Technology Infrastructure: Internet and WWW ISM 4480 University of South Florida

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Technology Infrastructure Internet and
WWWISM 4480University of South Florida
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Class Objectives

• The origin, growth, and current structure of the
  Internet.
• How packet-switched networks are combined to form
  the Internet.
• How Internet protocols and Internet addressing
  work.
• The history and use of markup languages on the
  Web, including SGML, HTML, and XML.
• How HTML tags and links work on the World Wide
  Web.
• The differences among internets, intranets, and
  extranets.
• Internet connection options, including cost and
  bandwidth.
• Internet2 and the Semantic Web.

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Networks, Internet, and Web

• Computer network
• A set of interconnected computers linked via
  wireline or wireless means for sharing
  data/resources among each other.
• Four types
• Local area network (LAN) Network of computers
  located in physical proximity (same room or
  building).
• Wide area network (WAN) Network spanning
  geographical distances (countries or continents).
• Metropolitan area network (MAN) Network spanning
  cities.
• Personal area network (PAN) Home networks.
• Internet
• A WAN connecting computer networks across the
  globe.
• World Wide Web
• A subset of computers on the Internet running the
  HTTP protocol.

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History of the Internet

• ARPANET (1960s-80s)
• US-DOD funded research to explore creating a
  computer network that can survive bombings during
  wars.
• 4 nodes in 1960 UCLA, SRI, Utah and UCSB.
• 15 nodes in 1971 connecting east and west coast
  universities.
• NSFNet (US-DOD, 1980s)
• Internet moved into the academic domain.
• Five supercomputing centers (Pitt/CMU, UIUC,
  UCSD, Cornell, Princeton) connected in 1986.
• Connected to networks in Europe and Canada in
  1988-1990.
• Todays Internet (1995-)
• Over 65,000 networks and 190M hosts worldwide
  (and growing).
• Reaching peak capacity backbone recently
  replaced by a new high-capacity network
  (Internet2).

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Growth of the Internet
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Internet Architecture
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Internet Concepts C/S Architecture

• Client/server architecture
• All computers connected to the Internet are
  treated as equals (peers).
• Computers request services/data from each other
  requesting computers are clients, responding
  computers are servers.
• Clients and servers are processes, not machines.
• Web (hypertext) communication (HTTP)
• Mode of communication between web clients (e.g.,
  Internet Explorer) and web servers (e.g.,
  Internet Information Server).
• Hypertext/web server stores files written in
  hypertext markup language
• Tim Berners-Lee developed code for first
  hypertext server and client.
• E-mail communication (SMTP)
• Mode of communication between e-mail clients
  (e.g., Microsoft Outlook) and e-mail servers such
  as Microsoft Exchange.

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Internet Concepts Switching

• Switching
• The process of moving messages using temporary
  connections on a connected network of
  computers/nodes.
• Packet-switching (Internet)
• Before transmission, messages are broken down
  into small pieces called packets (packetization).
• Each packet is affixed with the address of source
  and destination computers (addressing).
• Packets travel independently from source to
  destination via a series of switches/routers
  connected the Internet.
• Packets are reassembled at destination back into
  original message.
• Circuit switching
• Entire message transmitted as a whole (no
  packets) via a single temporary path over
  switches/routers.

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Internet Concepts Nodes

• Routers
• Computers that connect two networks (e.g., a LAN
  to the Internet).
• Used at the edge (periphery) of a network.
• Gateway Routers that connect LANs to Internet.
• Network access points (NAP) Routers used by ISPs
  to control access to Internet.
• Internet routers require specialized hardware and
  software that support TCP/IP stacks and routing
  protocols.
• Switches
• Computers that manage packet traffic within a
  network (e.g., a LAN or the Internet).
• Used at the center of a network.
• Requires specialized hardware and software to
  decide the best path for forwarding packets
  between two nodes.

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Internet Concepts Protocols

• TCP/IP protocol
• Collection of rules for formatting, ordering, and
  error-checking data sent over the Internet.
• Designed by Kahn Cerf in 1974 became ARPANET
  standard in 1984.
• Transmission Control Protocol (TCP)
• Rules that define how messages are broken into
  packets for transmission over the Internet.
• Also controls reassembly of packets at the
  destination nodes.
• Internet Protocol (IP)
• Rules for specifying address details for each
  packet.
• Two versions IPv4 and IPv6.
• Supports application protocols
• HTTP, SMTP, FTP, POP, PPP, UDP, etc.

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Packetizing
IP Datagram (Ver. 6)
Version Flow Total Next Hop
Source Destination
User number name length header limit
address address
data 4 bits 24 bits 16 bits 8 bits
8 bits 128 bits 128 bits
variable
40 byte header
64 KB max size
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IP Addressing

• IPv4 address
• Uses 32-bit address field (four 8-bit fields) to
  store globally unique address (e.g.,
  128.102.13.1) for every host on the Internet.
• Fixed or dynamic (DHCP, PPP) assignment.
• Each node also has a 6-byte physical address
  (e.g., 02-FE-87-4A-8C-A9) permanently encoded on
  NIC.
• IP subnets
• Computers in TCP/IP networks can be grouped into
  subnets.
• Subnets may be one of three types
• Class Subnet IP address Subnet mask Example
• A 128 255.0.0.0 ATT, Verizon
• B 128.192 255.255.0.0 USF, Intel
• C 128.192.98 255.255.255.0 coba.usf.edu

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IP Addressing Example
Mail/FTP Server 135.66.7.2
Database Server 135.66.7.3
135.66.1.254
Dial-in PCs
SMTP FTP
HTTP
SQL/ ODBC
135.66.1.255
Network 135.66.7
Internet Server
HTTP
135.66.7.1
135.66.3.2
135.66.3.2
LAN
LAN
135.66.3.3
135.66.3.4
135.66.3.3
135.66.3.4
Network 135.66.3 (Subnet 255.255.255.0)
Network 135.66.3 (Subnet 255.255.252.0)
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Limitations of IPv4

• 32-bit address fields in IPv4 can store a maximum
  of 4.3 billion IP addresses, which is nearly
  exhausted.
• Two ways of expanding the IP address space
• Subnetting
• Using private IP subnets (e.g., 255.255.255.0)
  within LAN/WANs to provide additional logical
  (not physical) addresses.
• Cannot be used on the Internet due to potential
  address conflict.
• Network Address Translation (NAT) service
  converts private IP addresses into normal IP
  addresses for Internet transmission.
• Widely deployed within corporate networks using
  proxy servers.
• IPv6
• Uses 128-bit address field (four 32-bit fields)
  to store several hundreds of trillions of IP
  addresses to eventually replace IPv4.
• Currently deployed only on the Internet backbone
  private companies dont yet have the
  software/resources to support IPv4.

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URL and DNS

• Uniform Resource Locator (URL) or Domain Names
• Easy-to-remember masks (e.g., http//www.nasa.gov)
  for actual TCP/IP addresses (e.g.,
  128.102.13.1).
• Domain Naming Service (DNS)
• A distributed database service on the Internet
  that maps IP addresses to domain names (e.g.,
  www.nasa.gov).
• DNS registration services provided by local ISP
  and others.
• Root DNS service managed by Internet Corporation
  for Assigned Names and Numbers (ICANN).
• Top-level domain (TLD)
• Rightmost part of a domain name.
• Original general TLD com, edu, gov, org, mil,
  net.
• Country TLD au, ca, de, fr, jp, uk.
• New general TLD (2000) info, biz, coop, aero,
  name, pro, museum.

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Other Key Internet Protocols

• Hypertext Transfer Protocol (HTTP)
• Set of rules for requesting/delivering web pages
  over the Internet.
• Application-layer protocol running on top of
  TCP/IP.
• Supports multiple services text, audio, video,
  file transfer, e-mail, etc.
• Stateless Each request-response pair is treated
  independently.
• Not secure Other protocols (e.g., SSL, SHTTP)
  required for security.
• Simple Mail Transfer Protocol (SMTP)
• Set of rules for specifying structure of an
  e-mail message.
• Post Office Protocol (POP)
• Set of rules for managing e-mails on mail
  servers.
• Specifies whether to delete e-mails from a mail
  server after they are send to users computer,
  how to inform user of arrival of new mail, etc.
• Interactive Mail Access Protocol (IMAP)
• Newer version of POP, including additional
  features such as mail folders, multiple reply
  options, view e-mail subject and sender before
  downloading mail, etc.

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Markup Languages

• Markup language Standard language for formatting
  web documents so that they can be read by all
  HTTP servers and clients.
• Standard Generalized Markup Language (SGML)
• A meta-language for all other markup languages
  developed by Charles Goldfarb in 1986 maintained
  by World Wide Web Consortium (W3C).
• Uses user-defined text-based tags, which are
  saved in special dictionaries called DTD
  (document type definition) and used for
  interpreting SGML pages.
• Nonproprietary and platform independent.
• Complex, costly, and labor intensive.
• Hypertext Markup Language (HTML)
• Simplified version of SGML (with standard DTD)
  for formatting the display of web documents.
• Developed in 1991 by Tim Berners-Lee and Robert
  Calliau (CERN).
• HTML tags are interpreted by web browsers.

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Styles

• Used to modify default display formats (e.g.,
  colors, fonts) for HTML tags.
• Inline styles
• Style information included within HTML tag.
• ltH1 STYLE"colorBlue font-size24pt
  font-familyArialgtMy Favorite Linkslt/H1gt
• ltA HREF"http//www.nasa.gov" STYLE"colorGreen
  font-size24pt font-familyArial
  text-decoration none"gtNASAlt/Agt
• Embedded styles
• Style info included in header section of HTML
  pages.
• ltHEADgt
• ltSTYLEgt
• Ahover colorRed text-decorationUnderline
  
• H1 colorGreen font-size18pt
  font-styleArial,sans-serif
• lt/STYLEgt
• lt/HEADgt
• ltBODYgt
• ltH1gtMy Favorite Citieslt/H1gt
• ltA HREF"http//www.sydney.au"gtSydney,
  Australialt/Agt
• lt/BODYgt

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Styles

• External linking/Cascading Style Sheets (CSS)
• Style info stored in a separate file and invoked
  by many HTML pages.
• Style applies uniformly across all calling pages,
  providing consistent look-and-feel for the
  entire website.
• ltHEADgt
• ltLINK REL"stylesheet" HREFMyStyles.css" gt
• lt/HEADgt
• ltBODYgt
• ltH1gtMy Favorite Citieslt/H1gt
• ltA HREF"http//www.sydney.au"gtSydney,
  Australialt/Agt
• lt/BODYgt
• MyStyles.css
• TD font-family verdana, sans-serif font-size
  10pt color Red
• H1 font-family "soft hits" font-size
  20pt

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Styles

• In case of conflicts, inline styles override
  embedded styles, which override CSS.
• With CSS, multiple stylesheets can be applied to
  one page to create distinctive user interfaces
  for different customer groups.
• CSS is the best because it isolates style info
  from HTML content, and makes styles easier to
  manage.

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Dynamic HTML (DHTML)

• HTML Styles Scripts
• Content varies with user actions (e.g., user
  search, form input).
• Scripts are written using JavaScript, VBScript,
  Perl, ASP, PHP, C, etc., and coded into HTML
  pages
• Scripts allow for database interaction.
• lthtmlgt
• ltbodygt
• lth3gtGodzilla Pizza - Order Confirmation and
  Invoicelt/h3gt
• lt?php
• echo "Order Date " . date("F d, Y") . "ltbrgt"
• echo "Customer Name " . _POST'name' .
  "ltbrgt"
• ?gt
• lttablegt
• lttrgtlttdgtlt/tdgtlt/trgt
• lt?php
• for (count 1 countlt5 count)
• if (NumToppings gt 1) Price Price
  (NumToppings - 1)
• ?gt

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eXtensible Markup Language (XML)

• Open-standards based SGML derivative developed by
  W3C in 1998 for specifying structures to
  store/manipulate document content (not display).
• Uses user-specified tags, that may be
  standardized via document type definition (DTD)
  files.
• Supports data management capabilities beyond
  HTML, such as data interchange between two
  systems.
• Created using a text editor (e.g., Visual
  Studio) viewed using XML parser (e.g., msxml
  built into Internet Explorer 5.0)
• Display format for XML specified using eXtensible
  style language (XSL).
• Industry-specific XML DTDs
• ebXML (E-business XML www.ebxml.org).
• WML (Wireless Markup Language).
• XRBL (Extensible Business Reporting Language).

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XML Example

• lt?xml version"1.0" ?gt
• lt?xml-stylesheet type"text/xsl"
  href"cd-catalog.xsl"?gt
• ltCATALOGgt
• ltCD SKU"23454456723"gt
• ltTITLEgtBest of 1980-1990lt/TITLEgt
• ltARTISTgtU2lt/ARTISTgt
• ltLABELgtPolygramlt/LABELgt
• ltPRICEgt13.49lt/PRICEgt
• ltYEARgt1998lt/YEARgt
• lt/CDgt
• ltCD SKU"53402782789"gt
• ltTITLEgtThe Immaculate Collectionlt/TITLEgt
• ltARTISTgtMadonnalt/ARTISTgt
• ltLABELgtWarner Brotherslt/LABELgt
• ltPRICEgt11.99lt/PRICEgt
• ltYEARgt1990lt/YEARgt
• lt/CDgt
• lt/CATALOGgt

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XML Processing
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HTML Tags versus XML Tags

• XML Tags
• Defines data structure.
• Tags user-defined (via DTD).
• Case sensitive.
• Must have closing tags.
• Must be properly nested.
• e.g., ltigtltbgt.lt/bgtlt/igt
• Attribute values must be quoted
• e.g., ltperson id3364gt

• HTML Tags
• Defines data formats (display).
• Tags predefined (in browser).
• Case insensitive.
• Some dont require closing tags.
• Some improper nesting allowed
• e.g., ltigtltbgt.lt/igtlt/bgt
• Not necessary to quote attribute values
• e.g., ltbody bgcolor990000gt

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Internet-Based Networks

• Intranet
• A TCP/IP based packet-switched internal network
  for connecting computers/networks within business
  premises.
• Firewalls used to secure the intranet from
  external hackers.
• Extranet
• Intranet extended to remote locations to allow
  suppliers, business partners, and customers
  securely access internal resources.
• Virtual Private Network (VPN)
• Secure (temporary) private connections on the
  public Internet using IP tunneling protocol.
• Requires special VPN software on source and
  destination nodes and VPN service (provided by
  Verizon, MCI, etc.).

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Internet Connection Options

• Plain old telephone service (POTS)
• Uses existing telephone lines and analog modem.
• Bandwidth 28-56 Kbps.
• Cheapest service available, not well-suited for
  businesses.
• Broadband connections (gt 200 Kbps)
• Digital Subscriber Line (e.g., Verizon DSL)
• High-speed communication protocol bandwidth 128
  Kbps.
• Delivered via phone lines using DSL router
  (modem).
• Asymmetric DSL (ADSL) 100-640 Kbps upstream,
  1.5-9 Mbps downstream.
• Cable modems (e.g., Brighthouse Roadrunner)
• Switched bandwidth 300 Kbps - 1 Mbps.
• Delivered via coaxial cable connections.
• Fiber optic (e.g., Verizon FiOS)
• Switched bandwidth up to 5 Mbps, delivered via
  fiber cable.

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Leased-Line Connections

• Dedicated connections expensive.
• Used only for connection from business premises
  to local ISP.
• DS0 (digital signal zero) Telephone line
  designed to carry 1 digital signal.
• T1 line (also called DS1) Carries 24 DS0 lines
  operates at 1.544 Mbps.
• Fractional T1 Provides service speeds in
  increments of 128 Kbps.
• T3 service (also called DS3) Offers 44.736 Mbps
  (equaling 30 T1 lines).

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Bandwidth Chart
Bandwidth Application Technology
1 Tbps
All U.S. telephone conversations simultaneously
1 Gbps
Gigabit Ethernet
Full-motion HDTV
OC12 622 Mbps
FDDI
Fiber
OC3 155 Mbps
T3/E3
Virtual Reality, Medical Imaging
T3 44.7 Mbps
Video Conferencing, Multimedia
ADSL
DSL 7 Mbps
T1 1.544 Mbps
Streaming Video Voice
T1/E1
ISDN
128 Kbps
Browsing, Audio
Modem
56 Kbps
Copper
E-mail, FTP
19.2 Kbps
Wireless WAN
Telnet
4.8 Kbps
Paging
Human speech 30 bps
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Wireless Connections

• Bluetooth
• Designed for short distance use (35 feet) in
  personal area networks.
• Can connect up to 8 devices PC, printer, cell
  phone, keyboard, etc.
• Low-bandwidth up to 722 Kbps.
• Consumes very little power, automatic detection
  (without login).
• Wireless Ethernet (Wi-Fi, 802.11)
• Wireless technology for LANs and short-haul ISP.
• Capable of roaming range up to 300 feet.
• Wireless access point (WAP) Device that connects
  Wi-Fi cards in PCs with network switches.
• Bandwidth
• 802.11 Up to 11 Mbps.
• 802.11a Up to 54 Mbps.
• 802.11n Up to 320 Mbps expected.
• Wi-Max
• Wireless technology for MANs.

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Cellular Telephone Networks

• Broadcast signals to/from antennas spaced 3 miles
  apart in hexagonal grids (cells).
• Originally designed for voice communication, can
  support low-speed data transmission at 10-384
  Kbps.
• Short message service (SMS)
• Protocol for sending/receiving text messages on
  cell phones.
• Third-generation (3G) cell phones
• Latest generation, supports mobile commerce such
  as auctions, stock trading, video downloads, etc.

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The Future of Internet Technology

• Internet2
• Backbone bandwidth of 10 Gbps.
• Will support IPv6 for many more IP addresses.
• Experimental test bed for new networking
  technologies.
• XML standards
• Resource description framework (RDF) Standards
  for XML syntax.
• Consolidation of XML DTD (e.g., Rosettanet) and
  their wider use.
• Web services
• Framework for sharing e-commerce services with
  remote service providers using SOAP protocol.
• Semantic Web
• Tim Berners-Lees project to tag words on web
  pages with their meanings (using XML).