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10
From Internet
to Information
Superhighway
Chapter Outline
• The Internet: A Network of
Networks
“It’s a bit like
climbing a
• Internet Applications:
mountain. You
Communication and Connection
don’t know
how far you’ve • Inside the World Wide Web
come until you
stop and look • The Evolving Internet
back.”
Vint Cerf
 2001 Prentice Hall
10.2
The Internet:
A Network of Networks
The Internet is an interconnected
network of thousands of networks
linking academic, research,
government, and commercial
institutions.
 2001 Prentice Hall
10.3
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
 2001 Prentice Hall
10.4
Internet Services
– Transferring files
(FTP - accessing
archives of data)
– Newsgroups (Usenet on-line public
discussions)
– World Wide Web (a
collection of
multimedia documents)
 2001 Prentice Hall
10.5
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
 2001 Prentice Hall
10.6
Internet Protocols
The language at the heart of the
Internet is TCP/IP…
Transmission Control Protocol/Internet Protocol
… that allows cross-network
communication
 2001 Prentice Hall
10.7
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
 2001 Prentice Hall
10.8
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
 2001 Prentice Hall
10.9
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
 2001 Prentice Hall
10.10
Internet Access Options
Dial-up 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
 2001 Prentice Hall
10.11
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
 2001 Prentice Hall
10.12
Internet Access Options
Internet Service Providers (ISPs)
– local ISPs provide connections through
local telephone lines
– national ISPs offer connections on a
nationwide scale
 2001 Prentice Hall
10.13
Intranets and Extranets
Intranets: self-contained intraorganizational networks
designed using the same
technology as the Internet
Firewalls: used to prevent unauthorized
communication and secure
sensitive internal data
 2001 Prentice Hall
10.14
Intranets and Extranets
Typical Intranets include:
– E-mail
– Newsgroups
– File transfer
– Web publishing
– Other services
 2001 Prentice Hall
10.15
Intranets and Extranets
Extranets:
Electronic
Commerce:
 2001 Prentice Hall
designed for outside use
by customers, clients,
and business partners
business transactions
through electronic
networks
10.16
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.
 2001 Prentice Hall
10.17
Internet Applications:
Communication 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.
 2001 Prentice Hall
10.18
Internet Addresses
“Each person
on the
“Internet” has a
unique e-mail
“address”
created by
having a
squirrel run
across a
computer
keyboard.”
Dave Barry
 2001 Prentice Hall
• E-mail addresses are made up
of two parts separated by an
at(@) sign:
– User name@host name
– Example:
[email protected]
• The host is named using DNS
(domain name system), which
translates IP addresses into a
string of names.
10.19
Internet Addresses
An Internet address includes:
[email protected]
– username is the person’s “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
 2001 Prentice Hall
10.20
Internet Addresses
Top level domains (the last part of the
address) include:
– .edu - educational sites
– .com - commercial sites
– .gov - government sites
– .mil - military sites
– .net - network administration sites
– .org - nonprofit organizations
 2001 Prentice Hall
10.21
Internet Addresses
Examples:
[email protected]
[email protected]
 2001 Prentice Hall
User President whose
mail is stored on the
host whitehouse in the
government domain
User hazel_filbert at
the server for Lane
County, Oregon, k-12
school district
10.22
E-mail on the Internet
Why are free e-mail 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
Remember that security is still an issue
 2001 Prentice Hall
10.23
E-mail on the Internet
E-mail 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)
 2001 Prentice Hall
10.24
Mailing Lists and
Network News
• Mailing lists allow you to participate
in email discussion groups on specialinterest 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).
 2001 Prentice Hall
10.25
Real-Time Communication
• Internet relay chat (IRC) allows
several users to chat simultaneously
• Internet Telephony turns the
Internet into a toll-free longdistance telephone service
• Video teleconferences allow multiperson videoconferences via the Web
 2001 Prentice Hall
10.26
Telnet and FTP
Information gathering
(the most popular use of the Internet)
Telnet
– makes remote login possible
FTP (file transfer protocol)
– allows files to be uploaded and
downloaded from remote computers
 2001 Prentice Hall
10.27
Telnet and FTP
A friendlier face…
• Web browsers locate and
transfer files without
typing commands
• When you click a Web
link to download a file,
you’re probably using
FTP
 2001 Prentice Hall
10.28
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
 2001 Prentice Hall
10.29
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
 2001 Prentice Hall
10.30
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
 2001 Prentice Hall
10.31
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 (or Favorites) can be set up
to mark your favorite Web locations
 2001 Prentice Hall
10.32
Web Addresses
Go directly to any Web
destination by typing its URL
(Uniform Resource Locator)
A typical URL looks like this:
http://www.prenhall.com.beekman
 2001 Prentice Hall
10.33
Web Addresses
Dissecting the address
The protocol used to transfer
Web pages across the Net
The path to the resource
on the host that contains
the information
http:// www.vote-smart.org/ help/database.html
The domain name of
the server containing
the resource
 2001 Prentice Hall
10.34
Searching the Web
Ways to search 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
 2001 Prentice Hall
10.35
Search Engines
Search engines help find
information when you type a
query using keywords.
 2001 Prentice Hall
10.36
Search Engines
Directory/subject tree
engines offer a menu of
subject choices
 2001 Prentice Hall
10.37
Search Engines
Ask questions in a Natural
Language Search Engine
 2001 Prentice Hall
10.38
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
 2001 Prentice Hall
10.39
From Hypertext to Multimedia
Typical Web pages can contain:
• Tables
• Frames
• Forms
• Downloadable
audio and video
 2001 Prentice Hall
• Streaming audio
and video
• Real-time live audio
or video
• 3-D environments
10.40
From Hypertext to Multimedia
Plug-Ins are software extensions that
add new features. Examples include…
• QuickTime
• Shockwave/Flash
• RealPlayer
• Acrobat
 2001 Prentice Hall
10.41
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
 2001 Prentice Hall
10.42
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
 2001 Prentice Hall
10.43
Publishing on the Web
This text coded as HTML …
<H1>Welcome to Computer Confluence</H1>
<b>Publishing on the Web</b>
Appears like this
on the screen …
 2001 Prentice Hall
10.44
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
 2001 Prentice Hall
10.45
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
 2001 Prentice Hall
10.46
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
 2001 Prentice Hall
10.47
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
 2001 Prentice Hall
10.48
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
 2001 Prentice Hall
10.49
Internet Issues
Ethical and Political Dilemmas
• Filtering software can prevent unwanted
and inappropriate content
• Encryption prevents credit card and email forgery
• Digital cash makes on-line transactions
safer
• Universal access is a problem
 2001 Prentice Hall
10.50
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
 2001 Prentice Hall
10.51