Zoyid Guide to the Web

8/14/2019 Zoyid Guide to the Web

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GUIDE TO THE WEB
http://www.zoyidtech.com/


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AGENDA

MODULE 1: Internet and the application layer protocols

MODULE 2:

Web and its difference from the internet

How the web works?

Web architecture


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INTERNET

MODULE 1


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INTRODUCTION

The Internet is a worldwide, publicly accessible series ofinterconnected computer networks

It transmits data by packet switching using the standard

Internet Protocol (IP)

It is a "network ofnetworks It consists of millions of smaller domestic, academic,

business, and government networks

These networks together carry information and services,

such as electronic mail, online chat, file transfer

The interlinked web pages and other resources of the World

Wide Web (WWW).


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Source: O te.com, Deviantart.com


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OSI MODEL

TCP/IP defines a set of rules to enablecomputers to communicate over anetwork

TCP/IP specifies how data should bepackaged, addressed, shipped, routed

and delivered to the right destination.

Application layer protocols help us withthe day to day use of the internet

Theoretically OSI model has 7 layers

For practical purposes top 3 layersof session, presentation andapplication are merged into onesingle application layers.


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WORLD WIDE WEB

MODULE 2


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TERMINOLOGY

The Internet and the World Wide Web are notsynonymous The Internet is a collection of interconnected computernetworks

linked by copper wires, fiber-optic cables, wirelessconnections, etc.

In contrast, the Web is a collection of interconnecteddocuments and other resources, linked by hyperlinks andURLs

The World Wide Web is one of the services accessible viathe Internet

Along with various others including e-mail, filesharing, online gaming and more

Source: Wiki edia


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INTRODUCTION

Web is a system of interlinked hypertextdocuments accessed via the Internet.

With a Web browser, a user views Web

pages

It may contain text, images, videos,

and other multimedia and navigates

between them using hyperlinks.

The World Wide Web was created in 1989 bySir Tim Berners-Lee

WWW's "historical"

logo, created byRobert Cailliau.

Tim Berners-Lee on

November 18, 2005.


10/31Source: Deviantart.com


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HOW THE WEB WORKS

Type the URL of the page into a Web browser, or follow ahyperlink to that page or resource

The server-name portion of the URL is resolved into an IP

address using the DNS database

This IP address is necessary to identify and contact the

computer (Web Server) that hosts the page

DNS sends back the IP address to the browser


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HOW THE WEB WORKS (cntd)

Now the browser requests the resource by sending anHTTP request

To the computer hosting the resource (ie, the Web

server) at that particular address

Web Server responds with the HTML text of the page

which is parsed immediately by the browser

Browser then makes additional requests for images

and any other files that form a part of the pageThe browser then renders the page onto the screen


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HOW THE WEB WORKS (cntd)


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LAYERED APPROACH

THE THREE LAYERS ARE: Presentation layer is the client machine that has a viewer

or a browser

Application layer executes all server side scripts Forms a bridge between the Server OS and the

scripts

Database layer holds all the data

This is done on a database server


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WEB ARCHITECTURE

There are two types: Two tier consists of the presentation and application

servers

Three tier consists of presentation, application anddatabase servers

In both the cases the presentation layer is on the client

machine


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PRESENTATION LAYER

Many viewers and browsers available. Famous ones are:IE

Firefox

Opera

Safari

Browsers react differently to different scripts Some scripts dont run on some browsers while they do on

others


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CLIENT SIDE SCRIPTS

These scripts run on the presentation layer andare classified as follows:

Static content is plain HTML and CSS content that

is normal typed content This content never changes unless edited

manually.

Dynamic:

Created as the result of a request from the client

machine to the server

Created when wanted, maybe different each time


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CLIENT SIDE SCRIPTS (cntd)

Active: Can interact with the user

Can change its display at any time

Can change the document contents in response to the

user, but without referring back to the server (egJavascript)


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Flash, Silverlight & Flex: Adobes Flash and Microsofts Expression studio are two

competing products that can create active content

This content plays in Flash player and Microsoft

silverlight player respectively Utilizes 2D vector graphics to draw content on the screen.

These applications are used to create rich internet

applications (RIAs)

Flex uses MXML , an XML-based markup language which is

compiled by the open source flex compiler

Flash and Flex achieve Interactivity through the use of

ActionScript, the core language of Flash Player.


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AJAX (Asynchronous JavaScript and XML) or Ajax: Is a group of inter-related web development techniques

used for creating interactive web applications

A primary characteristic is the increased responsiveness

and interactivity of web pages Achieved by exchanging small amounts of data with the

server "behind the scenes

So that entire web page does not have to be reloaded

each time there is a need to fetch data from the server


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AJAX IN ACTION


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DOMAIN NAMES

The term domain name has multiple related meanings: A name that identifies a computer or computers on the

Internet

These names appear as a component of a Web site's

URL, e.g. en.wikipedia.org. This type of domainname is also called a hostname

The product that domain name registrars provide to their

customers. These names are often called registered

domain names.

Names used for other purposes in the Domain Name

System (DNS), for example the special name which follows

the @ sign in an email address


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WEB SERVER

The term web server can mean one of two things:

A computer program that is responsible for

accepting HTTP requests from clients And serving them HTTP responses along with

optional data contents, which usually are web

pages such as HTML documents and linked

objects (images, etc.)

A computer that runs a computer program as

described above.


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SERVER SIDE SCRIPTING

The server needs to interpret the scripts sent to it These scripts are understood using the compiler that is

running on the web server

For example for PHP script we install the PHP

compiler etc

The browser calls those server scripts or functions (on the

server) using HTTP

Any variables necessary for the functions to start

processing is passed along with the HTTP request


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SERVER SIDE SCRIPTING (Cntd)

There are many server side scripting languages: CGI and PERL were the early ones. Now the most used

languages are PHP, ASP and ASP.NET

PHP: Hypertext Preprocessor is a widely-used general-purpose

scripting language that can be embedded into HTML.

PHP is the most used server side scripting language.

Ranked 4th most popular after Java, C, and Visual

Basic. It is platform independent.


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ASP: Active Server Pages (ASP) is Microsoft's first server-side

script engine for dynamically-generated web pages.

Programming ASP websites is made easier by

various built-in objects. Each object corresponds toa group of frequently-used functionality useful for

creating dynamic web pages.


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ASP.NET: Is a web application framework marketed by Microsoft

that programmers can use to build dynamic web sites, web

applications and web services.

It is part of Microsoft's .NET platform and is thesuccessor to Microsoft's Active Server Pages (ASP)

technology. ASP.NET is built on the Common

Language Runtime, allowing programmers to write

ASP.NET code using any Microsoft .NET language.


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DATABASE

A computer database is a structured collection of recordsor data that is stored in a computer system.

A database relies upon software to organize the storage of

data.

The computer that holds the database program is knownas the database server

The basic data structure of the relational model can be

thought of as a table, where information about a

particular entity (say, an employee) is represented in

columns and rows (also called tuples).


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DATABASE SERVERS

The main Database programs are:MySQL

PostGreSQL

MSSQL

OracleDB

For each of these database servers different type of SQL

queries needs to be written

MySQL is the most used server on the internet

The best way to ensure reliability of these Database

servers is by creating Database clusters


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THANK YOU

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Zoyid Guide to the Web