Node.js Tutorial for Beginners | Node.js Web Application Tutorial | Node.js Training | Edureka

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING Webpage

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING Agenda ❖ Client Server Architecture ❖ Limitations of Multi–Threaded Model ❖ What is Node.js? ❖ Features of Node.js ❖ Node.js Installation ❖ Blocking Vs. Non – Blocking I/O ❖ Creating Node.js First Program ❖ Node.js Modules ❖ Demo – Grocery List Web Application using Node.js

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING Client – Server Architecture

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING Client Server Architecture Client 1 Client 2 Client 3 Server Database

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING Traditional Multi-Threaded Model Handle Request A Handle Request B Handle Request C Read ResponseRead Request Assign Thread for A Assign Thread for C Assign Thread for B Thread Thread Thread User HTTP Request A User HTTP Request B User HTTP Request C User HTTP Request D

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING Limitations of Multi – Threaded Approach

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING Limitations of Multi-Threaded Models Shared Resources Updating Resources Wants to Update Wants to Update Thread A Thread C Thread B ➢ In a multi-threaded HTTP server, for each and every request that the server receives, it creates a separate thread which handles that request ➢ If a request acquires a lock in the shared resource and it is ‘exclusive’, it will affect result of other requests

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING High chances of deadlock if application is not designed properly Limitations of Multi-Threaded Models Web Servers need to handle thousands of HTTP requests. So, many threads may have to wait for network operations For thousands of simultaneous requests, spawning threads for all processes would not achieve the desired scalability Scalability Complex Deadlock

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING What is Node.js ?

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING What is Node.js? ➢Node.js is an open source runtime environment for server-side and networking applications and is single threaded. ➢Uses Google JavaScript V8 Engine to execute code. ➢It is cross platform environment and can run on OS X, Microsoft Windows, Linux, FreeBSD, NonStop and IBM. ➢Provides an event driven architecture and non blocking I/O that is optimized and scalable. N O D E

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING Features of Node.js

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING Features of Node.js 1. Asynchronous Caller Recipient request response callback ➢ When request is made to server, instead of waiting for the request to complete, server continues to process other requests ➢ When request processing completes, the response is sent to caller using callback mechanism Asynchronous Model Asynchronous Event Driven Very Fast Scalable

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING Features of Node.js ➢ When request is made to server, instead of waiting for the request to complete, server continues to process other requests ➢ When request processing completes, the response is sent to caller using callback mechanism Event Emitters Event Loop (Single - threaded) File System Network Process Other Event Queue Thread Pool 2. Single Threaded and Event Driven: Asynchronous Event Driven Very Fast Scalable

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING Features of Node.js 3. Very Fast 4. Single Threaded but Highly Scalable Being built on Google Chrome's V8 JavaScript Engine, Node.js library is very fast in code execution. Node.js is highly scalable because event mechanism helps the server to respond in a non- blocking way. Asynchronous Event Driven Very Fast Scalable

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING Node.js Installation

EDUREKA NODE JS CERTIFICATION TRAINING www.edureka.co/mastering-node-js Node.js Installation Go to https://nodejs.org/en/1 Download and Install2

EDUREKA NODE JS CERTIFICATION TRAINING www.edureka.co/mastering-node-js Node.js Installation Open node.js command prompt3 ➢ node –version Check the version of Node.js installed

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING Creating Your First Node.js Program

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING Node.js First Program Create a Directory: mkdir node_example1 Create a File: first_example.js2 Go to the node_example directory3 Execute the java script file: node first_example.js4 2 1 3 4

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING Simple Web Application Example

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING Simple Web Application Example Example: Importing Module: ‘require’ is used to load a Node.js modules. 1 Example: Creating Server ➢ Used to create web server object ➢ Function (request, response) is called once for every HTTP request to the server, so it's called the request handler. 2 listen(<port_no>) Bind the server instance for listening to a particular port.3 Example:

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING Simple Web Application Example 1 Import HTTP Module 2 Define Port No. 3 Creating Server Instance 4 Sending HTTP Header 6 Binding Server Instance with the Port No. 3000 5 Sending Data

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING Blocking vs Non - Blocking

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING Blocking vs Non–Blocking I/O ➢ Blocking is when the execution of additional JavaScript in the Node.js process must wait until a non-JavaScript operation completes. ➢ "I/O" refers primarily to interaction with the system's disk and network supported by libuv. More methods will be blocked till the read method is not executed More method will execute asynchronously (non-blocking way)

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING Blocking vs Non–Blocking I/O Non – Blocking Example:

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING Blocking vs Non–Blocking I/O Blocking Example: C O N C L U S I O N : ➢ In case of Asynchronous (non-blocking ), once file I/O is complete, it will call the callback function ➢ This allows Node.js to be scalable and process large number of request without worrying about blocking I/O

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING Node.js Modules 02 GLOBALS 03 FILE SYSTEM 04 CALLBACKS 05 EVENT 06 HTTP 01 NPM

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING NPM ➢ NPM stands for Node Package Manager ➢ Provides online repositories for node.js packages/modules ➢ Provides command line utility to install Node.js packages along with version management and dependency management.

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING NPM npm install Install all the modules as specified in package.json npm install <Module Name> Install Module using npm npm install <Module Name> -g Install dependency globally

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING Basic Concepts: 02 GLOBALS 03 FILE SYSTEM 04 CALLBACKS 05 EVENT 06 HTTP 01 NPM

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING Global Objects These objects are available in all modules and therefore, are referred as Global Objects specifies the name of the directory that currently contains the code. __dirname specifies the name of the file that currently contains the code. __filename

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING Global Objects A timer in Node.js is an internal construct that calls a given function after a certain period of time. setTimeout(callback, delay[, ...args]) ➢ Schedules execution of a one-time callback after delay milliseconds ➢ Returns a Timeout for use with clearTimeout( ) setInterval(callback, delay[, ...args]) ➢ Schedules repeated execution of callback every delay milliseconds. ➢ Returns a Timeout for use with clearTimeout( ) setImmediate(callback, [,..args]) ➢ Schedules an immediate execution of the callback after I/O events' callbacks but before setTimeout() and setInterval() timers are triggered. ➢ Returns an Immediate for use with clearImmediate().

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING Global Objects output

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING File System File I/O is provided by simple wrappers around standard POSIX functions. For importing File System Module (fs), we use: var fs = require("fs"); All methods have asynchronous and synchronous formsImportant Note: FS Methods Asynchronous Forms Synchronous Forms 1 var fs = require("fs"); // Asynchronous read fs.readFile(‘test.txt', function (err, data) { }); // Synchronous read var data = fs.readFileSync('input.txt');

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING File System The asynchronous form always takes a completion callback as its last argument. var fs = require("fs"); // Asynchronous read fs.readFile(‘test.txt’, function (err, data) { if (err) { return console.error(err); } console.log(data.toString()); }); FS Methods Arg 1 Callback Method (last argument) Arg 2 Arg 3 Callback As Last Arg. Important Note: 2

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING File System First argument in completion callback is always reserved for an exceptionImportant Note: 3 Callback Method Arg 1: exception Arg N Arg 2 Arg 3 var fs = require("fs"); // Asynchronous read fs.readFile(‘test.txt’, function (err, data) { if (err) { return console.error(err); } console.log(data.toString()); }); Reserved for exception returns null or undefined (successful completion)

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING Some Methods in File System Module – Open() fs.open( path, flags[, mode], callback ) fs.openSync( path, flags[, mode] ) fs.close( fd, callback ) ➢ var fs = require(‘fs’); Open File Asynchronously Open File Synchronously Closing File Arguments Description Path < string > Path of the file Flags < string > Access Modifiers Mode < integer > sets the permission and sticky bits, but only if the file was created Callback < function > Callback signature - function(err, fd)

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING Flag Modes in Open Method Modes Description r Open file for reading. an exception occurs if the file does not exist r+ Open file for reading and writing. Exception: if the file does not exist w Open file for writing. The file is created ( if it does not exist) or truncated (if it exists) wx Like 'w' but fails if path exists w+ Open file for reading and writing. File is created (if it does not exist) or truncated (if it exists) wx+ Same as 'w+' but fails if path exists a Open file for appending. The file is created if it does not exist ax Like 'a' but fails if path exists a+ open file for reading and appending. the file is created if it does not exist. ax+ Like 'a+' but fails if path exists

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING Some Methods in File System Module – Read() read(fd, buffer, offset, length, position, callback) readFile(file[, options], callback) readFileSync(file[, options]) Read Content of a File into Buffer Reads File Asynchronously Arguments Description fd < integer > File Descriptor buffer <string | Buffer | Unit8Array > The buffer that the data will be written to. offset < integer > Offset in the buffer to start writing at. length < integer > Specifies the number of bytes to read. position < integer > Specifies where to begin reading from in the file Callback < function > Read Callback signature - function(err, bytesRead, buffer) Reads File Synchronously

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING Some Methods in File System Module – Write() writeFile(file, data[, options], callback) writeFileSync(file, data[, options]) Writes into a File Asynchronously Arguments Description File Filename or File Descriptor Data The buffer that the data will be written to. Options: Encoding, Mode or flag Callback < function > Callback signature - function(err, bytesRead, buffer) Writes into a File Synchronously

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING Some Methods in File System Module – Write() Callback is an asynchronous equivalent for a function and is called at the completion of each task Callback: will execute after file read is complete Output:

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING Events ➢ Node.js follows event-driven architecture where certain objects (called "emitters") periodically emit named events which further invokes the listeners (function). ➢ Node.js provide concurrency by using the concept of events and callbacks ➢ All objects that emit events are instances of the EventEmitter class. var eventEmitter = event.EventEmitter(); Importing ‘events’ module Object of EventEmitter Class eventEmitter.emit(‘event’) Registering listeners Trigger event eventEmitter.on(‘event’, eventHandler) var event = require(‘events’);

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING Events Import Events Module Creating object of EventEmitter Emitting event Registering Listener and defining event handler OUTPUT

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING Web Application Architecture Client Client Client Client Mobile Browser Web Browser Application Web Server Application Server File System Database External File System Client Server Business Layer Data Layer Makes HTTP Request to the server Serve the request Made by client and pass the response contains application utilized by web server to do required processing. Consists of Database and other data storage

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING HTTP Import Required Modules Creating Server Parse the fetched URL to get pathname Request file to be read from file system (index.html) Creating Header with content type as text or HTML Generating Response Listening to port: 3000

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING HTTP Index.html Output Node.js cmd

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING Express

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING Express Framework ➢ Express is a minimal and flexible Node.js web application framework that provides a robust set of features for web and mobile applications. ➢ Inspired by Sinatra (web framework based on Ruby) and also, intertwined with Connect, a “plugin” library for Node. ➢ Express used to come bundled with Connect before version 4.0 ➢ After version 4.0, Connect (and all middleware except static) was removed to allow these middleware to be updated independently

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING Express Framework Importing express module Retrieve resources Sending html doc as response Listening to port: 3000

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING RESTful API REST stands for REpresentational State Transfer. Used create a new resource or update a existing resource 1 POST Used to provide a read only access to a resource 2 GET Used to create a update a resource 3 PUT Used to remove a resource 4 DELETE C R U DCreate Delete Read Update

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING Popular Frameworks Around Node.js

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING Popular Frameworks Around Node.js E X P R E S S Minimalistic Web Framework based on Node.js S A I L S Project generator, Middleware and Templating Engine M E T E O R Full Stack Framework that covers server, mobile, desktop & web apps K O A Web Framework designed by the team behind Express N O D E

www.edureka.co/mastering-node-jsEDUREKA NODE JS CERTIFICATION TRAINING Demo: Grocery List Web Application

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