My question could be flagged as "opinion based" but I am wondering which approach is the best for my application as I am able to do it in both ways.
I am building chat application in which users and conversations are saved in MongoDB. I will have my react application consuming API/APIs. The question is - is it better to have REST API and Socket.io applications running separate? For example:
Have REST API running on port 3005
Have Socket.io running on port 3006
React Application consuming these 2 separately and basically they will not know about each other. My endpoints in REST API endpoints and socket.io will be invoked only in front-end.
On the other hand, I can have my socket.io application and REST API working together in 1 big application. I think it is possible to make it working without problems.
To sum up, at first glance I would take the first approach - more cleaner and easy to maintain. But I would like to hear other opinions or if somebody had a similar project. Usually how the things are made in this kind of projects when you have socket.io and REST API?
I would check the pros and cons for both scenario. For example code and resource reusability is better if you have a single application and you don't have to care about which versions are compatible with each other. On the other hand one error can kill both applications, so from security perspective it is better to have separate applications. I think the decision depends on what pros and cons are important to you.
you can make a separate file for socket.io logic like this:
// socket.mjs file
import { Server } from "socket.io"
let io = new Server()
const socketApi = {
io: io
}
io.on('connection',(socket)=>{
console.log('client connected:', socket.id)
socket.join('modbus-room')
socket.on('app-server', data=>{
console.log('**************')
console.log(data)
io.to('modbus-room').emit('modbus-client', data)
})
socket.on('disconnect',(reason)=>{
console.log(reason)
})
})
export default socketApi
and add it to your project like this:
// index.js or main file
//...
import socketApi from "../socket.mjs";
//...
//
/**
* Create HTTP server.
*/
const server = http.createServer(app);
socketApi.io.attach(server);
//
Related
I am required to save logs into a MySQL database of each request and response made to the backend. The issue is that we are migrating to microservices architecture. The backend was made with NodeJS and Express, and it has a middleware that does this task. Currently, it has this middleware attached to each microservice.
I would like to isolate this middleware as its own microservice. The issue is that I don't know how to redirect the traffic this way. This is how I would like to manage it:
I would like to do it this way, because we can make changes or add features to the middleware without having to implement it in each microservice. This is the middleware's code:
const connection = require("../database/db");
const viewLog = (req, res, next) => {
const oldWrite = res.write,
oldEnd = res.end,
chunks = [],
now = new Date();
res.write = function (chunk) {
chunks.push(chunk);
oldWrite.apply(res, arguments);
};
res.end = function (chunk, error) {
if (chunk) chunks.push(chunk);
const bodyRes = Buffer.concat(chunks).toString("utf8");
connection.query("CALL HospitalGatifu.insertLog(?,?,?,?,?)", [
`[${req.method}] - ${req.url}`,
`${JSON.stringify(req.body) || "{}"}`,
bodyRes,
res.statusCode === 400 ? 1 : 0,
now,
]);
oldEnd.apply(res, arguments);
};
next();
};
module.exports = viewLog;
I think there might be a way to manage this with Nginx which is the reverse proxy that we are using. I would like to get an approach of how to change the logs middleware.
Perhaps you might want to take a look at the sidecar pattern which is used in microservice architectures for common tasks (like logging).
In short, a sidecar runs in a container besides your microservice container. One task of the sidecar could be intercepting network traffic and logging requests and responses (and a lot of other possible tasks). The major advantage of this pattern is that you don't need to change any code in your microservices and you don't have to manage traffic redirection yourself. The latter will be handled by the sidecar itself.
The disadvantage is that you are required to run your microservices containerized and use some kind of container orchestration solution. I assume this being the case since you are moving towards a microservices based application.
One question about the log service in between of the webapp and the NGNIX server. What if the logging services goes down for some reason, is it acceptable for the entire application to go down?
Let me give you not exactly what you requested but something to think about.
I can think on 3 solutions for the issue of logging in microservices, each 1 have its own advantages and disadvantages:
Create a shared library that handles the logs, I think its the best choice in must cases. An article I wrote about shared libraries
You can create API gateway, it is great solution for shared logic to all the requests. So it will probably be more work but then can be used for other shared logic. Further read (not written by me :) )
A third option (which I personally don't like) is create a log microservice that listens to LogEvent or something like that. Then from your MSs publish this event whenever needed.
I'm working on a project that uses the binance api to create an interface to make day trading cryptos easier.
The call to their api looks like this:
binance.websockets.candlesticks(['BNBBTC'], "1m", function(candlesticks) {
let { e:eventType, E:eventTime, s:symbol, k:ticks } = candlesticks;
let { o:open, h:high, l:low, c:close, v:volume, n:trades, i:interval, x:isFinal, q:quoteVolume, V:buyVolume, Q:quoteBuyVolume } = ticks;
console.log(symbol+" "+interval+" candlestick update");
console.log("open: "+open);
console.log("high: "+high);
console.log("low: "+low);
console.log("close: "+close);
console.log("volume: "+volume);
console.log("isFinal: "+isFinal);
});
It seems to be returning data at a fixed interval, so I'm skeptical as to whether it's actually real time, but regardless, I'm wondering how to send this data to the front end as it comes in.
Currently, I'm doing this with the static data:
router.get('/interface', function(req,res) {
binance.candlesticks("BNBBTC", "5m", function(ticks, symbol) {
console.log("candlesticks()", ticks);
let last_tick = ticks[ticks.length - 1];
let [time, open, high, low, close, volume, closeTime, assetVolume, trades, buyBaseVolume, buyAssetVolume, ignored] = last_tick;
console.log(symbol+" last close: "+close);
res.render('interface', {ticks:ticks});
});
});
I've messed with socket.io in the past, but am unsure how to utilize it. Any help would be much appreciated! And please hmu if you're interested in cryptos. We are putting together a group in discord to share our research, and trading strategies.
To initiate the data sending process from the backend, (instead of frontend requesting data), you should use websockets (socketIO as you have mentioned).
To do that, first, you should start a socketio server in your express app, by wrapping the http/https server or express app.
Then, from the frontend, you should initiate a socketio-client.
Next, your frontend client should establish a connection with the server using the connect method of the socketio-client. It will fire an event in the server, with the socket connection.
Finally, the server can use that socket connection, to send any amount of data to the client. (You might need to save the connection for latter use).
i'm trying to do basically the same thing, what discord group you talking about?
My goal is to build a chat application - similar to whatsapp
To my understanding, socket.io is a real-time communication library written in javascript and it is very simple to use
For example
// Serverside
io.on('connection', function(socket) {
socket.on('chat', function(msg) {
io.emit('chat', msg);
});
});
// ClientSide (Using jquery)
var socket = io();
$('form').submit(function(){
socket.emit('chat', $('#m').val());
$('#m').val('');
return false;
});
socket.on('chat', function(msg){
$('#messages').append($('<li>').text(msg));
});
1) do I always need to start an io.on('connection') to use the real-time feature or i could just start using socket.on object instead? for example i have a route
app.post('/postSomething', function(req, res) {
// Do i need to start an io.on or socket.on here?
});
because i want the real-time feature to be listen only on specific route.
2) Redis is a data structure library which handles the pub/sub, why do we need to use pub/sub mechanism?
I read alot of articles but couldn't grasp the concept. Article example http://ejosh.co/de/2015/01/node-js-socket-io-and-redis-intermediate-tutorial-server-side/
for example the code below
// Do i need redis for this, if so why? is it for caching purposes?
// Where does redis fit in this code?
var redis = require("redis");
var client = redis.createClient();
io.on('connection', function(socket) {
socket.on('chat', function(msg) {
io.emit('chat', msg);
});
});
3) Just wondering why I need nginx to scale node.js application? i found this stackoverflow answer:
Strategy to implement a scalable chat server
It says something about load balancing, read that online and couldn't grasp the concept as well.
So far I have only been dealing with node.js , mongoose simple CRUD application, but I'm willing work really hard if you guys could share some of your knowledge and share some useful resources so that I could deepen my knowledge about all of these technologies.
Cheers!
Q. Socket.on without IO.on
io.on("connection" ... )
Is called when you receive a new connection. Socket.on listens to all the emits at the client side. If you want your client to act as a server for some reason then (in short) yes io.on is required
Q. Redis pub/sub vs Socket.IO
Take a look at this SO question/anwer, quoting;
Redis pub/sub is great in case all clients have direct access to redis. If you have multiple node servers, one can push a message to the others.
But if you also have clients in the browser, you need something else to push data from a server to a client, and in this case, socket.io is great.
Now, if you use socket.io with the Redis store, socket.io will use Redis pub/sub under the hood to propagate messages between servers, and servers will propagate messages to clients.
So using socket.io rooms with socket.io configured with the Redis store is probably the simplest for you.
Redis can act like a message queue if it is a requirement. Redis is a datastore support many datatypes.
Q. Why Nginx with Node.js
Node.js can work standalone but nginx is faster to server static content.
Since nginx is a reverse proxy therefore servers are configured with nginx to handle all the static data (serving static files, doing redirects, handling SSL certificates and serving error pages.
) and every other request is sent to node.js
Check this Quora post as well: Should I host a node.js project without nginx?
Quoting:
Nginx can be used to remove some load from the Node.js processes, for example, serving static files, doing redirects, handling SSL certificates and serving error pages.
You can do everything without Nginx but it means You have to code it yourself, so why not use a fast and proven solution for this.
I'm writing an application in Node.js/Express based around websockets. I'm using Node's EventEmitter in conjunction with socket.io for a nearly completely event-driven app.
I wonder if this this is a good architecture though. My main socket is managed in app.js right now, and has code like this:
socket.on(Events.InitialFetch, function(battle_id){
dispatcher.emit(Events.InitialFetch, battle_id);
});
dispatcher.on(Events.InitialFetched, function(data){
socket.emit(Events.InitialFetched, data);
});
... while in my controller, I have code like this:
dispatcher.on('initial-fetch', function(data){
Battle.findOne({_id: data})
.populate('players')
.populate('owner')
.exec(function(err, battle){
if (err) {
}
else {
dispatcher.emit(Events.InitialFetched, battle);
}
});
});
Instead of the normal RESTful routing. My concern is that it's a little confusing (ie 'fetch' and 'fetched' for describing data flow) and the fact that I'm basically passing methods from one type of event emitter (socket.io) to another (Event.EventEmitter).
How can this be architected better? Would it be better to have the controllers directly access the socket instead of using EventEmitter as a bus? How can I make the names of my events more clear?
I wouldn't worry about using multiple event emitters. They are kind good primitive to build upon in Node.js. As for design, I find a good question to ask is how deeply I have coupled my components.
By using an non-socket.io event emitter for your controller, Socket.io is an independent transport from the controller. This is good.
As a final stage, you should wire the two together using dependency injection. In your server.js file create your dispatcher, then initialize your socket.io module passing the dispatcher as a dependency.
var dispatcher = require('./dispatcher')
var socket_transport = require('./socket_transport')
socket_transport.init_with_dispatcher(dispatcher);
This will let you test your dispatcher independently of the transport. Debugging socket.io can be difficult.
What are the differences between socket.io and websockets in
node.js?
Are they both server push technologies?
The only differences I felt was,
socket.io allowed me to send/emit messages by specifying an event name.
In the case of socket.io a message from server will reach on all clients, but for the same in websockets I was forced to keep an array of all connections and loop through it to send messages to all clients.
Also,
I wonder why web inspectors (like Chrome/firebug/fiddler) are unable to catch these messages (from socket.io/websocket) from server?
Please clarify this.
Misconceptions
There are few common misconceptions regarding WebSocket and Socket.IO:
The first misconception is that using Socket.IO is significantly easier than using WebSocket which doesn't seem to be the case. See examples below.
The second misconception is that WebSocket is not widely supported in the browsers. See below for more info.
The third misconception is that Socket.IO downgrades the connection as a fallback on older browsers. It actually assumes that the browser is old and starts an AJAX connection to the server, that gets later upgraded on browsers supporting WebSocket, after some traffic is exchanged. See below for details.
My experiment
I wrote an npm module to demonstrate the difference between WebSocket and Socket.IO:
https://www.npmjs.com/package/websocket-vs-socket.io
https://github.com/rsp/node-websocket-vs-socket.io
It is a simple example of server-side and client-side code - the client connects to the server using either WebSocket or Socket.IO and the server sends three messages in 1s intervals, which are added to the DOM by the client.
Server-side
Compare the server-side example of using WebSocket and Socket.IO to do the same in an Express.js app:
WebSocket Server
WebSocket server example using Express.js:
var path = require('path');
var app = require('express')();
var ws = require('express-ws')(app);
app.get('/', (req, res) => {
console.error('express connection');
res.sendFile(path.join(__dirname, 'ws.html'));
});
app.ws('/', (s, req) => {
console.error('websocket connection');
for (var t = 0; t < 3; t++)
setTimeout(() => s.send('message from server', ()=>{}), 1000*t);
});
app.listen(3001, () => console.error('listening on http://localhost:3001/'));
console.error('websocket example');
Source: https://github.com/rsp/node-websocket-vs-socket.io/blob/master/ws.js
Socket.IO Server
Socket.IO server example using Express.js:
var path = require('path');
var app = require('express')();
var http = require('http').Server(app);
var io = require('socket.io')(http);
app.get('/', (req, res) => {
console.error('express connection');
res.sendFile(path.join(__dirname, 'si.html'));
});
io.on('connection', s => {
console.error('socket.io connection');
for (var t = 0; t < 3; t++)
setTimeout(() => s.emit('message', 'message from server'), 1000*t);
});
http.listen(3002, () => console.error('listening on http://localhost:3002/'));
console.error('socket.io example');
Source: https://github.com/rsp/node-websocket-vs-socket.io/blob/master/si.js
Client-side
Compare the client-side example of using WebSocket and Socket.IO to do the same in the browser:
WebSocket Client
WebSocket client example using vanilla JavaScript:
var l = document.getElementById('l');
var log = function (m) {
var i = document.createElement('li');
i.innerText = new Date().toISOString()+' '+m;
l.appendChild(i);
}
log('opening websocket connection');
var s = new WebSocket('ws://'+window.location.host+'/');
s.addEventListener('error', function (m) { log("error"); });
s.addEventListener('open', function (m) { log("websocket connection open"); });
s.addEventListener('message', function (m) { log(m.data); });
Source: https://github.com/rsp/node-websocket-vs-socket.io/blob/master/ws.html
Socket.IO Client
Socket.IO client example using vanilla JavaScript:
var l = document.getElementById('l');
var log = function (m) {
var i = document.createElement('li');
i.innerText = new Date().toISOString()+' '+m;
l.appendChild(i);
}
log('opening socket.io connection');
var s = io();
s.on('connect_error', function (m) { log("error"); });
s.on('connect', function (m) { log("socket.io connection open"); });
s.on('message', function (m) { log(m); });
Source: https://github.com/rsp/node-websocket-vs-socket.io/blob/master/si.html
Network traffic
To see the difference in network traffic you can run my test. Here are the results that I got:
WebSocket Results
2 requests, 1.50 KB, 0.05 s
From those 2 requests:
HTML page itself
connection upgrade to WebSocket
(The connection upgrade request is visible on the developer tools with a 101 Switching Protocols response.)
Socket.IO Results
6 requests, 181.56 KB, 0.25 s
From those 6 requests:
the HTML page itself
Socket.IO's JavaScript (180 kilobytes)
first long polling AJAX request
second long polling AJAX request
third long polling AJAX request
connection upgrade to WebSocket
Screenshots
WebSocket results that I got on localhost:
Socket.IO results that I got on localhost:
Test yourself
Quick start:
# Install:
npm i -g websocket-vs-socket.io
# Run the server:
websocket-vs-socket.io
Open http://localhost:3001/ in your browser, open developer tools with Shift+Ctrl+I, open the Network tab and reload the page with Ctrl+R to see the network traffic for the WebSocket version.
Open http://localhost:3002/ in your browser, open developer tools with Shift+Ctrl+I, open the Network tab and reload the page with Ctrl+R to see the network traffic for the Socket.IO version.
To uninstall:
# Uninstall:
npm rm -g websocket-vs-socket.io
Browser compatibility
As of June 2016 WebSocket works on everything except Opera Mini, including IE higher than 9.
This is the browser compatibility of WebSocket on Can I Use as of June 2016:
See http://caniuse.com/websockets for up-to-date info.
Its advantages are that it simplifies the usage of WebSockets as you described in #2, and probably more importantly it provides fail-overs to other protocols in the event that WebSockets are not supported on the browser or server. I would avoid using WebSockets directly unless you are very familiar with what environments they don't work and you are capable of working around those limitations.
This is a good read on both WebSockets and Socket.IO.
http://davidwalsh.name/websocket
tl;dr;
Comparing them is like comparing Restaurant food (maybe expensive sometimes, and maybe not 100% you want it) with homemade food, where you have to gather and grow each one of the ingredients on your own.
Maybe if you just want to eat an apple, the latter is better. But if you want something complicated and you're alone, it's really not worth cooking and making all the ingredients by yourself.
I've worked with both of these. Here is my experience.
SocketIO
Has autoconnect
Has namespaces
Has rooms
Has subscriptions service
Has a pre-designed protocol of communication
(talking about the protocol to subscribe, unsubscribe or send a message to a specific room, you must all design them yourself in websockets)
Has good logging support
Has integration with services such as redis
Has fallback in case WS is not supported (well, it's more and more rare circumstance though)
It's a library. Which means, it's actually helping your cause in every way. Websockets is a protocol, not a library, which SocketIO uses anyway.
The whole architecture is supported and designed by someone who is not you, thus you dont have to spend time designing and implementing anything from the above, but you can go straight to coding business rules.
Has a community because it's a library (you can't have a community for HTTP or Websockets :P They're just standards/protocols)
Websockets
You have the absolute control, depending on who you are, this can be very good or very bad
It's as light as it gets (remember, its a protocol, not a library)
You design your own architecture & protocol
Has no autoconnect, you implement it yourself if yo want it
Has no subscription service, you design it
Has no logging, you implement it
Has no fallback support
Has no rooms, or namespaces. If you want such concepts, you implement them yourself
Has no support for anything, you will be the one who implements everything
You first have to focus on the technical parts and designing everything that comes and goes from and to your Websockets
You have to debug your designs first, and this is going to take you a long time
Obviously, you can see I'm biased to SocketIO. I would love to say so, but I'm really really not.
I'm really battling not to use SocketIO. I dont wanna use it. I like designing my own stuff and solving my own problems myself.
But if you want to have a business and not just a 1000 lines project, and you're going to choose Websockets, you're going to have to implement every single thing yourself. You have to debug everything. You have to make your own subscription service. Your own protocol. Your own everything. And you have to make sure everything is quite sophisticated. And you'll make A LOT of mistakes along the way. You'll spend tons of time designing and debugging everything. I did and still do. I'm using websockets and the reason I'm here is because they're unbearable for a one guy trying to deal with solving business rules for his startup and instead dealing with Websocket designing jargon.
Choosing Websockets for a big application ain't an easy option if you're a one guy army or a small team trying to implement complex features. I've wrote more code in Websockets than I ever wrote with SocketIO in the past, for ten times simpler things than I did with SocketIO.
All I have to say is ... Choose SocketIO if you want a finished product and design. (unless you want something very simple in functionality)
Im going to provide an argument against using socket.io.
I think using socket.io solely because it has fallbacks isnt a good idea. Let IE8 RIP.
In the past there have been many cases where new versions of NodeJS has broken socket.io. You can check these lists for examples... https://github.com/socketio/socket.io/issues?q=install+error
If you go to develop an Android app or something that needs to work with your existing app, you would probably be okay working with WS right away, socket.io might give you some trouble there...
Plus the WS module for Node.JS is amazingly simple to use.
Using Socket.IO is basically like using jQuery - you want to support older browsers, you need to write less code and the library will provide with fallbacks. Socket.io uses the websockets technology if available, and if not, checks the best communication type available and uses it.
https://socket.io/docs/#What-Socket-IO-is-not (with my emphasis)
What Socket.IO is not
Socket.IO is NOT a WebSocket implementation. Although Socket.IO indeed uses WebSocket as a transport when possible, it adds some metadata to each packet: the packet type, the namespace and the packet id when a message acknowledgement is needed. That is why a WebSocket client will not be able to successfully connect to a Socket.IO server, and a Socket.IO client will not be able to connect to a WebSocket server either. Please see the protocol specification here.
// WARNING: the client will NOT be able to connect!
const client = io('ws://echo.websocket.org');
I would like provide one more answer in 2021. socket.io has become actively maintained again since 2020 Sept. During 2019 to 2020 Aug(almost 2 years) there was basically no activity at all and I had thought the project may be dead.
Socket.io also published an article called Why Socket.IO in 2020?, except for a fallback to HTTP long-polling, I think these 2 features are what socket.io provides and websocket lacks of
auto-reconnection
a way to broadcast data to a given set of clients (rooms/namespace)
One more feature I find socket.io convenient is for ws server development, especially I use docker for my server deployment. Because I always start more than 1 server instances, cross ws server communication is a must and socket.io provide https://socket.io/docs/v4/redis-adapter/ for it.
With redis-adapter, scaling server process to multiple nodes is easy while load balance for ws server is hard. Check here https://socket.io/docs/v4/using-multiple-nodes/ for further information.
Even if modern browsers support WebSockets now, I think there is no need to throw SocketIO away and it still has its place in any nowadays project. It's easy to understand, and personally, I learned how WebSockets work thanks to SocketIO.
As said in this topic, there's a plenty of integration libraries for Angular, React, etc. and definition types for TypeScript and other programming languages.
The other point I would add to the differences between Socket.io and WebSockets is that clustering with Socket.io is not a big deal. Socket.io offers Adapters that can be used to link it with Redis to enhance scalability. You have ioredis and socket.io-redis for example.
Yes I know, SocketCluster exists, but that's off-topic.
Socket.IO uses WebSocket and when WebSocket is not available uses fallback algo to make real time connections.
TLDR:
'Socket.io' is an application layer specification that can be implemented on top of/using the application layer specification 'websockets'.
websocket spec
socket.io spec
I think the simple answer here is in basic web technology definitions:
Specification: A documented standard detailing the requirements for a program to achieve in order to be labeled as "an implimentation of some sepc." It is important to achieve this rubber stamp when building programs, because any program is only as good at the machine executing the code. Programming is fundamentally built upon specifications, and if, they are not followed code will not execute correctly. However, a specification does nothing. It is just a text document.
Implementation: This is actual, executable code that accomplishes what the specification says to do.
Application Layer - System that defines messages and handshakes sent over transport. This is the stuff you have to know when working with HTTP/Websockets/Socketio. It defines how the connections will be made, authenticated, data will be sent, and how it will arrive.