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

2 2 Technology Overview u Internet is the most obvious technology needed to conduct e-commerce u Other technologies are also required l Database software l Network switches and hubs l Encryption hardware and software l Multimedia support u Potential for business volume to double in less than a year

3 2 Objectives u General structure of the network of networks supporting the Internet and e- commerce u Protocols that move commerce across the Internet and send/receive u Internet utility programs to trace, locate, and verify the status of Internet host sites

4 2 Objectives u Popular Internet applications, including , Telnet, and FTP u History and use of Web markup languages, including SGML, HTML, and XML u HTML tags and links u Web client and server architectures and the messages they send to each other

5 2 Objectives u Differences and similarities between internets, intranets, and extranets u Options for connecting to the Internet, their cost and bandwidth tradeoffs

6 2 Web Clients and Servers u Client computers typically request services, including printing, information retrieval, and database access u Servers are responsible for processing the clients’ requests

7 2 Client/Server Structure of the WWW Figure 2-16

8 2 Web Client/Server Communication u Two-Tier Client/Server l All communication takes place between the client on the Internet and the target server at the other end u Request message consists of: l A request line l Optional request headers l An optional entity body

9 2 Message Flow Between a Web Client and Server Figure 2-17

10 2 Server Response Message Figure 2-18

11 2 Web Client/Server Communication Figure 2-19 u Three-Tiered Client/Server l First tier is the client l Second tier is the Web server l Third tier are the applications and their databases (Figure 2-19)

12 2 Open Architecture u Independent networks should not require any internal changes in order to be connected to the network u Packets that do not arrive at their destination must be retransmitted u Router computers do not retain information about the packets u No global control exists over the network

13 2 The TCP/IP Internet Protocol u Set of protocols developed by Vincent Cerf and Robert Kahn l Transmission Control Protocol (TCP) u Controls the assembly of a message into smaller packets before transmission, and reassembles them once received l Internet Protocol (IP) u Rules for routing packets from their source to their destination u Replaced NCP as used by ARPANET

14 2 TCP/IP Architecture Figure 2-2

15 2 IP Address and Domain Names u Appears as a series of up to four separate numbers delineated by a period, often referred to as a “Dotted Quad” l Each of the numbers range from 0 to 255 l First four numbers identify the network l Following numbers identify a node l Sample IP address:

16 2 IP Address and Domain Names u Uniform Resource Locator (URL) l Easier to remember than IP address l Consists of names and abbreviations l Contains at least two parts u First part contains the protocol used u Second part contains the location of the resource l

17 2 Top-Level Domain Names Figure 2-3

18 2 Other Internet Protocols u Hypertext Transfer Protocol (HTTP) l Responsible for transferring and displaying Web pages u Simple Mail Transfer Protocol (SMTP) l Specifies the exact format of a mail message u Post Office Protocol (POP) l Responsible for retrieving from a mail server

19 2 Other Internet Protocols u Interactive Mail Access Protocol (IMAP) l Latest protocol, may replace POP l Defines how a client program asks a mail server to present available mail u Download only selected messages, instead of all messages u View headers only u Create and manipulate mailboxes on the server

20 2 Other Internet Protocols u File Transfer Protocol (FTP) l Transfers files between TCP/IP-connected computers l Uses client/server model l Transfers both binary and ASCII text l Displays and manipulates remote and local computer file directories

21 2 Internet Utility Programs u Finger l Runs on UNIX computers and allows users to obtain limited information about other network users

22 2 Finger Program Output Figure 2-4

23 2 Internet Utility Programs u Packet InterNet Groper (Ping) l Tests the connectivity between two Internet hosts l Determines if the host is active u Sends a packet and waits for a reply l Determines number of hosts (hops) between two specified hosts

24 2 Tracert and Other Route-Tracing Programs u TRACE RouTe (Tracert) traces the round trip path between a user’s computer and another computer on the Internet u Incorporates a Graphical User Interface (GUI) for a visual representation of the route

25 2 Tracing a Path Between Two Computers Figure 2-5

26 2 Internet Applications: Electronic Mail u Began in the 1970s for use on the ARPANET u Most popular form of business communication u Can send documents, pictures, movies, worksheets, or other important pieces of information

27 2 Sending Attachments Figure 2-6

28 2 Internet Applications: Telnet u Allows users to log on to a remote computer that is attached to the Internet u Type commands to run on the remote host computer by using terminal emulation u Client software is available, and users can access Telnet through most Web browsers

29 2 Example of a Telnet Session Figure 2-7

30 2 Internet Applications: FTP u Fastest way to deliver digital business information from one computer to another u Commonly used to download software packages and updates u Also used to upload files to the host computer for access from the Internet

31 2 An FTP Session Figure 2-8

32 2 Markup Languages and the Web u Standard Generalized Markup Language (SGML) l Regulated ISO standard since 1986 l Nonproprietary l Supports user-defined tags l Costly to set up l Expensive compared to HTML l Steep learning curve

33 2 Markup Languages and the Web u Hypertext Markup Language (HTML) l Based on SGML l Easier to learn and support l Supports commonly used text markup features u Headings, title bars, bullets, lines, lists u Precise graphic positioning, tables, and frames l Standard language for Web pages

34 2 Markup Languages and the Web u Extensible Markup Language (XML) l Descendant of SGML l Defines which data to display, instead of how a page is displayed l Describes a page’s actual content, unlike HTML l Data-tracking capability

35 2 XML Example Figure 2-9

36 2 Traditional vs. Hyperlinked Document Pages Figure 2-10

37 2 More about HTML u HTML tags l Displayed information affected by tag u best - Bolds the word “best” u - Aligns text to the right u HTML code defines the formatting of the page, but a page may look different on two different browsers

38 2 Web Page and Paragraph Tag With Right-Align Property Figure 2-11

39 2 HTML Codes to Format Memo Page Figure 2-12

40 2 Internet Explorer Display of Memo Page Figure 2-13

41 2 More about HTML u HTML Links l Anchor tags used to link to text within the same document, or on a distant computer u Visible link text u Purdue University u References are found here l Text between the anchors appears as a hyperlink

42 2 Hyperlink Structures Figure 2-14

43 2 HTML Version History u Version 1.0 appeared in the summer of 1991 u Version 2.0 was released in September 1995 l Internet Explorer 2.0 and Netscape Navigator 2.0 appeared u Version 3.2 was released in 1997 l Provided support for tables, complex numbers, and text flow around images

44 2 HTML Version History u Version 4.0 was released in December 1997 l Support for OBJECT tag and Cascading Style Sheets (CSS) l Internationalization for various languages l Accessibility features

45 2 HTML Editors u Used to generate the HTML code l Simple text editors offer limited flexibility l Any word processor can be used l Web site builders offer more control u Microsoft FrontPage u Dreamweaver

46 2 Dreamweaver Site Builder Software Figure 2-15

47 2 Networks u Local and long distance telephone companies were early models in the 1950s u Single paths were created to connect two parties together, called circuit switching

48 2 Packet-Switched Networks u The Internet uses Packet switching l Files and messages are broken down into packets, which are electronically labeled with their origin and destination l The destination computer collects the packets and reassembles the data from the pieces in each packet l Each computer the packet encounters decides the best route towards its destination

49 2 Packet-Switched Network and Message Packets Figure 2-1

50 2 Internets, Intranets, and Extranets u Intranets l Only selected individuals are allowed access l Low-cost way to distribute corporate information l Collect and group information for external dissemination l Infrastructure requirements are usually in place if PCs are on a LAN

51 2 Internets, Intranets, and Extranets u Extranets l Connect companies with suppliers or other business partners l Provide the infrastructure for the coordination of purchases, EDI, and communications l Use the Internet for communicating among themselves

52 2 FedEx Ship Page Figure 2-20

53 2 Internets, Intranets, and Extranets u Public Network l An extranet that allows the public to access its intranet l When two or more companies agree to link their intranets using a public network (such as the Internet) u Private Network l A leased-line connection that physically connects two intranets

54 2 Internets, Intranets, and Extranets u Virtual Private Network (VPN) l Uses public networks and protocols to send sensitive data by using “tunneling” or “encapsulation” - private passageways through the Internet l Designed to save money and create a competitive advantage by alliances formed with cooperating companies

55 2 Secure VPN Extranet Figure 2-21

56 2 Internet Connections Options and Tradeoffs u Internet Service Providers (ISPs) offer connection choices to their users l Plain Old Telephone Service (POTS) u Existing telephone lines with modems u Bandwidth of 56Kbps (56,000 bits per second) l Integrated Services Digital Network (ISDN) u Bandwidths up to 128Kbps l Asymmetric Digital Subscriber Line (ADSL) u Upload at 640Kbps, download up to 9Mbps

57 2 Cable Modems u Same broadband coaxial cable that serves cable television u Upstream bandwidths of Kbps u Downstream bandwidths of 1.5Mbps

58 2 Internet Connection Choices Figure 2-22