CHAPTER 7 THE INTERNET AND INTRANETS

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CHAPTER 7THE INTERNETAND INTRANETS
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What is the Internet?

• The Largest computer network in the world (a
  network of networks)
• Exchanges information seamlessly by using the
  same open, non-proprietary standards and
  protocols, within interconnected networks
• Forms a massive electronic communications network
• Provides a true democratic communications forum
  and has produced a democratization of information

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The Evolution of the Internet
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The Infrastructure of the Internet

• Commercial communications companies provide the
  physical network backbone of the Internet
• Based on the networks of communications carriers
• Internet Service Providers
• Backbone providers
• Access provider
• Reciprocal agreement

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The Operation of the Internet

• Internet is packet-switched network
• Gateways most popular communications devices
• Internet Protocol
• Internet Model

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Internet Model

• Interface layer defines physical medium and frame
  for flow and error control
• Internet network layer defines the next intended
  receiver in the network. Use Internet Protocol
• Internet transport layer provides point-to-point
  reliable transmission of data. Use TCP and UDP.
• Internet application layer supports network
  application

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Internet Application Layer

• File Transfer Protocol
• Telnet
• Simple Mail transfer Protocol
• Simple Network Management Protocol
• Hyper-Text Transmission Protocol
• Domain Name System

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Addresses on the Internet

• IP address - uniquely identifies one from the
  other computers
• Hard to remember for people
• Each router must keep a master table with IP
  address
• Domain name system (DNS) - derives the names of
  the computers

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Domain name system (DNS)

• Domain group of networks
• Domains organized hierarchically
• DNS is based on hierarchical database
• Variable-depth hierarchy
• Distributed database
• Examplewww.atkinson.yorku.ca

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Accessing the Internet

• Connect via LAN Server
• Communication stack
• Connect via Serial Line Internet
  Protocol/Point-to-point Protocol (SLIP/PPP)
• Connect via an Online Service

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Communication Services Provided by the Internet

• E-mail (Gateways translate the format of e-mail
  messages)
• USENET Newsgroups
• Bulletin board
• Discussion threads (moderate vs. unmoderate)
• LISTSERV
• Chatting

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Communications Services Provided by the Internet
(continued)

• Telnet
• Internet telephony
• Voice-over IP
• Sharing digital lines
• Disadvantages
• Low quality of sounds
• Delays in transmission process

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Communications Services Provided by the Internet
(continued)

• Internet Fax
• Content streaming
• Audio
• Video
• Real-time audio and video

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Information Retrieval Services

• File Transfer Protocol
• Archie searches the file on FTP sites
• Gopher distributed document delivery system
• Based on TCP
• Flow control and sequencing
• Acknowledgment and Retransmission
• Checksums
• Veronica searches text in Gopher menus

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The World Wide Web

• The Internet functions as the transport
  mechanism
• The World Wide Web - a system with universally
  accepted standards for storing, retrieving,
  formatting, and displaying information
• Web Servers support WWW application, are
  scattered all over the world

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Web site

• Web Site
• Home Page - first, introductory page in a web
  site created on one of Markup languages
• Webmaster - the person in charge of a Web site
• Uniform Resource Locator (URL)

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Hypertext Transmission Protocol (HTTP)

• communications standard used to transfer pages
  across the WWW
• Web client establishes connection with server
• Web server receives a request
• Web server sends a message
• The connection is closed, if Web client does not
  use keep alive option

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Browsers

• software application that is used to access and
  navigate the Web
• Netscape Communicator
• a multipurpose suite that handles news, e-mail,
  audio- and video conferencing, and more
• Microsoft Internet Explorer
• Internet Explorers tight integration with
  Windows offers users the advantage of one-stop
  computing
• Offline Browser
• enables a user to retrieve pages automatically
  from Web sites at predetermined times

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Search Engines

• Programs that return a list of Web sites or pages
  that match some user-selected criteria
• Ways to select pages for inclusion in the
  database Web Crawlers and Registration
• Methods for information search
• Depth first
• Breadth first
• Metasearch engines

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Push vs. Pull Technology

• Pull Technology users select and retrieve
  Information from the Web
• Push Technology automatically supplies desirable
  information to users by means of a process
  running on either the users desktop or a network
  server
• provides timely, prioritized distribution of
  information over a corporate network in the
  workplace
• enhances traditional Web advertising in the
  consumer market

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Web Services

• Information Filters
• Platform for Internet Content Selection
• Intelligent agents
• Clipping Services
• track news topics and retrieve articles from
  database of publications
• Personalized Web Services
• offer the ability to generate Web content that is
  personalized for individual Web site visitors
• Collaborative Filtering

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Web Authoring

• Standard HTML is the common denominator
• Enhancements to HTML
• Dynamic HTML (DHYML)
• Extensible markup language (XML)
• Voice markup language (VoxML)
• Virtual reality modeling language (VRML)
• HTML editors, generators, publishers

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Internet Challenges

• New Technologies
• Vendors are adopting new technologies more
  rapidly than users can implement them
• Internet Regulation
• WWW Consortium, Internet Engineering Task Force
  technical standards
• Content regulation
• Internet Expansion
• The massive growth of Internet traffic has
  strained some elements of the network

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Internet Privacy

• Web sites collect information about visitors
• Registration
• Clickstream data
• Cookie is a mechanism that supports restoring
  client states
• small data file placed on users hard drives
  when they first visit a site
• Encrypting

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Three potential bills are in USA Congress

• the government should let groups develop
  voluntary privacy standards but not take any
  action now unless real problems arise
• the government should recommend privacy standards
  for the Internet but not pass laws at this time
• the government should pass laws now for how
  personal information can be collected and used on
  the Internet

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Intranets

• A private network that uses Internet software and
  TCP/IP protocols
• Process business data and information
  efficiently
• Data and information search
• Urgent information delivery
• Data and information processing
• Information distribution

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Intranet operation

• Intranet documents HTML pages
• HTTP used to transmit documents
• Browsers allow to view Intranet documents
• Supports applications to solve business problems
• Intranet vs. traditional networks
• HTTP and HTML platform independent
• A single input point a browser

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Intranet software

• Teamware
• used for team building, sharing ideas and
  documents, brainstorming, scheduling, and
  archiving decision to facilitate productivity
• Add-on to groupware

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Security

• Public Key security
• Encryption
• Digital certificates
• Firewalls
• Set of rules placed on the router
• One or more computers
• Assured pipelines