1 2 chapter 2 the internet and the web: infrastructure for electronic commerce

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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