Meggie  Flatley

Meggie Flatley


How to Build Secure Real-time Application using WebSockets and Node.js

Learn to build a secure realtime application using WebSockets and Node.js!

WebSockets is a technology for communicating between the client and the server in a web application, where an open socket creates a persistent connection between the client and the server. This method of communication works outside of the HTTP request/response paradigm that has existed since the earliest days of the internet. Since sockets don’t use HTTP they can eliminate the overhead that comes with HTTP for low latency communications.

In this tutorial, you will learn how to create a small chat room web application that will keep track of the users in the room and send messages using WebSockets. For the server, you will use Express on Node.js. Node.js is an event-driven JavaScript runtime that has made JavaScript one of the most popular back end languages. Express is the most popular web framework for Node.js. You will also learn how to set up Okta for authentication. To authenticate the socket communication, you will issue a JSON Web Token (JWT) to the client, and validate it when the client attempts to open the socket.

Create Your Okta App

To use Okta for authentication, you will first need to set up a new application. (You will need a free Okta Developer account if you don’t already have one.) Head to the Okta Developer Console and select Applications then Add Application. On the next page, select Web and click Next. On the Application Settings page, give your application a meaningful name. I called my SocketDemo. For this application, you can leave everything else the same, as you will use port 8080 in your application. Click Done and you will be redirected to the settings page.

Application Settings

Make note of your Client ID and your Client Secret, since you will need this in your application.

Create Your Node.js Application

Start by opening your favorite IDE and use the command mkdir to create a folder for your project. Navigate to that folder and enter the command npm init. You will need to walk through the instructions that follow. Next, you will want to install your dependencies.

First, you will need Okta’s Node.js SDK and the OIDC middleware. These two packages make integrating Okta’s authentication into your application simple. It’s easy to configure the middleware, but you will do that later. For now, install the packages with the following commands.

npm i @okta/oidc-middleware@4.0.1
npm i @okta/okta-sdk-nodejs@4.1.0

Next, install dotenv, which will store and retrieve sensitive configuration without pushing this information to your source code repository.

npm i dotenv

Next, you will need to install Express.

npm i express@4.17.1

You will also need express-session to help manage your session state.

npm i express-session@1.17.1

Next, install jsonwebtoken to help create JWTs that you will issue to your client.

npm i jsonwebtoken@8.5.1

To manage the sockets, you will use For validating the JWT in your socket management, you will use socketio-jwt. You will see later how these two connect to authenticate your socket requests.

npm i
npm i socketio-jwt@4.6.2

Finally, you will need pug. Pug is a view engine that was previously known as Jade.

npm i pug@3.0.0

Once you are all set up, add a new file to your root directory called .env. Add the following code to it. You can change your JWT_TOKEN_KEY to something more fitting if you wish.


Write Your Server Code

Now you are ready to begin writing your server-side code. First, add a file to your root called index.js and add the following code.

"use strict";

require( "dotenv" ).config();

const server = require( "./server" );

const port = process.env.APP_BASE_PORT;

server.start( {
  port: port
} ).then( app => {
  console.log( "Application is now running on port " + port );
} );

This file serves as your entry point for the application. It starts the server by listening to the port defined in your .env file. It also calls the config() function on dotenv, which should be called as early as possible in your application.

Next, add a file called rooms.js.

"use strict";

module.exports = function () {
  let rooms = [];

  rooms.push( {
    name: "General",
    users: []
  } );

  rooms.push( {
    name: "Sports",
    users: []
  } );

  rooms.push( {
    name: "Music",
    users: []
  } );

  return rooms;

This file is just in-memory storage for your chatrooms. In a production application, you would want to connect this to some sort of persistent storage but this solution works fine for this demo. You start by providing three default rooms—General, Sports, and Music. Each room consists of a name and a list of users. The lists are empty when the application first starts but they will be populated as users visit each room. You could also keep a list of messages here so that new users could view the history.

Next, you can define your routes. Create a new file called routes.js and add the following code to it.

"use strict";

module.exports = function ( app, opts ) {

  function ensureAuthenticated ( request, response, next ) {
    if ( !request.userContext ) {
      return response.status( 401 ).redirect( "/account/login" );


  app.get( "", ( request, response, next ) => {
    return response.render( "home" );
  } );

  app.get( "/dashboard", ensureAuthenticated, ( request, response, next ) => {
    return response.render( "dashboard", {
      user: request.userContext.userinfo,
      rooms: opts.rooms
    } );
  } );

  app.get( "/chat/:room", ensureAuthenticated, ( request, response, next ) => {
    return response.render( "room", {
      jwt: opts.jwt.sign( { user: request.userContext.userinfo, room: }, process.env.JWT_TOKEN_KEY ),
      room: opts.rooms.filter( ( r ) => == )[0]
    } );
  } );

  app.get( "/account/logout", ensureAuthenticated, ( request, response, next ) => {
    response.redirect( "/" );
  } );

  app.get( "/account/login", ( request, response, next ) => {
    return response.render( "home" );
  } );

As you can see we are defining a few routes here. First is the home page, second is the Dashboard page which will be the landing page for authenticated users. To ensure a user is authenticated you add the ensureAuthenticated middleware function to the route. This function is defined above and simply returns a 401 for unauthenticated users and redirects them to the login page. The chat route looks for a route parameter called room. This means a user who navigates to ~/chat/General will land in the general chat room. This route also creates a JWT and passes it to the client, using the jsonwebtoken object that was injected into the routes. There is also a logout route for logging out. (The login route will be configured using Okta in the server setup later.)

Next, you need to set up your socket.js file to handle the socket communications. Create the file in your root and add the following code.

"use strict";

const socketioJwt = require( "socketio-jwt" );

module.exports = function ( io, opts ) {

  io.sockets.on( "connection", socketioJwt.authorize( {
    secret: process.env.JWT_TOKEN_KEY,
    timeout: 15000 // 15 seconds to send the authentication message
  } ) ).on( "authenticated", function ( socket ) {
    socket.on( "entered", () => {

      let user =;
      let room =;

      opts.rooms.filter( ( r ) => === room )[0].users.push( user );
      socket.join( room ); room ).emit( "user entered", user );
    } );

    socket.on( "message sent", ( message ) => {
      let user =;
      let room =; room ).emit( "message received", user, message );
    } );

    socket.on( "disconnect", () => {
      let user =;
      let room =;

      opts.rooms.filter( ( r ) => === room )[0].users.splice( user, 1 ); room ).emit( "user exited", user );
    } );

    let users = [];

    users.push( {
      user: "test"
    } );

    socket.emit( "welcome", users );

  } );


Here you are using socketio-jwt to decode the JWT you passed to the client when the user enters the room. A JWT is a token whose payload holds some information representing claims to be sent to the server. The JWT can be signed or encrypted and then validated by the server to ensure their validity. Once established, the server can read the claims from the token and decide the proper course of action. You can send the JWT with the request to the server to ensure the sender of the request is authorized to perform the requested action.

(Note, you can read more about an alternative approach using Okta as an authentication server a, where you authenticate the user when they reach a room.)

The socket.js file also has the logic for receiving and sending messages as well as handling users entering and leaving the room. When a user enters or leaves, you add or remove them from the room’s user list and broadcast to the room that the user has left. The client side is responsible for displaying that information to the user.

Finally, to tie it all together you need to add a server.js file.

"use strict";

const express = require( "express" );
const bodyParser = require( "body-parser" );
const path = require( "path" );

const ExpressOIDC = require( "@okta/oidc-middleware" ).ExpressOIDC;
const session = require( "express-session" );
let jwt = require( "jsonwebtoken" );

const routes = require( "./routes" );
const sockets = require( "./socket" );

const start = function ( options ) {
  return new Promise( function ( resolve, reject ) {
    process.on( "unhandledRejection", ( reason, p ) => {
      console.log( "Unhandled Rejection at: Promise", p, "reason:", reason );
    } );

    if ( !options.port ) {
      reject( new Error( "no port specificed" ) );

    const app = express();
    const http = require( "http" ).createServer( app );
    const io = require( "" )( http );

    var rooms = [];

    app.use( express.static( "public" ) );
    app.set( "views", path.join( __dirname, "/public/views" ) );
    app.set( "view engine", "pug" );

    app.use( bodyParser.urlencoded( { extended: false } ) );

    app.use( function ( error, request, response, next ) {
      console.log( error );
      reject( new Error( "something went wrong" + error ) );
      response.status( 500 ).send( "something went wrong" );
    } );

    const oidc = new ExpressOIDC( {
      issuer: process.env.OKTA_BASE_URL + "/oauth2/default",
      client_id: process.env.OKTA_CLIENT_ID,
      client_secret: process.env.OKTA_CLIENT_SECRET,
      appBaseUrl: process.env.APP_BASE_URL,
      scope: "openid profile",
      routes: {
        login: {
          path: "/users/login",
        callback: {
          path: "/authorization-code/callback",
        loginCallback: {
          afterCallback: "/dashboard",
    } );

      session( {
        resave: true,
        saveUninitialized: false,
      } )

    app.use( oidc.router );

    var rooms = require( "./rooms" )();

    routes( app, {
      rooms: rooms,
      jwt: jwt
    } );

    sockets( io, {
      rooms: rooms
    } );

    const server = http.listen( options.port, function () {
      resolve( server );
    } );
  } );

module.exports = Object.assign( {}, { start } );

This file does a lot of the legwork getting the application set up. When the server is started, it registers your various middleware and dependencies. This includes the Okta middleware, which uses the variables in your .env file. It will register the route /users/login as the login page. This page is hosted by Okta and will manage the authentication for you.

#node #websockets #javascript #express #developer

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How to Build Secure Real-time Application using WebSockets and Node.js

NBB: Ad-hoc CLJS Scripting on Node.js


Not babashka. Node.js babashka!?

Ad-hoc CLJS scripting on Node.js.


Experimental. Please report issues here.

Goals and features

Nbb's main goal is to make it easy to get started with ad hoc CLJS scripting on Node.js.

Additional goals and features are:

  • Fast startup without relying on a custom version of Node.js.
  • Small artifact (current size is around 1.2MB).
  • First class macros.
  • Support building small TUI apps using Reagent.
  • Complement babashka with libraries from the Node.js ecosystem.


Nbb requires Node.js v12 or newer.

How does this tool work?

CLJS code is evaluated through SCI, the same interpreter that powers babashka. Because SCI works with advanced compilation, the bundle size, especially when combined with other dependencies, is smaller than what you get with self-hosted CLJS. That makes startup faster. The trade-off is that execution is less performant and that only a subset of CLJS is available (e.g. no deftype, yet).


Install nbb from NPM:

$ npm install nbb -g

Omit -g for a local install.

Try out an expression:

$ nbb -e '(+ 1 2 3)'

And then install some other NPM libraries to use in the script. E.g.:

$ npm install csv-parse shelljs zx

Create a script which uses the NPM libraries:

(ns script
  (:require ["csv-parse/lib/sync$default" :as csv-parse]
            ["fs" :as fs]
            ["path" :as path]
            ["shelljs$default" :as sh]
            ["term-size$default" :as term-size]
            ["zx$default" :as zx]
            ["zx$fs" :as zxfs]
            [nbb.core :refer [*file*]]))

(prn (path/resolve "."))

(prn (term-size))

(println (count (str (fs/readFileSync *file*))))

(prn (sh/ls "."))

(prn (csv-parse "foo,bar"))

(prn (zxfs/existsSync *file*))

(zx/$ #js ["ls"])

Call the script:

$ nbb script.cljs
#js {:columns 216, :rows 47}
#js ["node_modules" "package-lock.json" "package.json" "script.cljs"]
#js [#js ["foo" "bar"]]
$ ls


Nbb has first class support for macros: you can define them right inside your .cljs file, like you are used to from JVM Clojure. Consider the plet macro to make working with promises more palatable:

(defmacro plet
  [bindings & body]
  (let [binding-pairs (reverse (partition 2 bindings))
        body (cons 'do body)]
    (reduce (fn [body [sym expr]]
              (let [expr (list '.resolve 'js/Promise expr)]
                (list '.then expr (list 'clojure.core/fn (vector sym)

Using this macro we can look async code more like sync code. Consider this puppeteer example:

(-> (.launch puppeteer)
      (.then (fn [browser]
               (-> (.newPage browser)
                   (.then (fn [page]
                            (-> (.goto page "")
                                (.then #(.screenshot page #js{:path "screenshot.png"}))
                                (.catch #(js/console.log %))
                                (.then #(.close browser)))))))))

Using plet this becomes:

(plet [browser (.launch puppeteer)
       page (.newPage browser)
       _ (.goto page "")
       _ (-> (.screenshot page #js{:path "screenshot.png"})
             (.catch #(js/console.log %)))]
      (.close browser))

See the puppeteer example for the full code.

Since v0.0.36, nbb includes promesa which is a library to deal with promises. The above plet macro is similar to promesa.core/let.

Startup time

$ time nbb -e '(+ 1 2 3)'
nbb -e '(+ 1 2 3)'   0.17s  user 0.02s system 109% cpu 0.168 total

The baseline startup time for a script is about 170ms seconds on my laptop. When invoked via npx this adds another 300ms or so, so for faster startup, either use a globally installed nbb or use $(npm bin)/nbb script.cljs to bypass npx.


NPM dependencies

Nbb does not depend on any NPM dependencies. All NPM libraries loaded by a script are resolved relative to that script. When using the Reagent module, React is resolved in the same way as any other NPM library.


To load .cljs files from local paths or dependencies, you can use the --classpath argument. The current dir is added to the classpath automatically. So if there is a file foo/bar.cljs relative to your current dir, then you can load it via (:require [ :as fb]). Note that nbb uses the same naming conventions for namespaces and directories as other Clojure tools: foo-bar in the namespace name becomes foo_bar in the directory name.

To load dependencies from the Clojure ecosystem, you can use the Clojure CLI or babashka to download them and produce a classpath:

$ classpath="$(clojure -A:nbb -Spath -Sdeps '{:aliases {:nbb {:replace-deps {com.github.seancorfield/honeysql {:git/tag "v2.0.0-rc5" :git/sha "01c3a55"}}}}}')"

and then feed it to the --classpath argument:

$ nbb --classpath "$classpath" -e "(require '[honey.sql :as sql]) (sql/format {:select :foo :from :bar :where [:= :baz 2]})"
["SELECT foo FROM bar WHERE baz = ?" 2]

Currently nbb only reads from directories, not jar files, so you are encouraged to use git libs. Support for .jar files will be added later.

Current file

The name of the file that is currently being executed is available via nbb.core/*file* or on the metadata of vars:

(ns foo
  (:require [nbb.core :refer [*file*]]))

(prn *file*) ;; "/private/tmp/foo.cljs"

(defn f [])
(prn (:file (meta #'f))) ;; "/private/tmp/foo.cljs"


Nbb includes reagent.core which will be lazily loaded when required. You can use this together with ink to create a TUI application:

$ npm install ink


(ns ink-demo
  (:require ["ink" :refer [render Text]]
            [reagent.core :as r]))

(defonce state (r/atom 0))

(doseq [n (range 1 11)]
  (js/setTimeout #(swap! state inc) (* n 500)))

(defn hello []
  [:> Text {:color "green"} "Hello, world! " @state])

(render (r/as-element [hello]))


Working with callbacks and promises can become tedious. Since nbb v0.0.36 the promesa.core namespace is included with the let and do! macros. An example:

(ns prom
  (:require [promesa.core :as p]))

(defn sleep [ms]
   (fn [resolve _]
     (js/setTimeout resolve ms))))

(defn do-stuff
   (println "Doing stuff which takes a while")
   (sleep 1000)

(p/let [a (do-stuff)
        b (inc a)
        c (do-stuff)
        d (+ b c)]
  (prn d))
$ nbb prom.cljs
Doing stuff which takes a while
Doing stuff which takes a while

Also see API docs.


Since nbb v0.0.75 applied-science/js-interop is available:

(ns example
  (:require [applied-science.js-interop :as j]))

(def o (j/lit {:a 1 :b 2 :c {:d 1}}))

(prn (j/select-keys o [:a :b])) ;; #js {:a 1, :b 2}
(prn (j/get-in o [:c :d])) ;; 1

Most of this library is supported in nbb, except the following:

  • destructuring using :syms
  • property access using .-x notation. In nbb, you must use keywords.

See the example of what is currently supported.


See the examples directory for small examples.

Also check out these projects built with nbb:


See API documentation.

Migrating to shadow-cljs

See this gist on how to convert an nbb script or project to shadow-cljs.



  • babashka >= 0.4.0
  • Clojure CLI >=
  • Node.js 16.5.0 (lower version may work, but this is the one I used to build)

To build:

  • Clone and cd into this repo
  • bb release

Run bb tasks for more project-related tasks.

Download Details:
Author: borkdude
Download Link: Download The Source Code
Official Website: 
License: EPL-1.0

#node #javascript

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I am Developer


Real Time Chat App using Node JS Express Socket IO

Real time chat with nodejs and expressjs. In this tutorial, you will learn how to build real time chat with nodejs, jquery and expressjs.

This tutorial will help you step by step to on how to build chat application using Nodejs, Express and Socket.IO.

How to build chat application using Nodejs, Express and Socket.IO

Follow the following steps and create chat application using Nodejs, Express and Socket.IO:

  • Step 1 - Create Chat App Directory
  • Step 2 - Install Node Express JS, and jQuery
  • Step 3 - Create Index.html and Style.css
  • Step 4 - Create Chat.js
  • Step 5 - Create index.js
  • Step 6 - Run Development Server

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Aria Barnes

Aria Barnes


Why use Node.js for Web Development? Benefits and Examples of Apps

Front-end web development has been overwhelmed by JavaScript highlights for quite a long time. Google, Facebook, Wikipedia, and most of all online pages use JS for customer side activities. As of late, it additionally made a shift to cross-platform mobile development as a main technology in React Native, Nativescript, Apache Cordova, and other crossover devices. 

Throughout the most recent couple of years, Node.js moved to backend development as well. Designers need to utilize a similar tech stack for the whole web project without learning another language for server-side development. Node.js is a device that adjusts JS usefulness and syntax to the backend. 

What is Node.js? 

Node.js isn’t a language, or library, or system. It’s a runtime situation: commonly JavaScript needs a program to work, however Node.js makes appropriate settings for JS to run outside of the program. It’s based on a JavaScript V8 motor that can run in Chrome, different programs, or independently. 

The extent of V8 is to change JS program situated code into machine code — so JS turns into a broadly useful language and can be perceived by servers. This is one of the advantages of utilizing Node.js in web application development: it expands the usefulness of JavaScript, permitting designers to coordinate the language with APIs, different languages, and outside libraries.

What Are the Advantages of Node.js Web Application Development? 

Of late, organizations have been effectively changing from their backend tech stacks to Node.js. LinkedIn picked Node.js over Ruby on Rails since it took care of expanding responsibility better and decreased the quantity of servers by multiple times. PayPal and Netflix did something comparative, just they had a goal to change their design to microservices. We should investigate the motivations to pick Node.JS for web application development and when we are planning to hire node js developers. 

Amazing Tech Stack for Web Development 

The principal thing that makes Node.js a go-to environment for web development is its JavaScript legacy. It’s the most well known language right now with a great many free devices and a functioning local area. Node.js, because of its association with JS, immediately rose in ubiquity — presently it has in excess of 368 million downloads and a great many free tools in the bundle module. 

Alongside prevalence, Node.js additionally acquired the fundamental JS benefits: 

  • quick execution and information preparing; 
  • exceptionally reusable code; 
  • the code is not difficult to learn, compose, read, and keep up; 
  • tremendous asset library, a huge number of free aides, and a functioning local area. 

In addition, it’s a piece of a well known MEAN tech stack (the blend of MongoDB, Express.js, Angular, and Node.js — four tools that handle all vital parts of web application development). 

Designers Can Utilize JavaScript for the Whole Undertaking 

This is perhaps the most clear advantage of Node.js web application development. JavaScript is an unquestionable requirement for web development. Regardless of whether you construct a multi-page or single-page application, you need to know JS well. On the off chance that you are now OK with JavaScript, learning Node.js won’t be an issue. Grammar, fundamental usefulness, primary standards — every one of these things are comparable. 

In the event that you have JS designers in your group, it will be simpler for them to learn JS-based Node than a totally new dialect. What’s more, the front-end and back-end codebase will be basically the same, simple to peruse, and keep up — in light of the fact that they are both JS-based. 

A Quick Environment for Microservice Development 

There’s another motivation behind why Node.js got famous so rapidly. The environment suits well the idea of microservice development (spilling stone monument usefulness into handfuls or many more modest administrations). 

Microservices need to speak with one another rapidly — and Node.js is probably the quickest device in information handling. Among the fundamental Node.js benefits for programming development are its non-obstructing algorithms.

Node.js measures a few demands all at once without trusting that the first will be concluded. Many microservices can send messages to one another, and they will be gotten and addressed all the while. 

Versatile Web Application Development 

Node.js was worked in view of adaptability — its name really says it. The environment permits numerous hubs to run all the while and speak with one another. Here’s the reason Node.js adaptability is better than other web backend development arrangements. 

Node.js has a module that is liable for load adjusting for each running CPU center. This is one of numerous Node.js module benefits: you can run various hubs all at once, and the environment will naturally adjust the responsibility. 

Node.js permits even apportioning: you can part your application into various situations. You show various forms of the application to different clients, in light of their age, interests, area, language, and so on. This builds personalization and diminishes responsibility. Hub accomplishes this with kid measures — tasks that rapidly speak with one another and share a similar root. 

What’s more, Node’s non-hindering solicitation handling framework adds to fast, letting applications measure a great many solicitations. 

Control Stream Highlights

Numerous designers consider nonconcurrent to be one of the two impediments and benefits of Node.js web application development. In Node, at whatever point the capacity is executed, the code consequently sends a callback. As the quantity of capacities develops, so does the number of callbacks — and you end up in a circumstance known as the callback damnation. 

In any case, Node.js offers an exit plan. You can utilize systems that will plan capacities and sort through callbacks. Systems will associate comparable capacities consequently — so you can track down an essential component via search or in an envelope. At that point, there’s no compelling reason to look through callbacks.


Final Words

So, these are some of the top benefits of Nodejs in web application development. This is how Nodejs is contributing a lot to the field of web application development. 

I hope now you are totally aware of the whole process of how Nodejs is really important for your web project. If you are looking to hire a node js development company in India then I would suggest that you take a little consultancy too whenever you call. 

Good Luck!

Original Source

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