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Engr. Abdul-Rahman Mahmood MS, PMP, MCP, QMR(ISO9001:2000)
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VC++, VB, ASP
Introduction to Computing
The Internet and the World Wide Web
In the beginning... 1957: Russians launch Sputnik.
Eisenhower saw the need for the Advanced Research
Projects Agency (ARPA)
ARPA becomes a “technological think-tank for
American defence”
Several years later, ARPA starts looking into computer
communication and networking
1962: ARPA appoints J. Licklider and L. Roberts to
head its computer research program
In the beginning... ARPA 1962: ARPA appoints J. Licklider and L.
Roberts to head its computer research
program
Focus on computer communication for
military purposes
Problem: Data traffic is bursty!
Packet Switching
Data traffic is bursty – intervals of activity followed by
periods of inactivity.
E.g. Think of a web browsing session
Circuit switched networks would be inefficient
Image Source: CEFRIEL, Milan
Packet Switching 1961: Leonard Kleinrock uses
queuing theory, proposes packet
switched networks
More bandwidth efficient
Robust – not reliant on single
route
Image Source: Leonard Kleinrock's homepage, http://www.cs.ucla.edu/~lk/
ARPANET 1967: Lawrence Roberts of
ARPA publishes plan for the
first computer network system
– the ARPANET
Packet switches were needed.
Called Interface Message
Processors (IMP), the contract
was awarded to BBN
Oct 1969: IMPs installed in
UCLA
Image Source:http://aleph.llull.net/wp-content/files/imp.jpg
Interface Message Processor
“Internetting” principles Decentralized control
Stateless routers
Autonomy - networks should be independent,
require no modification to participate in the
Internet
Best Effort Service Model - Packets would be
routed through the fastest available route
2A-9
The Internet’s History
1969 – ARPANET
Developed by the Department of Defense
Connected universities and defense bases
1973 – ARPANET connects to Europe
2A-10
ARPANET 1973
1980s Time of tremendous growth
Networks for linking universities together
BITNET – email and ftp (Northeast)
CSNET – linking universities without access to
ARPANET
NSFNET: provide access to NSF supercomputing
resources
1983: TCP/IP replaces NCP as universal host protocol on
Jan 1.
By the end of the 80s, there were 100,000 hosts
1990s...commercialization! NSFNET began to serve as backbone, linking
regional networks in US and networks abroad
ARPANET was decommissioned
NSFNET was decommissioned in 1995, most
Internet backbone traffic carried by
commercial ISPs
Increased commercialization, advent of
WWW, all lead to explosion of growth
2A-13
The Internet’s History
Mid-1980s – NSFNet
Network between supercomputers
Internet was the link to ARPANET
No commercial traffic allowed
1990s
ARPANET shut down
NSFNet abandoned
Commercial networks take over
1990s...commercialization! NSFNET began to serve as backbone, linking
regional networks in US and networks abroad
ARPANET was decommissioned
NSFNET was decommissioned in 1995, most
Internet backbone traffic carried by
commercial ISPs
Increased commercialization, advent of
WWW, all lead to explosion of growth
2A-15
Today and the Future
100,000 new web sites per month
More than 50% of U.S. households online
Access is available throughout the U.S.
Eventually access will be global
2A-16
U.S. Internet Growth
2A-17
The Internet’s Major Services
The World Wide Web (WWW) Developed in 1993 by Tim-Berners Lee
Required a browser to read documents
The World Wide Web is
a system of Internet servers that supportspecially formatted documents. The
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.
This means you can jump from one document to another simply
by clicking on hot spots.
Not all Internet servers are part of the World Wide Web.
Electronic mail (e-mail)
Instantaneous transmission of documents
2A-18
The Internet’s Major Services
News
Often called newsgroups
Electronic discussions on several topics
File Transfer Protocol (FTP)
Sends and receives files
2A-19
The Internet’s Major Services
Chat
Public real time conversation
Instant messaging
Private real time conversation
Peer-to-peer services
Allows sharing of files among users
Napster and Kazaa are examples
Illegal to share copyrighted material
2A-20
Accessing The Internet
Internet Service Provider (ISP)
Company that provides Internet access
Dialup
Connects to Internet through phone line
Modem connects to the phone line
Slow connection
2A-21
Accessing The Internet
High-speed access
Connect through a special line
2 – 25 times faster than dialup
DSL, Cable, T1 are common
Both were invented at the same time by the same person
HTTP vs HTML
HTML: hypertext markup language
Definitions of tags that are added to Web documents to control their appearance
HTTP: hypertext transfer protocol
The rules governing the conversation between a Web client and a Web server
23
The World Wide Web The Web
An infrastructure of information combined and the network software used to access it
Web page
A document that contains or references various kinds of data
Links A connection between one web page and another
What are the links used for?
24
The World Wide Web
Website
A collection of related web pages
Web browser
A software tool that retrieves and displays eb pages
Web server
A computer set up to respond to requests for web pages
25
The World Wide Web
Uniform Resource Locator (URL)
A standard way of specifying the location of a Web page, containing the hostname, "/", and a file
What is the relationship between the Internet and the Web?
26
The World Wide Web
Why is the expression
"visiting a website"
confusing?
27
Search Engines
Search Engine
A website that helps you find other websites
Can you name at least two?
How do they work?
28
Weblogs
Blog or Weblog
An online journal or newsletter that is frequently updated and intended for public consumption
Do you have a blog?
Do you read blogs?
29
Cookies
Cookie
A small text file that a web server stores on your local computer’s hard disk
A cookie contains information about your visit to the site
Cookies can be used to determine number of unique visitors to the site
to customize the site for future visits
to implement shopping carts that can be maintained from visit to visit
Cookies are not dangerous
2A-30
Understanding The Internet
Browsers
Read and translate the HTML
Display web content
Uniform Resource Locator (URL)
Address of a web page
2A-31
Understanding The Internet
Helper applications
Plug-ins
Enhance a browser’s functionality
Streaming audio and video
Sends the file in small chunks
Chunks downloaded while others play
2A-32
Streaming Audio
2A-33
Using a Browser And The WWW
Browser starts on the home page
Navigating the web
Enter a URL in the browser
Click a link
Links are typically blue underlined words
Image maps are picture links
When finished, close the browser
2A-34
Searching the Web
The Web is unorganized
Directories
Categorize the Internet
Search engines
Find sites by keyword
2A-35
Searching the Web
Site searches
Large sites have an internal search
Metasearch sites
Search several web sites at once
Sponsored links
Sites pay for better search results
2A-36
Search Techniques
Quote the exact phrase
Use the keyword AND
Use the keyword NEAR
Avoid common words
Use the site’s advanced tools
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