Technology Infrastructure:

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Chapter 2

• Technology Infrastructure
• The Internet and the World Wide Web

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Learning Objectives

• In this chapter, you will learn about
• the general technical structure of the Internet
• Internet utility programs
• common internet applications
• the history and use of markup languages

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Learning Objectives (cont.)

• HTML tags and links and how they work
• the client-server architecture of the Web
• the differences among internets, intranets, and
  extranets
• options for connecting to the Internet

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Technology Overview

• Computer networks and the Internet form the basic
  technology structure for electronic commerce.
• The computers in these networks run such software
  as
• Operating systems, database managers, encryption
  software, multimedia creation and viewing
  software, and the graphical user interface

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Technology Overview

• The Internet includes
• The hardware that connects the computers together
  and the hardware that connects the networks
  together
• Rapid change in these technologies requires
  businesses to be flexible.

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Packet-Switched Networks

• A local area network (LAN) is a network of
  computers close together.
• A wide area network (WAN) is a network of
  computers connected over a great distance.
• Circuit switching is used in telephone
  communication.
• The Internet uses packet switching
• Files are broken down into small pieces (called
  packets) that are labeled with their origin,
  sequence, and destination addresses.

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Routing Packets

• The computers that decide how best to forward
  each packet in a packet-switched network are
  called routers.
• The programs on these routers use routing
  algorithms that call upon their routing tables
  to determine the best path to send each packet.
• When packets leave a network to travel on the
  Internet, they are translated into a standard
  format by the router.
• These routers and the telecommunication lines
  connecting them are referred to as the Internet
  backbone.

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Routing Packets
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Data Transmission Protocols

• A protocol is a collection of rules for
  formatting, ordering, and error-checking data
  sent across a network.
• ARPANET is the earliest packet-switched network.
• The open architecture of this experimental
  network used Network Control Protocol (NCP) which
  later became the core of the Internet.

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Data Transmission Protocols (cont.)

• This open architecture has four key rules that
  have contributed to the success of the Internet.
• Independent networks should not require any
  internal changes to be connected to the network.
• Packets that do not arrive at their destinations
  must be retransmitted from their source network.
• Router computers act as receive-and-forward
  devices they do not retain information about the
  packets that they handle.
• No global control exists over the network.

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Internet Protocols

• The Transmission Control Protocol (TCP) and the
  Internet Protocol (IP) are the two protocols that
  support the Internet operation (commonly referred
  to as TCP/IP).
• TCP controls the disassembly of a message into
  packets before it is transmitted over the
  Internet and the reassembly of those packets when
  they reach their destination.
• The IP protocol specifies the addressing details
  for each packet being transmitted.

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IP Addresses

• IP addresses are based on a 32-bit binary number
  that allows over 4 billion unique addresses for
  computers to connect to the Internet.
• IP addresses appear in dotted decimal notation
  (four numbers separated by periods).
• They are assigned by three not-for-profit
  organizations (ARIN, RIPE and APNIC).

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IP Addresses

• Approximately two billion IP addresses are either
  in use or unavailable for use.
• Private IP addresses are a series of IP numbers
  that have been set aside for subnet use and are
  not permitted on the Internet.
• IPv6 is a possible solution that uses a 128-bit
  hexadecimal number for addresses.

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Domain Names

• To make the numbering system easier to use, an
  alternative addressing method that uses words was
  created.
• An address, such as www.course.com, is called a
  domain name.
• The last part of a domain name (i.e., .com) is
  the most general identifier in the name and is
  called a top-level domain (TLD).

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Top-level Domain Names
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Internet Services Protocols

• The Internet provides a variety of services to
  users known as application services.
• Application services include Web page delivery,
  network management tools, remote login, file
  transmission, electronic mail, and directory
  services.

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Web Page Delivery

• Hypertext Transfer Protocol (HTTP) is the set of
  rules for delivering Web pages over the
  Internet.
• HTTP uses the client/server model
• 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.
• The combination of the protocol name and the
  domain name is called a uniform resource locator
  (URL).

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SMTP, POP, MIME, and IMAP

• E-mail sent across the Internet must also be
  formatted to a common set of rules, otherwise
  e-mail created by one company (or Web site) could
  not be read by a person at another company.
• Simple Mail Transfer Protocol (SMTP) specifies
  the exact format of a mail message and describes
  how mail is to be administered at the Internet
  and network level.

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SMTP, POP, MIME, and IMAP (cont.)

• An e-mail program running on a users computer
  can request mail from the companys main e-mail
  computer using the Post Office Protocol (POP).
• Multipurpose Internet Mail Extensions (MIME)
  allow the user to attach binary files to e-mail.
• The Interactive Mail Access Protocol (IMAP)
  performs the same basic functions as POP, but
  includes additional features.

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Internet Utility Programs

• Finger runs on UNIX computers and allows users to
  obtain limited information about other network
  users.
• Ping tests the connectivity between two computers
  connected to the Internet.
• Tracert, a route-tracing program, sends data
  packets to every computer on the path (Internet)
  between your computer and another computer and
  clocks the packets round-trip times.

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Internet Utility Programs
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Internet Applications

• Electronic Mail
• E-mail is the most popular form of business
  communication surpassing the telephone,
  conventional mail, and fax in volume.
• One benefit is the ability to send documents and
  other information as attachments.
• The drawbacks of email include such things as
  Spam (or bulk mail) and computer virus delivered
  to your computer as email attachments.

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Internet Applications
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Internet Applications (cont.)

• Telnet
• Telnet is an application that allows you to log
  on to a remote computer that is attached to the
  Internet.
• It allows the user to run software that doesnt
  have a Web interface on a remote computer.
• As more companies place information on Web pages
  (accessible through any Web browser), the use of
  Telnet will continue to decrease.

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Internet Applications
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Internet Applications

• FTP
• File Transfer Protocol (FTP) defines the formats
  used to transfer files between TCP/IP-connected
  computers.
• FTP transfers both binary data and ASCII text.
• Full privilege FTP allows remote uploading and
  downloading of files.
• Anonymous FTP allows you to log on to a remote
  computer as a guest.

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Internet Applications
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Markup Languages and the Web

• Web pages are marked with tags to indicate the
  display and formatting of page elements.
• SGML is a meta language, which is a language that
  can be used to define other languages.
• HTML and XML are both derivatives of SGML.

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Standard Generalized Markup Language

• SGML offers a system of marking up documents that
  is independent of any software application.
• Advantages of SGML include its long-term
  viability, it is nonproprietary and
  platform-independent, and it supports
  user-defined tags and architectures.
• Disadvantages of SGML include a costly and
  complicated set up, expensive tools, creating
  document-type definitions that are time
  consuming, and extensive learning time.

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Hypertext Markup Language

• HTML is a simplified subset of SGML that includes
  tags defining the format and style of text
  elements in a document.
• HTML is an instance of one particular SGML
  document type Document Type Definition (DTD).
• HTML now includes tags for tables, frames, and
  other features that help Web designers create
  more complex page layouts.

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Extensible Markup Language

• Unlike HTML, XML uses markup tags to describe the
  meaning of the text rather than its display
  characteristics.
• XML uses paired start and stop tags in much the
  same way as database software defines a record
  structure.
• An XML document can be embedded within an HTML
  document.
• XML allows a user to extend the language by
  creating their own tags.

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Markup Languages and the Web
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Markup Languages and the Web
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HTML Tags

• An HTML document contains both document text and
  elements.
• Tags are codes that are used to define where an
  HTML element starts and (if necessary) where it
  ends.
• In an HTML document, each tag is enclosed in
  brackets (ltgt).
• A two-sided tag set has an opening tag and a
  closing tag.

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HTML Tags
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HTML 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 are
• Linear hyperlink structure
• Hierarchical hyperlink structure

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Scripting Language and Style Sheet Capabilities

• Web designers can use the OBJECT tag to embed
  scripting language codes in HTML pages (this is
  also called client-side scripting).
• Scripts can execute programs on computers that
  display those pages.
• Cascading Style Sheets (CSS) let designers define
  formatting styles that can be reapplied to
  multiple Web pages.

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HTML Editors

• HTML documents can be created in any
  general-purpose text editor or word processor.
• Sophisticated editors can create full-scale,
  commercial-grade Web sites with database access,
  graphics, fill-in forms, and display the Web page
  along with the HTML code.
• Microsoft FrontPage and Macromedia Dreamweaver
  are examples of Web site builders.

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HTML Editors
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Web Clients and Web Servers

• Your PC is a Web client in a worldwide
  client-server network.
• Web software is platform-neutral, which allows
  your PC to communicate with different types of
  computers easily and effectively.
• Computers that are connected to the Internet and
  that contain documents made publicly available
  are called Web servers.
• The word server is used to describe several
  types of computer hardware and software.

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Web Clients and Web Servers
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Web Client-Server Architecture

• Client-server architecture is used on LANs, WANs,
  and the Web.
• The computers that perform the server function
  usually have more memory and larger, faster disk
  drives than the client computers they serve.
• Web pages containing many objects can be slow to
  appear in the clients Web browser because each
  page element requires a separate request and
  response.

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Two-Tier Client-Server Architecture

• The basic client-server model is a two-tier model
  because it has only one client and one server.
• A typical request message from a client to a
  server consists of three major parts (a request
  line, optional request headers, and an optional
  entity body).
• A servers response to a request message also
  consists of three parts (a response header line,
  one or more response header fields, and an
  optional entity body).

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Two-Tier Client-Server Architecture
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Three-Tier and N-Tier Client-Server Architectures

• A three-tier architecture extends the two-tier
  architecture to allow additional processing to
  occur before responding to the clients request.
• The third tier usually includes software
  applications that supply information to the Web
  server.
• Higher-order architectures (those with more than
  three tiers), are called n-tier architectures.

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Three-Tier and N-Tier Client-Server Architectures
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Intranets and Extranets

• Intranets
• An intranet is an interconnected network (or
  internet small i intended) that does not
  extend beyond the organization that created it.
• Intranets are an extremely popular and low-cost
  way to distribute corporate information.
• An intranet uses Web browsers and Internet-based
  protocols (including TCP/IP, FTP, Telnet, HTML,
  and HTTP) and often includes a firewall.

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Intranets and Extranets (cont.)

• Extranets
• Extranets are intranets that have been extended
  to include specific entities outside the
  boundaries of the organization (business
  partners, suppliers, etc.).
• An extranet can be a public network, a secure
  (private) network, or a virtual private network
  (VPN).

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Intranets and Extranets (cont.)

• A public network is any computer or
  telecommunications network that is available to
  the public.
• 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 IP tunneling or
  encapsulation.

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Intranets and Extranets
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Internet Connection Options and Trade-Offs

• The Internet is a set of interconnected
  networks.
• Large firms that provide Internet access to other
  businesses are called Internet Access Providers
  (IAPs) or Internet Service Providers (ISPs).

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Connectivity Overview

• The most common connection options that ISPs
  offer to the Internet are telephone, broadband,
  leased-line, and wireless.
• Bandwidth is the amount of data that can travel
  through a communication line per unit of time.
• Bandwidth can differ for data traveling to or
  from the ISP.

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Voice-Grade Telephone Connections

• The most common way to connect to an ISP is
  through a modem connected to your local telephone
  service provider.
• POTS uses existing telephone lines and an analog
  modem to provide a bandwidth of 28-56 Kbps.
• ISDN uses the DSL protocol suite to offer
  bandwidths between 128-256 Kbps.

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Broadband Connections

• Connections that operate at speeds of greater
  than 200 Kbps are called broadband services.
• ADSL uses the DSL protocol to provide bandwidths
  between 100-640 Kbps upstream and 1.5-9 Mbps
  downstream.
• Cable modems provide transmission speeds between
  300 Kbps-1 Mbps from the client to the server and
  a downstream rate as high as 10 Mbps.
• Satellite microwave transmissions handle internet
  downloads at speeds around 500 Kbps.

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Leased-Line Connections

• Large firms can connect to an ISP using
  higher-bandwidth connections that they can lease
  from telecommunications carriers.
• A T1 line operates at 1.544 Mbps and a T3
  line operates at 44.736 Mbps.

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Wireless Connections

• Many researchers and business managers see great
  potential for wireless networks and the devices
  connected to them.
• The term m-commerce (mobile commerce) is used to
  describe the kinds of resources people might want
  to access using devices that have wireless
  connections.

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Internet 2

• Internet 2 is an experimental test bed for new
  networking technologies that is separate from the
  original Internet.
• 200 universities and a number of corporations
  joined together to create this network.
• It has achieved bandwidths of 10 Gbps.
• Internet 2 promises to be the proving ground for
  new technologies and applications of those
  technologies that will eventually find their way
  to the Internet.

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Internet 2