is bad for my chat app, which has connection-based events. The client consoles all show:
WebSocket connection to 'ws://[some socket info]' failed: Connection closed before receiving a handshake response
Here's what I think are the important parts of my code.
proxy-server.js
var http = require('http');
var httpProxy = require('http-proxy');
//create proxy template object with websockets enabled
var proxy = httpProxy.createProxyServer({ws: true});
//check the header on request and return the appropriate port to proxy to
function sites (req) {
//webapps get their own dedicated port
if (req == 'mychatwebsite.com') {return 'http://localhost:3001';}
else if (req == 'someothersite.com') {return 'http://localhost:3002';}
//static sites are handled by a vhost server on port 3000
else {return 'http://localhost:3000';}
}
//create node server on port 80 and proxy to ports accordingly
http.createServer(function (req, res) {
proxy.web(req, res, { target: sites(req.headers.host) });
}).listen(80);
chat-app.js
/*
...other modules
*/
var express = require("express");
var app = exports.app = express(); //I probably don't need "exports.app" anymore
var http = require("http").Server(app);
var io = require("socket.io")(http);
io.on("connection", function (socket) {
/*
...fun socket.on and io.emit stuff
*/
socket.on("disconnect", function () {
//say bye
});
});
http.listen(3001, function () {
console.log("listening on port 3001");
});
Now from what I've read on socket.io's site, I might need to use something to carry the socket traffic through my proxy server. I thought that node-http-proxy did that for me with the {ws: true} option as it states in their docs, but apparently it doesn't work like I thought it would. socket.io mentions three different things:
sticky session based on node's built in cluster module
socket.io-redis, which allows separate socket.io instances to talk to each other
socket.io-emitter, which allows socket.io to talk to non-socket.io processes
I have exactly no idea what any of this means or does. I am accidentally coding way above my skill level here, and I have no idea which of these tools will solve my problem (if any) or even what the cause of my problem really is.
Obligatory apology: I'm new to node.js, so please forgive me.
Also obligatory: I know other apps like nginx can solve a lot of my issues, but my goal is to learn and understand how to use this set of tools before I go picking up new ones. And, the less apps I use, the better.
I think your intuition about needing to "carry the socket traffic through" the proxy server is right on. To establish a websocket, the client makes an HTTP request with a special Upgrade header, signalling the server to switch protocols (RFC 6455). In node, http.Server instances emit an upgrade event when this happens and if the event is not handled, the connection is immediately closed.
You need to listen for the upgrade event on your http server and handle it:
var proxy = httpProxy.createProxyServer({ws: true})
var http = http.createServer(/* snip */).listen(80)
// handle upgrade events by proxying websockets
// something like this
http.on('upgrade', function (req, socket, head) {
proxy.ws(req, socket, head, {target:sites(req.headers.host)})
})
See the node docs on the upgrade event and the node-http-proxy docs for more.
Using node and express, the below works just fine.
var app = express();
app.listen(app.get('port'), function() {
});
I assume that a server is created implicitly in the above construct.
When adding socket.io, I've seen the following being done.
var app = express();
var server = http.createServer(app);
var io = require('socket.io').listen(server);
app.listen(app.get('port'), function() {
});
What is the need for explicitly adding http.createServer(app) ? Won't the creation of an additional server mess up things ? Or put it other way, is it ok to create many more http.createServer(app) ?
In either case, only one server is created. When using socket.io, you share the same http server between socket.io and express. Both libraries attach event listeners to the same server and have a chance to respond to the same events. They cooperate nicely because socket.io only handles relevant requests and express handles all the non-websocket requests. And just FYI you could not create more than one server on the same port. Only one process can listen on a TCP port at a time in the OS, so the second one would fail with an error when attempting to bind an in-use port.
I am newbie about Meteor.
I am developing a realtime multiplayer game. I want to implement everything about the game but game engine states with Meteor. For example chat messages, available game rooms, invitations, online members etc. I want to make those functionalities withMeteor.
But I want to implement game states manually without Meteor with socket.io. Because, the game is real time and every 45 msec(in my architecture), game states will be streaming to the clients and I think Meteor is not for this and not flexiable. So I developed multiplayer concept and synchronising clients and server with socket.io. There is no problem about it.
I want to use Meteor and socket.io both and together. I tried to implement it. I installed socket.io with npm inside .meteor/local/build/programs/server/app under my meteor app. After that I include require statement on server side Meteor startup;
Meteor.startup(function () {
var require = Npm.require;
var sio = require('socket.io')
var socketIO = sio.listen(this.http)
socketIO.configure(function () {
socketIO.set('log level', 0);
socketIO.set('authorization', function (handshakeData, callback) {
callback(null, true); // error first callback style
});
socketIO.set("transports", ["xhr-polling"]);
socketIO.set("polling duration", 30);
});
socketIO.sockets.on('connection', function (client) {
console.log(client.id + ' is connected')
client.on('disconnect', function () {
console.log(client.id + ' is diconnected')
});
})})
And I put the connection statement on client side Meteor startup;
Meteor.startup(function () {
socket = io.connect();
socket.on('connect', function () {
console.log('connecting');
});
})
On client side, io variable is not defined error is occurred. This is seen to me that,Meteor does not import client side socket.io.js on client side. So I tried to put socket.io.js manually under clients folder to load it on client side. This is not good way I know, I should not do this. But, even I do and client loads it, there is another client side error about transport variable of io for the statement;
io.transports.push('xhr-polling');
It says that Uncaught TypeError: Cannot call method 'push' of undefined. Somehow, client side socket.io.js can not be loaded properly.
I could not find an example for usage of Meteor and socket.io together. Is there a simple way to use them both together?
Thank you!