Lecture Week 2

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Lecture Week 2

• The Internet and the World Wide Web (WWW)

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What is the Internet?

• The Internet is a worldwide collection of
  computer networks that use international
  standards to exchange data and information.

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Protocol

• In order for the Internet to work in connecting
  many different types of computers, software, and
  files together, standardized rules called
  protocols must be used to define how computers
  communicate.
• TCP/IP is the basic protocol or set of rules
  which Internet computers use to communicate with
  each other.

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Service of Internet

• The Internet itself does not contain information,
  but provides a conduit which allows users to
  communicate and locate information resources.
• Services include communication (e-mail, chat,
  instant messaging, newsgroups and mailing lists),
  the World Wide Web, file transfer (FTP), and
  telnet or remote login.

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Service of Internet

• the Internet has become a powerful tool of
  commerce, for shopping, banking, filing taxes,
  etc.

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ways the Internet shares information

• Ask an information question by sending and
  receiving messages and files via electronic mail
• Search or browse for information using Web search
  engines and directories (indexes of web
  resources)

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ways the Internet shares information

• Search for information using subscription-based
  databases
• Complete a tutorial or take a college class using
  online courseware or web-based course management
  software
• Read and post information to Usenet newsgroups or
  mailing lists
• Send and retrieve files and programs with FTP
  (File Transfer Protocol)

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ways the Internet shares information

• Participate in real-time online conversations or
  resource-sharing conferences via IRC (Internet
  Relay Chat), web-based chat rooms, conferencing
  systems or instant messaging services.
• Log onto and use remote computers or systems with
  Telnet or terminal emulation programs

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ways the Internet shares information

• Since the Internet is a medium of information
  sharing that allows users to self-publish, you
  can mount your own site to share your expertise
  or opinions with others

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WWW Internet

• Many people erroneously think the World Wide Web
  and the Internet are the same. Although the Web
  began as just one of several Internet services,
  web browsing software has expanded to facilitate
  or incorporate most Internet applications and
  services, such as e-mail, chat, Telnet, FTP, and
  discussion groups.
• The Web is currently the service that most people
  use to access Internet services.

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Internet History

• The Internet officially began in 1969 as a
  network called ARPANET, designed for the Advanced
  Research Projects Agency (ARPA) of the U.S.
  Department of Defense.
• the original ARPANET was designed as an
  experiment in developing a network which would
  withstand a nuclear attack

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Design Philosophy

• In case of a nuclear attack, if a section of the
  network disappeared, the entire network would not
  be destroyed. To that end, the network was
  decentralized, data was distributed among all the
  network computers, and data was transferred in
  small packets.

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Design Philosophy

• The network design was based on observations of
  the human brain, since brain functions don't rely
  on a centralized set of cells. Brain circuitry
  can be rerouted around damaged cells and neural
  networks can be re-created over new pathways.

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Internet History

• The 1970s and early 1980s were spent developing
  basic standards called protocols for data
  transfer.
• In 1983, TCP/IP became the core Internet
  protocol.

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Internet History

• The ARPANET's founders originally allowed only
  defense scientists and military researchers to
  logon and run programs from remote computers.
• By the early 1980s. educators discovered the
  value of interconnected computers, and created
  BITNET.

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Internet History

• BITNET was an academic and research network that
  links IBM computer centers around the world.
• CSNET (Computer Science Network) that linked
  university computer science departments.
• In 1986 the NSFNet was created and named after
  the National Science Foundation, which provided
  most of the funding.

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Internet History

• NSFNet linked academic researchers across the
  country with five supercomputer centers.
• The NSFNet continuously linked more powerful
  supercomputers through faster connections,
  upgrading the network in 1988 and 1990.

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How Does the Internet Work?

• The Internet connects many different types of
  computers, software and files together.
• standardized rules called protocols are used to
  define how computers communicate.
• an early communications protocol was Morse Code,
  which used standardized dots and dashes.

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The Internet protocol TCP/IP

• TCP/IP defines a packet-switched network
• TCP/IP sends data out in many directions in many
  small packets
• When you type in a URL to retrieve a file (Web
  page or other file) on the Internet, TCP/IP
  protocol is used to transfer the requested data
  in chunks or packets.
• Each packet contains a piece (up to 1500 bytes)
  of the data

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Other types of Internet protocols

• HTTP (Hypertext Transfer Protocol) The Web uses
  HTTP to transfer data. The HTTP protocol contains
  commands that allow you to jump to another
  hypertext document and retrieve the information
  in that document.

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Othr Internet protocols

• SMTP (Simple Mail Transfer Protocol) SMTP is used
  to send e-mail messages between servers. Most
  e-mail systems that send mail over the Internet
  use SMTP to send messages from one server to
  another the messages are retrieved with an
  e-mail client using POP (Post Office Protocol) or
  IMAP (Internet Message Access Protocol).

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Other Internet protocols

• FTP (File Transfer Protocol) FTP is a standard
  method of moving files from one computer to
  another on the Internet. The transfer of files
  using FTP can work in either direction. You may
  retrieve files from a remote server, or transfer
  files to a remote server, if you have been
  granted access to that server. FTP indicates a
  connection to a file server rather than a Web
  server.

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Client/Server Networking

• Most Internet services rely on the client/server
  model.
• The Internet user is the client
• he uses client software to connect to server
  programs

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URLs (Uniform Resource Locators)

• Every document on the Internet has a unique
  address called a URL.
• The URL consists of three parts
• the protocol,
• the domain name
• and the path.

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URLs (Uniform Resource Locators) The protocol

• The protocol is the set of rules the computer
  follows in order to communicate with another
  computer.
• If the protocol is http//, for example, the
  computer knows it will be processing a hypertext
  document from the World Wide Web.

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Other protocols

• ftp// file transfer protocol, for downloading
  files
• telnet// provides connections to remote
  computers
• news connects to news servers, though many news
  readers now use Web services such as Google
  Groups to access newsgroups

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Domain Name

• The domain name or server name is the Internet
  address of the computer or server which is
  hosting the site and storing the documents.

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World Wide Web

• The World Wide Web is a branch or subsection of
  the Internet that provides access to hypertext
  documents
• Hypertext resources are documents which provide
  links or connections to other documents.
• Hypertext lets you move through a text in a
  nonlinear manner and allows you to explore a vast
  worldwide "web" of information.

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WWW

• The World Wide Web
• began in 1989
• communications project in SwitzerlandEuropean
  Laboratory for Particle Physics called CERN
  (Conseil Europeen pour Researche Nucleaire).
• Tim Berners-Lee, a graduate of Oxford University
  proposed a global hypertext information system to
  be used as a means of transporting research and
  ideas throughout CERN.

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WWW (Berners-Lee)

• Created an information system using hypertext,
  combined with the global connections provided by
  the Internet, to produce a "web" of connected
  documents.
• solution to two problems
• information storage
• Information retrieval, and communication on a
  global scale,
• since the members of CERN were located in a
  number of countries.

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WWW (Berners-Lee)

• As part of this project Berners-Lee wrote the
  initial specifications for URIs (a URL is a kind
  of a URI), HTTP and HTML
• Berners-Lee is currently the director of the
  World Wide Web Consortium, a membership
  organization that develops web protocols and
  standards, ensures interoperability, and promotes
  the evolution of the World Wide Web.

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Now go to the following URLs

• http//tutorials.beginners.co.uk/read/id/52
• http//tutorials.beginners.co.uk/read/id/53
• Take the next section of the class-time to read
  the information of the above two web pages