Internet and World Wide Web

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Internet and World Wide Web

• Hun Myoung Park, Ph.D.,
• Public Management and Policy Analysis Program
• Graduate School of International Relations
• International University of Japan

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Outline

• Packet Switching
• Internet History
• TCP/IP
• IP Address
• Domain Name Systems
• Internet Services
• Web Servers and Browsers

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• Packet Switching

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Circuit Switching

• Circuit switching establishes a connection
  (dedicated path and circuit) that cannot be used
  by others.
• PSTN (public switched telephone network)

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Packet Switching 1

• No fixed or dedicated path
• Packet switching sends data in a series of
  packets and then assembles them in the
  destination.
• Paul Baran, Donald Davies, Leonard Kleinrock in
  the 1960s.
• PSDN (public switched data network)

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Packet Switching 2

• Data are split into small chunks, packets
• Each packet has a header with information about
  its sequence number and the destination
• Each packet may independently travel a different
  routes to get to the destination and be buffered
  and queued depending on network traffic.
• No order in transmission.

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Packet Switching 3

• The packet header at the destination is stripped
  off and then packets are put together (assemble)
  in the proper order.
• In case of failures of packets (e.g., damaged),
  they will be requested and sent again.
• Safe way to communicate each other.

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• Internet History

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Internet History 1
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• Systems of interconnected computer networks
• ARPAnet (Advanced Research Project Agency) of
  Department of Defense in 1969

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Internet History 2
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• Packet switching as a method of network
  communications in the 1960s.
• Paul Baran at RAND
• Leonard Kleinrock at UCLA

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Internet History 3
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• File Transfer Protocol (FTP) in 1971. SSH FTP
  (SFTP)
• Mail protocol in 1973. (Simple Mail Transfer
  Protocol) SMTP in 1981
• Open Systems Interconnection (OSI) in 1977
• Transmission Control Protocol/Internet Protocol
  (TCP/IP) in 1983

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Internet History 4
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• World Wide Web in 1991
• Tim Berners-Lee at CERN
• World Wide Web Consortium (W3C) was proposed by
  Berners-Lee in 1989
• Web standard HTML 5.0 in 2014

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• TCP/IP

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TCP/IP 1
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• Transmission Control Protocol/Internet Protocol
  (TCP/IP)
• Internet Protocol Suite
• Communication protocol for Internet
• Five layers (from the lower one)
• Replaced ISOs OSI w/o session and presentation
  layers under applications

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TCP/IP 2
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• Physical layer converts bits into signals on
  media
• Data link node-to-node delivery of frames
• Network (delivery of packets by routing and
  Internet Protocol (IP). IPv4 and IPv6
• Transport (logical delivery of messages)
• Application (provide services to users)

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• IP Address

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IP Address 1
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• IP address (Internet address) is a numerical
  label assigned to devices wired on Internet
• To uniquely identify the device on the Internet
• Network interface identification and location
  addressing under TCP/IP

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IP Address 2
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• IPv4 (32bits) 28.28.28.284,294,967,296
• Scarcity of domain names in IPv4
• Move toward IPv6 (128bits) in 1998 supporting up
  to 2128

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IP Address 3
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IP Address 3
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• Static address has a fixed IP address
• Dynamic address is assigned when a machine is
  networked
• Dynamic Host Configuration Protocol (DHCP) server
  manages dynamic addresses

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• Domain Name Systems

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Domain Name Systems 1
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• IP address is not easy to memorize
• Hierarchical naming systems translates a human
  friendly name to its associated IP address
• Identification string of memorable names for
  Internet resources (e.g., computer, network, and
  service)

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Domain Name System 2
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• Domain names registrations controlled by Internet
  Corporation for Assigned Names and Numbers
  (ICANN), nonprofit organization
• Domain Name System (DNS) servers
• Each domain name vendor has its own DNS servers
  (GoDaddy.com, inmotionhosting.com, etc.)

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Domain Name System 3
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• Top-level domain (TLD)
• edu, gov
• com, org, net
• Second-level domain (SLD)
• one to the left of the TLD
• co, ac,

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Domain Name System 4
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• Types of email addresses
• User_ID_at_domain.root_domain_type
• User_ID_at_domain.domain_type.country
• User_ID_at_subdomain.domain.domain_type
• Root domain edu, com, ..
• Domain type .ac, .co, .re, .go
• Country .us, .jp, .kr, .fr

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Web Address 1
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• Uniform Resource Locator (URL) as a URI (Uniform
  Resource Identifier)
• http//www.iuj.ac.jp/faculty/kucc625/or.html
• Protocol or scheme (http, https, ftp, etc.)
• Domain name, domain type, country

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Web Address 2
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• Port number (http//www.iuj.ac.jp80)
• Directory or path (forward slash / not \)
• Document name and arguments of CGI (e.g.,
  search.php?keyWebbookyes)

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• Internet Services

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Internet Service 1
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• E-mail (Electronic mail)
• SMTP (Simple Mail Transfer Protocol)
• MIME (Multipurpose Internet Mail Extension)
• POP (Post Office Protocol)
• IMAP (Internet Mail Access Protocol)
• Most reliable and widely used
• Cost effective

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Internet Service 2
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• FTP (Filer transfer protocol)
• Telnet (Terminal Network) for establishing remote
  connection.
• Traditional FTP and Telnet have security problems
  and were thus replaced by secured FTP (SFTP) and
  secured telnet.
• SSH (Secured shell) includes both SFTP and
  Secured telnet

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Internet Service 3
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• Gopher, browsing and searching services
• Usenet (user network) newsgroup of Internet
  discussion system
• Listservs, e-mail based discussion groups
• Internet chatting (Internet relay chat)

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Internet Service 4
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• WWW (World Wide Web) integrates other Internet
  services using hyperlinks
• Transmit multimedia using hyptertext
• Share data with access to the public
• HTTP (Hypertext Transfer Protocol)
• Static and dynamic documents (HTML)
• CGI (Common Gateway Interface)
• Plug-in or applets (Java applets)

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Internet Service 5
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• Web Document
• HTML (Hypertext Markup Language)/XHTML Structure
  and context
• Cascading Style Sheets (CSS) style
• Extensible Markup Language (XML)
• Web programming languages Perl, PHP, Python, etc.

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Internet Service 6
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• Who provides Internet Services?
• Internet Service Providers (ISP)

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• Web Servers and Browsers

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Web Servers
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• Process requests from Web browsers and send the
  result back to the browsers
• Use CGI to generate dynamic documents
• Apache and its variants (HTTP/Tomcat, IBM HTTP
  Server, Oracle Http Server, Sun Web Server),
  Nginx (BSD license), IIS (Microsoft), Google Web
  server (GWS), other vendors products
• Server-side scripts (SSI)

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Web Browsers 1
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• Interpret markup languages (HTML/XML) and display
  the result on the screen
• This process is called as Web rendering
• Each Web browser has its own rendering engine
  that has different default values in settings.
• May include plug-ins (add-ons)

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Web Browsers 2
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• Web standards Mozilla and Firefox
• Web compatible Safari, Google chrome
• Others Opera, Konqueror
• Text-based Lynx
• Microsoft Internet Explorer (MSIE) and ActivX do
  not comply with Web standards

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Web Features and Web 2.0
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• Interface for input and output of text, image,
  audio, and video
• Replacing or integrating existing Internet
  services like FTP, Gopher, Listservs.
• Push technology (Webcasting) for information
  delivery by software
• Improved interactivity ?Web 2.0
• Internet radio and television

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References

• Stair and Reynolds. 2016. Principles of
  information systems, 12th ed. Cengage Learning.
• Stair and Reynolds. 2012. Information systems,
  10th ed. Cengage Learning.
• Morley and Parker. 2015. Understanding computers,
  15th ed. Cengage Learning.
• Hutchinson and Sawyer. 2000. Computers,
  Communications, and Information, 7th ed.
  Irwin/McGraw-Hill