Transcript ARPAnet - Computing Science

Chapter 1: Introduction to Internet &
Web
• Objectives:
– To show the developments of Internet and its
protocols from a historical perspective
– To introduce basic terminology of Internet &
Web.
• Ref.:
(http://dir.yahoo.com/Computers_and_Inter
net/Internet/History/)
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ARPAnet
• Sponsor: Defense Advanced Research Projects Agency
(US)
• Backbone Network speed: 64Kbits/second
• Years: 1969 to 1988
• Purpose: connection of govt. labs and major research
institutes/universities.
• Major achievements:
– TCP/IP, Domain Name Service, e-mail (SMTP), FTP, Telnet,
USENET newsgroups, computer-computer communications, etc.
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NSFnet
• Sponsor: National Science Foundation (US)
• Backbone Network speed: T1 (1.5mb/sec.)
to T3 (45mb/sec.)
• Years: 1984 – 1994
• Replaced ARPAnet as the backbone of
Internet in 1990
• Purpose: connection of five supercomputer
centres
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Post NSFnet Developments
• Privately-funded, interconnected backbone
networks.
• Internet2: funded by US universities, a
sequel to NSFnet.
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CA*net
Year
Speed
US Equiv.
CA*net
1990
T1 (?)
NSFnet
CA*net II
1997
OC3
(155 Mb/s)
Internet2
CA*net III
1998
OC48
(2.5 Gb/s)
Internet2
(Abilene &
vBSN projects)
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CA*net III Map
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Internet Traffic Growth
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Local Loop – The Last Mile
• Telephone
– Modem: analog between home and telco
– ISDN: digital between home and telco
– ADSL: direct (digital) line to telco (broadband)
• Cable (broadband)
• Satellite
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Internet Access Protocols
• Command Line:
– FTP (1971)
• Menu-based
– gopher (1991)
• Search engine
– WAIS (1991)
• Hypermedia (hypertext & multimedia)
– WWW (1991)
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FTP
User Interface
Server Protocol
Interpreter
FTP
Commands
User
User Protocol
Interpreter
FTP
Replies
File
System
Server Data
Transmission
Process
Data
Connection
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User Data
Transmission
Process
File
System
10
HTTP/CGI
HTTP Server
HTTP
Messages
HTTP Client
(Browser)
User
Environment
Variables
File
System
CGI Process
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Browser Developments
• Browser as part of WWW project: 1991
(restricted to Next computer)
• Viola: 1992
• Midas: 1992
• NCSA Mosaic: 1993
– Netscape 1994
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Growth of WWW
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Web-based Systems
• HTTP Server: part of WWW project at
CERN
• The dawn of web-based systems:
– CGI (Common Gateway Interface): (1991).
• Browser as application front-end:
– Dynamic HTML (client-side script)
– Java Applets (1995)
– ActiveX controls (1996)
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Web-based 3-tier Architecture
• Presentation layer: Browser
• Business logic layer: Server and middleware
• Database layer: Database system
• Protocol between client and server: HTTP
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Web-based vs. Non Web-based Systems
•
•
•
•
Browser functionality
Limitations of HTML
Limitations of HTTP
Coverage of targeted user community
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Examples of Web Applications
• E-Commerce
– Establishes interactive relationships among prospects,
customers, partners, suppliers, and employees.
• Videoconferencing
– Enables real-time communication and collaboration.
• Online Learning
– facilitates life-long learning, anywhere, anytime.
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Internet Governance
• Internet Society:
– Non-profit, non-governmental, membershipbased, body
– Two standards bodies:
• IETF (Internet Engineering Task Force): e.g.
internet security standards
• IAB (Internet Architecture Board): e.g. Internet
addresses
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Web Governance
• World Wide Web Consortium (W3C)
• Organizational Hosts: MIT, Keio University
(Japan), and INRIA (France)
• W3C is responsible for web-related
protocols (e.g. HTTP, HTML, and XML).
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