Transcript Internet - Computer Science

The
Information
Superhighway
An Information
Infrastruture
Infrastructure
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promote economic gain
increase a country’s competitive edge
National Information Infrastructure
expensive to build - last mile problem
funding- National Research and
Educational Network (NREN) - link
universities
Services
• need new services to pay for expensive
structure
• example - on demand video
• downstream bandwidth - refers to the
capacity of a channel to deliver info to
the customer
• upstream bandwidth - from the
customer to the service provider
Growth
• over 150,000 customers are becoming
connected to Internet
• look at the problem of CompuServe
• the superhighway is not yet here, but
close and we call it the Internet
• Internet is a WAN
History
• started in 1969
• ARPANET - Advanced Research
Projects Agency Network
• linked DOD research centers with
universities
• developed the popular TCP/IP protocol
• no central headquarters - possible
nuclear attack
History
• Backbone first provided by National
Science Foundation (NSF) – NSF net
• Backbone now provided by various
corporations
• Various corporations help define
standards
• Internet2
• Next Generation internet (NGI)
NGI and Internet 2
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2 big networks in the US
NGI - Next Generation Internet
promise to be 10 to 1000 xs faster
more than 600 million earmarked
first offer services to educational and
governmental research
Decentralized
• uncontrollable growth
• largest e-mail system in the world
• 1/3 of all business mail is sent
electronically
• mail addresses have 2 parts
• user name and domain name
HOW THE INTERNET
WORKS
• Internet Service Providers and Online
Services
– Have permanent connections to the
Internet
– Provide temporary connections to
individuals and companies for a fee
– Local and national ISPs
– Online services offer member only areas
HOW THE INTERNET
WORKS
• Connecting to the Internet
– Business or school network connected to
the Internet
– Dial-up Access
– ISDN
– Cable Modems
– Wireless
– Digital Subscriber Line (DSL)
HOW THE INTERNET
WORKS
• How Data travels the Internet
– Servers
– Clients
– Packets
– Routers
– Packet Switching
– TCP – IP (Transmission Control Protocol –
Internet Protocol)
HOW THE INTERNET
WORKS
• How Data Travels the Internet
– Backbone
– Network Access Points (NAPs)
– Metropolitan Area Exchanges (MAEs)
– National ISPs (Backbone providers)
HOW THE INTERNET
WORKS
• Internet Addresses
– IP (Internet Protocol) Address
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Geographic Region
Company or Organization
Computer Group
Specific Computer
– Domain Name
• Top Level Domain (.edu, .com, .net etc..)
• Purdue (purdue.edu) and MIT(mit.edu) were among the
first 10 domain names registered in the world
Communications &
Connectivity
The
Internet
Communications &
Connectivity
The
Internet
Communications &
Connectivity
The
Internet
Communications &
Connectivity
The
Internet
Electronic
Mail (E-Mail)
E-MAIL
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[email protected]
jdoe is username
account is a name of a machine
smith is the name of the company
.com is the domain name category
Communications &
Connectivity
The
Internet
Electronic
Mail (E-Mail)
Communications &
Connectivity
The
Internet
Electronic
Mail (E-Mail)
Telnet
Telnet
• run programs on a remote host, play
interactive games, and use remote
library card catalogs
• Internet’s remote login application
• once connected , the session appears
to be same as if you terminal connected
to that host
Communications &
Connectivity
The
Internet
Electronic
Mail (E-Mail)
Telnet
Communications &
Connectivity
The
Internet
Electronic
Mail (E-Mail)
Telnet
File Transfer
Protocol
FTP
• File Transfer Protocal
• ftp is a client program
• use it to access public files (archives)
Communications &
Connectivity
The
Internet
Electronic
Mail (E-Mail)
Telnet
File Transfer
Protocol
Communications &
Connectivity
The
Internet
Electronic
Mail (E-Mail)
Telnet
File Transfer
Protocol
Gopher
Communications &
Connectivity
Electronic
Mail (E-Mail)
The
Internet
Telnet
File Transfer
Protocol
Gopher
WWW
Communications &
Connectivity
Electronic
Mail (E-Mail)
The
Internet
Telnet
File Transfer
Protocol
Gopher
WWW
World Wide
Web
THE WORLD WIDE WEB
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WWW
Started in 1991
Hyperlinks (Links)
Uniform Resource Locator (URL)
Hyper Text Transfer Protocol (http://)
Web Server
Web Master
Browser
• Software that retrieves, interprets and
displays Web pages
• 2 major browsers : Internet Explorer,
Netscape Navigator
• Netscape is the improved commercial
version of Mosaic, the first graphical
web browser created in 1993 by
University of Illinois students
URL
• Uniform Resource Locator
• address composed of a protocol
identifier, a server address and a file
pathname
• example:
http://www.netscape.com/home/welcom
e.html
URL Disected
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http is the protocol
netscape is the server
com is the type
netscape.com is the domain name
/home/welcome.html is the pathname
/home is the folder
welcome is the filename
html is the extension
URL
• domain names in a URL are casesensitive
• Internet sites continuously undergo
name and address changes
Finding What’s Cool
• spend too much time searching for unique
and interesting site
• Netscape routinely scouts the Internet for
unusual sites and then places links to those
URLs on its What’s Cool page.
• Netscape also compiles a list of What’s New.
Anyone can submit the name and URL of a
new page, but Netscape reserves the right to
reject any entry
OTHER INTERNET
SERVICES
• Chat Rooms
– Real Time Conversation
– Channels
– Chat Clients
• Internet Relay Chat (IRC)
• Microsoft Chat
OTHER INTERNET
SERVICES
• Instant Messaging
– Notifies when certain people you select are
online
– Allows you to exchange messages or join
private chat
OTHER INTERNET
SERVICES
• Portals
– A Web site designed to offer a variety of Internet
services from a single convenient location
– Free Services
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Search Engine
News
Weather
Sports
E-mail, shopping and chat rooms
– Web communities
ELECTRONIC COMMERCE
(e-commerce)
• Conducting Business Activities Online
• Electronic Data Interchange
• Three types of commerce
– Business to Consumer (B-to-C , B2C)
– Consumer to Consumer (C-to-C , C2C)
– Business to Business (B-to-B , B2B)
• Electronic Money
• Digital Certificates
Connectivity
Fall
1996
Full Access to
World-Wide
Computer Network
Future
• modem speeds have increased, so has
the amount of bandwidth the many
Internet applications use
• to prevent future traffic jams, some
major Internet projects are underway