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CHAPTER 7 THE INTERNET AND INTRANETS 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

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chapter 7

CHAPTER 7

THE INTERNETAND INTRANETS

what is the internet
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

Marina G. Erechtchoukova

the evolution of the internet
The Evolution of the Internet

Marina G. Erechtchoukova

the infrastructure of the internet
The Infrastructure of the Internet
  • Commercial communications carriers provide the physical network backbone of the Internet
  • Internet Service Providers:
    • Backbone providers
    • Access providers
  • Reciprocal agreement

Marina G. Erechtchoukova

the operation of the internet
The Operation of the Internet
  • Internet is packet-switched network
  • Client-Server architecture
  • Internet Protocol
  • Internet Model

Marina G. Erechtchoukova

internet model
Internet Model
  • Interface layerdefines physical medium and frame for flow and error control
  • Internet network layer defines the path to intended receiver in the network. Uses Internet Protocol (IP)
  • Internet transport layer provides point-to-point reliable transmission of data. Uses TCP and UDP.
  • Internet application layer supports network application

Marina G. Erechtchoukova

osi model vs internet model
OSI Model vs. Internet Model

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internet application layer
Internet Application Layer
  • File Transfer Protocol
  • Telnet
  • Simple Mail Transfer Protocol
  • Simple Network Management Protocol
  • HyperText Transfer Protocol
  • Domain Name System

Marina G. Erechtchoukova

addresses on the internet
Addresses on the Internet
  • IP address uniquely identifies each computer in the network
  • Example: 130.63.160.120
    • The necessity to keep a master table with IP addresses on each router
    • Hard to remember for people
  • Domain name system (DNS) - derives the names of the computers

Marina G. Erechtchoukova

domain name system dns
Domain name system (DNS)
  • Domain – a group of networks
  • Domains are organized hierarchically
  • DNS is based on hierarchical database:
    • Variable-depth hierarchy
    • Distributed database
  • Examples:www.atkinson.yorku.ca

www.yorku.ca

Marina G. Erechtchoukova

accessing the internet
Accessing the Internet
  • Connect via LAN Server
    • Communications stack
  • Connect via Serial Line Internet Protocol/Point-to-point Protocol (SLIP/PPP)
  • Connect via an Online Service

Marina G. Erechtchoukova

internet services
Internet Services
  • Communications services
  • Information retrieval services
  • World Wide Web
  • Web services

Marina G. Erechtchoukova

communications services provided by the internet
Communications Services Provided by the Internet
  • E-mail
    • Mail Gateway – a computer dedicated to forwarding e-mail
  • USENET Newsgroups:
    • Bulletin board
    • Discussion threads (moderate vs. unmoderate)
  • LISTSERV
  • Chatting

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communications services provided by the internet continued
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

Marina G. Erechtchoukova

communications services provided by the internet continued15
Communications Services Provided by the Internet (continued…)
  • Internet Fax
  • Content streaming:
    • Audio
    • Video
  • Real-time audio and video

Marina G. Erechtchoukova

information retrieval services
Information Retrieval Services
  • FTP service
    • File Transfer Protocol can be used to copy an arbitrary file from one computer to another
    • Client–Server architecture
    • A control connection is established to a remote computerand remains in place until the user closes it.
    • Data connection
    • File name translation
  • Archie searches the file on FTP sites

Marina G. Erechtchoukova

information retrieval services continued
Information Retrieval Services (continued…)
  • Gopher – distributed document delivery system:
    • Based on TCP
    • Flow control and sequencing
    • Acknowledgment and Retransmission
    • Checksums
  • Veronica searches text in Gopher menus

Marina G. Erechtchoukova

the world wide web
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

Marina G. Erechtchoukova

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

Marina G. Erechtchoukova

hypertext transfer protocol http
Hypertext Transfer 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

Marina G. Erechtchoukova

browser
Browser
  • 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 Explorer’s 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

Marina G. Erechtchoukova

search engines
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
      • Registration
    • Methods for information search:
      • Depth first
      • Breadth first
  • Metasearch engines

Marina G. Erechtchoukova

push vs pull technology
Push vs. Pull Technology
  • Pull Technology – users select and retrieve information from the Web
  • Push Technology automatically supplies information to users by means of a process running on either the user’s 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

Marina G. Erechtchoukova

web services
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

Marina G. Erechtchoukova

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

Marina G. Erechtchoukova

internet challenges
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

Marina G. Erechtchoukova

internet privacy
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

Marina G. Erechtchoukova

intranets
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
    • Information distribution

Marina G. Erechtchoukova

intranet operation
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. traditionalnetworks:
    • HTTP and HTML platform independent
    • A single input point – a browser

Marina G. Erechtchoukova

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

Marina G. Erechtchoukova

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

Marina G. Erechtchoukova

extranet
Extranet
  • A network that links business partners to one another over the Internet by providing access to certain areas of each other’s corporate intranets
  • Components
    • Intranets of business partners
    • Internet as communications links

Marina G. Erechtchoukova

extranet infrastructure
Extranet infrastructure
  • Telecommunications systems (VPNs)
  • TCP/IP Protocols
  • Internet Services
  • Intranets infrastructure

Extranet

Company A

Company B

Intranet

corporate data, e-mail,

orders, customer data,

inventory, documents

Internet

Intranet

Internet

Internet

Internet

Other users

customers, suppliers, contractors, distributors, government

Corporate employees

travelling or at home

Marina G. Erechtchoukova

types of extranet
Types of Extranet
  • A company and its dealers, customers, or suppliers
    • centered around one company
  • An industry’s extranet teamed up and created by the major players in an industry
  • Joint ventures and other business partnerships
    • used for communications and collaboration among several companies partnering in a joint venture

Marina G. Erechtchoukova

slide35

Benefits of Extranets

  • Reduce the number of help-desk and data-entry employees
  • Improve quality of data and information exchange
  • Accelerate processes and information flows
  • Reduce paperwork
  • Provide better communications

Marina G. Erechtchoukova