Transcript The Internet and the Web

Chapter 2
2
The Internet and the Web:
Infrastructure for
Electronic Commerce
Electronic Commerce
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Objectives
 General
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structure of the network of
networks supporting the Internet and ecommerce
 Protocols that move commerce across
the Internet and send/receive e-mail
 Internet utility programs to trace, locate,
and verify the status of Internet host
sites
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Objectives
 Popular
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Internet applications, including
e-mail, Telnet, and FTP
 History and use of Web markup
languages, including SGML, HTML,
and XML
 HTML tags and links
 Web client and server architectures and
the messages they send to each other
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Objectives
 Differences
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and similarities between
internets, intranets, and extranets
 Options for connecting to the Internet,
their cost and bandwidth tradeoffs
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Technology Overview
 Internet
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is the most obvious technology
needed to conduct e-commerce
 Other technologies are also required
Database software
 Network switches and hubs
 Encryption hardware and software
 Multimedia support

 Potential
for business volume to double
in less than a year
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Packet-Switched Networks
 Local
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and long distance telephone
companies were early models in the
1950s
 Single paths were created to connect
two parties together, called circuit
switching
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Packet-Switched Networks
 The
Internet uses Packet switching
Files and messages are broken down into
packets, which are electronically labeled
with their origin and destination
 The destination computer collects the
packets and reassembles the data from
the pieces in each packet
 Each computer the packet encounters
decides the best route towards its
destination

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Packet-Switched Network
and Message Packets
Figure 2-1
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Open Architecture
 Independent
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networks should not
require any internal changes in order to
be connected to the network
 Packets that do not arrive at their
destination must be retransmitted
 Router computers do not retain
information about the packets
 No global control exists over the
network
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The TCP/IP Internet Protocol
 Set
of protocols developed by Vincent
Cerf and Robert Kahn
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
Transmission Control Protocol (TCP)
 Controls
the assembly of a message into
smaller packets before transmission, and
reassembles them once received

Internet Protocol (IP)
 Rules
for routing packets from their source to
their destination
 Replaced
NCP as used by ARPANET
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TCP/IP Architecture
Figure 2-2
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IP Address and Domain Names
 Appears
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as a series of up to four
separate numbers delineated by a
period, often referred to as a “Dotted
Quad”
Each of the numbers range from 0 to 255
 First four numbers identify the network
 Following numbers identify a node
 Sample IP address: 126.204.89.56

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IP Address and Domain Names
 Uniform
Resource Locator (URL)
Easier to remember than IP address
 Consists of names and abbreviations
 Contains at least two parts

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 First
part contains the protocol used
 Second part contains the location of the
resource

http://www.adobe.com
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Top-Level Domain Names
Figure 2-3
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Other Internet Protocols
 Hypertext

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Responsible for transferring and displaying
Web pages
 Simple

Mail Transfer Protocol (SMTP)
Specifies the exact format of a mail
message
 Post

Transfer Protocol (HTTP)
Office Protocol (POP)
Responsible for retrieving e-mail from a
mail server
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Other Internet Protocols
 Interactive
Mail Access Protocol (IMAP)
Latest protocol, may replace POP
 Defines how a client program asks a mail
server to present available mail

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 Download
only selected messages, instead of
all messages
 View headers only
 Create and manipulate mailboxes on the
server
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Other Internet Protocols
 File
Transfer Protocol (FTP)
Transfers files between TCP/IP-connected
computers
 Uses client/server model
 Transfers both binary and ASCII text
 Displays and manipulates remote and
local computer file directories

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Internet Utility Programs
 Finger

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Runs on UNIX computers and allows
users to obtain limited information about
other network users
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Finger Program Output
Figure 2-4
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Internet Utility Programs
 Packet
InterNet Groper (Ping)
Tests the connectivity between two
Internet hosts
 Determines if the host is active
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 Sends

a packet and waits for a reply
Determines number of hosts (hops)
between two specified hosts
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Tracert and Other Route-Tracing
Programs
 TRACE
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RouTe (Tracert) traces the
round trip path between a user’s
computer and another computer on the
Internet
 Incorporates a Graphical User Interface
(GUI) for a visual representation of the
route
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Tracing a Path Between Two Computers
Figure 2-5
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Internet Applications:
Electronic Mail
 Began
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in the 1970s for use on the
ARPANET
 Most popular form of business
communication
 Can send documents, pictures, movies,
worksheets, or other important pieces
of information
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Sending E-Mail Attachments
Figure 2-6
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Internet Applications: Telnet
 Allows
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users to log on to a remote
computer that is attached to the
Internet
 Type commands to run on the remote
host computer by using terminal
emulation
 Client software is available, and users
can access Telnet through most Web
browsers
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Example of a Telnet Session
Figure 2-7
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Internet Applications: FTP
 Fastest
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way to deliver digital business
information from one computer to
another
 Commonly used to download software
packages and updates
 Also used to upload files to the host
computer for access from the Internet
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An FTP Session
Figure 2-8
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Markup Languages and
the Web
 Standard
Generalized Markup
Language (SGML)
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Regulated ISO standard since 1986
 Nonproprietary
 Supports user-defined tags
 Costly to set up
 Expensive compared to HTML
 Steep learning curve
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Markup Languages and
the Web
 Hypertext
Markup Language
Based on SGML
 Easier to learn and support
 Supports commonly used text markup
features
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 Headings,
title bars, bullets, lines, lists
 Precise graphic positioning, tables, and frames

Standard language for Web pages
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Markup Languages and
the Web
 Extensible
Markup Language
Descendant of SGML
 Defines which data to display, instead of
how a page is displayed
 Describes a page’s actual content, unlike
HTML
 Data-tracking capability

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XML Example
Figure 2-9
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Traditional vs. Hyperlinked Document Pages
Figure 2-10
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More about HTML
 HTML

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tags
<tagname properties>Displayed
information affected by tag</tagname>
- Bolds the word “best”
 <P align=“right”> - Aligns text to the right
 <B>best</B>
 HTML
code defines the formatting of
the page, but a page may look different
on two different browsers
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Web Page and Paragraph Tag
With Right-Align Property
Figure 2-11
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HTML Codes to Format Memo Page
Figure 2-12
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Internet Explorer Display of Memo Page
Figure 2-13
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More about HTML
 HTML

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Links
Anchor tags used to link to text within the
same document, or on a distant computer
 <A
HREF=“address”>Visible link text</A>
 <A HREF=http://www.purdue.edu>Purdue
University</A>
 <A HREF=“#references”>References are
found here</A>

Text between the anchors appears as a
hyperlink
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Hyperlink Structures
Figure 2-14
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HTML Version History
 Version
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1.0 appeared in the summer of
1991
 Version 2.0 was released in September
1995

Internet Explorer 2.0 and Netscape
Navigator 2.0 appeared
 Version

3.2 was released in 1997
Provided support for tables, complex
numbers, and text flow around images
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HTML Version History
 Version
4.0 was released in December
1997
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Support for OBJECT tag and Cascading
Style Sheets (CSS)
 Internationalization for various languages
 Accessibility features

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HTML Editors
 Used
to generate the HTML code
Simple text editors offer limited flexibility
 Any word processor can be used
 Web site builders offer more control
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 Microsoft
FrontPage
 Dreamweaver
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Dreamweaver Site Builder Software
Figure 2-15
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Web Clients and Servers
 Client
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computers typically request
services, including printing, information
retrieval, and database access
 Servers are responsible for processing
the clients’ requests
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Client/Server Structure of the WWW
Figure 2-16
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Web Client/Server Communication
 Two-Tier
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Client/Server
All communication takes place between
the client on the Internet and the target
server at the other end
 Request
message consists of:
A request line
 Optional request headers
 An optional entity body
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Message Flow Between a
Web Client and Server
Figure 2-17
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Server Response Message
Figure 2-18
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Web Client/Server Communication
Figure 2-19
 Three-Tiered
Client/Server
First tier is the client
 Second tier is the Web server
 Third tier are the applications and their
databases

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(Figure 2-19)
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Internets, Intranets, and Extranets
 Intranets
Only selected individuals are allowed
access
 Low-cost way to distribute corporate
information
 Collect and group information for external
dissemination
 Infrastructure requirements are usually in
place if PCs are on a LAN

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Internets, Intranets, and Extranets
 Extranets
Connect companies with suppliers or other
business partners
 Provide the infrastructure for the
coordination of purchases, EDI, and
communications
 Use the Internet for communicating among
themselves

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FedEx Ship Page
Figure 2-20
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Internets, Intranets, and Extranets
 Public
Network
An extranet that allows the public to
access its intranet
 When two or more companies agree to
link their intranets using a public network
(such as the Internet)

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 Private

Network
A leased-line connection that physically
connects two intranets
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Internets, Intranets, and Extranets
 Virtual
Private Network (VPN)
Uses public networks and protocols to
send sensitive data by using “tunneling” or
“encapsulation” - private passageways
through the Internet
 Designed to save money and create a
competitive advantage by alliances formed
with cooperating companies
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Secure VPN Extranet
Figure 2-21
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Internet Connections Options and
Tradeoffs
 Internet
Service Providers (ISPs) offer
connection choices to their users
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
Plain Old Telephone Service (POTS)
 Existing
telephone lines with modems
 Bandwidth of 56Kbps (56,000 bits per second)

Integrated Services Digital Network (ISDN)
 Bandwidths

up to 128Kbps
Asymmetric Digital Subscriber Line (ADSL)
 Upload
at 640Kbps, download up to 9Mbps
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Cable Modems
 Same
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broadband coaxial cable that
serves cable television
 Upstream bandwidths of 300-500 Kbps
 Downstream bandwidths of 1.5Mbps
 Current “sweet spot” (optimal price and
performance)
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Internet Connection Choices
Figure 2-22
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