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02.Introduction to N-tired architecture with NodeJS

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on okay so we'll be using njs as our

programming language uh so nodejs is

basically a JavaScript runtime that you

can install within your machine and um

you can develop lot of applications

including backend front end or even

mobile application if you like so all

you need to do is um based on your uh

operating system uh you need to install

not Chas within your machine in order to

get started on this so I'll be uh using

um the latest not not the latest one at

least the um not JS version available

right now so let me share my screen and

show you guys what I

screen okay so uh basically what you

need to do is you you need to make sure

that um you guys have njs installed

within your machine and if you if you do

not have nodejs just it's like a basic

simple installation if you're on Windows

you just have to download the binary

execute same goes to Linux and Mac as

well so I'm in my Mac Show the

instructions um for downloading and

downloading and installing is pretty

much simple I all I have to do do is

install it and

uh for my personal preference I would

like uh to use not the binary version

but uh something called

nbm uh not version manager as it calls

so NVM is an tool that help us to

build uh a tool that gives us ability to

change our not environment so you guys

know they um not has different versions

or different environments that I can run

with so I have

uh the latest version maybe some my

projects would be in older not version

so in order to do the version changes

everything NVM is a great tool so first

install NVM and using NVM we can install

uh the

desired um

desired um desired no um n as as as we

speak uh so right now if I I run not

minus V that indicates the version that

I am in currently I am running version

19.9 it might be changed based on what

you have installed at least install

something latest something about

from node uh 18 so that's uh that is

like the latest one do not install very

old version that would uh definitely

leave you guys um with some um headaches

okay so right now I'm having not

1944 and not come coming with um a lot

of uh tools that we can uh use okay so

basically when we are developing an web

application or when we are developing

some sort of uh um some sort

of um mobile or web application we do

not start from the scratch nowadays okay

so the different Frameworks um different

uh uh uh different programming languages

most of the time they have what we call a

CLI uh a CLI would be helpful if you if

you like to generate um application

rather than doing it yourself rather

than doing it you're doing it from

scratch sometimes those Frameworks help

us with not not only setting it up but

when we when we want to deploy the

application okay so for instance we want

to run this in uh some sort of a

containerized environment or if if you

need to run it somewhere somewhere in

the cloud the Frameworks and the CLS

gives us those abilities as well so we

do not want to reinvent the wheel okay

so the application itself will generate

uh very self sustained uh self maintain applic

applic

that application would uh will be able

to run and uh you you guys can uh

leverage the uh leverage the existing

applications or leverage the existing

testing Frameworks and lot of things

pre-built for you okay so the CLI tool

that I'm going to be using is what we

call index okay so index is um index

what we call called uh monor repo tool

okay if you do not know about monor

repos uh just give you a simple hint

like uh rather than putting all your

codes in different different

repositories we have one single

repository that use for all our code

management so uh make sure uh you have

NX installed in your machine so if you

have not installed okay if you have it

not installed then you can have the

command npm npm also is a command that

comes with not okay so once you have not

installed you have not npm as well npm

stand for not package manager which will

help us to install dependencies packages

third party dependencies and all those

things so I have npm installed in here

as well so not package manager uh this

is the version that I'm currently

in so using npm I can install NX

okay so by default as I mentioned

earlier you have not and npm using npm

you can in you guys can install LX so

simple command will be

npm install minus

GNX okay so uh let me double check the

[Music]

NX yeah so you can use the in uh NX

command uh if you if you if you like or

you can have uh what we call the uh npx

command npx stand for like uh rather

than having NX globally installed minus

G in here indicating that okay for the

whole computer we'll be using NX but

right now uh if you do not want to have

NX within your whole machine uh so what

we will do is we will install using npx

it's like a temporary thing that we will

be developing so uh I will be using npx

in this example so I'll be working with

um I'll be uh I'll be in my temper

directory so I'm I'm not going to be

able to um have this project afterwards

and I hope not to continue um uh this

after the lectures as as soon as I'm

done with it I'm going to be get ring of

this project so what I'm going to do is

uh I I will say NX again and NX will

give us okay uh this is the command if

you want to create a workspace okay so

workspace is something rather than other

than generating a simple um simple

application a workspace uh contains uh

uh tools uh generated application and so

on and so forth so do not worry about

those things right now all you need to

know is is like workspaces single uh

single place that you can work with Okay

so all you have to do is run this

command npx create NX workspace at

latest which means we will be using the

latest workspace in here we have not

selected any um anything um anything for

the application right now we'll be

working in uh Solly on the simplest uh

workspace generation so I'll I I will um

I will uh uh I will just name me my

um um name my uh

uh name my workspace as f s ft okay so

uh you can name it whatever you want and

probably you'll go with something more

meaningful so um it will ask whether you

to proceed I'll say yes and depending on

your internet connection depending on

what what what sort of uh what sort of

uh connection that you guys have you

will get uh immediate response on all so

uh next thing is um it will ask what

sort of uh application that you need to

generate so NX is a multi uh multiple

platform supporter that means you can

create a react application new

application angular or not application

since we are working with a web

application so these are like front end

web applications so we'll be focusing on

in a different uh lecture on those

things right now we will be focusing on

N architecture so it's easy to

demonstrate n architecture with the

backend project so I'll choose a not and

there are lot of options that you can uh

select from

here so these are the Frameworks or

the um all the templates that you guys

can use so I'm going to be using

something that um I find

quite easy to work with which is called

njs okay you guys can select either one

of these make sure you know the

um make sure you guys follow the same

architectural pattern that we're going

to be using so I'm going to select

njs and whether it's asking for

Standalone or integrated right now I can

go with integrated mono or standalone

the difference is if I if I selected

integrated monor repo then I can have my

front end uh application in the same

repository that's what I meant by monor

repos if I say Standalone that's going

to generate on the njs application I

don't I won't be having any other

application other than an sjs

application that means only a back end

application since I'm not going to be

integrating anything to this one I'll

just stand

alone and this is a Docker file I would

rather not go in

there uh CI building no thanks I do not need

need

that so right now we what NX is doing is

it is um based on the inputs that I have

given uh it is creating a simple web

application uh for us

and by by the time uh the application is

generated uh we'll be able to uh work

with the that so uh it is downloading

all the dependencies it needs that means

the web application it's not going

to not going to be developing itself

that means it needs third party

dependencies there are dependencies in

hand right now it is generating all the

dependencies and take caring of

generating my project so what I'll do is

I will um I will see into the newly

created workspace so I will go to CD wsf

and I'll start code from here

here

uh let me share a new share you guys won't

see I have show code and terminal and

Sh okay um

so uh make sure you guys open it with

your stud code or something that that's

that's uh up to your liking right now

developing web application using

um uh using uh vs code is like really

easy so uh I would uh I would suggest

use something like vs code or

intellig uh platforms if you like

so um it's going to it's still

generating an application for me and um

I'll um brief briefly talk about uh the

application architecture otherwise you

guys U find a lot of files in here and

which will overwhelm you guys so I'll

just give you a brief introduction on

what each of these file represent if you

want more detail uh let's uh look in in

a separate session on those things okay

right now the most important things that

you guys know is this package as so

package simply represent all the

dependencies that we have within our

project let me Zoom it in a little bit

so you guys can

see so this uh this give us a little bit

idea of uh the uh little bit idea about

the our application so these are the

scripts these are the things like we

will be um using to start the

application build the application and

test the application okay so these

script will help us to um do those

things these are like metad datas about

the lensings and everything and we have

these these things called uh

dependencies so these dependencies

represents um what sort of things that

we'll be using within our application

since we using sjs so there are like

dependencies which needs to run the

application um so these dependencies are

needed and there are few de dependencies

these de dependencies what we call is um

these are the things that we need in

order to develop the application but at

the end we won't be using these U Dev

dependencies at the production build we

we would not use um

um [Music]

[Music] uh

um um uh something like uh we'll be

using uh using these things in um in

development but not

uh um development using um in the de

sorry we'll be using these things at the

development time but not at the um not

at the uh frun time okay uh give me a

what Happ

Happ

so um in here uh we we have the Linux uh

terminal so if you do not have a

terminal um there are few options for

Windows uses uh you can use the command

line CMD tool which is available you can

just uh search for CMD tools it pop up

something similar not the exact thing

but something similar zmd tool will um

will help you guys to uh come across uh

the command line uh tool and the easiest

way to verify that you have installed

nodejs is to execute this command not

minus V okay so if will give you guys

whether you have installed nodejs or

not okay so so this indicates we have

installed nodejs successfully using this

nodejs we can

uh start uh developing applications okay

we we this is the runtime for our

application we have the runtime ready

now we can develop applications okay so

noj comes with a package manager okay a

package manager we can simply put it

help us to uh develop application faster

build application faster and execute

some comms so not has a package manager

we called it not package manager simply

put npm okay npn stand for not package

manager so not package manager will help

us to get uh libraries uh from internet

that we can use so we don't need to

develop our own libraries from scratch

we can use existing not uh libraries

within our application okay for example

uh let's say we want to write a a simple

web application okay we need to write a

simple web application in order to write

a simple web application there are like

servers available in handling request

response and everything so we can do it

from scratch of course we can write a

nj's class for that but there are

already built packages that can do the

do the thing so for

example uh if you go noj's uh website sry

sry

npm npm

repository okay so this is where you

guys can get um [Music]

[Music]

um um this is where you guys can check

upon what are the existing package

managers out there okay so packages uh

what are out there so for example I can

search package something called a web

server so the well known web server is called

called

Express okay uh do I have Express yes so

expr is a package or a library that we

can use that to generate a simple web

application okay simple web application

so I I can use express rather than

developing everything from scratch I can

simply use express to develop a simple

application you guys can see there are

examples in here that you guys can use

to develop a uh simple uh web

application all right so um the next

thing that uh we need to do is we need

to install this exess application right

we need to install this web web culation

in our machine so how do we use that we

use the command npm install or npm I for

short so using this command what it will

do is it will uh install um the express

uh library or Express package then we

can use within our JavaScript code okay

so we do not develop everything from

scratch we use an existing package and

using that package we can develop the

software so likewise there are like

thousands of not packages that you can

um use with

uh when we are building application we

will be using lot of not packages okay

like Express there is TS Libs you don't

need to know everything even I don't

know what are the all the libraries are

doing for but at least what are the

JavaScript development uh helping

libraries out there you guys can use

those okay so right now I'm I'm uh

simply using uh a simple not

uh simple not package simply using not

package manager to install a bunch of

other softwares that will help me to

develop a simple application okay so

make sure nod is there npm is there and

when you're using npm make sure you know

what is the uh what is the library or

the Frameworks or the things that you're

going to be using in here otherwise it

won't help you to work with Okay so uh

we have npm installed so we can I can

even see the not package manager version

okay so right now I'm we're using the version

version

9.0 which came along with the this note

version so not package manager help us

to get uh all the dependencies and

running those script and everything U so

we should know what are the packages

that we going to be using Okay anything

up until this any questions with the no

unclear any questions with regarding

all

good just give me the go ahead then I will

getting yes

sir all right

so uh so we have npm installed uh not

package manager and

now what we need to do is um as I

mentioned earlier um we need to generate

a web application okay especially uh web

application which will uh which will

give us some

U API okay uh we can expose some uh data

so what what we're going to do is we

going to um develop a rest API uh which

is uh which is something like uh when

when we using a browser or a web client

we will request something from the

server and the server will respond a

certain um certain information backwards

it's like when we are looking into a web

web page okay right now when we go to a

npmjs.com we get uh HTML

response right we get the HTML response

so in a rest API we would get uh we

would not get X HTML response but a

simple Json response we will see all

these things in action so right now what

we're going to be building is uh a

simple rest API okay if you do not know

rest API um have a have a quick look

around it that is like the most common

way of communicating these days and rest

days and there is grab ql one of the

major uh major things that we will be

using so make sure if you do not know

what we going to be building just have a

look around what is a rest API but in

this scenario we'll be uh developing a

simple rest API okay and we will be

developing the API and we will be

applying the basic architecture patterns

in while we are doing that we will uh

you guys can see if you guys can see um

take this example this example the

express example it's it is also

developing something like what we call

uh a rest API it's not practically a

rest API but it is something like that

but we can also work uh we can

also uh we can also show a simple

application uh using um these packages

okay let's let me demonstrate uh so you

guys can get a better idea we'll just

use a simple express application and we

will see the pros and cons of this

application and why this application or

why this architecture will not suffice

for uh uh suffice for a huge application

why we need to architect better than

let uh let me quickly grab this example

and try to run this so let me uh once

again um I'll go to a directory uh where

I can work uh work without an issue I am

in my M temporary directory which is

like u a directory will be uh once I'm

restarting the computer whatever in this

temp will be gone okay but if you're

working uh something solid uh project uh

choose my documents or projects or

somewhere else so you guys can work

there so I will create a

directory mkd or you can say right click

new folder mkd I will say

Express okay so I can go to express uh

Express uh directory now if I use vs

code and I will open the project in that

same directory so I am I'm actually in

the directory that I have created in

under TMP Express I have opened it using

V code you can use file and open and you

will you will have the same thing as as

I did earlier

on so

uh let me share that as well

now okay so I have the open editor for

that so uh within the express uh Express

directory I'll I'll simply create a

simple application I normally we called

it at app.js which indicate application

so I hit

enter and I will copy paste the

application that is giving in here and

you guys can see um this is going to be a

developing I'll show you guys what is

the outcome of this so the outcome of

this application would be simply showing

a message called hello world that is the

outcome of this

things okay so in order to run this code

in order to run this code what I need is

something called Express so I I did not

I do not have Express install in my

machine I I do not have Express

uh within uh my U within my app.js so

what I'm going to do is I'm going to

install Express the package that I show

you guys in here using this command npmi

Express so make sure uh my terminal is

where I I am in the current uh in the

current project I'm going to say npm install

Express uh let me copy the command in

here and I will install Express so what

it's going to do is using npm I will

install Express into my uh Express into

my coding area so if I go back in here

you guys will see few things have

changed around here okay the first thing

is um there is something called not

modules so not modules containing all

the dependence is within my application

so I have only depended on Express but

the thing is Express is not going to run

its own Express is depending on other

packages okay so this is the express

that we have installed but Express is

not going to work alone Express

depending on other packages like e Tec

is something Express will be depending

on all the other packages directly or

indirectly depend on Express so Express

is depending on all these packages so npm

npm

is smart enough

okay uh if you are using Express you

need uh e Tec also within you so it will

install e Tec so sometimes e teac might

be e teac is uh e te is uh depending on

something else it will download that we

can actually see what's depending on

what so if I go to the

package this is like where we uh where

we uh have all the dependence is list

out in our application so right now you

can see uh my application am depending

on Express especially Express version 4 uh

18.2 so I'm depending on this version

okay so this version you can find within

not modules this is where the express

binaries are the library things are and

you will find Express in my not module

and if you go to express also there will

be a package Json and within Express JS

you can see what are the packages

Express is depending on so it depending

on accept cookies fresh lot of things

are in here I will take something like

accepts so whenever Express is is

installed it automatically also download

accepts this Library I don't know I

actually do not know what it even the

purpose is it is installing accepts so

if I go back to accepts in here and I

can see packages accet is depending on M

types and everything so you guys get the

picture there's a tree of dependencies

all these tree of dependencies will get

resolved until the package do not have

any dependency IES to depend on okay so

the last one would definitely not have

any dependencies by that

time we will uh we will have all the

dependencies installed so now in order

to run my application in order to run this

this

application all the dependencies all the

necessary application stuff is here here

with me I do not need anything else to

run everything is runnable at this

moment so you guys get the idea on the

package Json so package Json F all the

dependencies what are the libraries that

we are develop depending on it's going

to have uh those information in here and

all the dependencies that we going to

have will be within this not module

application now so this this is going to

contain all the binaries and this is

going to express what are the things we

are depending on okay for now just

ignore the package lockon it's going to

specifically lock the version okay so we

created appjs app.js this is the file

that we have created and this is the

package we are depending on so anything

up until this uh you guys did not

get please confirm that you guys got

continue any

anything if if you if you have anything

at the moment just interrupt me and I

will I'll will answer okay so basically

this is what what not JS application

would look like but if you if you if you

use uh if you use something like a Java

application the terminologies will

change but the application uh structure

most of the time remain same so for

example if you're using Java web

application then uh we will have we we

won't find Express in Java right Java

Java is a different ecosystem it has own

libraries and everything you won't find

Express in Java but you will find

something similar you will find

something like Tom cat underthrow or

even um there are reactives web services

there are a lot of similar products

which represent a webite okay

so Java do not have npm not package

manag is available for not npm available

for not JS

only so you won't find that in Java but

you will find something similar like

Maven gr the echo system grows okay so

you all you need to know is uh there are

strikingly similar things that happens

in different Frameworks different world

but they they have the same thing okay

if you're developing a same thing if you

go to C World okay so if you go to cop

World okay you have Frameworks like net

Co and IIA server those kind of things

same thing you will have the new get

package manager like you see npm in cop

you will say new get package manager all

you need to do is adapt to that

framework okay so there are a lot of

Frameworks and everything's going on if

you're using python you will see um you

will see uh uh Frameworks like d Jango

okay fast API as your server and you

have unicorn servers and the package

manager or when you want to handle your

dependencies you will use something like

pip Python uh package manager for

installing different like so you guys

get the idea they have all similar

things we will get uh we will uh

when we are looking at other

architectural patterns I'm not going to

go everything inj we will have other

projects concluding in other Frameworks

like we'll create a mobile application

you'll create uh

uh [Music]

[Music]

uh you will create um micros service

application so we will use different

Frameworks and different things okay

only thing that you guys need to know

that different Frameworks have different

package managers different uh servers

depending on what you are developing you

guys need to adap to that that's it okay so

um so what we can do is uh um we have

installed the necessary packages which

we can run this uh application now we

need to run this okay we will run this

and see the see the result and we will

get back and try to understand this

piece of code okay all right in order to

run this application what I need to do

is I need to be in the same directory

where my project

is yeah so if I list down all the things

uh in my directory I can see that appjs

is one one in here that means I can run this

this

application and you guys can see the not

modules and everything so all I need to

do is run this application and see

whether it is starting a web server so

in order to run this application all I

have to do is say not app do sorry

sorry

app.js okay so if everything is in order

if I if I do not uh if I do if I did

everything correctly so what should

happen is it seems to be running

running

um it's not giving me an error so I I

suppose this is running so all I need to

do is um you guys can see uh it is

listening on P 3,000 that means this

application is now running the web

server is running uh the web server is

running on Port 3,000 okay so if I go to

Port 3,000 within my machine I would see

something okay let's see what we can get

when we go to Port 3,000 so how we can

access since this is a rest rest API and

simple simple rest API is there how

definitely I can use uh our browser okay

we can use the browser if I'm not using

the browser I can use a

client okay so I can use a client like

curl um so I can look around it so I can

use something like curl uh

local local Post Port

3000 okay so it's simply saying uh go to

this address Local Host is my own

machine since I'm working on my same

machine I it will be Local Host the port

I'm interested in is 3,000 so if I hit

enter and I get the response back

message hello work okay so I can get the

similar or the same result since this is

a simple web API if I go to my

browser and if I go to Port 3,000 Local

Host 3000 then I get this same message

but in a little bit of Json format you

might see something like this I have

this um Json passer which help me to

understand this one a little bit easier

so you guys can see that I am seeing the

message hello world which I put in the

section but if I want to say

hello R leer

this would not probably show yeah so I

have changed the code hello R so now

what I have to do is go to my terminal

and you guys can see it is still running

the old version I will terminate it you

can use control C uh or in in MOS would

use uh in even contrl C by hitting

control C it will terminate the running

process now I can run again then not

app.js and if I go back to controller uh

if I go back to my browser uh still I'm

seeing the old one if I refresh and I

can see

hello okay so simple web message got

back to me so this is in a format called

Json uh Json is like the uh goto

representation of uh rest API right now

what we are using so if you do not know

Json have a look around Json and Json um

what it represent simply it is a

representation of information okay so if

you look at the noj's uh

website the website that we are seeing

right now this is represented in XML

okay XML and everything if you go to uh

inspect and if you go to source and if

you go to the uh uh current you guys can

see this is a representation let me try

to get it more around here so this is

the representation that we are getting

out of this XML okay this XML represent

this a lot of information is there but

using this uh HTML language we can

render out here but there might be some

styling going on there might be going on

some JavaScript still the representation

is is giving us this page okay likewise

uh the

njs um the

noj um soorry the Json that we what we

are seeing if you go to inspect and you

guys can see this is like past a little

bit but uh uh if I close this and go to

view page Source you guys can see it is

simply a representation like this so the

browser does not how to format Json like

this but we can uh we can just see what

it is sending us back in here I have a

plugin a chrome plugin which uh show

this one as a little bit nicer but if I

show the raow version this is what I'm

getting from the server itself okay so

let me go back to the code and try to

explain what we are trying to do in here

so what we are simply doing is first uh

in the line first line we are importing

we are requiring the express server okay

so we will be creating a server using

Express so in order to use express we

need to First import it okay so the

first line is definition of uh getting

uh Express into our code and there is

more elegant way to uh import this is

also something that you will find

similar so basically like languages like

python uh Java uh we find similar

implementation when we are importing

such you can use the required version it

is also okay in JavaScript world but uh

probably the latest es6 modules will

represent importing like this okay

remember this is also okay but this is

like the old version it say use uh es

module Imports so it will import

something like this so we are basically

saying we are importing Express the the

package we have installed and we are

creating an instance of it okay we are

creating an instance of the express okay

the next thing is uh we are instructing

Express okay we have created the express

app simply if somebody try to get so uh

get in the sense uh get is like what we

call uh rest

operations okay we as I mentioned

earlier we are developing a rest API in

here so if somebody get uh get to this

URL that means we call this as the root

if somebody gets to the root of our

application this function will uh this

function will be executed this is the

function that if somebody comes to the

root of our application this function

will be executed and the function will

contain two things the request and the

response the request is whenever the

user is requesting something it

represent the request and whenever we

want to send something it represent the

response okay so we have the request and

the response all we need to do is we are

not much caring about the request itself

in the response I would say the response

send a Json with this message so I am

responding responding whoever whenever

whenever somebody is coming to the root

of the application I am responding a

Json uh it is going to be representing

like this it's going to have a message

and the message value itself so I'll be

responding a message if somebody comes

to the root of my application okay and

next thing we need to do is we need to

say h okay the application is created

now it need to go like need to uh start

working so that's why we use the listen

uh method that means we need to say okay

we will uh start our application in Port

3,000 so this since this is a web server

web service we'll simply uh have

something in in the uh Port 3,000 you

can use any other Port uh which is

available in your machine uh something

something that is reserved in your

machine like do not use port under 1,24

which are like we consider Reserve ports

like Port 8 443 those things have

different uh meanings different use

cases do not use something like that use

a higher Port like 3,000 or anything

about 3,000 or 2,000

above so we will create express

application and if somebody comes to the

root of our application we will simply

respond with the J L containing this and

it uh and we will start listening on for

3,000 and we can have more API end

points okay we can have more API end

points I would say if somebody comes to

root and in uh message end point so now

the uh end point is different as long as

the the the two point two end points are

not the same value we can have any end

number of end points

points

so I think there is a limit but

technically we can have any um lot of

end points to our use so if somebody

comes to um root of our application or

root of our end points it will save this

if somebody comes to root 4/ message I

will say hello uh hello

users of rest okay so basically a simple

uh if somebody comes to the root they

will get this message and root 4/ I mean

4/ message if somebody comes it the

response will be little bit different so

let's see this in action uh I will

terminate the running application by

hitting contr C and I will run it

okay this is uh this is like when we are

using the express version with es module

so I'll R this back it's going to give

me um turns Express

require Express okay I I'll keep the

same version I might need to do some

package changes so in order to avoid

that as a shortcut I would definitely

use the required uh import section okay

we'll see Import in our next one right

now we will use require as import

mechanism all right let's clear and run

it again no issues right now so if I go

to force you guys can see the force

slice is not there if you put it there

it will be disappeared that's done by

browser so we consider this as the root

so hello randika is sh and if I put for

SL message in here and you guys can see

Hello users of rest okay so we get

different response based on the

different routes that you can go so

there can

be we can generate uh any number of

routes which will corresponding which will

will

correspond the correspond our

application so this is like simple rest

API that we have

generated okay so up until this uh you

guys have any questions with the simple

rest API we have developed any

clarify get you a clarification and move

forward if you do not understand just

let me

know do not think that asking question

is a weaker mind or something that that

you put in that you will be put in

highlight or something like that more

questions that you ask the more

knowledge that you

know okay so so right now let me explain

it one more time so you guys can get the

idea um so right now uh we are trying to

get some message in in our browser okay

so it's going to be represented in Json

so Json is like a

way of uh showing you showing us some

messages or showing us some information

so the the message or the uh information

that we are trying to uh show is

something called message and the message

is going to be this okay so let me um

change the response so say for

instance I would go to endpoint like of

or uh 3,000 run vehicle so in my web

service I will I should have a web

endpoint call R right now you if you

guys go here uh you won't find an

endpoint like this okay you don't find

the end point so let me create an

endpoint which represent the

URL so I will have an endpoint a get

endpoint by default when we are doing a

request is going to be a get request so

the rest end point is going to be Rand

okay the end point is going to be Rand

and whoever comes to this endpoint

whoever comes to this R endpoint will

receive a message whatever in in within

this function itself okay so the message

that I'm going to be showing in here is

um is going to be uh something called

name name okay so it's showing me R and

I would say uh I have something like age

I think I'm 30 not sure I haven't

counted it yet and I will say C and I say

say

Mar so if somebody comes to endpoint

call randika and it will give

information about me something like this

name is going to be randika age going to

be 30 city will be Mark okay so if

somebody comes to this URL the end point

we will get this message as in a Json

format it's going to be a Json format

that we will be seeing this so how I'm

going to run this I'm going to

completely stop the running application

control C and I'm going to run it again

okay now if I go to endpoint Local Host

3,000 as you guys can see I am running

this web server in Port 3000 Port 3000

is where I'm running this application

the port 3000 application will uh run my

express application okay so this express

application has three end points the

root endp Point message endpoint run the

end point okay so if I go to root Local

Host 3,000 root I will get this Local

Host 3,000 message I will get whatever

in this function Local Host randika I

will get whatever in this function as a

Json okay so if I go to Local Host

randika and you guys can see name age

and city is represented to me so this is

a representation of Randa okay so you

can have anything like like what you

have so for example I need

to um I need to show the current time

okay I need to return the current time

and I need to uh return uh say for

example I need

to um return the current country and

everything so I can do that uh so uh let

me create another

Endo my endpoint would be uh time okay

to show the time and the representation

of the time is going to be something

like time and I can show the time by

simply calling new date function so the

time will be represented by new date

that means it will return uh the current

time and I want to represent

country country and I can say Sri [Music]

[Music]

Lanka Sri [Music]

[Music]

Lanka and I'll format my document so it

will look like this so I have an

endpoint called time and the time

endpoint will return the latest time and

the country of so the country will not

change but the time or the date uh the

time in here what we'll see it's going

to be little bit different as we request

because each time when we request it's

going to create a new date and it will

show let's see it in action so you guys

get the idea so we have create an

endpoint call

time I'll stop the application I'll run it

again okay now if I go to an endpoint

call time you get can see the time is uh

this okay so it's going to represent the

date uh and the

time and the Zone okay so remember these

numbers at least these ones at least

these n n

numbers okay and if I refresh again you

guys can see the time changes because

whenever I am requesting whenever I am

requesting it's going to give me the

current time it's going to to give me

the current time so how do I get the

current time by simply calling new date

function or new date class so if I

refresh every time I refresh you guys

can see at least the milliseconds of it

it is changing so we get different time

each time when we refresh or when we

call the class okay so basically what we

are doing is we are creating an endpoint

we are creating an endpoint which will

represent some data if you're going to

Rand the uh endpoint you will get about

information about run if you go to the

time end point you will get something uh

something like the date and everything

it can

be uh

uh uh it can be have it can have

anything that you like it can it can

represent data from a database right now

what we are representing data which is

hardcoded in here okay we are not

getting any data from a database even we

can do that even even okay we will see

that in later on right now we are shown

some Dynamic data and some static data

so the time is at least Dynamic the

country is actually uh static

information okay so we can represent any

information like this okay I have a

question is like

object if we can create more objects

okay so the question is we have

uh app Express in here so what we are

creating is yes it is something similar

to an uh similar to an object it is not

a simple object that we see uh like like

when we are creating a new date yes this

will create a new object but in here we

are instantiating a new Express instance

it is uh something similar to

instantiation object but little bit

different okay so yeah the question is

uh we can have many app expresses we can

have uh multiple uh app Express instance

but it's very rare to have two different

apps in one single application believe

me having one single express application

in this scenario is getting more

complicated than you think okay we can

have several Express instances we can

have listening them on different ports

yes we can do that but that is like

really really bad idea to do it will it

will not be very U what do you call

Simply it won't be able to Simply scale

and everything it won't happen so

basically we will create a one single

express application and we will serve it

under this F if you need need more I

would recommend to have another Express

instance probably an separate

application a separate let's say we want

to have another app we can create app

two and have the same thing do not use

the same port you can't actually use the

same port if you use port 3,000 in one

single application until the program is

terminated this one is blocked okay you

have to use a different port so for

example if you can see that right now I

am using Port 3000 in this application

and if I try to run this again I say not

app.js you guys can say you guys can see

listening address already in use so I

can't run it again because it's already

in use so make sure to change the port

number at least it is not used by

something then you can create another

app instance and run and my

recommendation is do not use two app

instance in here in the same same

application at least uh have to uh

separate uh files so it will make more sense okay yes good good questions uh

sense okay yes good good questions uh any anything you guys need to ask

more um I need your confirmation if all all of you guys get these

all of you guys get these things

oops okay how do we know the reserved ports yes so basically reserved ports

ports yes so basically reserved ports are uh as I mentioned the ports normally

are uh as I mentioned the ports normally we consider Reserve ports up until Port

we consider Reserve ports up until Port uh 1024 if you do a Google search you

uh 1024 if you do a Google search you will get uh Reserve

ports um

OS Port yes normally yes uh from zero to two uh uh 1023 is known as Reserve P so

two uh uh 1023 is known as Reserve P so anything above uh you can use this but

anything above uh you can use this but probably do not use like 10,24 something

probably do not use like 10,24 something like that use a higher port number the

like that use a higher port number the more higher you get you can go but there

more higher you get you can go but there is high upper limit I think 16,000 or

is high upper limit I think 16,000 or something like that so do not use

something like that so do not use Reserve Port these ports will will not

Reserve Port these ports will will not simply the operating system will not

simply the operating system will not allow to run so if I if I go here and

allow to run so if I if I go here and change this to like uh 80 so 80 or

change this to like uh 80 so 80 or something like that and if I try to stop

something like that and if I try to stop this and if I try to run

this and if I try to run this uh think the 80 is not taken at the

this uh think the 80 is not taken at the moment I have allow

moment I have allow it LO

it LO host yeah for for for this machine you

host yeah for for for this machine you get the 80 since I am not using 80 but

get the 80 since I am not using 80 but probably you would not be using a

probably you would not be using a reserved Port okay so you guys can see

reserved Port okay so you guys can see since I'm using Port 80 I do not need to

since I'm using Port 80 I do not need to use even the port 80 over here you can

use even the port 80 over here you can just simply yeah you can simply have

just simply yeah you can simply have that c but if you I'm not sure 443 is

that c but if you I'm not sure 443 is https what we call let me try if I can I

https what we call let me try if I can I get definitely get an error at

get definitely get an error at least

least Port

Port 43 still comes uh let me know a

43 still comes uh let me know a wellknown port

wellknown port like2 be

like2 be S4 still

yeah you do not use these kind of ports you know you can you can't get the hold

you know you can you can't get the hold of it sometimes it works sometimes it

of it sometimes it works sometimes it not because the port 22 is known as the

not because the port 22 is known as the SFTP ports so those ports won be in use

SFTP ports so those ports won be in use so do not use something like well known

so do not use something like well known ones use something like 3,000

ones use something like 3,000 3,33 they're like there other numbers

3,33 they're like there other numbers you guys can play around do not have

you guys can play around do not have like a very small

like a very small number so so wellknown ports uh skip

number so so wellknown ports uh skip those

those things and use a very higher up okay so

things and use a very higher up okay so probably wellknown ports are like like

probably wellknown ports are like like 22 443 80 um there are like different

22 443 80 um there are like different TCP connection based on on those things

TCP connection based on on those things do not use these

things anything else guys

so it's going to differ from the operating system as well some some

operating system as well some some operating system have different uh but

operating system have different uh but but standard wise you you don't try do

but standard wise you you don't try do not try any reserve ports up until

not try any reserve ports up until 1023 good questions yes any other things

1023 good questions yes any other things that you guys need to know before we

the the server in this I did not get the question

correctly is the port used for the as access the service is this

the as access the service is this application maybe you can explain the

application maybe you can explain the question a little bit uh I do not get

question a little bit uh I do not get the question like what you asking right

now uh last chat message I do not I can't understand actually uh

can't understand actually uh so index number I think 10 1048 but

so index number I think 10 1048 but you're asking I'm not getting that

you're asking I'm not getting that please clarify me

please clarify me more okay any other questions

more okay any other questions guys 1048 you can ask if you if you want

guys 1048 you can ask if you if you want you can unmute and

names okay what is the purpose of port number okay so the port number is

number okay so the port number is something like um when you're using a

something like um when you're using a port

port um you don't you don't have any other

um you don't you don't have any other application interfering with your data

application interfering with your data okay so for example uh a certain Port

okay so for example uh a certain Port will only only uh deliver certain

will only only uh deliver certain content Let me Give an example if if you

content Let me Give an example if if you find uh internet as a huge tube okay

find uh internet as a huge tube okay think uh the

think uh the the connections that you have is as a

the connections that you have is as a huge tube okay uh and within that huge

huge tube okay uh and within that huge tube you have different different

tube you have different different smaller tubes which is running on inside

smaller tubes which is running on inside that okay so you when you are sending a

that okay so you when you are sending a certain values in a smaller tube what

certain values in a smaller tube what will happen is the other tubes around it

will happen is the other tubes around it does not know what is the contain is

does not know what is the contain is okay what what you are sending in uh in

okay what what you are sending in uh in a smaller tube does not know or does not

a smaller tube does not know or does not interfere with other other um other

interfere with other other um other other tubes so it's the same scenario in

other tubes so it's the same scenario in here so if you if you have a single

here so if you if you have a single connection and you want to send multiple

connection and you want to send multiple data multiple protocols and uh the by

data multiple protocols and uh the by the way to divide those things is use a

the way to divide those things is use a port so when you're using a port the

port so when you're using a port the data which is

data which is coming uh from one single port is not

coming uh from one single port is not interfering with something else for

interfering with something else for example we have wellknown ports like the

example we have wellknown ports like the SSH ssh we use port 22 SSH is the well

SSH ssh we use port 22 SSH is the well known port for sshing to that means

known port for sshing to that means remote connecting to a machine we use

remote connecting to a machine we use the port 22 for that okay that is like a

the port 22 for that okay that is like a well standard you can use any other Port

well standard you can use any other Port okay with the well known Port is 22 so

okay with the well known Port is 22 so if you you if you're ssing from Port 22

if you you if you're ssing from Port 22 and the wellknown port for serving web

and the wellknown port for serving web application is Port 80 8C Z so you can

application is Port 80 8C Z so you can serve a web page in Port 80 while you

serve a web page in Port 80 while you are sing it in Port 22 so those

are sing it in Port 22 so those different two things do different things

different two things do different things so you you don't not interfere the SSH

so you you don't not interfere the SSH stuff with the HTTP stuff so make the

stuff with the HTTP stuff so make the differences and different port different

differences and different port different ports can have different uh applications

ports can have different uh applications running they can have different uh data

running they can have different uh data going on there so uh the protocols can

going on there so uh the protocols can be different and it's uh it is easy to

be different and it's uh it is easy to manage data in a in a way that they do

manage data in a in a way that they do not conflict with each other okay so

not conflict with each other okay so that's why we use ports so we can Rite

that's why we use ports so we can Rite run uh one single application in Port

run uh one single application in Port 3,000 we can WR we can run another

3,000 we can WR we can run another application in Port 4,200 or anything

application in Port 4,200 or anything above wellknown PS okay so those two

above wellknown PS okay so those two will not get interfere with each other

will not get interfere with each other those those two ports will serve content

those those two ports will serve content in different

in different hope that answer your

yes all good anyone have any other in things to ask so few things that you

things to ask so few things that you guys need to do research on your end

guys need to do research on your end first I might take this as an assignment

first I might take this as an assignment as well uh I'll send it in the

as well uh I'll send it in the group uh what

group uh what is uh

is uh rest

rest API and name for

API and name for rest

rest methods okay the second one

methods okay the second one is

is uh what is Json that one is what is

uh what is Json that one is what is XML okay so do your research

XML okay so do your research and

and find uh find what are these things and

find uh find what are these things and prepare a small assignment on that

prepare a small assignment on that okay all right any more questions yes

okay all right any more questions yes good any more questions that you need to

okay all [Music]

right okay so we we develop a very simple uh rest API using Express and um

simple uh rest API using Express and um using some of the um

using some of the um uh some of the methods only we use the

uh some of the methods only we use the rest API method called get there are

rest API method called get there are other methods while you're doing we will

other methods while you're doing we will find other methods as well learn the

find other methods as well learn the difference that is the rest commands and

difference that is the rest commands and what are the different methods that you

what are the different methods that you can work with Okay so if if if you uh if

can work with Okay so if if if you uh if you're coming to in the industry you as

you're coming to in the industry you as a web developer or maybe a mobile

a web developer or maybe a mobile developer someone else something like

developer someone else something like that you're definitely going to learn

that you're definitely going to learn right in much more detail I mean at

right in much more detail I mean at least you need to interact with this so

least you need to interact with this so better you guys know the um uh things

better you guys know the um uh things behind these uh Technologies so you guys

behind these uh Technologies so you guys get a good

get a good idea um yeah for references part use

idea um yeah for references part use Internet it's the best best I can do um

Internet it's the best best I can do um uh you would probably find um lot of U

uh you would probably find um lot of U information in Internet you guys

information in Internet you guys uh even Wikipedia would

uh even Wikipedia would do okay and uh if you if you need more

do okay and uh if you if you need more uh web Focus one I would probably use W3

uh web Focus one I would probably use W3 schools it has all these

things okay any more questions uh before we move

on so we we create a simple web service okay web

okay web server by creating this simple web

server by creating this simple web server we were able to uh generate few

server we were able to uh generate few end points which is the root end point

end points which is the root end point the message end point randika and time

the message end point randika and time end point so different endpoints give us

end point so different endpoints give us uh different outputs okay and um some

uh different outputs okay and um some all all these uh all these uh endpoints

all all these uh all these uh endpoints give us a

give us a Json uh by default that is like most

Json uh by default that is like most commonly used in rest so in here we are

commonly used in rest so in here we are using Json as well

using Json as well so

so uh uh the the Json output that we are

uh uh the the Json output that we are seeing is different from one to another

seeing is different from one to another that is okay um so you

that is okay um so you guys

guys go go and develop some simple restant

go go and develop some simple restant points like this so this is going to be

points like this so this is going to be very very uh simple one but the problem

very very uh simple one but the problem arise uh when we are developing um uh

arise uh when we are developing um uh when we are developing web

when we are developing web applications it's it's going to be it's

applications it's it's going to be it's going to get really really complicated

going to get really really complicated than this okay so for

than this okay so for example uh when we want when we want to

example uh when we want when we want to uh uh show some data in in a Json format

uh uh show some data in in a Json format it's not going to be something like uh

it's not going to be something like uh We call we call these hard code values

We call we call these hard code values okay the values are uh

okay the values are uh [Music]

[Music] the values that we get when we go to the

the values that we get when we go to the Endo are hardcoded into the source code

Endo are hardcoded into the source code okay it's it's embedded in the source

okay it's it's embedded in the source code but for some reason say for

code but for some reason say for instance we need uh some uh something

instance we need uh some uh something like um something like this information

like um something like this information some information to be fetched from the

some information to be fetched from the database okay we we we can't have those

database okay we we we can't have those everything in here so we need to connect

everything in here so we need to connect to the database and retrieve the

to the database and retrieve the database

database values uh and once we retrieve those

values uh and once we retrieve those values we need to show or we need to uh

values we need to show or we need to uh send it back

send it back so uh pretty simply the application will

so uh pretty simply the application will get complicated enough so we can't

get complicated enough so we can't handle um our request so the database

handle um our request so the database queries going to be there you guys know

queries going to be there you guys know database queries so database queries

database queries so database queries will be there we need to execute those

will be there we need to execute those queries we need to make a database

queries we need to make a database connection and um once the connection

connection and um once the connection once the query is executed we need to

once the query is executed we need to return the

uh we need to return the value there are lot of things going to

value there are lot of things going to add into this application this

add into this application this application is going to get really

application is going to get really really messy really really in a really

really messy really really in a really small time okay so in order to make sure

small time okay so in order to make sure uh that our application can grow okay

uh that our application can grow okay the application can grow and our

the application can grow and our application will have

application will have um our application will

um our application will um application will be able to scale and

um application will be able to scale and you know when the next developer comes

you know when the next developer comes uh they they won't find thousand and

uh they they won't find thousand and points within the same application and

points within the same application and we have written written a good amount of

we have written written a good amount of test cases to test our application so

test cases to test our application so this uh this way of coding this what we

this uh this way of coding this what we call the architecture the this one that

call the architecture the this one that the simple one that we have come come

the simple one that we have come come across would not suffice this this

across would not suffice this this application will simply fail okay so

application will simply fail okay so what we can do is we can develop an

what we can do is we can develop an architecture we can develop an

architecture we can develop an architecture that will be

architecture that will be less uh complicated okay remember these

less uh complicated okay remember these by applying an architecture it doesn't

by applying an architecture it doesn't not mean everything that we have is

not mean everything that we have is going to be uh it's going to be

going to be uh it's going to be [Music]

[Music] um it's going to be solved

um it's going to be solved okay by simply applying an software

okay by simply applying an software architecture it will reduce the

architecture it will reduce the complexity of course it will reduce the

complexity of course it will reduce the complexity and it uh it will um it will

complexity and it uh it will um it will be understand by the most majority of

be understand by the most majority of our uh our users or our developers so

our uh our users or our developers so for example if we develop an applic

for example if we develop an applic appliation like this this might be our

appliation like this this might be our own style okay this I can develop an

own style okay this I can develop an application like this I can I have

application like this I can I have everything working fine okay if I can

everything working fine okay if I can manage th000 end points like this yes

manage th000 end points like this yes that is fine but the problem is if I

that is fine but the problem is if I want to give this source code to someone

want to give this source code to someone else will that person understand what

else will that person understand what I'm trying to do okay will that person

I'm trying to do okay will that person will have a hard time understanding the

will have a hard time understanding the code itself so by providing a simple

code itself so by providing a simple architecture by providing a simple

architecture by providing a simple methodology to that what will happen is

methodology to that what will happen is it

it will it will guarantee that okay

will it will guarantee that okay everybody knows this is how it should

everybody knows this is how it should get done okay this is a methodology that

get done okay this is a methodology that everybody is following so the next

everybody is following so the next person would come and say ah okay I know

person would come and say ah okay I know this methodology I have to just

this methodology I have to just Implement using these things so and an

Implement using these things so and an architecture gives us uh guidance or we

architecture gives us uh guidance or we it gives us proper structure and

it gives us proper structure and uh uh proper way of doing things but um

uh uh proper way of doing things but um remember a software architecture the way

remember a software architecture the way of we organize our code the way of we

of we organize our code the way of we going to implement such and such a thing

going to implement such and such a thing is going to be different on the uh

is going to be different on the uh different uh project or different uh

different uh project or different uh application that we are developing okay

application that we are developing okay so for an web application we can have a

so for an web application we can have a different architecture for a mobile

different architecture for a mobile application we can have a different

application we can have a different architecture that's because the purpose

architecture that's because the purpose of the application is different from one

of the application is different from one one one to another so mobile application

one one to another so mobile application have different restrictions different

have different restrictions different mechanisms how they works and different

mechanisms how they works and different limitations with the resources and all a

limitations with the resources and all a web a web application such as rest API

web a web application such as rest API that we have developed it's going to be

that we have developed it's going to be running on a server we have certain

running on a server we have certain server limitations we have certain uh

server limitations we have certain uh database limitation and all all sort of

database limitation and all all sort of things so based on the application that

things so based on the application that we're going to be developing based on

we're going to be developing based on the technologies that we are having the

the technologies that we are having the architecture of the program will differ

architecture of the program will differ but most commonly with web

but most commonly with web applications right now when we are

applications right now when we are developing a web

developing a web application uh we find that the NT

application uh we find that the NT architecture or 3D architecture at least

architecture or 3D architecture at least works better with our uh with our code

works better with our uh with our code organization the NTI architecture if you

organization the NTI architecture if you write uh an NTI architecture

write uh an NTI architecture application it would make our life easy

application it would make our life easy and if somebody comes tomorrow and join

and if somebody comes tomorrow and join our team and they we can say okay uh our

our team and they we can say okay uh our application is following n architecture

application is following n architecture and we all agree upon how n architecture

and we all agree upon how n architecture should work okay we'll certain we will

should work okay we'll certain we will learn certain things in N architecture

learn certain things in N architecture so next time when you go to Industry and

so next time when you go to Industry and you guys can ask okay uh we have a web

you guys can ask okay uh we have a web application you can ask okay good what

application you can ask okay good what is the architecture that we using so

is the architecture that we using so they might say oh we are using n

they might say oh we are using n architecture so you don't need to know

architecture so you don't need to know okay n architecture by by n architecture

okay n architecture by by n architecture we have certain component we have such

we have certain component we have such and such then you will easily understand

and such then you will easily understand what what they are talking about okay

what what they are talking about okay the software architecture is something

the software architecture is something like that it is a well-known practices

like that it is a well-known practices well-known things that will

well-known things that will overcome overcome the uh common problems

overcome overcome the uh common problems that we are having so for example we all

that we are having so for example we all know okay when we are talking about n

know okay when we are talking about n architecture the whole whole development

architecture the whole whole development teams have the idea of okay when we are

teams have the idea of okay when we are developing this application there will

developing this application there will will be this this this and we have to

will be this this this and we have to follow those things so it it

follow those things so it it won't it won't make you an outcast or

won't it won't make you an outcast or the project uh leads Outcast so we know

the project uh leads Outcast so we know okay when we are developing this

okay when we are developing this application we are following these

application we are following these principles we are we are at this point

principles we are we are at this point and we are using these things okay so in

and we are using these things okay so in as I mentioned earlier for web

as I mentioned earlier for web applications so simple

applications so simple applications uh we find the NTI

applications uh we find the NTI architecture to be working perfectly

architecture to be working perfectly okay as I mentioned

okay as I mentioned earlier n architecture will not be very

earlier n architecture will not be very suitable for our mobile application we

suitable for our mobile application we we we um sometimes it might work

we we um sometimes it might work sometimes it not there are different

sometimes it not there are different architectural patterns that we can use

architectural patterns that we can use but for stus the simplest form uh

but for stus the simplest form uh developing a simple web application we

developing a simple web application we will talk about the n architecture okay

will talk about the n architecture okay so any questions uh about what we have

so any questions uh about what we have discussed why we need an architectural

discussed why we need an architectural pattern and what sort of things it um uh

pattern and what sort of things it um uh it's it try to resolve it's trying uh

it's it try to resolve it's trying uh the basically an architecture pattern we

the basically an architecture pattern we give

give formal uh formal structure to our

formal uh formal structure to our project and all the all the the software

project and all the all the the software team will be

team will be in uh in in sync up with the

in uh in in sync up with the Technologies and when you when you want

Technologies and when you when you want to when you want to learn uh the way how

to when you want to learn uh the way how software is

software is organized so you guys can refer that

organized so you guys can refer that architect and add up to that so there

architect and add up to that so there are a lot of Architects going on

are a lot of Architects going on remember based on the project those

remember based on the project those Architects can be different okay so any

um okay definitely this will be uploaded no

questions okay hope not okay let's see so we'll move into the NTI architecture

so we'll move into the NTI architecture so you guys can see in the sample

so you guys can see in the sample application the sample express

application the sample express application that we have

application that we have created um we have several things things

created um we have several things things okay we have several things so you guys

okay we have several things so you guys can see um we are accepting uh a request

can see um we are accepting uh a request okay we are accepting a request the

okay we are accepting a request the client is asking something and we are

client is asking something and we are responding to that so we have what we

responding to that so we have what we call a request and we have something

call a request and we have something called a response okay

called a response okay so uh some request some request can be

so uh some request some request can be uh can be group

uh can be group some request represent the same uh same

some request represent the same uh same set

set of uh values for example in this uh in

of uh values for example in this uh in this uh in this scenario we do not see

this uh in this scenario we do not see uh strikingly similar things so all

uh strikingly similar things so all these things are like several uh several

these things are like several uh several different things but when we are working

different things but when we are working with um a good uh applic ific ation some

with um a good uh applic ific ation some features have typed together some

features have typed together some features will um have different purposes

features will um have different purposes okay for

okay for example um we call uh normally we call

example um we call uh normally we call these things as crud operations okay

these things as crud operations okay crud operations we call these things so

crud operations we call these things so uh the crud operations stick together so

uh the crud operations stick together so what do you understand by a crud

what do you understand by a crud operation so in CR c r u we call this

operation so in CR c r u we call this create uh read update delet interest

create uh read update delet interest okay so that's that's the basic of uh

okay so that's that's the basic of uh what what it stand for at least uh crud

what what it stand for at least uh crud okay do uh uh do a simple uh Implement

okay do uh uh do a simple uh Implement look at around crud so crud stand for

look at around crud so crud stand for create read update and delete so uh in a

create read update and delete so uh in a system say for example we want to

system say for example we want to develop a simple user management system

develop a simple user management system we want to develop a simple user

we want to develop a simple user management system in that user

management system in that user management system we need to able to

management system we need to able to create users so for example uh we want

create users so for example uh we want to uh create a user with the name email

to uh create a user with the name email that's it okay we do not need anything

that's it okay we do not need anything else within our system what it will do

else within our system what it will do is create a user with a user

is create a user with a user name um username or uh

name um username or uh email uh on that we call we we need to

email uh on that we call we we need to create the user okay that's we call the

create the user okay that's we call the create

create operation and some sometimes back

operation and some sometimes back sometimes later we need to read all the

sometimes later we need to read all the users that means we need to get all the

users that means we need to get all the users within our system let's say for

users within our system let's say for example now we have 100 registered

example now we have 100 registered people we need to get those 100 people

people we need to get those 100 people okay that is what we called a read

okay that is what we called a read operation okay sometimes we do not need

operation okay sometimes we do not need the 100 uh 100 users but we need a

the 100 uh 100 users but we need a certain user one single certain user

certain user one single certain user which have the uh let's say which have

which have the uh let's say which have the email uh example.com okay we need a

the email uh example.com okay we need a one single particular user which has one

one single particular user which has one single we one single user we need to

single we one single user we need to read it back from the system so that we

read it back from the system so that we call a read we can have multiple users

call a read we can have multiple users or we can have one single user either

or we can have one single user either way we going to be reading users from

way we going to be reading users from the system and there will be other

the system and there will be other operations such as update operations

operations such as update operations what we call uh uh update request so

what we call uh uh update request so sometimes uh some sometimes we when we

sometimes uh some sometimes we when we are working with the system uh we need

are working with the system uh we need to update a particular users information

to update a particular users information for example a user can have a first name

for example a user can have a first name and a last last name and we need for

and a last last name and we need for some reason they have either misfill the

some reason they have either misfill the first name and we need to update that

first name and we need to update that record we we do not need to create a new

record we we do not need to create a new record okay we need to create we need to

record okay we need to create we need to update an existing record so we call

update an existing record so we call that a update request and finally we

that a update request and finally we have something like a delete request

have something like a delete request which will uh Delete the record from

which will uh Delete the record from from our application okay so that is

from our application okay so that is what we call a delete request

what we call a delete request so these three uh these four request

so these three uh these four request types are mostly common within a system

types are mostly common within a system that you you guys will develop so this

that you you guys will develop so this is very common in web application so we

is very common in web application so we call this crud operations so we will

call this crud operations so we will create a crud operation that is only for

create a crud operation that is only for users we can create users read users

users we can create users read users update users and delete users and we can

update users and delete users and we can have Crow operations for another thing

have Crow operations for another thing for example uh we we also want to

for example uh we we also want to manage uh let's

manage uh let's say uh schools okay so we need to create

say uh schools okay so we need to create a school we need to read an school name

a school we need to read an school name or information about one single school

or information about one single school or more than one single school so we

or more than one single school so we need to read we need to update some

need to read we need to update some certain information and we need to

certain information and we need to sometimes we need to delete okay the C

sometimes we need to delete okay the C is not like always going to be the all

is not like always going to be the all the SP things going to be there but

the SP things going to be there but basically when we are developing an

basically when we are developing an application we Implement all those craft

application we Implement all those craft operations okay so when we develop uh

operations okay so when we develop uh such a thing so we have the user C and

such a thing so we have the user C and screw crab and think about another thing

screw crab and think about another thing like we need to manage teachers okay so

like we need to manage teachers okay so the teachers C so so we have teacher

the teachers C so so we have teacher create teacher reads teacher update

create teacher reads teacher update teacher delete so you guys can see in a

teacher delete so you guys can see in a very complex system uh we will have lot

very complex system uh we will have lot of CR operations not only CR operations

of CR operations not only CR operations there will be some actions as well so we

there will be some actions as well so we will definitely we'll look into actions

will definitely we'll look into actions later on but for now we will simply look

later on but for now we will simply look at hard operations okay so when we are

at hard operations okay so when we are when we when we talk about the user use

when we when we talk about the user use head for CR operations okay let's uh for

head for CR operations okay let's uh for the for those four CR operations we will

the for those four CR operations we will have four end points okay so right now

have four end points okay so right now we have one single end point in here

we have one single end point in here another one here and another one here so

another one here and another one here so we have totally four end points but all

we have totally four end points but all are read operations these are what we

are read operations these are what we call read operation get is a read

call read operation get is a read operation but for user you can have four

operation but for user you can have four different uh um four different uh

different uh um four different uh endpoints one for create one for read

endpoints one for create one for read one for update one for delete okay so we

one for update one for delete okay so we guys you guys can see a single user will

guys you guys can see a single user will have four end points at least four end

have four end points at least four end points and uh school can have four end

points and uh school can have four end points and this

points and this file uh which handle all these uh all

file uh which handle all these uh all these request is going to get bigger and

these request is going to get bigger and bigger okay so at for four for for

bigger okay so at for four for for operations we have we we will add uh for

operations we have we we will add uh for one uh type we will have four so think

one uh type we will have four so think about we in a pro professional system

about we in a pro professional system normally it contains like um 10 to 20 uh

normally it contains like um 10 to 20 uh of such things then it will explode the

of such things then it will explode the file will not be able you can't even

file will not be able you can't even find whatever you need in the single

find whatever you need in the single file so uh what we will do what we need

file so uh what we will do what we need to do is we need to separate things we

to do is we need to separate things we need to separate okay so when we are

need to separate okay so when we are talking about user user will have its

talking about user user will have its own Crut uh operations when we talking

own Crut uh operations when we talking about the school it it school will have

about the school it it school will have a separate C operation file and so list

a separate C operation file and so list goes on so we will be developing such

goes on so we will be developing such application so we we would have the all

application so we we would have the all the C end points in the different

the C end points in the different locations okay okay

locations okay okay so uh that is one thing the C end points

so uh that is one thing the C end points the end points what we have

the end points what we have discussed and the next thing that we be

discussed and the next thing that we be that would that uh that requires is the

that would that uh that requires is the logic behind it okay the logic behind it

logic behind it okay the logic behind it so some something in here we are simply

so some something in here we are simply returning all all these things are uh

returning all all these things are uh just simply uh showing a showing a value

just simply uh showing a showing a value but in

but in reality what will happen is we we can't

reality what will happen is we we can't have such uh simple get test that means

have such uh simple get test that means we are not going to Simply show these

we are not going to Simply show these values by hardcoding this we will

values by hardcoding this we will definitely talk to a database okay we

definitely talk to a database okay we will definitely need some operations to

will definitely need some operations to happen Okay so for

happen Okay so for example uh we want to we want to

example uh we want to we want to delete uh a school okay we want to

delete uh a school okay we want to delete a school in our system there will

delete a school in our system there will be certain rules that we need to follow

be certain rules that we need to follow you can't just delete uh you can't just

you can't just delete uh you can't just delete um school from the system you

delete um school from the system you might need special permission if you are

might need special permission if you are doing such a thing okay you can't just

doing such a thing okay you can't just anybody comes and delete delete a school

anybody comes and delete delete a school that system would not be a really good

that system would not be a really good one sometimes uh if you want to delete

one sometimes uh if you want to delete uh if you want to delete such important

uh if you want to delete such important record you need permissions sometimes

record you need permissions sometimes you you you will uh as two some two

you you you will uh as two some two people should vote on it once they have

people should vote on it once they have done the voting then you can delete that

done the voting then you can delete that that's kind of what we call Logics going

that's kind of what we call Logics going to be there we call those things logic

to be there we call those things logic in system like this we call those things

in system like this we call those things as business logic okay when we want to

as business logic okay when we want to operate something we want when we want

operate something we want when we want to do something we we will have

to do something we we will have something called a business Logics okay

something called a business Logics okay say for instance that logic should be

say for instance that logic should be implemented in here as well so somebody

implemented in here as well so somebody send a delete request and delete request

send a delete request and delete request need to be going through some business

need to be going through some business Logics and you need to check all those

Logics and you need to check all those Logics and everything and this file what

Logics and everything and this file what will happen all those Logics going to be

will happen all those Logics going to be within this simple file this file will

within this simple file this file will explod okay and when somebody is looking

explod okay and when somebody is looking at this file the file is going to be

at this file the file is going to be like 10,000 or 20,000 long and it will

like 10,000 or 20,000 long and it will not make sense to look like look into a

not make sense to look like look into a hinge file like

that all right so what we will do is we rather than writing everything in one

rather than writing everything in one single file or one single location we

single file or one single location we will move the business logic into a

will move the business logic into a separate file or we call a separate

separate file or we call a separate layer okay so all the request that are

layer okay so all the request that are coming the

coming the request that can be a read request

request that can be a read request update request delete request or any CR

update request delete request or any CR request so all the request that is

request so all the request that is coming will be handled by a a single

coming will be handled by a a single layer okay all the request handling will

layer okay all the request handling will be done by a single layer and once that

be done by a single layer and once that layer get the message the business logic

layer get the message the business logic will be handled in a separate layer okay

will be handled in a separate layer okay it will be handle in a separate layer so

it will be handle in a separate layer so why we are layering these things the

why we are layering these things the first thing is the complexity will grow

first thing is the complexity will grow okay everything if you put everything in

okay everything if you put everything in one single one single file one single

one single one single file one single layer the layer will really be uh really

layer the layer will really be uh really really will get big and you can't have

really will get big and you can't have all these Logics and everything in one

all these Logics and everything in one single file it's hard to read okay so

single file it's hard to read okay so what we'll do is all the requests that

what we'll do is all the requests that we are getting will be in one single

we are getting will be in one single layer

layer and once the request is receiv received

and once the request is receiv received to us the business logic will be in a

to us the business logic will be in a different layer okay the business logic

different layer okay the business logic will be in a different layer okay so the

will be in a different layer okay so the business logic when we when we move the

business logic when we when we move the business logic to a different layer the

business logic to a different layer the business logic might

business logic might need uh something uh from

need uh something uh from another uh another place for example in

another uh another place for example in order to in order to uh get in order to

order to in order to uh get in order to create uh in order to create a single

create uh in order to create a single single user or something like that the

single user or something like that the business logic need to talk to a

business logic need to talk to a database we need to talk to a database

database we need to talk to a database in a scenario where we want to talk to a

in a scenario where we want to talk to a database then uh the database

database then uh the database connections and everything should be in

connections and everything should be in uh in that business logic so that's

uh in that business logic so that's going to crowd the business logic layer

going to crowd the business logic layer so in order to access

so in order to access databases anything related to database

databases anything related to database we separate the data layer the data

we separate the data layer the data communication layer especially with the

communication layer especially with the database or another service we separate

database or another service we separate another layer out of the business logic

another layer out of the business logic to a data layer so we have three layers

to a data layer so we have three layers now the first one is the request layer

now the first one is the request layer second one is the business logic layer

second one is the business logic layer third one is the data layer so any

third one is the data layer so any request coming in we will first

request coming in we will first encounter with the request layer

encounter with the request layer anything that need to be calculated any

anything that need to be calculated any business logic need to be happened we

business logic need to be happened we will do it in the uh business logic

will do it in the uh business logic layer and we have a third layer which

layer and we have a third layer which will be accessing all those data okay so

will be accessing all those data okay so you guys can see three tiers the request

you guys can see three tiers the request tier distance logic and the data okay so

tier distance logic and the data okay so that's how a three tier architecture

that's how a three tier architecture representation happens so we have three

representation happens so we have three tiers request business logic and model

tiers request business logic and model or the database

or the database to so this is like the common

to so this is like the common architecture pattern that you guys can

architecture pattern that you guys can use okay it is only three layers but it

use okay it is only three layers but it is not limited to three as I mentioned

is not limited to three as I mentioned earlier the architectural patterns the N

earlier the architectural patterns the N architecture pattern n okay the word n

architecture pattern n okay the word n represent any number but for more most

represent any number but for more most common problems that you will see today

common problems that you will see today with um with uh applications such as web

with um with uh applications such as web application three tier would be enough

application three tier would be enough okay I'm not saying it is always going

okay I'm not saying it is always going to be the case three tiers will be

to be the case three tiers will be enough if you want more layers of course

enough if you want more layers of course you can add say for example your

you can add say for example your business logic is really complex okay

business logic is really complex okay the business logic is really complex in

the business logic is really complex in in a case like that you can divide the

in a case like that you can divide the business logic into

business logic into two or three layers so that will add

two or three layers so that will add more layers in between okay it is not

more layers in between okay it is not limited to three but you can have

limited to three but you can have multiple layers okay depending on your

multiple layers okay depending on your project and it is it is

project and it is it is complexity so the request layer normally

complexity so the request layer normally stays around with one layer that is that

stays around with one layer that is that is like uh that is like normal but as I

is like uh that is like normal but as I mentioned earlier it is not limited to

mentioned earlier it is not limited to having one single layer for handling

having one single layer for handling request it it can have multiple layers

request it it can have multiple layers that is also fine this logic as I

that is also fine this logic as I mentioned earlier if it is very complex

mentioned earlier if it is very complex we separate the business logic into

we separate the business logic into separate layers data layer is also there

separate layers data layer is also there normally we can have many more layers

normally we can have many more layers okay but simply there will be three

okay but simply there will be three layers as most you sometimes somebody

layers as most you sometimes somebody can use two layers if they want but a

can use two layers if they want but a recommendation for a web application my

recommendation for a web application my recommendation at least what of what

recommendation at least what of what most users will get is a three tier or

most users will get is a three tier or three uh three tier architecture right

three uh three tier architecture right now we have all those three tiers in one

now we have all those three tiers in one single file okay so we have the request

single file okay so we have the request this is the request endpoint and we have

this is the request endpoint and we have our business logic in here since we do

our business logic in here since we do not have a data layer the data layer is

not have a data layer the data layer is also in here okay so all these three

also in here okay so all these three three layers three things are within one

three layers three things are within one single request so so this is considered

single request so so this is considered to be bad practice let me tell you why

to be bad practice let me tell you why this is bad after we Implement a sample

this is bad after we Implement a sample application using 3ar architecture okay

application using 3ar architecture okay so this is uh this is working okay this

so this is uh this is working okay this is working perfectly anyone can anyone

is working perfectly anyone can anyone can code like this a project can run

can code like this a project can run like this yes you can but uh on the long

like this yes you can but uh on the long term long run this would definitely give

term long run this would definitely give us headache Okay so so we have the

us headache Okay so so we have the request layer we have the uh business

request layer we have the uh business logic layer and we have the data layer

logic layer and we have the data layer all in one single location we will try

all in one single location we will try to tear this up into three different

to tear this up into three different layers and see how we can work with that

layers and see how we can work with that okay so anyone have any questions um

okay so anyone have any questions um with the three tiers the request

with the three tiers the request distance logic and the data anyone have

distance logic and the data anyone have any questions regarding those three

any questions regarding those three layers anything that need to be

layers anything that need to be clarified

okay suppose everybody got uh the DTs that we'll be working on and we will see

that we'll be working on and we will see how we can create a simple web

how we can create a simple web application that represent this 3s okay

application that represent this 3s okay so as you guys can see I used a very

so as you guys can see I used a very simple um single

simple um single um single file the appjs file to create

um single file the appjs file to create a simple application that as as

a simple application that as as mentioned

mentioned earlier nowadays we do not uh develop

earlier nowadays we do not uh develop application like this okay so you need

application like this okay so you need to find all the packages we need to have

to find all the packages we need to have all these things um there are like

all these things um there are like certain other aspect of program that we

certain other aspect of program that we need to work on like certainly the

need to work on like certainly the structure of the program how we going to

structure of the program how we going to structure it okay and what are the um

structure it okay and what are the um what are the testing Frameworks of

what are the testing Frameworks of course our code need to be tested okay

course our code need to be tested okay so what is the testing framework that we

so what is the testing framework that we going to use and how we going to set up

going to use and how we going to set up within our

within our program and what are the things that we

program and what are the things that we that we will be using uh to deploy this

that we will be using uh to deploy this okay so all those things are done over

okay so all those things are done over and over and over again we come to a

and over and over again we come to a what we call a template okay a template

what we call a template okay a template that we can that we can use to or to

that we can that we can use to or to start Kickstart our project okay rather

start Kickstart our project okay rather than putting all the de dependencies all

than putting all the de dependencies all the testing Frameworks and all the

the testing Frameworks and all the building script and everything you don't

building script and everything you don't need to worry all this all this from

need to worry all this all this from scratch what we can do is we can use a

scratch what we can do is we can use a code

code generation uh tool that will help us to

generation uh tool that will help us to create an application so that we don't

create an application so that we don't know to do the heavy lifting when we are

know to do the heavy lifting when we are creating a file so that's what I use uh

creating a file so that's what I use uh in

in here

here uh we use the program called

uh we use the program called uh

uh um We call we use the program called NX

um We call we use the program called NX okay the NX is a tool that we can boost

okay the NX is a tool that we can boost up our application that we can create an

up our application that we can create an application so we don't have to create

application so we don't have to create in from scratch okay so in we first we

in from scratch okay so in we first we need to install NX like we did injs we

need to install NX like we did injs we need to install NX okay or we can use NX

need to install NX okay or we can use NX uh NX based simple tools that we can um

uh NX based simple tools that we can um that we can create the application let

that we can create the application let me um

me um okay

okay let me stop the current application I will see the

I will see the back so in order to create uh an NX

back so in order to create uh an NX application as I mentioned earlier there

application as I mentioned earlier there is the website called NX Dev okay so you

is the website called NX Dev okay so you can create a simple workspace that means

can create a simple workspace that means a simple project uh using um this

a simple project uh using um this command so you can install this npx

command so you can install this npx create NX workspace command in order to

create NX workspace command in order to create a new

create a new Fresh uh fresh web web um web

Fresh uh fresh web web um web application okay so what I did was I use

application okay so what I did was I use this command npx create workspace at

this command npx create workspace at latest that means we I am going to

latest that means we I am going to create a new workspace and I'm going to

create a new workspace and I'm going to name it

name it SF SF that is the workspace name that

SF SF that is the workspace name that can that's think as the project name

can that's think as the project name that that I'm giving for this okay so

that that I'm giving for this okay so I'm going to give that name

I'm going to give that name and by using this it will ask some basic

and by using this it will ask some basic questions what are the Frameworks and

questions what are the Frameworks and all I think we have already covered if

all I think we have already covered if you want to go back and see the video

you want to go back and see the video once again basically it will create a

once again basically it will create a simple

simple application that is

application that is uh close

one close window I don't not need this yes that is this application you guys

yes that is this application you guys can see there are all I mean don't get

can see there are all I mean don't get overwhelmed by all the things that you

overwhelmed by all the things that you see it in here basically it it has set

see it in here basically it it has set up a simple web application to us okay

up a simple web application to us okay simple very simple web application with

simple very simple web application with all the uh testing Frameworks it's all

all the uh testing Frameworks it's all the basic starting point for application

the basic starting point for application and all the dependencies and everything

and all the dependencies and everything to run our project okay so um there are

to run our project okay so um there are a lot of uh prebuilds things uh done for

a lot of uh prebuilds things uh done for us especially with the you know when we

us especially with the you know when we when we are done with the application we

when we are done with the application we need to build this application this is

need to build this application this is the source code once we need to uh once

the source code once we need to uh once once we are done with the source code we

once we are done with the source code we need to uh run it somewhere before we

need to uh run it somewhere before we run it we need to build it so we have

run it we need to build it so we have the build script running we have the

the build script running we have the developments um script uh de script are

developments um script uh de script are there building script are there testing

there building script are there testing script are there so basically a simple

script are there so basically a simple web application is created for us by by

web application is created for us by by simply using those uh code generation

simply using those uh code generation tools so first thing that we need to

tools so first thing that we need to look at is this package Json okay as you

look at is this package Json okay as you guys can remember with the express one

guys can remember with the express one so we are not seeing Express directly

so we are not seeing Express directly but if you go to to njs C and something

but if you go to to njs C and something like that you would would find Express

like that you would would find Express bu deep behind them so there are other

bu deep behind them so there are other libraries that we are using or packages

libraries that we are using or packages that we are using and there are de de

that we are using and there are de de packages that we are using that means

packages that we are using that means while developing we will be using these

while developing we will be using these packages but when we want to deploy

packages but when we want to deploy these things these are no longer valid

these things these are no longer valid we do not need these things in the

we do not need these things in the running application so for

running application so for example um we have testing Frameworks

example um we have testing Frameworks right we will test our program while we

right we will test our program while we are building it while we are in the

are building it while we are in the development place okay once we

development place okay once we developments are done once we want to go

developments are done once we want to go to a hosting server and once we want to

to a hosting server and once we want to share this with the world we do not need

share this with the world we do not need the uh tools that we use while we are

the uh tools that we use while we are testing the frame testing the

testing the frame testing the application so we would

application so we would have we would have left left down all

have we would have left left down all the test T in stuff um while we are

the test T in stuff um while we are building the application after we build

building the application after we build it we do not use the testing libraries

it we do not use the testing libraries so that's why we have two dependencies

so that's why we have two dependencies type uh the D dependencies which

type uh the D dependencies which represent uh the dependencies that we'll

represent uh the dependencies that we'll be using while we are developing and

be using while we are developing and dependencies so these are dependencies

dependencies so these are dependencies we need in order to run and develop at

we need in order to run and develop at the same time okay so these are

the same time okay so these are development time need

development time need and these are on time needed okay

and these are on time needed okay so we will not look into these libraries

so we will not look into these libraries we we probably won't be looking more

we we probably won't be looking more into this unless we need to add a

into this unless we need to add a certain certain functionality to our

certain certain functionality to our application for example if you want to

application for example if you want to add database connectivity then we will

add database connectivity then we will install a certain package that we will

install a certain package that we will be using okay we will see that uh in a

be using okay we will see that uh in a moment right now

moment right now uh we'll be we'll be focusing on uh

uh we'll be we'll be focusing on uh getting the N architecture and running

getting the N architecture and running it once again okay so in order to get uh

it once again okay so in order to get uh uh the application structure so we need

uh the application structure so we need to know the package Json we can have a

to know the package Json we can have a look around it and the most important

look around it and the most important folder is going to be this SRC de okay

folder is going to be this SRC de okay so

so SRC stand for Source at the the source

SRC stand for Source at the the source code of our application and inside there

code of our application and inside there are few files the main main file which

are few files the main main file which is something like the adjs file that we

is something like the adjs file that we have seen earlier on

have seen earlier on and probably you will find something

and probably you will find something similar the app directory and we will

similar the app directory and we will have the listen Port thing so it's going

have the listen Port thing so it's going to also run on Port

to also run on Port 3000 okay so we we can also while we are

3000 okay so we we can also while we are running we can change that but if we if

running we can change that but if we if you do not specify something it's

you do not specify something it's automatically going to run on Port 3,000

automatically going to run on Port 3,000 okay so this is like do not worry about

okay so this is like do not worry about all these uh Global Prix and everything

all these uh Global Prix and everything which uh which and the bootstrap methods

which uh which and the bootstrap methods all these things just think uh when we

all these things just think uh when we run this application it's going to start

run this application it's going to start a web service on to 3,000 okay you can

a web service on to 3,000 okay you can have look around these things in in

have look around these things in in later on

later on right now we are running an application

right now we are running an application with Pro 3,000 and uh you guys can

with Pro 3,000 and uh you guys can remember the end points that we had on

remember the end points that we had on the njs application right now uh as a as

the njs application right now uh as a as a good practice we uh we

a good practice we uh we have uh endpoint prefix uh with all the

have uh endpoint prefix uh with all the apis that that means we I'll show you

apis that that means we I'll show you that means if you if you have endpoint

that means if you if you have endpoint call message by default it will it will

call message by default it will it will be it will be Rewritten to API message

be it will be Rewritten to API message if you have an endpoint called user by

if you have an endpoint called user by default it will be ritten to API users

default it will be ritten to API users okay so that that is something uh the

okay so that that is something uh the community follows when we are developing

community follows when we are developing an rest API we normally have the prefix

an rest API we normally have the prefix called API in front of that okay so when

called API in front of that okay so when we run this application it will uh start

we run this application it will uh start it will start application in code 3,000

it will start application in code 3,000 okay so let me run this application

okay so let me run this application simply I will I will um I will go to the

simply I will I will um I will go to the directory uh from the terminal where I

directory uh from the terminal where I start the application so uh it is

start the application so uh it is in uh s swt so this is the location that

in uh s swt so this is the location that I have choose uh the project right now

I have choose uh the project right now it is in the TMP and SF sft directory it

it is in the TMP and SF sft directory it can be within your programs or

can be within your programs or documents projects whatever the location

documents projects whatever the location that you say so basically uh go to

that you say so basically uh go to your terminal or command line uh open

your terminal or command line uh open the command line where your project is

the command line where your project is there so how do you know that is the

there so how do you know that is the same directory so you guys can see the

same directory so you guys can see the package Jon okay if you like try to

package Jon okay if you like try to explore it and if you see the package

explore it and if you see the package Jon right there then that that is that

Jon right there then that that is that means you are in the correct location

means you are in the correct location okay make sure the packages and or the

okay make sure the packages and or the at least what whatever the files that

at least what whatever the files that you have seen is visible that means you

you have seen is visible that means you are in the correct location okay so in

are in the correct location okay so in order to run this application like what

order to run this application like what we did in the earlier on we we have

we did in the earlier on we we have certain other things uh uh prepared for

certain other things uh uh prepared for us especially what we call a hot preload

us especially what we call a hot preload and there are certain things uh we we we

and there are certain things uh we we we have already configured in this so if

have already configured in this so if you guys can remember when I write the

you guys can remember when I write the next year's

next year's application uh if I do a change I need

application uh if I do a change I need to stop and I need to run it again and

to stop and I need to run it again and uh if I do a simple modification on my

uh if I do a simple modification on my source code I need to stop it and run it

source code I need to stop it and run it again but uh with the with this project

again but uh with the with this project setup that we have come across we do not

setup that we have come across we do not need to do that whenever we do a project

need to do that whenever we do a project uh when we do a project change and we

uh when we do a project change and we save it and it will be automatically

save it and it will be automatically reload for us we don't need need to

reload for us we don't need need to reload our servers we do not need to

reload our servers we do not need to stop or anything like that we do our

stop or anything like that we do our coding we save it and it will be

coding we save it and it will be automatically reloaded okay so you don't

automatically reloaded okay so you don't have to stop every time and go back and

have to stop every time and go back and do those things so everything is set up

do those things so everything is set up for us we don't want to worry about that

for us we don't want to worry about that we'll simply try to run this application

we'll simply try to run this application so we can run these application by by

so we can run these application by by simply looking at one single command

simply looking at one single command under the package H Json file you'll

under the package H Json file you'll find scripts okay these scripts are what

find scripts okay these scripts are what able to run this application so in order

able to run this application so in order to run there is the commands might be

to run there is the commands might be different but in in this in this in this

different but in in this in this in this example or in this project we can see

example or in this project we can see the start script that means we will be

the start script that means we will be starting our server then we there will

starting our server then we there will be build script that means it will build

be build script that means it will build our build our application and there test

our build our application and there test script that means it will test our

script that means it will test our application so the name implies what it

application so the name implies what it does so if I want to start the

does so if I want to start the application I can run this script okay

application I can run this script okay so simply I can uh run by npm start

so simply I can uh run by npm start command okay if I run if I run npm start

command okay if I run if I run npm start the application will start and if I want

the application will start and if I want to build I can uh run this script in

to build I can uh run this script in different way okay so if I want to test

different way okay so if I want to test I can run npm this by looking at it I

I can run npm this by looking at it I will say npm startop okay so if I hit

will say npm startop okay so if I hit npm staff you guys can see uh it will

npm staff you guys can see uh it will take a little bit time for the first

take a little bit time for the first time and it is uh not like the njs

time and it is uh not like the njs application uh sorry the express JS

application uh sorry the express JS application that we created it will show

application that we created it will show some logs okay it we say okay our

some logs okay it we say okay our application is running on localport 3000

application is running on localport 3000 and API we'll just simply go there and

and API we'll just simply go there and see what's going on so the API endpoint

see what's going on so the API endpoint is given for us you can just simply copy

is given for us you can just simply copy or we and just uh copy uh copy this

or we and just uh copy uh copy this and uh paste it in our application and

and uh paste it in our application and what you guys get a simple me uh message

what you guys get a simple me uh message saying hello API okay so we will get a

saying hello API okay so we will get a simple message a simple

simple message a simple Json uh the key is message and the value

Json uh the key is message and the value is hello AP okay so we get a

is hello AP okay so we get a simple Json response when we go to Local

simple Json response when we go to Local Host port 3,000 and API inome okay

Host port 3,000 and API inome okay so you you you guys might think okay

so you you you guys might think okay there is app. get like what we have seen

there is app. get like what we have seen in the previous example there will be

in the previous example there will be something

like something similar there right yes but it bit little bit of different is

but it bit little bit of different is that we

that we have in this uh in this framework in

have in this uh in this framework in this m this framework we have introduced

this m this framework we have introduced what we called tier architecture we will

what we called tier architecture we will see the ti

see the ti architecture anything with this project

architecture anything with this project setup I know the there are lot of files

setup I know the there are lot of files in here with kep config what are these

in here with kep config what are these don't do not want to worry about these

don't do not want to worry about these files in in in this stage all you just

files in in in this stage all you just need to know okay the package is there

need to know okay the package is there and the SRC directory is here at least

and the SRC directory is here at least SRC and familiar one is not modules as I

SRC and familiar one is not modules as I mentioned earlier this contain all the

mentioned earlier this contain all the runtime libraries and other things just

runtime libraries and other things just for now just ignore any questions up

for now just ignore any questions up until this okay at least you guys need

until this okay at least you guys need to create a project and you need to

to create a project and you need to start okay so you know where to get the

start okay so you know where to get the script you can say npm start and the

script you can say npm start and the application will start okay and there is

application will start okay and there is another command that you can run if you

another command that you can run if you look at the project Jon so Project G

look at the project Jon so Project G sorry not the project Jon package Json

sorry not the project Jon package Json file the start command is also can be

file the start command is also can be achieved by index Ser okay you can say

achieved by index Ser okay you can say two things you can say npm start or you

two things you can say npm start or you can say NX

can say NX server the both will do the same thing

server the both will do the same thing it will start the application okay any

it will start the application okay any questions up until this because we will

questions up until this because we will be into the enti architecture

okay awesome if you guys have anything just interrupt me anytime

just interrupt me anytime okay all right let's go back to the

okay all right let's go back to the source code

source code itself as we uh discuss we will be

itself as we uh discuss we will be starting from the SRC directory and we

starting from the SRC directory and we looked at the main just simply look at

looked at the main just simply look at it as

it as uh it's starting the web server on Port

uh it's starting the web server on Port 3000 and it's starting the boot strap

3000 and it's starting the boot strap okay

okay and one thing that we need to look is in

and one thing that we need to look is in here something

here something called uh app module okay there is a uh

called uh app module okay there is a uh there is when you are looking at this

there is when you are looking at this file it is creating or it is using

file it is creating or it is using something called app module this is what

something called app module this is what this is not something that you find in

this is not something that you find in the nests application we we have but

the nests application we we have but simply uh in here what we have done is

simply uh in here what we have done is uh as I mentioned earlier we will be

uh as I mentioned earlier we will be splitting up our application we'll be

splitting up our application we'll be separating these things in different

separating these things in different forms so module is modularization is

forms so module is modularization is something that we will consider so a

something that we will consider so a module think a module

as as a single uh single uh feature within our application

single uh feature within our application for

for example we we talked about uh several

example we we talked about uh several things in our system we talked about

things in our system we talked about users we talked about schools and we

users we talked about schools and we talked about um teachers okay so within

talked about um teachers okay so within our system we will have three uh three

our system we will have three uh three features user

features user School user school and teachers so we

School user school and teachers so we have three different features within our

have three different features within our application so we can we can categorize

application so we can we can categorize or we can uh have things related to

or we can uh have things related to users within the user module okay

users within the user module okay something related to user we will have

something related to user we will have within the user module something related

within the user module something related to

to um something related to the school we

um something related to the school we can have a school modu if something

can have a school modu if something related to teacher we can have a teacher

related to teacher we can have a teacher module so think of the

module so think of the um think all the DS and everything

um think all the DS and everything linking to one another linking to

linking to one another linking to another as in a single entry point or

another as in a single entry point or single packaging point or single feature

single packaging point or single feature point we can call it as a module okay so

point we can call it as a module okay so the app module is a special module in in

the app module is a special module in in this framework okay the app module is

this framework okay the app module is where we have

where we have uh all the modules report this is like

uh all the modules report this is like the starting point for our application

the starting point for our application okay so we have a starting point for

okay so we have a starting point for application so the uh app module uh have

application so the uh app module uh have uh few things you guys can see these an

uh few things you guys can see these an what we call these decorations do not

what we call these decorations do not worry about these things right now so we

worry about these things right now so we have things like controllers so if you

have things like controllers so if you guys can remember we have three tiers

guys can remember we have three tiers within our application the first one is

within our application the first one is the uh end point or the controller layer

the uh end point or the controller layer what we call so we can have all the

what we call so we can have all the controllers defined in a controller

controllers defined in a controller layer okay and we can have the business

layer okay and we can have the business Logics we discuss business logic we call

Logics we discuss business logic we call in this framework we call these things

in this framework we call these things providers okay do not expect uh all the

providers okay do not expect uh all the Frameworks in the world we'll call these

Frameworks in the world we'll call these things as uh control

things as uh control or endpoint uh business Logics or data

or endpoint uh business Logics or data layers okay each Frameworks has its own

layers okay each Frameworks has its own definition okay so in NJ the um the

definition okay so in NJ the um the controller layer is basically controlers

controller layer is basically controlers but the business logic layer what we

but the business logic layer what we call is something called uh we in in

call is something called uh we in in here we call like providers or Services

here we call like providers or Services okay and in the data layer in a data

okay and in the data layer in a data layer we do not call that as a data

layer we do not call that as a data layer but we call it as a repository

layer but we call it as a repository okay so different things have different

okay so different things have different namings but the architecture the three

namings but the architecture the three tis will remain most of the time the

tis will remain most of the time the same okay so within the app module you

same okay so within the app module you will find controllers and services okay

will find controllers and services okay the providers and controllers so these

the providers and controllers so these are the controllers that we saw if I go

are the controllers that we saw if I go to the app. controller file you will see

to the app. controller file you will see the

the um controller as you guys can

um controller as you guys can remember you guys can see the to API

remember you guys can see the to API nothing no end points are available

nothing no end points are available there so it's going to be responding for

there so it's going to be responding for this okay and the data that we are

this okay and the data that we are getting is coming from the app service

getting is coming from the app service okay and you guys can see the thing that

okay and you guys can see the thing that we have seen in here that is called the

we have seen in here that is called the hello APM okay that is what we are

hello APM okay that is what we are getting here so we will forget about all

getting here so we will forget about all these things just want to show you guys

these things just want to show you guys how it works and we will create a module

how it works and we will create a module from scratch okay we'll create a module

from scratch okay we'll create a module from scratch we will Define the uh

from scratch we will Define the uh controller layer we will Define the

controller layer we will Define the service layer and uh probably a dummy

service layer and uh probably a dummy repository layer okay because we do not

repository layer okay because we do not have the database everything set up

have the database everything set up right now right now we will create uh a

right now right now we will create uh a simple module and we will incorporate

simple module and we will incorporate into our application okay we'll see how

into our application okay we'll see how we can create multiple modules and

we can create multiple modules and incorporate okay so basically

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YouTube Transcript:02.Introduction to N-tired architecture with NodeJS

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02.Introduction to N-tired architecture with NodeJS