Basic's of Django | Django Beginner's To Advanced |

Django is a Framework , developed by Python . It's Used to develop a Web application We can use this to Provide a Dynamic Content web Application . Like Spotify Pinterest Instagram Mozilla ................;

Step : 1 

              We Need to check That we have Installed Python on our Machine Make sure You installed on That 

        Make Sure You check Using -- PYTHON --VERSION

Installing Django On local Machine

// Installation Djago pip install Django

Step : 2

                We are about to create a Django Project as it was a Framework . We need to create a Project Inside we do Our work .

                python mange.py runserver -> It's used to run our Project

Create a Django Project

// Create Project djano-admin startproject name

Step : 3

               

                

                    Run our Project on Local Server Because Django has own Development environment we run using that (Local server)

           python mange.py runserver -- It's used to run our Project

We can also used to mention a specify port like

         python manage.py runserver 4000

Write a Program to calculate Two Numbers

// Specify Server python manage.py runserver 4000

Step 4 :

                        We need to create a APPLICATION inside a Project , Because One project can Contain Multiple Application , So that Why ... we Create a App inside a Project

Creating a Application Inside a Project

// Django-app python manage.py startapp test1

In default app we have (__init__ ,admin ,apps ,models ,tests ,views and Migratrions folders)

In default Project we have (__init__ ,asgi ,settings,urls,wsgi and db.sqllite)

Step - 5:

                        Getting into a Real Thing ............HELLO WORLD!

        First of all we need for that to Create a urls.py File under your application folder , Beacuse we have file url.py under only project folder we need to connnect these app to project like wise we can connect Multiple Project ...

Create a URL.PY file

// Urls.py from django.urls import path from . import views

Step : 6

                                Edit Views.py to make Print Hello World!

First of all We make this as Print Using a HTTP response ,That will be lot more Easier

Add a Function on Views

// Views.py from django.http import HttpResponse def home (request): return HttpResponse ("Hello world!")

Step : 7

                            We need to Map a Views.py to our url.py from APP

    This is will be a path of helloworld , in views.home we have a func

Url.py from app folder

// url.py urlpatterns = [ path('',views.home ,name='home') ]

Step : 8

                    The final Step...    Connection Between App to Project

This is a Urls file on your project already there , You can add the app urls in here to comabine a app and project

add these '' path to project , 'test1.urls is an app file  

Url.py from Project Folder

// urls.py urlpatterns = [ path('',include('test1.urls')), path('admin/', admin.site.urls), ]

Step : 9

                    So far we did Will Make enough to Print Hello world!

What is Computer Networking ? In Lay man Understanding Terms !

­­­­C O M P U T E R   N E T W O R K I N G

Protocols :

 

1.       TCP – TRANSMISSION CONTROL PROTOCCOL

   

It will used like a data Will reach a Target at 100%.  Do not data loss.

 

2.       UDP  - USER DATAGRAM PROTOCOL

 

It doesn’t care about 100 % data reach to a Destination, but it will reach. e.g. Video ZZConference

 

3.       HTTP – HYPER TEXT TRANSFER PROTOCOL

 

This being used by Web browser,

It will defined a format of web browser

 

HOW THE DATA IS TRANSFERRED IN IP ADDRESS :

If we send any data or large file it will comes like CHUNKS OR BUNDELS

We’re Getting like Individual Packets

Computers and  servers  are being known as IP address

Scenario :

If we type Google.com how this will get us ?

                  Every thing in Internet has known as IP address Google has one IP address like Phone log

                  Name – number  == Website – Ip address

 IP ADDRESS – FORMAT

x.x.x.x ----- (0-255). (0-255). (0-255). (0-255).

 

curl ifconfig.me –s

This  Command shows the IP ADDRESS Of your Internet provider eg:VI,JIO

                                    These       three       has       a           Local      IP         address

Device 1 (MOBILE) made a Request Google.com

It will go through Modem/wifi .

After our ISP will Connect to the Internet It will search a Google server.

Once the Google.com was Get and Response to a ISP

ISP--à To Modem/router à it will Give to Which device made a Request using Local IP Address à USING NAT (network address TRANSLATION)

PORT NUMBER :

 We have lot of online Application in our Device’s , Which one is Made a Request

IP Address Is used to find Which Device , But also Port number is important to find Which application made a Request in the Device .

PORT are Actually a 16 BIT Number

Total Port = 65,000   à 2¹⁶

Web Based are Reserved  -- > 80 port

0-1023 are Reserved Ports

 

Wires :

Every thing in internet Via connect through wires ,

The wires are actually in OCEAN    Check out this link : https://www.submarinecablemap.com/

PHYSICALLY : OPTICAL FIBRE CABLE , COAXIAL CABLE

WIRELESS : WIFI , BLUETHOOTH ,3G ,4G LTE , 5G

LAN MAN WAN :

 

LAN – LOCAL AREA NETWORK

SmallHouse / OFFICE  à Ethernet,Wifi

 

MAN – METROPOLITAN AREA NETWORK

Across a city

 

WAN – WIDE AREA NETWORK

Across a Country  - Fibre Optical Cable

1.       SONET   - Synchronize Optical Network 

2.       FRAME VALLEY

 

MODERM / ROUTER

MODERM -  That used to Convert Digital Signal into Analog Signal

Eg: You have a Digital data On your computer (Text/image/) it will Tranfer into Electrical Signal and send it to another and Convert into Orginal form

 

Router – It is an Device , Is used to route a data Packet to a Correct IP Address

 

Topologies :

BUS :

Every Single computer connected through a Line(INTERNET) if a connection cut a Computer goes down .

RING: 

If a one connection goes down other one also get out.

If we transfer data from first to six it will need to pass through all devices .

STAR :

If a Center HUB get Failure all get Out/down

TREE :

It’s actually a Combination of both BUS and STAR

MESH :

 

Expensive – Wire’s need to much

IF we need to add a New computer it also make a New wire and make sure that need to connect all computer

STRUCTURE OF THE NETWORK :

OSI MODELS : - OPEN SYSTEMS INTERCONNECTION (it used more Conceptually)

7 types of Layers:

 

1.       Applictaion Layer : It implemented on software eg: browser,messenger,etc

2.       Presention Layer : (Encription/compression/Translation)

·       When Application Layer à PresentationLayer

It convert the data What we give to Application Layer(Software) IT convert into Machine readable code .

Also It Compress the data, and provide some Encription To that Default Encryption .

3.       Session Layer : (Autherization/Autentication):

Application LayeràPresentation LayeràSession Layer

When a Session Layer is the asking for Login/Crenditials

And which page you go / Not to go

Create a Session for you and the Server At a Time , When everything is done, it will Terminate both .

4.       Transport Layer – (TCP – Connection Oriented/UDP – Connection less)

When the Data was Transferred into Transport Layer ,It will be ( Segments ) Each and every segments have A sequence To order the Segments In correct order .

Application LayeràPresentation LayeràSession Layerà Transport Layer

5.       Network Layer – (It assign a IP Address of Sender and Receiver To The Segments  To reach the Destination

In network Layer Router Will Involve , Here we Route Our Data to Other Network

6.       Data Link Layer – (It will talk directly to a device)

It is responsible for the node-to-node delivery of data.

ü  It get Packets From Network Layer and Send a Frame into Physical Layer

7.       Physical Layer – (Wired / Hardware)

It will send a Message to A Router of your Friend IP address.

TCP/IP MODEL : (it used more Practically)

It’s an Another Model , Like OSI But Application Layer , Presentation Layer and Session layer are merged into one ,

ü  Application Layer

ü  Transport Layer

ü  Network Layer

ü  Data Link Layer

ü  Physical Layer

Data Center:

Collection of Server/Computer in a Place called Data Center.

It have a Static IP address That do not Change   .

It have good internet/ and High uploadind in speed .

PEER – TO – PEER ARCHIRECTURE (P2P) :    Eg: torrent app

Before one Model is Client and Server model.

But p2p is  More like Many computer are Connecting together and They act as a SERVER AND CLIENT

PROTOCOLS :

              WEB PROTOCOLS :

              TCP/IP à

1.        HTTP – How the data is Transferred In Web

2.       DHCP (DYNAMUIC HOST CONTROL PROTOCOL) – it basically allocate the IP address to the People they connected to your network

3.       FTP (File transfer Protocol) – how the file are Transferred

4.       Smtp (simple mail transfer protocol) -  used to send a mail

5.       Pop3 ,imap (INTERNET MESSAGE RECIVING PROTOCOL ) --- = These are used to Receive Mails

6.       SSH (SECURE SHELL)  - If we want to Login into Another one’s computer /terminal it will use

7.       VNC (VIRTUAL NETWORK COMPUTER) – It used for graphical computer.

8.       Telnet – it’s  a Terminal Emulator.

9.       UDP USER DATAGRAM PROTOCOL – Stateless Communication/ Data will loss

 

THREADS/PROCESSERS:

Eg – Whatsapp

If a Apllication run it will, message, video record ,

Thread is nothing but run under a Processers.

SOCKETS :

It is like Interface between a Processer and Internet.

Ports :

Port is about find a Application On the Device to Send a Message , But in a Browser we have an Number of tabs  ,

 

Epheremal Ports  à It’s the one used to find a Correct Tab , It will Create  only Client Side , Once the job is done it will get Terminated

 

HTTP:

HTTP uses TCP protocol

Http is Stateless , It doesn’t store a Client information On server (Client Status Doesn’t save)

HTTP à APPLICATION LAYER      TCP à Transport Layer

HTTP METHODS :

GET PUT POST DELTE

Mehods : Is nothing but talking to a server what to do .

ERROR/CODES : HTTP

1XX à INFORMATION

2XX à SUCCESS

3XX à Redirected

4XX àClient Error

5xx àServer Error

COOKIES : à IT’S a User value

It is UNIQE STRING

HTTP IS Stateless à it doesn’t maintain OUR passsowrd/rember.

But some times it will wont ask anything and continue where we left , so that were we COOKIES comes .

I’s a file Stored our Browser. When we Visit  a New website a Cookie will Set , And next time we go that website it will automatically header cokkie will send and get the server data.

Third Party Cookies:

Cookies will set that we doesn’t visit .

 HOW THE EMAIL WORKS :

Protocol used foe EMAIL.

SMTP – SENDING , POP3 ,IMAP  , - RECVING

This is the Application Layer protocol But

What can we used for Transport Layer Protocal. (TCP  OR   UDP )

DNS (DOMAIN NAME SYSTEM ):

Domain name service are mapped into Ip ADDRESS

EG:WE type . google.com it convent into google ip address and connected.

This is the Work of DNS .

Instead of Storing a Everything in One database , There are Multiple database .

1.       Root DNS Servers   à .IO            .COM                  .ORG              (top level domain)

2.       Second Level Doamin à student.IO       google.com        Oragle.org               (SLD )

TRANSPORT LAYER/ NETWORK LAYER :

Network :

Data needs to transfer from one network to another network i.

Transport :

Data That shared to network to a Computer application is Transport Layer.

Congestion Layer :

 If a Network Bandwidth is Low speed but if u keep Sending Packets that is called congestion .

CHECKSUM:    - Is used to check the Data is Correpted or not

Calulating a Msg by formula data/checksum

 Timers :

If we send a Package to Internet to our friend , Timer got started, And it received the timer will stop.

 But , When the packet got Lost Timer will expire and we will known as Packet got Loss

We will Resend it But The packet Has already iN Frd device , so There’s Were we use a Sequence Number, if it’s There on a Device It will Duplicate value .

UDP (USER DATAGRAM PROTOCOL):  In this protocol,

·       changed on the way

       ·       Our data May or may not be delived

  ·       Data Cannot be Sequence order .

It is Connection Less – Protocol :

UDP Packet :                                                                                                                                      

Source port no : 2bytes

Destination Port no :2 bytes                   These are all in Packets.                     And these are Headers

Length of datagram: 2 bytes

Checksum : 2 bytes

 

UDP is More faster …

Eg : Video Conference apps

DNS also uses  à UDP

Game apps uses UDP .

 

TCP – TRANSMISSION CONTROL PROTOCOL :                                                                     

Transport Layer Protocol - = - TCP (Something Like that TLP)

Application layer – Sends Lots of raw data

TCP – Segment this data/ Divide in Chunks / Add headers / Checksums /

·       It may also collect data from Network Layer . 

·       Congestion Control .

It take Care 2 Things

1.       Data Not arraived

2.       Maintained order of data

EG : (TCP) -- EMAIL,HTTP , WEB BROWSER,ETC…

Features :

It is Connection Oriented

              First connection need to establish After That we need to send data.

Error control

Congestion Control

Full duplex – Computer A and B send a file Simultonelsly .

3-way Hand shake :