Transcript Internet & WWW - International University of Japan

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
Systems of interconnected computer
networks
ARPAnet (Advanced Research Project
Agency) of Department of Defense in 1969
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Internet History 2
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
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
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
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
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TCP/IP 2
1. Physical layer converts bits into signals on
media
2. Data link: node-to-node delivery of frames
3. Network (delivery of packets by routing
and Internet Protocol (IP). IPv4 and IPv6
4. Transport (logical delivery of messages)
5. Application (provide services to users)
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IP Address
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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
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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
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IP Address 3
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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
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Domain Name Systems
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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)
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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.)
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Domain Name System 3
Top-level domain (TLD)
o edu, gov
o com, org, net
Second-level domain (SLD)
o one to the left of the TLD
o co, ac,
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Domain Name System 4
Types of email addresses
o [email protected]_domain_type
o [email protected]_type.country
o [email protected]_type
Root domain: edu, com, ..
Domain type: .ac, .co, .re, .go …
Country: .us, .jp, .kr, .fr
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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
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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)
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Internet Services
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Internet Service 1
E-mail (Electronic mail)
o SMTP (Simple Mail Transfer Protocol)
o MIME (Multipurpose Internet Mail Extension)
o POP (Post Office Protocol)
o IMAP (Internet Mail Access Protocol)
Most reliable and widely used
Cost effective
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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
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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)
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Internet Service 4
WWW (World Wide Web)
integrates other Internet services
using hyperlinks
o Transmit multimedia using hyptertext
o Share data with & access to the public
o HTTP (Hypertext Transfer Protocol)
o Static and dynamic documents (HTML)
o CGI (Common Gateway Interface)
o Plug-in or applets (Java applets)
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Internet Service 5
Web Document
o HTML (Hypertext Markup
Language)/XHTML: Structure and
context
o Cascading Style Sheets (CSS): style
o Extensible Markup Language (XML)
o Web programming languages: Perl,
PHP, Python, etc.
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Internet Service 6
Who provides Internet Services?
Internet Service Providers (ISP)
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Web Servers and Browsers
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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)
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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)
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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
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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
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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