Transcript Introduction to Computing

CS101 Introduction to Computing
Lecture 28
Introduction to the Internet
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During the Last Lecture
(Computer Networks)
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We looked at the role of networks in
computing
•
We looked at several different types of
networks
•
We familiarized ourselves with networking
topologies and protocols
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Computer Network
Multiple computers that are
connected together to share
information and other resources
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Types of Computer Networks
according to the network access policy
• Private
• Public
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Types of Computer Networks
according to the distance between nodes
• LAN: Local Area Network
• WAN: Wide Area Network
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Network Topologies
• The pattern in which computers are connected
to form a network
• Popular patterns:
– Point-to-point
– Star
– Bus
– Ring
• Networks are also formed by combining 2 or
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more of these 4 basic patterns
Networking Protocols
• Networks use protocols, or rules, to exchange
information through shared channels
• These protocols prevent collisions of data
caused by simultaneous transmission between
two or more computers
• Several protocols are available for various
types of networks. Here we discuss two that
are popular for LANs: Ethernet; Token Ring 7
Types of Communication Channels
• Wire
• Wireless
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Wireless (Radio) LANs Are Becoming Popular
Key benefits:
– Set-up time
– Set-up cost
– Maintenance cost
– Cost
Key challenges:
– Security & privacy
– Quality of service
– Cost
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Today’s Goal:
Introduction to the Internet
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To become able to appreciate the role of the
Internet in today’s computing
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To become familiar with the history and
evolution of the Internet
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an accident!
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This car was involved in that accident
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It belongs to …
Mr. Tom Peters
of
Palo Alto, California
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After the accident, Mr. Peters …
filled out a form, giving info about:
– Himself
– The circumstances of the accident
– Estimated repair expenses
& then …
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1/ 7
Mr. Peters’s fax machine
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2/ 7
ACME Insurance Group’s
server in New York
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3/ 7
Bhola eServices (Pvt) Ltd’s
server at Davis Rd, Lahore
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4/ 7
Claims processing in Lahore
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5/ 7
Bhola eServices (Pvt) Ltd’s
server at Davis Rd, Lahore
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6/ 7
ACME Insurance Group’s
server in New York
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7/ 7
Mr. Peters’s home PC
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Key Question!
Why process the insurance
claim in Pakistan?
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Answer: Everybody Wins!
•
•
•
Tom Peters
ACME Insurance
Bhola eServices
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Answer: Everybody Wins!
•
•
•
Tom Peters
ACME Insurance
Bhola eServices
Lower premium
&
Quicker turnaround
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Answer: Everybody Wins!
•
•
•
Tom Peters
ACME Insurance
Bhola eServices
Better margins due to
50% saving on claim
processing costs
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Answer: Everybody Wins!
•
•
•
Tom Peters
ACME Insurance
Bhola eServices
Internal rate of
return (IRR) of
60-80%
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The Key Point …
Bhola eServices (Pvt) Ltd is …
… supplying a service
… using local, attractively-priced workers
… to a remote, overseas client
… over the Internet
… & making good money in the process!
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Internet:
the enabler!
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What else does
the Internet
enable?
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What Else?
• Enables users located at far-way locations to
easily share information with others located all
over the world
• Enables users to easily and inexpensively
communicate with others located all over the
world
• Enables the users to operate and run programs
on computers located all over the world
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The Internet is unlike
any previous human
invention. It is a
world-wide resource,
accessible to all of
the humankind.
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Internet Users Worldwide
673M in 2002
1B+ in 2005
(48% wireless)
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1.2M Internet users in Pakistan in 5/2000
(1% of population)
In early 2002,
54% of Australian population
51% of Singaporean population
39% of Japanese population
3% of Chinese population
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Key Characteristics (1)
Geographic Distribution
Global - reaches around the world
Robust Architecture
Adapts to damage and error
Speed
Data can travels at near ‘c’ on copper,
fiber, airwaves
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Key Characteristics (2)
Universal Access
Same functionality to everyone
Growth Rate
The fastest growing technology ever
Freedom of Speech
Promotes freedom of speech
The Digital Advantage
Is digital: can correct errors
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inter net
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Internet: Network of Networks
• A large number of networks,
interconnected physically
• Capable of communicating and sharing
data with each other
• From the user’s point view, Internet – a
collection of interconnected networks –
looks like a single, unified network
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Internet ---- Web
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Internet ---- Intranet
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Internet Networking Protocols
Communications on the Internet is
controlled by a set of two protocols:
TCP and IP
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TCP/IP (1)
Transmission Control Protocol/Internet Protocol
• Networking protocol used by all computers and
networks on the Internet
• Originally developed by the US DoD for Unix,
but now available for most other OSes
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TCP/IP (2)
Transmission Control Protocol/Internet Protocol
• TCP breaks down the message to be sent over
the Internet into packets
• IP routes these packets through the Internet to
get them to their destination
• When the packets reach the destination
computer, TCP reassembles them into the
original message
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Tools & Services Available on the Internet
• Electronic mail (POP, IMAP, SMTP)
• Instant messaging (ICQ, MSN)
• Remote login (telnet)
• File transfer (ftp)
• Network news (nntp)
• WWW (http)
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Chronology of events that led
to today’s Internet
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1960's
1969 - DoD-ARPA creates an experimental
network – ARPANET – as a test-bed for
emerging networking technologies
ARPANET originally connected 4 universities &
enabled scientists to share info & resources
across long distances
ARPANET continued to expand throughout the
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70's and 80's
1970's
Networking tools developed in the 70's include:
1972 - The National Center for
Supercomputing Apps. (NCSA) develops the
telnet application for remote login, making it
easier to connect to a remote computer
1973 - FTP (File Transfer Protocol) is
introduced, standardizing the transfer of files
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between networked computers
1980's
1983 - The TCP/IP protocols becomes the only
set of protocols used on the ARPANET
This sets a standard for all networks, and
generates the use of the term Internet as the
net of nets
ARPANET splits into two nets to keep military
& non-military network sites separate:
ARPANET and MILNET
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1980's
In 1982 and 1983, the first desktop computers
begin to appear
Many are equipped with an OS called Berkeley
Unix, which includes networking SW, allowing
easy connection to the Internet using telnet
The PC revolution continues through the 80’s,
making access to computer resources & networked info increasingly available to public
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1980's
1985-86: NSF connects the US’s six
supercomputing centers together, calling it the
the NSFNET, or NSFNET backbone
To expand access to the Internet, NSF
developed regional nets, which were then
connected to the NSFNET backbone
Plus, NSF supported institutions (universities,
etc.) in their efforts to connect to the regional
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nets
1980's
1987 - NSF awards a grant to Merit Network,
Inc. to operate & manage future development
of the NSFNET
Merit collaborates with IBM & MCI on R&D for
fast networking technologies
1989 - The backbone network is upgraded to
T1, making it able to transmit data at speeds of
1.5 Mb/s (approx. 60 pages of text/second)
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1990's
1990 - The ARPANET is dissolved
1991 - Gopher is developed at the U of MN
It provides a hierarchical, menu-based method
for providing & locating info on the Internet
1993 - CERN releases WWW, developed by
Tim Berners-Lee
It uses HTTP and hypertext, revolutionizing the
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way info is presented & accessed on Internet
1990's
1993 - The NSFNET is upgraded to T3 (45
Mb/s or about 1800 pages/s)
1993-1994 - Web browsers Mosaic & Netscape
Navigator are introduced
Their GUI makes WWW & Internet more
appealing to the general public
1995 - NSFNET is replaced by a new
architecture, called vBNS which utilizes
regional networks and Network Access Points
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A lot has happened
since 1995
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Who runs the Internet?
Who owns it?
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Today’s Goal:
Introduction to the Internet
•
We looked at the role Internet plays in today’s
computing
•
We reviewed some of the history and
evolution of the Internet
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Next Lecture:
Internet Services
We will try to familiarize ourselves with with
some of the Internet services:
– http (surfing, shopping, searching)
– eMail
– ftp
– News groups, message boards, forums
– Instant messaging
– Multimedia delivery
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