Infrastructure for Electronic Commerce

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Chapter 2

• Infrastructure for Electronic Commerce

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Learning Objectives

• In this chapter, you will learn about
• The general structure of the network
• Protocols of electronic commerce and e-mail
• Internet utility programs
• Popular Internet applications

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Learning Objectives

• This history and use of Web markup languages
• Web client and server architecture
• Differences and similarities between the
  Internet, intranets, and extranets
• Cost and bandwidth of connecting to the Internet

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E-commerce Technology

• The Internet
• Database software
• Network switches and hubs
• Encryption hardware and software
• Multimedia support
• World Wide Web

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Packet-Switched Networks

• Circuit switching is used in telephone
  communication.
• The Internet uses packet switching.
• Packet switching needs the computers called
  routers and the programs called routing algorithms

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ARPANET

• ARPANET is the earliest packet-switched network.
• This wide area network used the Network Control
  Protocol (NCP).
• A protocol is a collection of rules for
  formatting, ordering, and error-checking data
  sent across a network.

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Open Architecture of ARPANET

• Independent networks should not require any
  internal changes in order to be connected to the
  network.
• Packets that do not arrive at their destinations
  must be retransmitted from their source network.
• The router computers do not retain information
  about the packets that they handle.
• No global control exists over the network.
• Click to see Figure 2-1

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The TCP/IP Protocol

• The Transmission Control Protocol (TCP) and the
  Internet Protocol (IP) are the two protocols that
  support the Internet operation.
• TCP controls the assembly of a message into
  smaller packets before it is transmitted over the
  Internet.
• The IP protocol includes rules for routing
  individual data packets from their source to
  their destination.

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TCP/IP Architecture

• TCP/IP Protocol layers (from the highest to the
  lowest)
• Application
• Transport
• Internet
• Network Interface
• Hardware
• Click to see Figure 2-2

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IP Address

• Internet addresses are based on a 32-bit number
  called an IP address.
• IP addresses appear as a series of up to four
  separate numbers delineated by a period.
• An address such as 126.204.89.56 uniquely
  identifies a computer connected to the Internet.

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Domain Names

• A Uniform Resource Locator (URL) consists of
  names and abbreviations that are much easier to
  remember than IP addresses.
• The HTTP protocol defines how an Internet
  resource is accessed.
• An address such as www.microsoft.com is called a
  domain name.
• Click to see Figure 2-3

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HTTP

• Hypertext Transfer Protocol (HTTP) is responsible
  for transferring and displaying Web pages.
• A users Web browser opens an HTTP session and
  sends a request for a Web page to a remote
  server.
• In response, the sever creates an HTTP response
  message that is sent back to the clients Web
  browser.

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SMTP, POP, and IMAP

• E-mail is sent across the Internet is managed and
  stored by mail servers.
• Simple Mail Transfer Protocol (SMTP) is the
  standard for e-mail client program.
• Post Office Protocol (POP) is the standard for
  e-mail server program.
• The Interactive Mail Access Protocol (IMAP) is a
  newer e-mail protocol.

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FTP

• The File Transfer Protocol (FTP) implements a
  mechanism to transfer files between
  TCP/IP-connected computers.
• FTP transfers both binary and ASCII text.
• Full privilege FTP allows remote uploading and
  downloading files.
• Anonymous FTP allows you to log on as a guest.

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Internet Utility Programs

• Finger
• Ping
• Tracert
• Other route-tracing programs
• Click to see Figure 2-4

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Internet Applications

• Three representative Internet applications
• Electronic mail
• Telnet
• FTP
• Click to see Figure 2-6 Click to see
  Figure 2-7
• Click to see Figure 2-8

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Overview of Markup Languages

• SGML is a rich meta language that is useful for
  defining markup languages.
• HTML is particularly useful for displaying Web
  pages.
• XML defines data structures for electronic
  commerce.

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Standard Generalized Markup Language

• The ISO adopted SGML standard in 1986.
• SGML is nonproprietary and platform-independent.
• SGML supports user-defined tags and architecture
  to complement the required richness of documents.

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Hypertext Markup Language

• Tim Berners-Lee invented HTML.
• HTML is a document production language that
  includes a set of tags that define the format and
  style of a document.
• HTML is based on SGML.
• HTML is an instance of one particular SGML
  document type Document Type Definition (DTD).

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Extensible Markup Language

• XML is a descendant of SGML.
• XML allows designers to easily describe and
  deliver structured data from any application in a
  standard, consistent way.
• XML can be embedded within an HTML document.
• XML allows you to create your own customized
  markup language.
• Click to see Figure 2.9

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HTML Tags

• An HTML document contains both document content
  and tags.
• The tags are the HTML codes inserted in a
  document to specify the format on screen.
• Each tag is enclosed in brackets (lt gt).
• Most tags are two-sided opening and closing
  tags.

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HTML Links

• Hyperlinks are bits of text that connect the
  current document to
• Another location in the same document
• Another document on the same host machine
• Another document on the Internet
• Hyperlinks are created using the HTML anchor tag.
• Two popular link structures
• Linear hyperlink structure
• Hierarchical hyperlink structure
• Click to see Figure 2-14

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HTML Version History

• HTML version 1.0 was introduced in 1991.
• HTML 2.0 was released in Sept. 1995.
• HTML 3.2 was introduced in 1997.
• HTML 4.0 was released by W3C in Dec. 1997.
• HTML 4.01 was released in Dec. 1999.
• XHTML 1.0 became a W3C recommendation in Jan.
  2000.

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HTML Editors

• Low end editor displays HTML code on the screen
  and allow you to insert HTML tag pairs by
  clicking selected buttons.
• High end editor are Web site builder programs,
  they provide a rich environment that displays the
  Web page, not the HTML code.
• Microsoft FrontPage and Macromedia Dreamweaver
  are examples of Web site builders.
• Click to see Figure 2-15

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Web Clients and Severs

• Your PC is a Web client in a worldwide
  client/server network.
• Web software is platform-neutral.
• Computers that are connected to the Internet and
  contain documents made publicly available are
  called Web servers.
• Click to see Figure 2-16

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Web Client/Server Architecture

• Client/server architecture may be used on LANs,
  WANs, and the Web.
• The servers workload is heavy, it needs to be
  high-ended computers with lots of disk capacity,
  fault-tolerant processors, and ample memory.
• The term thin client describes a clients
  relatively low workload, compared with that of a
  server.

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Two-Tier Client/Server

• A two-tier architecture is one in which only a
  client (tier 1) and a server (tier 2) are
  involved in the requests and the responses that
  flow between them over the Internet.
• A typical request message from a client to a
  server consists of three major parts
• A request line
• Optional request headers
• An optional entity body
• Click to see Figure 2-17
• Click to see Figure 2-18

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Three-Tier Client/Server

• A three-tier architecture builds on the
  traditional two-tier approach.
• The first tier is the client, the second tier is
  the Web server, and the third tier consists of
  applications and their databases.
• A Common Gateway Interface (CGI) is a protocol
  which allows Web servers to interact dynamically
  with clients.
• Click to see Figure 2-19

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Intranets

• An intranet is a Web-based private network that
  hosts Internet applications on a LAN.
• Intranets are an extremely popular and low-cost
  way to distribute corporate information.
• The intranet infrastructure includes a TCP/IP
  network, Web authoring software, Web server
  hardware and software, Web clients, and a
  firewall server.

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Intranet Benefits

• Increased, less expensive, environmentally
  friendly internal communication.
• Low acquisition and deployment costs.
• Low maintenance costs.
• Increased information accessibility.
• Timely, current information availability.
• Easy information publication, distribution, and
  training.

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Extranets

• Extranets connect companies with suppliers or
  other business partners.
• An extranet can be a public network, a secure
  (private) network, or a virtual private network
  (VPN).
• Extranets provide the private infrastructure for
  companies to coordinate their purchase and
  communications with one another.

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Extranets

• A public network extranet exists when an
  organization allows the public to access its
  intranet from any public network.
• A private network is a private, leased-line
  connection between two companies that physically
  connects their intranets to one another.
• A VPN extranet is a network that uses public
  networks and their protocols to send sensitive
  data to partners, customers, suppliers, and
  employees using a system called tunneling.
• Click to see Figure 2-20
• Click to see Figure 2-21

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Internet Connectivity

• Internet Service Providers (ISPs) provide
  Internet access services to other businesses.
• Ways to connect to an ISP
• Dial-up connection
• DSL connection
• ISDN connection
• Cable connection
• T1 connection
• T3 connection
• Click to see Figure 2-22

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