Internet

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Internet

• 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 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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Intranets and Extranets

• Intranets - self-contained intra-organizational
  networks designed using the same technology as
  the Internet
• Firewalls - used to prevent unauthorized
  communication and secure sensitive internal data

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Intranets and Extranets

• A typical Intranets include
• E-mail
• Newsgroups
• File transfer
• Web publishing
• Other services

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Intranets and Extranets

• Extranets designed for outside use by customers,
  clients, and business partners
• Electronic Commerce business transactions
  through electronic networks

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Intranets and Extranets

• Electronic data interchange (EDI) a decade-old
  set of specifications for ordering, billing, and
  paying for parts and services over private
  networks.
• Virtual private networks not subject to the
  traffic and security problems.

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Internet ApplicationsCommunication and
Connection

• The user interface varies depending on which
  client/server application is being used.
• UNIX - developed by Bell Labs, allows a
  timesharing computer to communicate with several
  other computers or terminals at once.

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Internet Addresses

• E-mail addresses are made upof two parts
  separated by an at(_at_) sign
• User name_at_host name
• Example johnsmith_at_mindspring.com
• 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

• 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

• 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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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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E-mail on the Internet

• What appears on the screen depends on the type of
  Internet connection and mail program you use

Eudora is an easy to use Email software. Outlook
and Netscape Communicator are popular e-mail
software
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E-mail on the Internet

• Why are free email accounts made available?
• often offered to attract Web site visitors
• available for users of public computers
• sensible for those wanting multiple e-mail
  addresses not associated with a workplace

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E-mail on the Internet

• EEmail Formats include
• ASCII text so they can be viewed with any client
  program
• MIME that can be used to send and receive text
  with enriched text or HTML (displays text
  formatting, graphics, and links to Web pages)

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Mailing Lists and Network News

• Mailing lists allow you to participate in email
  discussion groups on special-interest topics.
• Network News are public discussions that you can
  go in and out as you please.
• Messages are posted on virtual bulletin boards
  (for everyone to read).

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Real-Time Communication

• Internet relay chat (IRC) allows several users to
  chat simultaneously
• Internet Telephony turns the Internet into a
  toll-free long-distance telephone service
• Video teleconferences allow multi-person
  videoconferences via the Web

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Real-Time Communication

• See

Type
Hear
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Telnet and FTP

• Information gathering
• Telnet - makes remote login possible
• FTP (file transfer protocol) - allows files to
  be uploaded and downloaded from remote computers

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Telnet and FTP

• Web browsers locate and transfer files without
  typing commands
• When you click a Web link to download a file,
  youre probably using FTP

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Inside the World Wide 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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Browsing 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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Browsing 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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More on Browsing 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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Searching the Web

• Search engines
• produce a list of pages that match a keyword
• they are built around a database that catalogs
  Web locations based on content
• Directory or Subject Tree
• A hierarchical catalog of Web sites
• Natural Language Search Engines
• Allows users to ask for what they want

The ability to ask the right question is more
than half the battle of finding the
answer. Thomas J. Watson
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Search Engines

• Search engines help find information when you
  type a query using keywords.

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Search Engines

• Directory/subject tree engines offer a
  menu of subject choices

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Search Engines

• Ask questions in a Natural Language Search
  Engine

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Portals

• Portals offer quick and easy access to a
  variety of services such as e-mail,
  chat,maps, news, shopping, etc.
• Examples of consumer portals include
• Yahoo!, Excite, Lycos, Alta Vista, Netscape
  Netcenter, Snap
• Specialized portals target specific industries
  and economic sectors

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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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Webcasting Push Technology

• Client computers pull information
• Browsers initiate a request for information
• Push technology delivers information
  automatically to the client computer
• Up to the minute weather reports
• News headlines

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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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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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The Evolving Internet
Internet2 and the Next Generation Internet

• provides faster network communications for
  universities and research institutions
• virtual laboratories, digital libraries, and
  distance learning applications are being built on
  Internet 2

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Internet Issues
Ethical and Political Dilemmas

• Filtering software can prevent unwanted and
  inappropriate content
• Encryption prevents credit card and e-mail
  forgery
• Digital cash makes on-line transactions safer
• Universal access is a problem

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Internet Everywhere The Invisible Information
What Next? Electronic Frontier

• A blurring of Web and interpersonal communication
  applications
• Internet appliances connected to the Web
• Continued computer crime and security issues

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