Inside the Internet and the Web

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Chapter 10

• Inside the Internet and the Web

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Topics
Its a bit like climbing a mountain. You dont
know how far youve come until you stop and look
back. Vint Cerf

• The Internet A Network of Networks
• Internet Applications Communication and
  Connection
• Inside the World Wide Web
• The Evolving Internet

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The Internet A Network of Networks

• The Internet is an interconnected network of
  thousands of networks linking academic, research,
  government, and commercial institutions.

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Internet Services

• The Internet provides scientists, engineers,
  educators, students, business people, and others
  with a variety of services such as
• Electronic mail (send/receive mail messages)
• Remote login (Telnet - access to other computers)

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Internet Services

• Transferring files (FTP - accessing archives of
  data)
• Newsgroups (Usenet - on-line public discussions)
• World Wide Web (a collection of multimedia
  documents)

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Counting Connections

• Today, the Internet connects computers to about
  every country in the world. However, the
  Internet is
• growing too fast to measure its growth
• too decentralized to quantify
• a network with no hard boundaries

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Internet Protocols

• The language at the heart of the Internet is
  TCP/IP
• Transmission Control Protocol/Internet Protocol
• Allows cross-network communication

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Internet Protocols

• TCP breaks messages into packets
• Each packet has all the information needed to
  travel from network to network
• Host systems called Routers determine how to
  route transmissions

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Internet Protocols

• IP is the address for the packets
• Each Internet host computer has a unique IP
  Address
• Each address is comprised of four sets of numbers
  separated by periods, such as 123.23.168.22

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Internet Addresses

• The host is named using DNS (domain name system),
  which translates IP addresses into a string of
  names.

Each person on the Internet has a unique
e-mail address created by having a squirrel run
across a computer keyboard. Dave Barry
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Internet Addresses

• Top level domains include

• .edu - educational sites
• .com - commercial sites
• .gov - government sites
• .mil - military sites
• .net - network administration sites
• .org - nonprofit organizations

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Country Top-Level Domains
ISO approved country domains

• ccTLDs Country Code Top-Level Domains
• Follows ISO 3166-1
• ca -- Canada
• jp Japan
• nu -- Niue
• uk United Kingdom
• us United States
• tv Tuvalu
• And more

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Internet Addresses

• An Internet address includes username_at_hostname.su
  b.dom

• username is the persons mailbox
• hostname is the name of the host computer and is
  followed by one or more domains separated by
  periods
• host.subdomain.domain
• host.domain
• host.subdomain.subdomain.domain

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Internet Addresses
Examples
User President whose mail is stored on the host
whitehouse in the government domain

• president_at_whitehouse.gov

User hazel_filbert at the server for Lane County,
Oregon, k-12 school district
hazel_filbert_at_lane.k12.or.us
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Internet Access Options

• Direct (dedicated) Connection

• Computer has its own IP address and is attached
  to a LAN
• No need to dial up
• Files are stored on your computer
• Response time is quick

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Internet Access Options

• Dialup Connections
• limited connection using a modem
• Full access dial up uses SLIP or PPP via modem
• Broadband Connections
• DSL service is newer, faster, and cheaper than
  ISDN
• Can share phone line with voice traffic

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Internet Access Options

• Cable Modem Connection
• allow Internet connections using shared TV cables
• can exceed DSL speeds
• Carry increased privacy and security risks
• Satellite Connections
• provides connections using DirecTV satellite
  dishes

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Internet Access Options

• Internet Service Providers (ISPs)
• local ISPs provide connections through local
  telephone lines
• national ISPs offer connections on a nationwide
  scale

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Internet ApplicationsCommunication and
Connection

• The Internet use the client/server model for most
  Internet applications.
• In the client/server model a client program asks
  for information, and a server program fields the
  request and provides the requested information
  from databases and documents.

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Internet ApplicationsCommunication and
Connection

• An email server acts like a local post office for
  a particular Internet hosta business, an
  organization, or an ISP.
• File servers are common within LANs, but theyre
  also used to share programs, media files, and
  other computer data across the Internet.

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Internet ApplicationsCommunication and
Connection

• File transfer protocol (FTP) allows users to
  download files from remote servers to their
  computers and to upload files.
• File compression saves storage space on disk and
  saves transmission time when files are
  transferred through networks.

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Internet ApplicationsCommunication and
Connection

• An application server stores applications- PC
  office applications, databases, or other
  applications - and makes them available to client
  programs that request them.
• An application server might be housed at an
  application service provider (ASP) - a company
  that manages and delivers application services on
  a contract basis.
• A Web server stores Web pages and sends pages to
  client Web browsers.

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Inside the Web

• WWW is a distributed browsing and searching
  system developed at CERN
• System was designed to give Internet documents
  unique addresses
• HTML language was created for encoding and
  displaying documents
• Browser software was built for viewing documents
  from remote locations

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Inside the Web
Web site Jargon

• Web pages are made up of text and images
• A Web site is a collection of web pages
• A Home page is the main entry to a Web site
• A Web browser like Netscape Communicator or
  Internet Explorer allows you to explore the Web
  by clicking links

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Inside the Web
Hyperlinks (links) are words or pictures that
act as buttons, allowing you to go to another Web
page

• Links are typically underlined or displayed in a
  different color

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Inside the Web

• More Web site Jargon
• Links allow you to locate information without
  knowing its exact location (it may move from time
  to time)
• Back and Forward buttons let you retrace your
  steps
• Bookmarks and Favorites can be set up to mark
  your favorite Web locations

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Web Addresses
Pronounced Earllike the name
A typical URL looks like this http//www.prenhall
.com.beekman
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Web Addresses

• Dissecting Web Page address

• Protocol for Web pages

Resource Page
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Publishing on the Web
HTML (Hypertext Markup Language)

• An HTML document includes codes that determines
  the format, layout, and structure of a Web
  document

HTML is not WYSIWYG
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Publishing on the Web

• This text coded as HTML

ltH1gtWelcome to Computer Confluencelt/H1gtltbgtPublish
ing on the Weblt/bgt
Appears like this on the screen
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Publishing on the Web

• Alternatives to HTML
• Programs that convert document format features
  into HTML codes
• Microsoft Word, FileMaker
• Web authoring programs
• HomePage, GoLive, FrontPage

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From Hypertext to Multimedia
Typical Web pages can contain

• Tables
• Frames
• Forms
• Downloadable audio and video

• Streaming audio and video
• Real-time live audio or video
• 3-D environments

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From Hypertext to Multimedia

• Plug-Ins are software extensions that add new
  features. Examples include

• QuickTime
• Shockwave/Flash
• RealPlayer
• Acrobat

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Beyond HTML

• Dynamic HTML
• adds more programming power to HTML by allowing
  code to automatically modify itself under certain
  circumstances

JavaScript a simple language for enhancing HTML
Web pages
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Beyond HTML

• WML
• Wireless Markup Language helps create Web
  documents containing stock quotes, phone numbers,
  and other small nuggets of information
• XML
• Will replace HTML plus provide additional
  features and extensions
• VRML
• Virtual Reality Modeling Language creates 3-D
  virtual worlds

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Beyond HTML

• Java
• A full-featured, cross platform, object-oriented
  programming language
• Java applets
• Small Java programs that can be automatically
  downloaded onto your client computer and can run
  on any platform

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