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Chapter 2
The Internet and the Web:
Infrastructure for
Electronic Commerce
Electronic Commerce
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Technology Overview
Internet 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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Objectives
General structure of the network of networks supporting the Internet and e-commerce
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 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 and similarities between internets, intranets, and extranets
Options for connecting to the Internet, their cost and bandwidth tradeoffs
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Web Clients and Servers
Client 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 WWWFigure 2-16
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Web Client/Server Communication
Two-Tier 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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Web Client/Server CommunicationFigure 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
(Figure 2-19)
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Open Architecture
Independent 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 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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IP Address and Domain Names
Appears 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
First part contains the protocol used Second part contains the location of the
resource
http://www.adobe.com
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Other Internet Protocols
Hypertext Transfer Protocol (HTTP) Responsible for transferring and displaying
Web pages Simple Mail Transfer Protocol (SMTP)
Specifies the exact format of a mail message
Post 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 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 Applications: Electronic Mail
Began 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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Markup Languages and
the Web
Standard Generalized Markup Language (SGML) 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 (HTML) Based on SGML Easier to learn and support Supports commonly used text markup
features 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 (XML) 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 ExampleFigure 2-9
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Traditional vs. Hyperlinked Document PagesFigure 2-10
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More about HTML
HTML tags <tagname properties>Displayed
information affected by tag</tagname> <B>best</B> - Bolds the word “best” <P align=“right”> - Aligns text to the right
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 TagWith Right-Align Property
Figure 2-11
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HTML Codes to Format Memo PageFigure 2-12
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Internet Explorer Display of Memo PageFigure 2-13
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More about HTML
HTML 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 StructuresFigure 2-14
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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
Microsoft FrontPage Dreamweaver
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Networks
Local 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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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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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)
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 ExtranetFigure 2-21
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Internet Connections Options and Tradeoffs
Internet Service Providers (ISPs) offer connection choices to their users 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 broadband coaxial cable that serves cable television
Upstream bandwidths of 300-500 Kbps Downstream bandwidths of 1.5Mbps
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