Web Application Technologies - FTMS - Web... · Chapter 1 –Introduction to Internet History of...

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Web Application Technologies

Chapter 1

Introduction to Internet

Chapter 1 – Introduction to Internet

What is The Internet?

• The Internet is a global

connection of computers.

• These computers are

connected through Wide

Area Network (WAN).


The Internet Usages

• Exchange of data, news and opinion.

• Upload and download files.

• Electronic Mail (E-Mail)

• Communicate and socialize

• Marketing

• Online banking

• Online shopping

• Entertainment


History of The Internet

• The Internet originated in the late 1960s when the United States Defense Department developed ARPAnet (Advanced Research Projects Agency network), an experimental network of computers designed to withstand partial outages such as a bomb attack.

• The agency sought to create a web of computers that could continue to communicate with each other, even if some of the computers were disabled.



• In the mid-1980s, when desktop computer workstations became increasingly popular, organizations wanted to connect their local area networks (LANs) to ARPAnet. If computers could link together and share resources, everyone would benefit.



• 1991 was a big year for the Internet: The National Research and Education Network (NREN) was founded and the World Wide Web was released.

• The Internet is still dominated by scientists and other academics, but begins to attract public interest.



• With the release of the Mosaic Web browser in 1993 and Netscape in 1994, interest in and use of the World Wide Web exploded.

• More and more communities become wired, enabling direct connections to the Internet.


How Does the Internet Works?

• The unique thing about the Internet is that it allows

many different computers to connect and talk to each

other.

• This is possible because of a set of standards, known

as protocols, that govern the transmission of data

over the network: TCP/IP (Transmission Control

Protocol/Internet Protocol).

• All computers must use same protocol.

• To gain access to the Internet, the user need to

register to any Internet Service Provider (ISP).


How Does the Internet Works?

• Each computer on the Internet is called the host

computer.

• Many of the host computer on the internet offer

services to other computers on the Internet.

• Computer which provides services for other

computers is called server.

• A host computer may run mail servers, web server,

FTP server, IRC server, etc.


The Internet Requirements

• Computer with modem / network card

• Internet connection

• Account with Internet Service Provider (ISP)

• Web browser

– Example: Internet Explorer, Firefox, Opera

• 3rd-party software

– Example: Flash player, QuickTime Player, Adobe

Reader


Internet Connections

• Dialup is naturally the slowest type of connection to

the Internet. It runs over analog telephone lines, and

its speed is limited by the quality of these lines, which

were designed for low-quality voice calls, not data

transmissions. Dialup relies on modems (modulator-

demodulators), which max out at 57600 bps (in

practice, 53000 bps).



• ISDN (Integrated Services Digital Network) is a digital

connection over a conventional telephone line.

• It is not in common use, because it has been

supplanted by DSL.

• ISDN offers speeds up to twice as fast as dialup.



• DSL (digital subscriber line) sends signals on a higher

frequency than voice signals over telephone lines. It offers high

speeds, but bandwidth degrades as the length of the telephone

line increases from the modem to the telephone company's

central office

• DSL comes in two flavours:

– ADSL - Asynchronous DSL means that uploading is much

slower than downloading. Internet service providers (ISPs)

adopt this technology so that they can spend less on

bandwidth and so that they discourage users from running

bandwidth-intensive servers.

– SDSL - Synchronous DSL provides equally fast

upstream/downstream bandwidth. SDSL is expensive and

generally used by businesses hosting web servers.



• Cable uses television coaxial cable to connect to the

Internet.

• Cable has the potential to offer very high speeds, but

is limited because cable is shared in a

neighbourhood.

• If the aggregate bandwidth being used by customers

exceeds the bandwidth of the physical cable

connection in a neighbourhood, then slowdowns are

observed.



• Satellite also comes in two types:

– Modem-Satellite - A modem is used to send

upstream data requests, while a dish receives

data from a satellite. This method is plagued by

latency, as it takes a long time for a request to

travel via dial-up to the web server in question,

and for the response to arrive through the satellite

system.

– Satellite two-way - The satellite dish sends and

receives data. This technology is more recent, but

still suffers from latency problems, simply because

satellites are far away.



• Corporations may use T1, T3, and above for hosting

web servers, serving office users, and so forth.

• These lines are dedicated digital trunks, reliable, and

fast, but prohibitively expensive for home users.


Internet Applications

• An Internet application is an interactive, compiled application that can be accessed through a corporate or through the .

• Internet applications can perform complex business processes on either the client or the server.

• In a server-based Internet application, the application uses the Internet protocol to receive requests from a client, typically a Web browser, process associated code, and return data to the browser.


Internet Applications

1. World Wide Web

2. Search Engine

3. E-mail

4. FTP

5. WHOIS

6. Telnet

7. WAIS

8. Gopher

9. Ping

10. Traceroute

Chapter 1 – Introduction to Internet and World Wide

Web

Internet Applications - World Wide Web

• The World Wide Web, or simply Web, is a way of accessing information over the medium of the Internet.

• It is an information-sharing model that is built on top of the Internet.

• The Web uses the HTTP (HyperText

Transfer Protocol), only one of the

languages spoken over the Internet,

to transmit data.


Web


• The Web also utilizes browsers, such as Internet Explorer or Firefox, to access Web documents called Web pages that are linked to each other via hyperlinks.

• The web documents are formatted in a markup language called HTML (HyperText Markup Language) that supports links to other documents, as well as graphics, audio, and video files.


Web


Advantages of World Wide Web

• Easy linking of documents to other documents.

• Content is simple to create and make available for

use.

• Support for mixed multimedia elements.

• Open standards.

• Accessible for everyone.

• Facilities the publication, dissemination and sharing

of information on a global basis.


Web


Website vs. Web page

• A website is a collection of one or more web pages

designed to convey information on a particular

subject or theme to a web user.

• A web page is one screen full of information (from a

web site) that may contain links to other pages in the

web site or links to external information. The web

page will normally be written as (or rendered as) an

HTML document.


Web


Uniform Resource Locator (URL)

• The global address of documents and other resources on the World Wide Web.

• A URL can be typed into the address bar.

• It consists of three parts:

– A protocol name

– A host part

– A document name

• Example:

– http://www.yahoo.com


Web

Internet Applications - Search Engine

• Search engines are programs that search documents

for specified keywords and returns a list of the

documents where the keywords were found.

• Examples: Yahoo!, Google, Altavista, Lycos,

Metacrawler, and Hotbot.


Web

Internet Applications - Search Engine

• Search engines work by sending out a spider to

fetch as many documents as possible.

• Another program, called an indexer, then reads

these documents and creates an index based on the

words contained in each document.


Web

Internet Applications - Gopher

• A system that pre-dates the World Wide Web for

organizing and displaying files on Internet

servers.

• A Gopher server presents its contents as a

hierarchically structured list of files.


Web

Internet Applications - File Transfer Protocol (FTP)

• The protocol for exchanging files over the Internet.

• FTP is most commonly used to download a file from

a server using the Internet or to upload a file to a

server.


Web

Internet Applications - Telnet

• Telnet is an application used on the internet to

connect to a remote computer, enabling access to

the computer and its resources.

• A protocol that enables a user on one machine to log

onto another networked machine.

• This enables you to control the server and

communicate with other servers on the network.


Web

Internet Applications - E-mail

• Short for Electronic Mail.

• The transmission of messages over communications networks.

• Email allows you to:

– Sent and Receive message

– Forward message

– Send attachment

• Used two different protocols:

– Simple Mail Transfer Protocol (SMTP)

– Post Office Protocol (POP) / Internet Message Access Protocol (IMAP)


Web

Internet Applications - Email

• Email address consist of three parts:

– User name

– @ sign

– Server name

• Example:

[email protected]


Web


Email Client

• An application that runs on a personal computer or workstation and enables you to send, receive and organize e-mail.

• The advantage of using an email client is that the emails are stored on your computer and are accessible faster than using a web based email interface.


Web


Email Client

Examples:

• Outlook

• Outlook Express

• Thunderbird


Web


Webmail

• Webmail (or Web-based e-mail) is an e-mail service

intended to be primarily accessed via a web browser.

• They allow you to check your email from any

computer that has an Internet connection.


Web


Webmail

• Example:

– Gmail

– Yahoo! Mail

– Hotmail.


Web

Internet Applications - WHOIS

• An Internet utility that returns information about a

domain name or IP address.

• NSLOOKUP is another application that has similar

function as WHOIS.


Web

Internet Applications - Finger

• A program that takes an e-mail address as input and

returns information about the user who owns that e-

mail address.


Web

Internet Applications - Wide Area Information Server

(WAIS)

• Wide Area Information Server (pronounced ways),

is a program for finding documents on the Internet.

• WAIS is rather primitive in its search capabilities.


Web

Internet Applications - Usenet/Newsgroup

• A worldwide bulletin board system that can be

accessed through the Internet or through many

online services.

• It consists of a set of "newsgroups" with names that

are classified hierarchically by subject.

• "Articles" or "messages" are "posted" to these

newsgroups by people on computers with the

appropriate software.

• It uses a protocol called Network News Transfer

Protocol (NNTP).


Web

Internet Applications - Usenet/Newsgroup


Web

Internet Applications - Ping

• Ping is a computer network administration utility used

to test the reachability of a host on an Internet

Protocol (IP) network and to measure the round-trip

time for messages sent from the originating host to a

destination computer.

• A utility to determine whether a specific IP address is

accessible.

• It works by sending a packet to the specified address

and waiting for a reply.

• PING is used primarily to troubleshoot Internet

connections.


Web

Internet Applications - Ping


Web

Internet Applications - Traceroute

• A utility that traces a packet from your computer to an

Internet host, showing how many hops the packet

requires to reach the host and how long each hop

takes.

• If you're visiting a Web site and pages are appearing

slowly, you can use traceroute to figure out where the

longest delays are occurring.


Web

Internet Applications - Traceroute

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