So, I am trying to get data on my node.js file instead of directly getting it on my JS file.
I a using Socket.io 2 here, Below is a snapshot of my code and this is also the first time I am using Websocket with Node.
I am doing something like
var socket = require('socket.io')
//Home Page
app.get("/", function(req, res) {
var cryto = io.connect("https://xyfz.com/);
cryto.on('trades', function (tradeMsg) {
console.log(tradeMsg);
});
res.render("index");
});
I also tried something like
var io = socket("https://abc.io/");
and
var socket = require('socket.io')
var io = socket();
which was throwing errors like server.listeners is not a function and io.connect is not a function.
I am certain that I messing up stuff here so can someone guide me about the correct way of doing it?
Two things which are wrong .
First Consider using Socket.io-client instead of Socket.io.
Second and very much important.
Never ever make API calls inside your routes. This will trigger a API call everytime user opens your website or webpage
You can also expect an error "Unexpected headers" or something like that.
Always, Try do declare it outside any routes in your NodeAPP.
Same goes for socket.io as well
Related
I have a proprietary math formula written in a javascript function that I need to make available for a website to use it without them actually having access to the code itself.
Is it possible?
The idea is to make the formula available online without people being able to read the code. I have no idea how to do it.
I read about private packages on npm, but it seems to restrict prople who can use and read the code. I need them to use it but not read it.
If the code is run on the client's machine in any way, it will be possible for any sufficient dedicated and persistent user to find it, eventually; all code that runs on a page can be found through the browser devtools.
The only way for true privacy for such a thing would be to not send the code that implements the formula to the client in the first place. Set up a server, if you don't already have one, and create a very simple API for it - one that takes the inputs for the formula as, say, a POST request, runs the formula that calculates the result on the server, and responds to the client with the result.
Use node.js to create an express server that listens for incoming requests and then send back the result to the client in the response
const express = require('express');
const app = express();
function proprietaryFormula(x, y) {
// the formula goes here
return x + y;
}
app.get('/formula', (req, res) => {
let x = req.query.x;
let y = req.query.y;
let result = proprietaryFormula(x, y);
res.send(result);
});
app.listen(3000, () => {
console.log('started listening on port 3000');
});
The website can call this API to access the formula's functionality, and the code for the formula is kept on the server and never exposed to the client-side.
I am working with NodeJs with expressjs and I would like to use a middleware that will read a variable from dynamic configuration file before each request (some js file that holds an object that I can change manually while the server is running).
I would like to store a flag that will close down all requests (i.e send response without proceeding to next routes) until I change the variable value to true and then the middleware will call next() so all routes will work.
I prefer to avoid shutting down the server for that, and I also don't want to store this variable in a database...
Is there something similar to what I need?
Thanks
You will read config.json file each time, if you just put it inside function. If you will use require('config.json), then you will read this file only once on start.
var fs = require("fs");
function (req,res,next) {
var config = fs.readFileSync('./config.json');
config = JSON.parse(config.toString());
if (config.registrationStatus === "open") {
next();
} else {
res.send("registration closed");
}
}
Check supervisor: https://github.com/petruisfan/node-supervisor
It will watch for file changes and crashes and will restart your application each time.
You will get much better performance.
I have a MEAN app setup with npm socket.io with expressjs and btford.socket-io on the client.
angular.module('myApp',['btford.socket-io'])
.factory('socket',function(socketFactory){
return socketFactory();
}
).controller('myAppCtrl',['$scope','socket',
function(a,b){
b.on('test',function(data){
console.log(data);
});
}
]);
Here's the node-express setup:
var app = express(),
server = app.listen(3000);
var socket = require('socket.io'),
io = socket.listen(server);
require('/config/routes/index.js')(app,io);
require('/config/routes/test.js')(app,io);
Routes : (config/routes/index.js)
module.exports = function(app,io){
app.get('/',function(req,res){
io.on('connection',function(socket){
socket.join(req.session._id);
});
res.render('index');
});
};
config/routes/test.js
module.exports = function(app,io){
app.get('/route1',function(req,res){
io.to(req.session._id).emit('test',{
data : 'Works'
});
res.render('route1');
});
};
A) Whenever the user goes to route1, the emit event is being fired and sent to all the users.
B) Is there a better approach to avoid using unique room for each user? This is not a chat application but rather implements push notifications
You have a couple major misunderstandings about how sockets and requests work. They are very separate operations and are not connected the way you appear to think they are. I will try to explain the problems with your code.
In this block of code:
module.exports = function(app,io){
app.get('/',function(req,res){
io.on('connection',function(socket){
socket.join(req.session._id);
});
res.render('index');
});
};
You are processing the / page request and EVERY time that request is hit, you add yet another event handler for io.on('connection', ...), thus you could have many of those.
Further, if the connection event happens BEFORE the user hits the / page, then you will miss it entirely and that socket will not be placed into the proper chat room.
Then, in this block of code:
module.exports = function(app,io){
app.get('/route1',function(req,res){
io.to(req.session._id).emit('test',{
data : 'Works'
});
res.render('route1');
});
};
io.to() takes a string that is the name of a chat room. So, this will send a message to every socket that is in the req.session._id chat room. For this to work, you'd have to make absolutely sure that req.session._id was completely unique to this user and that the desired user had already joined a chat room by this name. This could work, but it depends upon those specific things being correct.
You need to think of the connection from socket.io separately from a request. They are NOT tied together the way that you think they are. Your connection listener is for any connection not just a connection related to a given request... what you are trying to do simply will not work that way.
Imagine that your socket.io portions of your project are completely separate from the http requests in the web/express portions of your application. This is how you should think of passing messages.
Also worth consideration is that if you are using cluster or similar scaling methods, your default socket.io setup in one instance doesn't communicate with other instances.
So, I was told that passing around the request and or response variable in nodeJS is "bad practice". But this means that most of your code has to be in the server.js file, making it cluttered and kind of ugly.
How can you modularize your nodejs server, passing around req/res appropriately and be able to organize your code into separate files?
For example, I would like to split my socket routing, .get and .post into different files, but still be able to use the callback parameters like so:
app.io.route("disconnect", function(req,res) { <--- these params
db.query("UPDATE player_data SET online=0 WHERE id="+mysql.escape(req.session.user));
req.io.broadcast("event", {msg:req.session.username+" has logged out!"});
app.io.broadcast("reloadXY");
});
As of right now they're all in one file and I don't like that.
I think what the person meant by 'passing around' was something like this (in plain express):
app.get('/kittens', function(req, res) {
db.doAthing(req);
updateSomethingElse(res);
upvoteThisAnswer(res);
});
That is, passing around the two variables beyond the first function. This is bad because it becomes increasingly difficult to figure out where the call actually ends. One little res.end(500) in updateSomethingElse can cause the whole house of cards to come tumbling down.
It's perfectly ok (in fact, standard to the point of being the default in express) to declare that callback elsewhere (usually the /routes directory of your project.)
// app.js
var user = require('./routes/user')
, kittens = require('./routes/kittens');
// express stuff...
app.get('/settings', user.getSettings);
app.get('/fur', kittens.shed);
Then, in routes/user.js:
exports.getSettings = function(req, res) {
// Note how we're passing around properties of req/res, not the objects themselves.
db.getUserSettings(req.user.id).then(function(settings) {
res.render('settings', settings);
});
};
This video from TJ Holowaychuk (the guy who wrote Express and a ton of other Node infrastructure that we all use) helped me take Express modularization to the next level. Basically you can make individual apps in their own folders and consume them as middleware very easily. I have managed to extend this technique to socket.io with some tricks.
http://vimeo.com/56166857
You should not pass req and res to another modules but pass callbacks from another modules to route.
It should look like.
var someModule = require("./someModule")
app.get("/someAction", someModule.handleSomeAction) ;
If You want to have post and get in another modules You should pass reference to app (from express()) once to that module and operate on that.
For example :
var express = require("express") ;
var app = express();
var get_handler = require("./get_handler ")
var post_handler = require("./post_handler ")
get_handler.init(app);
post_handler.init(app);
and in post/get_handler :
var app;
exports.init = function( eApp){
app = eApp;
// operate on app
}
I am working on a node.js project that I am leveraging Socket.IO in, and am having an issue getting my head around a scoping issue. Here is what I am trying to do:
var io = require('socket.io').listen(80);
session_manager = require('./includes/session_manager');
// client joins the socket server
io.sockets.on('connection', function(client) {
client.on('X.Session.join', function(session_id, client) {
session_manager.joinSession(session_id, function(err, session) {
// do whatever
});
});
// BRING IN MORE LISTENERS/EMITTERS?
require('someModuleIBuild');
});
As you can see I am basically setting up the initial connection, joining a session via a managing class (so I know who to emit to for which session) and then I am trying to dynamically bring in some custom stuff that ALSO is going to be emitting and listening via the socket connection.
So how do I reference this current connection from within the confines of my custom modules? All the examples I have seen have all the "on" and "emit" functions in one file, which seems like it could get out of control pretty quickly.
I am possibly over-thinking/over-complicating this (this is my first node.js project, first socket-based project, first mostly-javascript project....etc) but any help would be appreciated.
create your modules like this and you can pass the client into the module
module.exports = function(client) {
client.on("whatever", function () {
});
client.on("whenever", function (data) {
});
};
and then do the require like this
require('someModuleIBuild')(client);