The Internet and the Web: 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 Internet utility programs to trace, locate, and verify the status of Internet host sites

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

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

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

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 Replaced NCP as used by ARPANET

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 node Sample 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 server

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

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

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

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

Tracing a Path Between Two Computers Figure 2-5

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

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

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

An FTP Session Figure 2-8

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

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

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

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

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

Hyperlink Structures Figure 2-14

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

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

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

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

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)

Internets, Intranets, and Extranets 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

Internets, Intranets, and 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

FedEx Ship Page Figure 2-20

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

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

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

Cable Modems Same broadband coaxial cable that serves cable television Upstream bandwidths of 300-500 Kbps Downstream bandwidths of 1.5Mbps Current “sweet spot” (optimal price and performance)

Internet Connection Choices Figure 2-22