Electronic commerce fundamentals ch2

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 ut

Chapter 2

The Internet and the Web:

Infrastructure for Electronic Commerce

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

◆ HTML tags and links

◆ Web client and server architectures and the messages they send to each other

● Network switches and hubs

● Encryption hardware and software

● Multimedia support

◆ Potential for business volume to double

in less than a year

Packet-Switched 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

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

Packet-Switched Network and Message Packets

Figure 2-1

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

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

TCP/IP Architecture

Figure 2-2

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 nodeSample IP address: 126.204.89.56

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

Top-Level Domain Names

Figure 2-3

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

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

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

Finger Program Output

Figure 2-4

Internet Utility Programs

◆ Packet InterNet Groper (Ping)

● Tests the connectivity between two Internet hosts

● Determines if the host is active

◆ Sends a packet and waits for a reply

● Determines number of hosts (hops) between two specified hosts

◆ Incorporates a Graphical User Interface (GUI) for a visual representation of the route

Tracing a Path Between Two Computers

Figure 2-5

Sending E-Mail Attachments

Figure 2-6

Internet Applications: Telnet

◆ Allows 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

Example of a Telnet Session

Figure 2-7

An FTP Session

Figure 2-8

● 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

XML Example Figure 2-9

Traditional vs Hyperlinked Document Pages

Figure 2-10

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

Web Page and Paragraph Tag With Right-Align Property

Figure 2-11

HTML Codes to Format Memo Page

Figure 2-12

Internet Explorer Display of Memo Page

Figure 2-13

◆ <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 Structures

Figure 2-14

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

Dreamweaver Site Builder Software

Figure 2-15

Web Clients and Servers

◆ Client computers typically request services, including printing, information retrieval, and database access

◆ Servers are responsible for processing the clients’ requests

Client/Server Structure of the WWW

Figure 2-16

◆ Request message consists of:

● A request line

● Optional request headers

● An optional entity body

Message Flow Between a Web Client and Server

Figure 2-17

Server Response Message

Figure 2-18

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

(Figure 2-19)

● Use the Internet for communicating among themselves

FedEx Ship Page

Figure 2-20

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

Secure VPN Extranet

Figure 2-21

● 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)

Internet Connection Choices

Figure 2-22