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

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

Packet Switching

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

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)

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.

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.

Internet History

Internet History 1 Systems of interconnected computer networks 9 Internet History 1 Systems of interconnected computer networks ARPAnet (Advanced Research Project Agency) of Department of Defense in 1969

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

11 Internet History 3 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

Internet History 4 World Wide Web in 1991 Tim Berners-Lee at CERN 12 Internet History 4 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

TCP/IP

TCP/IP 1 Transmission Control Protocol/Internet Protocol (TCP/IP) 14 TCP/IP 1 Transmission Control Protocol/Internet Protocol (TCP/IP) Internet Protocol Suite Communication protocol for Internet Five layers (from the lower one) Replaced ISO’s OSI w/o session and presentation layers under applications

TCP/IP 2 Physical layer converts bits into signals on media 15 TCP/IP 2 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)

IP Address

18 IP Address 1 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

IP Address 2 IPv4 (32bits); 28.28.28.28=4,294,967,296 19 IP Address 2 IPv4 (32bits); 28.28.28.28=4,294,967,296 Scarcity of domain names in IPv4 Move toward IPv6 (128bits) in 1998 supporting up to 2128

20 IP Address 3

IP Address 3 Static address has a fixed IP address 21 IP Address 3 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

Domain Name Systems

Domain Name Systems 1 IP address is not easy to memorize 23 Domain Name Systems 1 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)

24 Domain Name System 2 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.)

Domain Name System 3 Top-level domain (TLD) Second-level domain (SLD) 25 Domain Name System 3 Top-level domain (TLD) edu, gov com, org, net Second-level domain (SLD) one to the left of the TLD co, ac,

Domain Name System 4 Types of email addresses 26 Domain Name System 4 Types of email addresses User_ID@domain.root_domain_type User_ID@domain.domain_type.country User_ID@subdomain.domain.domain_type Root domain: edu, com, .. Domain type: .ac, .co, .re, .go … Country: .us, .jp, .kr, .fr

27 Web Address 1 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

Web Address 2 Port number (http://www.iuj.ac.jp:80) 28 Web Address 2 Port number (http://www.iuj.ac.jp:80) Directory or path (forward slash / not \) Document name and arguments of CGI (e.g., search.php?key=Web&book=yes)

Internet Services

Internet Service 1 E-mail (Electronic mail) 30 Internet Service 1 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

Internet Service 2 FTP (Filer transfer protocol) 31 Internet Service 2 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

Internet Service 3 Gopher, browsing and searching services 32 Internet Service 3 Gopher, browsing and searching services Usenet (user network) newsgroup of Internet discussion system Listservs, e-mail based discussion groups Internet chatting (Internet relay chat)

33 Internet Service 4 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)

Internet Service 5 Web Document 34 Internet Service 5 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.

Internet Service 6 Who provides Internet Services? 35 Internet Service 6 Who provides Internet Services? Internet Service Providers (ISP)

Web Servers and Browsers

37 Web Servers Process requests from Web browsers and send the result back to the browsers Use CGI to generate dynamic documents Apache (HTTP/Tomcat), IIS (Microsoft), other vendors’ products (IBM, Oracle, etc.) Server-side scripts (SSI)

39 Web Browsers 1 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)

Web Browsers 2 Web standards: Mozilla and Firefox 40 Web Browsers 2 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

41 Web Features and Web 2.0 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

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