Transcript CHAP02

Business Data
Communications and
Networking, 6th ed.
FitzGerald and Dennis
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Copyright © 1999 John Wiley & Sons, Inc.
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Chapter 2
Network Applications
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Objectives of Chapter 2
Become familiar with…
 the Internet,
 FTP and Telnet,
 several different types of groupware,
 electronic commerce,
Understand how the Web and e-mail operate.
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INTRODUCTION
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Introduction
In the early days of information systems,
most systems were design to improve the
productivity of entire departments or
organizations.
In the 1980s, the introduction of
microcomputers enabled the wide-spread
development and use of information
systems to support individuals.
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Introduction
By the 1990s, the widespread availability of
data communications and networking had
begun to change our vision of the
computer.
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Introduction
Three sets of applications are the future of
information technology.
• The Internet
• Groupware
• Electronic Commerce
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THE INTERNET
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The Internet
The Internet (or “information superhighway”)
is one of the most important
developments in the history of information
systems.
Some people see the Internet and the World
Wide Web as the same thing, but they
aren’t. The Internet is a set of thousands
of networks linked together all around the
world. The Web is one application that
uses the Internet as its network.
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History of the Internet
The Internet was started by the U.S.
Department of Defense in 1969 as a
network of four computers called ARPANET.
In 1985, the Canadian government completed
its leg of BITNET to link all Canadian
Universities from coast to coast and
provided connections into the American
Internet.
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History of the Internet
Performance began to slow down due to
increased network traffic, so in 1987, the
National Science Foundation decided to
improve performance by building a new
high speed backbone network for NSFNET.
Similar initiatives were undertaken by most
other countries around the world, so that by
the early 1990s, most of the individual
country networks were linked together into
one worldwide network of networks.
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History of the Internet
Originally, commercial traffic was forbidden on
the Internet, because the hey portions of
these networks were funded by the various
national governments and research
organizations.
In the early 1990s, commercial networks
began connecting into these networks,
opening it to commercial traffic.
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History of the Internet
The Internet has continued to grow at a
dramatic pace.
Because it is a collection of networks, the
Internet has no central administration,
however, most networks have their own
acceptable use policies that define what
behavior is permitted.
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Internet Addresses
Anyone with access to the Internet can
communicate with any computer on the
Internet.
Addresses consist of two parts, the computer
name and its domain.
computer.domain
Each domain has an addressing board that
assigns addresses for its domain.
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Internet Domain Names
Domain Names
EDU
COM
GOV
MIL
ORG
NET
Country Codes
CA
AU
UK
DE
FR
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INTERNET APPLICATION
SOFTWARE
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Internet Application Software
There are four important Internet application
software tools
•
•
•
•
the Web
electronic mail (e-mail)
FTP
Telnet
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Internet Application Software
Electronic mail, Telnet, and FTP have been
around as long as the Internet itself. The
Web, however, was developed in the early
1990s.
These applications were originally developed
for the Internet, but many organizations are
using them on their LANs or for private use
on the Internet.
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World Wide Web
One of the fastest growing Internet software
applications is the World Wide Web.
The Web was first conceived in 1989 by Tim
Berners-Lee at the European Laboratory for
Particle Physical (CERN) in Geneva.
CERN’s first Web browser was written in
1990, but it was 1991 before it was
available on the Internet for other
organizations to use.
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How the Web Works
Each client computer needs an applications
layer software package called a Web
browser.
Each server on the network needs an
application layer software package called a
Web Server.
In order to get a page from the Web, the user
must first type the Internet Uniform
Resource Locator (URL) for the page, or
click on a link that provides the URL.
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How the Web Works
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How the Web Works
In order for the request from the Web browser
to be understood by the Web server, they
must use the same standard protocol.
The standard protocol for communication
between a Web browser and a Web server
is Hypertext Transfer Protocol (HTTP).
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How the Web Works
An HTTP request from a Web browser to a
Web server has three parts. Only the first
part is required, the other two are optional.
• the request line
• the request header
• the request body
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How the Web Works
Command
URL
HTTP version
GET http://tcbworks.cba.uga.edu/~adennis/res.htm HTTP/1.1 ]- Request Line
Date: Mon 03 Aug 1998 17:35:46 GMT ]- Date
User-Agent: Mozilla/3.0 ]- Web browser (this is Netscape)
Request Header
From: [email protected] ]- User’s e-mail address
Referer: http://tcbworks.cba.uga.edu/~adennis/home.htm
URL that contained the link to the requested URL
A Request from a Web browser to a Web server
using the HTTP standard
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How the Web Works
Many people believe that the Web is
anonymous. However, every Web access
must provide the Internet address of the
requester’s computer; otherwise the server
would not know where to send the
requested page.
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How the Web Works
The format of an HTTP response from the
server to the browser is very similar to the
browser request.
Only the last part is required, the other two
are optional.
• the response status
• the response header
• the response body
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A response from a Web server to a Web browser
using the HTTP standard
HTTP version Status code Reason phrase
HTTP/1.1
200
OK
Date: Mon 03 Aug 1998 17:35:46 GMT ]- Date
Server: NCSA/1.3 ]- Web server
Location: http:// tcbworks.cba.uga.edu/~adennis/res.htm ]- URL
Content-type: text/html ]- Type of file
Response Header
<html>
<head>
<title>Business Data Communications and Networking Web Resources </title>
</head>
<body>
<H2>Resources on the Web </H2>
Response
<P>This section contains links to other resources on the WEB that pertain to
Body
the field of data communications and networking </P>
</body>
</html>
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How the Web Works
Hypertext Markup Language (HTML), the
most commonly used Web format, was
developed by CERN at the same time as
the first web browser.
HTML is fairly easy to learn, so you can
develop your own Web pages.
The only certainty about the Web is that it will
change.
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Finding Information
The key problem with the Web is finding the
information you need. There is no formal
directory of all Web pages because almost
anyone can develop and post a page on a
Web server.
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Finding Information
There are three ways to discover interesting
and useful Web pages:
1. Someone could tell you about a page, or
you could read an advertisement listing the
Web address.
2. You could find a link from one page to
another.
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Finding Information
3. You could use a search engine.
Search engines are Web sites that routinely use
software spiders to explore the Web. There are
literally dozens of search engines and
directories on the Web. Three of the best are:
 Yahoo
 Altavista
 Excite
A metasearch engine (like MetaCrawler)
simultaneously sends requests to many search
engines and then integrates the responses.
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Webcasting
Webcasting is a special application of the web
in which the user signs up for a type of
information on a set of channels.
Webcasting changes the nature of the Web
from the user searching for information
(“pull”) to accepting information from the
Webcast server (“push”).
Webcasting can be used for news or financial
reports, corporate announcements, and as
a replacement for broadcast e-mail.
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Electronic Mail
Electronic mail (e-mail) was one of the
earliest applications on the Internet and is
still among the most heavily used today.
Most e-mail packages allow you to do the
same things you do with regular paper mail.
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Electronic Mail
E-mail has several advantages over regular
mail:
1. It is fast (arrives in seconds or minutes).
2. It is cheaper (costs virtually nothing)
E-mail can substitute for the telephone,
allowing you to avoid telephone tag.
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E-mail Standards
Several standards have been developed to
ensure compatibility between different email software packages.
Three most commonly used standards are:
• SMTP
• X.400
• CMC
All three e-mail standards work in the same
basic fashion.
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E-mail Clients & Servers
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E-mail Standards
Each client computer in the LAN runs an
application layer software package called a
user agent, which formats the message into
two parts:
• The header (source & destination address)
• The body (message)
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E-mail Standards
The user sends the message to a mail server
that runs a special application layer
software package called a message
transfer agent, which reads the header and
sends the message through the network to
the receiver’s mail server, where it is stored
in the receiver’s mailbox.
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E-mail Standards
When the receiver next accesses his or her email, the user agent on his or her computer
contacts the mail transfer agent on the mail
server and requests the contents of the
mailbox, which the user reads with the user
agent.
The Simple Mail Transfer Protocol (SMTP) is
one of the most commonly used e-mail
standards simply because it is the e-mail
standard used on the Internet.
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E-mail Standards
TO: “Pat Someone” <[email protected]>
From: “Alan Dennis;”<[email protected]>
Message Header
Date: Mon 03 Aug 1998 17:35:46 GMT
Subject: Sample Note
]- Message Body
DATA: This is an example of an e-mail message
An example of an e-mail message using the SMTP standard
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E-mail Standards
The SMTP standards covers message
transmission between message transfer
agents.
A different standard called Post Office
Protocol (POP) defines how user agents
operate and how messages to and from
mail transfer agents are formatted.
POP is gradually being replaced by a newer
standard called Internet Mail Access
Protocol (IMAP).
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E-mail Standards
Two other commonly used e-mail standards
are X.400 and CMC, which are different
from SMTP, POP and IMAP, so that they
cannot be used interchangeably.
The X.400 e-mail standards was developed
by CCITT in 1984.
The Common Messaging Calls (CMC)
standard is a simpler version of the X.400
standard, developed by CCITT with IBM,
Lotus and Microsoft in 1994.
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E-mail Directories
Before you can send an e-mail message, you
must know the receiver’s e-mail address.
Currently there are no universal e-mail
directories.
Several computing standards have been
developed in an attempt to provide this
universal directory, but as yet little progress
has been made to actually implement a
worldwide system based on the standards.
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E-mail Directories
X.500 is the directory service for X.400 mail
users, but at present there are few standard
application software packages that conform
to X.500.
Lightweight Directory Directory Protocol
(LDAP) is a subset of X.500.
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File Transfer Protocol (FTP)
File Transfer Protocol (FTP) enables you to
send and receive files over the Internet.
There are two types of FTP sites:
• Closed (requires users to have permission before
they can connect and gain access to files)
• Anonymous (permits any Internet user to login
using the account name of Anonymous)
Many files and documents available via FTP
have been compressed to reduce the amount
of disk space they require.
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Telnet
Telnet enables users on one computer to
login into other computers on the Internet.
Telnet can be useful because it enables you
to access your server or host computer
without sitting at its keyboard.
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GROUPWARE
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Groupware
Software that helps groups of people to work
together more productively.
Group support system
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Groupware
Groupware allows people to exchange ideas,
debate issues, make decisions, and write
reports without actually having to meet
face-to-face.
There are four popular types of groupware:
•
•
•
•
Discussion groups
Document-based groupware
Group support systems
Videoconferencing
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Discussion Groups
Discussion groups are Internet users who
have joined together to discuss some topic.
Two discussion groups commonly used for
business:
• Usenet Newsgroups
• Listservs
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Usenet Newsgroups
Usenet Newsgroups are the most formally
organized of the discussion groups.
The newsgroups are just a series of
discussions about each topic.
The exact commands to gain access to these
newsgroups varies from computer to
computer.
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Listservs
Listserver (Listserv) group is similar in
concept to the usenet newsgroups but is
generally less formal.
One part, the listserv processor, processes
commands such as requests to subscribe,
unsubscribe, or to provide more information
about the listserv.
The second part is the listserv mailer. Any
message sent to the listserv mailer is resent to everyone on the mailing list.
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Document-based Groupware
E-mail lacks a structured way to support an
ongoing discussion.
A document database (like Lotus Notes)
designed to store and manage large
collections of text and graphics was the
first solution.
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Document-based Groupware
Notes can be also be used to organize a
discussion among certain people (a project
team working to improve manufacturing
quality).
Notes can also automate certain documentbased processes (called work-flow
automation).
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Document-based Groupware
One of Notes’ greatest strengths is its
replication ability (the automatic sharing of
information among servers when
information changes).
More than 2 million people world-wide now
use Lotus Notes.
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Group Support Systems
Both e-mail and document-based groupware
are designed to support individuals and
groups working in different places and
different times.
Group Support Systems (GSS) are software
tools designed to improve group decision
making.
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Group Support Systems
In a GSS meeting, group members can
discuss idea verbally as they could in any
meeting room; however, they can also use
the computer to type ideas and informatio,
which are then shared with all other group
members via the network..
With large groups, however, typing ideas is
faster than talking because only one person
can speak at a time.
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Group Support Systems
GSS enables users to make comments
anonymously.
These systems also provide tools to support
voting and ranking of alternatives, so that
more structured decision-making processes
can be used.
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Videoconferencing
Discussion groups, document-based
groupware, and GSS all focus on the
transmission of text and graphical images.
Videoconferencing provides real-time
transmission of video and audio signals to
enable people in two or more locations to
have a meeting.
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Desktop Videoconferencing
The fastest growing form of videoconferencing
is desktop videoconferencing.
Small cameras installed on top of each
computer permit meetings to take place from
individual offices.
The key benefits of videoconferencing area the
time and cost savings that can result.
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Desktop Videoconferencing
The transmission of video requires a lot of
network capacity.
Like e-mail, most videoconferencing systems
were originally developed by vendors using
different formats so that many products
were incompatible.
Three commonly used standards for
videoconferencing have the promise to
reduce many incompatibilities once
adopted: H.320, H.323, and MPEG-1 & -2.
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Managing in a
Groupware World
Groupware dramatically changes the way
people interact. Communication is simpler
and faster.
Nonetheless, groupware’s ability to greatly
improve communications can also create
problems (e-mail overload).
Social norms are one of the greatest limiting
factors in the widespread use of groupware
technologies, because technology changes
faster than the people who use it.
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ELECTRONIC COMMERCE
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Electronic Commerce
Almost all large and medium-sized
companies use the Internet. Many are
using it for electronic commerce - doing
business on the Internet.
Making money on the Internet is a risky
proposition.
Most people automatically focus on the retail
aspects of electronic commerce; that is
selling products to individuals.
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Electronic Commerce
There are four major ways in which the Web
can be used to support electronic
commerce:
•
•
•
•
Electronic store
Electronic marketing
Information/entertainment provider
Customer service
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Electronic store
The most obvious approach to electronic
commerce is an electronic store, where a
company develops the Internet equivalent
of a local store or mail order catalog.
There are many examples of electronic
stores.
One of the more interesting electronic stores
is that run by Boeing.
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Electronic Store
Since there are few additional costs to
providing more information on the Web
(unlike a print catalog), electronic stores
can provide much information
One problem is verifying the transaction is
accurate and is from whom it claims to be
from.
A variation on the electronic store is the
electronic mall: a collection of electronic
stores.
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Electronic Marketing Site
A second common approach is the electronic
marketing site which supports the sales
process, but does not make the actual
sales. The goal is to attract and keep
customers.
Many companies use electronic marketing
sites to provide newsletters with information
on latest products and tips on how to use
them. Electronic marketing is cheaper in
may ways to traditional marketing.
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Information/Entertainment
Provider
An Information/entertainment provider
supplies information and/or entertainment.
Information/entertainment providers can be
very broad or very focused in topic
coverage and can present information in a
variety of media.
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Information/Entertainment
Provider
Most Web users expect information to be free
so most Information/Entertainment
Providers doe not charge, although a few
require subscriptions before they will allow
access.
Like their print counterparts,
Information/entertainment providers
generate revenue by selling advertising.
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Customer Service
A customer service site provides a variety of
information for customers after they have
purchased a product or service.
Federal Express has been one of the leading
innovators in the use of the Web for
customer service.
Customer service sites benefit both the
company and its customers.
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End of Chapter 2
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