I was trying to implement web-sockets (npm ws) in my express application, but got stuck on how I should implement my websockets so that they work with express router.
Currently, my endpoints look like this...
router.post('/create-note', jwtAuthentication, NotesController.createNote);
router.get('/get-notes/:id',jwtAuthentication, NotesController.getUserNotes);
router.??('/socket-endpoint', NotesController.wssNote);
As you can see, I am unsure of what method to call on my router. I have tried using 'get' and 'post, but for some reason it only works after I try a second connection on postman. (I click connect, nothing happens, I then click disconnect and connect again and it works.)
I know that I can pass in the path when creating the WebSocketServer...
var wss = new WebSocketServer({server: server, path: "/hereIsWS"});
This does work, but if it is possible to use routers with web-sockets, I think it would make my whole project much cleaner and more organised.
I have come across people recommending 'express-ws', but was wondering if there was a better method to solve my problem, specifically a method that does not involve other packages.
Thanks in advance!
You do not use Express routers with webSockets. That's not the proper architecture for webSockets. Your webSocket server can share an http server with Express, but that's pretty much all the two have to do with one another.
webSockets connect on a particular path which you pass to the webSocketServer() constructor as it appears you already know. Once they are connected they stay connected and form a TCP pipe that you can send packets of data from client to server or from server to client. There is no Express routing used for that.
You can create your own message handling within a webSocket message by creating a message name as part of the webSocket payload if you want (this is something that the socket.io layer on top of webSockets does for you), but it has nothing to do with Express at that point. That's just in how you choose to handle the incoming webSocket packets.
if there was a better method to solve my problem
What is your specific problem? Perhaps if you stated the specific problem you want help with, we could provide further assistance.
To handle incoming webSocket messages, you can follow the example in the ws server doc:
wss.on('connection', function connection(ws) {
ws.on('message', function message(data) {
console.log('received: %s', data);
});
ws.send('something');
});
To further break up this to handle different types of incoming webSocket messages, you have to create your own message format that you can branch on or use socket.io instead on both client and server that does that for you.
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?
When I start my server, I get 1 response from the web socket that shows information about bitcoin but I either never get updates whenever the price changes or I suddenly get loads of updates. I assume I should be getting a new message every second or so. I'm using this web socket https://www.cryptocompare.com/api/#-api-web-socket-current-
Here's my code:
var ioClient = require('socket.io-client');
var cryptocompare = ioClient.connect('wss://streamer.cryptocompare.com')
var subscription = '2~Poloniex~BTC~USD';
cryptocompare.emit('SubAdd', { subs: [subscription] });
cryptocompare.on('error', console.error)
cryptocompare.on('m', function(message) {
console.log(message);
});
In the first instance I would very strongly encourage you to use the Tidwall websockets library
https://github.com/tidwall/SwiftWebSocket
It's incredibly well-written, it's one of the best libraries of any type out there.
Again in the first instance, you'll struggle to know what is going on, until you are using a rock-solid library ...
I'm reading up on websockets and after reading a lot of tutorials and blogs (mostly about creating a simple chat application) there is still 1 question unanswered :
Type of technology used aside (node.js or php of python) I find no way of sending a message to 1 user or a group of users without first getting an event of the client to the websocket server ( often called onconnect() or onmessage() ).
Is it then not possible to have some external application or event call some script (bash or php) that uses the existing running websocket instance to send/broadcast some information (text) to one or more connected browsers (websocket clients) ??
Sorry if this is a stupid question but I am not able to find an answer by reading these blogs on the web.
Thank you for this clarification.
From what I've understand, you can easily use sockets like:
// main.js
this.sockets = {};
myOtherModule.init(sockets);
io.on('connection', function(socket)) {
sockets[socket.id] = socket;
socket.on('command', myOtherModule.onSocketCommand);
}
// myOtherModule.js
this.init = function(sockets) {
this.sockets = sockets;
}
this.onSocketCommand = function() {
this.sockets['other.socket.id'].emit('message');
}
You can always save the socket somewhere, no matter if it's within object or single variable. Then you can always use it to emit messages.
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.