1> What is node 2> What is node.js 3> Installation steps 4> Create first Node application 5> How it works ? 6> Why node is so popular ? 7> Where to use ? 8> Advantages 9> Disadvantages 10> Statistics

1. INTRODUCTION TO NODE.JS
MANOJ CHAUHAN
kalpcorporateinfo@kalpcorporate.com
kalpcorporate.com
Nodejs Developer

2. Overview
 What is node
 What is node.js
 Installation steps
 Create first Node application
 How it works ?
 Why node is so popular ?
 Where to use ?
 Advantages
 Disadvantages
 Statistics

3. What is Node
 In a network, a node is a connection point, either a
redistribution point or an end point for data
transmissions.
 A node is a point of intersection/connection within
a network

4. What is Node.Js
 Node.js is a platform built on
Chrome's JavaScript runtime for
easily building fast and scalable
network applications.
A Node.js is a JavaScript
runtime built on Chrome's V8
JavaScript engine.

5.  Node.js is an open-source, cross-platform runtime
environment for developing server-side Web
applications.
 Although Node.js is not a JavaScript framework,
many of its basic modules are written in JavaScript,
and developers can write new modules in JavaScript.
 The runtime environment interprets JavaScript
using Google's V8 JavaScript engine.

6.  V8 is the JavaScript execution engine built for
Google Chrome and open-sourced by Google
in 2008.
 Written in C++, V8 compiles JavaScript
source code to native machine code instead
of interpreting it in real time.
 Node.js uses an event-driven, non-blocking
I/O model that makes it lightweight and
efficient

7. How to install
• Download: https://nodejs.org/en/download/
• Installation on UNIX/Linux/Mac OS X, and SunOS
Extract the download archive into /usr/local, creating a
NodeJs tree in /usr/local/nodejs.
• For example:
• tar -C /usr/local -xzf node-v0.12.0-linux-x86.tar.gz
• Add /usr/local/nodejs to the PATH environment variable.
• export PATH=$PATH:/usr/local/nodejs

8. • Installation on Windows
• Use the MSI file and follow the prompts to install the
Node.js. By default, the installer uses the Node.js
distribution in C:Program Filesnodejs.
• The installer should set the C:Program Filesnodejs
directory in window's PATH environment variable.
Restart any open command prompts for the change
to take effect.

9. Let’s start with First Application
• Before creating actual Hello World ! application using
Node.js, let us see the parts of a Node.js application. A
Node.js application consists of following three important
parts :
• import required module: use require directive to load
a javascript module
• create server: A server which will listen to client's
request similar to Apache HTTP Server.
• read request and return response: server created in
earlier step will read HTTP request made by client
which can be a browser or console and return the
response.

10. Creating Node.js Application
• Step 1: import required module
use require directive to load http module.
var http = require("http")
• Step 2: create an HTTP server using
http.createServer method. Pass it a function with
parameters request and response. Write the sample
implementation to always return "Hello World". Pass
a port 8081 to listen method.

11. http.createServer(function (request, response) {
// HTTP Status: 200 : OK // Content Type: text/plain
response.writeHead(200, {'Content-Type': 'text/plain'});
// send the response body as "Hello World"
response.end('Hello Worldn');
}).listen(8081);
// console will print the message
console.log('Server running at http://127.0.0.1:8081/');

12. • Step 3: Save as a .js file eg. “test.js”and run :
C:Nodejs_WorkSpace>node test.js
console message : “Server running at http://127.0.0.1:8081/”
Make a request to Node.js server

13. How it works

14. Both the REST API and the DB Query return the same queried
response but the response differs in the format. Also, there is a big
difference in the way you make requests.
For DB Query, you need to connect your app to the database, install
appropriate drivers if required and even parse the response.
For a normal query, the response is the raw data. On the other hand,
the REST API does not care about the app that is requesting the data.
A simple request can be can drafted and sent to the API just with the
help of a simple old URL. The API parses it, queries the database on
your behalf (which eliminates the need of drivers and sdks) and
returns the structures response to you.

15. Why Node.JS is so popular ?
• It is Non-blocking
To start using Node.JS, you must first understand the difference between
Node.JS and traditional server-side scripting environment.
Other scripting languages uses separate server like Apache to run the
application, which is the thread and process based, which means if the
process is waiting for the I/O, whole thread is blocked.
Thread : In computer science, a thread of execution is the smallest
sequence of programmed instructions that can be managed
independently by a scheduler, which is typically a part of the
operating system

17. Whereas Node.JS using the ‘HTTP’ module
can run on a stand-alone web server.
It is asynchronous, event driven I/O. Every
nodes instance runs in a single thread, so it
can handle more number of concurrent
requests as compared to Apache.

19. • It is Fast
First, Node is powered by Google’s V8 JavaScript Engine.
The thing running you JavaScript code is the exact same
thing the Chrome browser uses to run JavaScript code.
Now Question is why V8 JavaScript Engine?
-It has unique speed compare to other JavaScript engines, it
compiles JavaScript directly into native machine code, while
other languages PHP & Ruby, Java all have to run through
an interpreter every time when they are accessed.
Node will run your code as though it’s native application.
So it screams with speed.

20. Second, How fastly Node handles connections.

21. When 100 people connect at once, rather than having different
threads, Node will loop over those connections and fire off any
events your code should know about.
If a connection is new it will tell you .If a connection has sent you
data, it will tell you .If the connection isn’t doing anything ,it will skip
over it rather than taking up CPU time on it.
Everything in Node is based on responding to these events. So we
can see the result, the CPU stay focused on that one process and
doesn’t have a bunch of threads for attention. There is no buffering
in Node.JS application
it simply output the data in chunks.

22. It is Event-Driven
“ Node.js uses an event-driven, non-blocking I/O model that makes
it lightweight and efficient ”
Event driven programming
Event driven programming is a programming in which the flow of
the program is determined by events such as user actions (mouse
clicks, key presses), sensor outputs, or messages from other
programs/threads.
Today, this concept is largely using in GUI Applications a
mechanism is in place that listens for events and executes an
action once the event occurs.
This is the basic principle behind node.js!

23. The Event Loop
The event loop gives Node the capability to handle highly
concurrent requests while still running “single-threaded”.
In any event-driven application, there is generally a main
loop that listens for events, and then triggers a callback
function when one of those events is detected. Similarly,
the event loop delegates I/O operations via POSIX
interface while it still handles new requests and callbacks.
Here is my take on how things work inside the node.js
server:

25. The event loop simply iterate over the event queue which is
basically a list of events and callbacks of completed
operations. All I/O is performed asynchronously by the
threads in the thread pool. Libuv component of Node.js plays
a vital part in this.
If an item requires an I/O the event loop simple delegates the
operation to the thread pool. Event loop continues execution
of items in the event queue. Once the I/O operation is
complete, the callback is queued for processing.. Event loop
executes the callback and provide appropriate results. Since,
it’s in a loop.. The process simply keeps going.

26. NPM
The npm is the default package manager for the javascript
runtime environment Node.js.
As of Node.js version 0.6.3, npm is bundled and installed
automatically with the environment.
npm runs through the command line and manages
dependencies for an application. It also allows users to install
Node.js applications that are available on the npm registry.
npm is written entirely in JavaScript and was
developed by Isaac Z.

27. • Built-in support for object databases It is really common
for Node.js applications to use object databases such as
MongoDB. MongoDB, contrary to traditional SQL databases,
it uses a document-based model instead of a relational
model; this means that instead of tables, it uses
objects resembling JSON.
• Wide support from IDEs and code editors JavaScript has
been around for a long time, so code hinting and highlighting
is featured by a bunch IDEs like Visual Studio and Eclipse;
also editors like Notepad++ and Sublime Text.

28. • Can be hosted almost anywhere
Several web servers and cloud-based hosting providers
support hosting of Node.js web applications out-of-the-
box. To mention a couple: Google, Microsoft IIS, Heroku,
Microsoft Azure, Amazon (AWS), and a bunch others.

29. • Debugger
• Node.js includes a full-featured out-of-process
debugging utility accessible via a simple TCP-based
protocol and built-in debugging client. To use it, start
Node.js with the debug argument followed by the path to
the script to debug; a prompt will be displayed indicating
successful launch of the debugger:
• $ node debug myscript.js
• < debugger listening on port 5858
• connecting... ok

30. • Debugging Node.js in Chrome DevTools
npm install -g devtool

31. Where to use ?
Here’s just a sample of the many companies using Node in production
or ramping up projects:

32. • If you want to build streaming applications
• If you plan to build CPU intensive applications
(e.g. image processing)
Then Node.js is not the perfect choice. You'll be
able to get the job done, but other technologies
may be a better fit.

33. Advantages
Open Source
Node.js is open source, so it’s free to use and no need to pay for license.
There are also many open source modules supported by Node.js.
JavaScript as Programming Language
It uses JavaScript as a programming language for both front-end and back-
end which increase programmer productivity and code reusability.
Scalable
• You can scale your Node.js application by using two ways – Horizontal
Scaling and Vertical Scaling, which helps you to improve your
application performance.
• In Horizontal scaling you can add more nodes to your existing system.
In Vertical scaling you can add more resources to a single node.

34. Better Performance
It provides better performance, since Node.js I/O operations are non-
blocking.
Also, it uses V8 JavaScript engine to execute JavaScript code. V8
engine compiles the JS code directly into machine code which make it
fast.
Caching Support
Node.js supports caching of modules. Hence, when a Node.js modules
is requested first time, it is cached into the application memory. So
next calls for loading the same module may not cause the module
code to be executed again.

35. Lightweight and Extensible
Node.js is based on JavaScript which can be executed on client
side as well as server side. Also, it supports exchange of data using
JSON which is easily consumed by JavaScript. This makes it light
weight as compared to other frameworks.
REST API Support
Using Node.js you can also develop RESTful services API easily.

36. Unit Testing
It supports unit testing out of box. You can use any JS unit testing
frameworks like Mocha, Jasmin to test your Node.js code.
Server Development
Node.js has some built-in API which help you to create different
types of Server like HTTP Server, DNS Server, TCP Server etc.
Community Support
Node.js has a wide community of developers around the world.
They are active in development of new modules or packages to
support different types of applications development.

37. Disadvantages
It doesn’t support multi-threaded programming.
It doesn’t support very high computational intensive
tasks. When it executes long running task, it will queue
all the incoming requests to wait for execution, since it
follows JavaScript event loop which is single threaded.
Not good for executing synchronous and CPU
intensive tasks.

38. Statistics

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