Node.js is an open source JavaScript runtime environment used to build real-time web applications. The document introduces Node.js, the npm package manager, the Express web application framework, and how to connect a Node.js application to MongoDB. Key points covered include Node.js being single-threaded and event-driven, using npm to install and use packages locally or globally, Express providing features for building web apps and APIs, and using modules like Mongoose to connect a Node app to MongoDB.

1. Node.js
BUILD real time Web Application Development

2. Objectives
Introduction to Node.js
What is NPM
Express framework in Node.js
How to create API
MongoDB Configuration
At the end of the session you will be able to learn:

3. Introduction to node.js
 Node.js is an open source , cross platform runtime environment for server-side and
networking applications
 Node.js applications are written in JavaScript, and can be run within the Node.js
runtime on OS X, Microsoft Windows, Linux, etc – Wikipedia
 This is based on Google ‘s V8 Javascript Engine

4. What is Node.js
 It is SINGLE THREADED
 No Worries about : race conditions , deadlocks and other problems that go with
MultiThreading.
 Almost no function in Node directly perform I/O, so the process never blocks. Because
nothing blocks, less-than-expert programmers are able to develop scalable systems.
EVENT LOOP
NETWORK
FILE SYSTEM
PROCESS
OTHER
THREAD POOLEVENT QUEUE

5. Basics of Node.js : npm
 NPM stands for Node Package Manager.
 npm is a registry of reusable modules and packages written by various developers
 You can publish your own packages
 There are two ways to install npm packages:
 Locally: To use and depend on the package from your own module or project
 Globally: To use across the system, like a command line tool
 Installing a package locally:
 The package is easily downloaded by just running “npm install <package name>”
 This will create a node_modules directory (If it doesnot exist yet) and will download the
package there.
 Once installed you can use it in any js file of your project by saying: var obj =
require(‘<package name>’);

6. Express Framework
 Express is a web application framework which provides a robust set of features for web and
mobile applications
 It is open source designed for building web application and APIs
 It is a server framework for Node.js
 It is backend part of MEAN Stack together with MongoDB, database and Angular JS frontend.
 Creating robust API is quick and easy
 It provides a thin layer of fundamental web application feature
 It offers a simple way to get a server up and running
 Features:
 Router
 Middleware
 Template Engine
 Error Handling

7. Express : Simple Application Example
Var express = require(‘express’);
Var app = express();
app.listen(9000, function(){
Console.log(‘Server listening to port 9000’);
})
app.get(‘/getUsers’, function(req,res){
res.json({‘message’:’data from getUsers’});
})

8. Connecting MongoDB with Node.js
 MongoDB has rapidly grown to become a popular database for web application
and is perfect fit for Node.JS applications
 We have lot of third party modules to connect to MongoDB
 Mongoose
 MongoDB
 MongoClient
 First we have to establish a connection between node app and MongoDB
 Once connection is establish, fire the query to perform a crud operation
var mongoose = require(‘mongoose’);
//Middleware
mongoose.connect(‘mongodb://localhost:2701/userManagement’);