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Chapter 2

Chapter 2. The Internet and the Web: Infrastructure for Electronic Commerce. 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

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Chapter 2

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  1. Chapter 2 The Internet and the Web: Infrastructure for Electronic Commerce Electronic Commerce

  2. 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

  3. 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

  4. Objectives • Differences and similarities between internets, intranets, and extranets • Options for connecting to the Internet, their cost and bandwidth tradeoffs

  5. 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

  6. 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

  7. 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

  8. Packet-Switched Network and Message Packets Figure 2-1

  9. 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

  10. 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

  11. TCP/IP Architecture Figure 2-2

  12. 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:

  13. 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

  14. Top-Level Domain Names Figure 2-3

  15. 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

  16. 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

  17. 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

  18. Internet Utility Programs • Finger • Runs on UNIX computers and allows users to obtain limited information about other network users

  19. Finger Program Output Figure 2-4

  20. 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

  21. Tracert and Other Route-Tracing Programs • TRACE 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

  22. Tracing a Path Between Two Computers Figure 2-5

  23. 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

  24. Sending E-Mail Attachments Figure 2-6

  25. 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

  26. Example of a Telnet Session Figure 2-7

  27. Internet Applications: FTP • Fastest 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

  28. An FTP Session Figure 2-8

  29. 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

  30. Markup Languages and the Web • Hypertext Markup Language • 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

  31. 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

  32. XML Example Figure 2-9

  33. Traditional vs. Hyperlinked Document Pages Figure 2-10

  34. 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

  35. Web Page and Paragraph Tag With Right-Align Property Figure 2-11

  36. HTML Codes to Format Memo Page Figure 2-12

  37. Internet Explorer Display of Memo Page Figure 2-13

  38. 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

  39. Hyperlink StructuresFigure 2-14

  40. HTML Version History • Version 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

  41. HTML Version History • Version 4.0 was released in December 1997 • Support for OBJECT tag and Cascading Style Sheets (CSS) • Internationalization for various languages • Accessibility features

  42. 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

  43. Dreamweaver Site Builder Software Figure 2-15

  44. Web Clients and Servers • Client computers typically request services, including printing, information retrieval, and database access • Servers are responsible for processing the clients’ requests

  45. Client/Server Structure of the WWW Figure 2-16

  46. 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

  47. Message Flow Between a Web Client and Server Figure 2-17

  48. Server Response Message Figure 2-18

  49. 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)

  50. 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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