Introduction to the Web - gozips.uakron.edu

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2440: 141
Web Site Administration
Introduction the Internet and the Web
Instructor: Enoch E. Damson
Computer Network
 Two or more computers connected together to
share resources like printers and programs
 Fall into two categories:
 Local Area Network (LAN) – computers connected within a
small geographic area like a building
 Wide Area Network (WAN) – a connection of computers
over a few miles or thousands of miles

E.g. the Internet
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The Internet
 A large collection of computers all over the world that are
connected to one another
 A large network of networks
 Also called the “Net”
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Intranet
 LAN or WAN that uses TCP/IP within a firm
 Uses the same concepts and technologies on the Internet
to share part of an organization’s information or
operation with its employees
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Origins of the Internet
 No one person invented the Internet
 However, certain people contributed major breakthroughs
 Leonard Kleinrock (Massachusetts Institute of Technology): published
a paper in 1961 on packet switching which was essential to the Internet

Packet switching: packets of data can be sent from one place to another
based on address information carried in the data
 J.C.R. Licklider: the first to describe an internet-like worldwide network
of computers, in 1962 as the “Galactic Network"
 Larry G. Roberts: created the first functioning long-distance computer
networks in 1965

He designed the Advanced Research Projects Agency Network (ARPANET),
under the auspices of the Defense Advanced Research Projects Agency, as a
means to share information on defense research
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Origins of the Internet…
 Vinton (Vint) Cerf and Robert (Bob) Kahn: invented the
Transmission Control Protocol (TCP) and the Internet
Protocol (IP) in 1972 and 1973
 Most credited for being the “Fathers of the Internet”
 TCP/IP - moves data on the modern Internet
 Transmission control protocol (TCP) includes rules that
networked computers use to establish and break connections
 Internet protocol (IP) includes rules for routing individual data
packets (small chunks of data)
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Origins of the Internet…
 The US Department of Defense (DoD) created a research
agency known as:
 Advanced Research Projects Agency (ARPA) – later known
as Defence ARPA (DARPA), created a network called:

Advanced Research Projects Agency Network (ARPANET) – an
experimental WAN primarily for academic research, scientific,
and military purposes

Made up of about four main computers located at:
 University of California, Los Angeles (UCLA)
 University of California, Santa Barbara (UCSB)
 University of Utah
 Stanford Research Institute (SRI) International
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Origins of the Internet…
 Some of the other well known interconnecting networks that joined into
the Internet are:
 Military Network (MILNET) – split from ARPANET as a specialized network




reserved for high-security military usage
Computer Science Network (CSNET) – funded by the National Science
Foundation (NSF) for educational and research institutions with no access to
the ARPANET
National Science Foundation Network (NSFnet) – developed as an addition to
CSNET
Because It’s Time Network (BITNET) – developed by City University of New
York to link IBM mainframes at universities
Joint Academic Network (Janet) – developed in the United Kingdom to link
universities
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Commemorative Plague on the
Birth of the Internet
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Internet Connectivity
 Major changes to Internet began in the 1990s when
new Internet backbone was created with the four
network access points (NAPs), and more of them
later
 Backbone – a high-speed network that connects to other
networks
 Peering agreements between network owners and
Internet service providers (ISPs) were created to
exchange network traffic
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Internet Connectivity…
 Internet service providers (ISPs) provide the software needed to connect
to the Internet, browse the Web, send and receive e-mails messages, and
transfer files. They sell Internet access to users
 A modulator-demodulator (modem) is device that enables an Internet
connections by converting signals between a computer and the
transmission line
 Common connections that allow data to travel between computers and the
Internet include:
 T1 and T3 line connections
 Digital Subscriber Line (DSL)
 Cable
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Internet Resources
 Resources used on the Internet include:







World Wide Web (WWW)
Electronic Mail (E-mail)
Commercial Services
Newsgroups
Web blogs
Social Networking
Games
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World Wide Web (the Web)
 Origins started at the European Laboratory for
Particle Physics (CERN) in Geneva, Switzerland
 By Tim Berners-Lee in 1990/91
 Also called the “Web”
 After the initial surge of interest on the Web, a need
arose for a standards organization to set
recommended practices for the Web
 The World Wide Web Consortium (W3C) was founded to
meet the growing need on the Web
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World Wide Web Consortium (W3C)
 The W3C (http://www.w3.org) was founded in 1994 at the
Massachusetts Institute of Technology (MIT)
 Led by Tim Berners-Lee
 The W3C sets standards for the Web and provides an open,
nonproprietary forum for industry and academic
representatives to add to the evolution of the Web
 Various committees that make up the W3C look to expand and
set standards for many new Web technologies
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Web Terminologies
 Link (hyperlink or hypertext link) – text, graphic, or other Web
elements that connects to additional data on the Web
 Web Page – a document on the Web
 Uniform Resource Locator (URL) - a unique address used to
identify documents on the Web
 Web Browser – software for displaying Web pages
 E.g. Mosaic, Navigator, Internet Explorer, Opera
 Web server – makes Web pages available on the Web
 Hypertext Transfer Protocol (HTTP) – the default protocol
(program) used on the Web to help transfer files
 Hypertext Markup Language (HTML) – the language used to
define the structure and content of Web pages
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Hypertext Markup Language (HTML)
 HTML is a markup language – a structured language to
identify common sections of a document such as headings,
paragraphs, and lists
 Tim Berners-Lee formally created HTML in 1992 at the CERN
labs (in Switzerland) originally for simple document structure
 Berners-Lee adopted only elements of SGML (Standard Generalized
Markup Language) for representing basic office documents such as
memos and reports

SGML – an international standard for representing text in an electronic form
for exchanging documents independently
 The first draft included elements such as titles, headings, paragraphs,
and lists
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Properties of HTML
 Web browsers interpret HTML markup elements and
display the results
 HTML adopts many features of SGML including:
 Cross-platform compatibility
 Markup elements such as headings, lists, paragraphs, etc
 HTML is an open, nonproprietary language
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Structure of HTML
 HTML uses a combination of tags, attributes, and values
to generate results
 E.g. <body bgcolor=“red”>



body – is the element in a tag
bgcolor – is the attribute of the <body> tag
red – is the value of the attribute in optional single/double
quotes
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HTML Page Format
<html>
<head>
</head>
<body>
</body>
</html>
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eXtensible Markup Language
(XML)
 A set of guidelines for delimiting text through a system of
tags
 Follows rigid guidelines
 Allows information to be defined with tags
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eXtensible Hypertext Markup Language
(XHTML)
 Combines the rules and syntax guidelines of XML with
HTML
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XHTML Page Format
 XHTML pages follow a basic structure as follows
1.
2.
3.
4.
5.
6.
7.
8.
<?xml version”1.0” ?>
<!DOCTYPE html public “-//W3C//DTD XHTML 1.0
Strict//ENhttp://www.w3.org/TRxhtml1/DTD/xhtml1-strict.dtd>
<html xmlns=“http://www.w3.org/19999/xhtml”>
<head>
</head>
<body>
</body>
</html>
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XHTML Page Format…

Below are the explanations to the XHTML page structure
1.
2.
XML declaration – identifies document as XHTML document
Document Type Definition (DTD) – URL points to a file that outlines
the available elements, attributes, and usage and the three XHTML
DTDs available are:
1.
2.
3.
3.
XHTML Transitional – helps to maintain backward compatibility with older
browsers and access to HTML 4.01 elements
XHTML Strict – does not provide any HTML elements for page appearance
XHTML Frameset – gives access to HTML elements for framesets
XHTML Names – URL points to a files that gives detailed information
about the particular XML vocabulary (XHTML)
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HTML vs. XHTML
 Some major differences between HTML and XHTML
include the following:
 All element attributes names are in lowercases
 E.g. <p> instead of <P>
 All attribute values must be contained within single or
double quotes

E.g. <body bgcolor=“#ffffff”> instead of <body bgcolor=#ffffff>
 All nonempty elements must have a closing tag
 E.g. <p>XHTML</p> instead of <p>HTML
 All empty tags should be written with a space and a /
symbol at the end of the tag

E.g. <br /> instead of <br>
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HTML & XHTML Developments
 HTML versions 1.0, 2.0, 3.0, 3.2, 4.01 released from 1989
through 1999
 XHTML versions 1.0, 1.1 released in 2001, 2002 respectively
 XHTML version 2.0 was discontinued
 HTML 5.0 and XHTML 5.0 in development
 HTML 5.0 – by Web Hypertext Application Technology Working Group
(WHATWG) led by Ian Hickson (from Google, formerly of Opera
Software)
 XHTML 5.0 – by an HTML Working Group
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Versions of HTML & XHTML
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HTML5 Page Format
 XHTML pages follow a basic structure as follows
<!DOCTYPE html >
<html>
<head>
</head>
<body>
</body>
</html>
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Dynamic HTML (DHTML)
 A collection of different technologies including:
 HTML/XHTML
 CSS
 JavaScript
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Style Sheets
 Style sheets separate display properties from the content
 The separation of style and structure was accomplished in 1996 by the
W3C’s specification for a Web style language named Cascading Style
Sheets (CSS)
 SGML and HTML were designed to represent document
structure, not style
 Style elements such as <fonts> were introduced by browser
developers to help HTML authors bypass this HTML design
limitation
 Mixing style information within a document limits the crossplatform compatibility of Web contents
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Cascading Style Sheets (CSS)
 Allows authors to create style rules for elements and
express them externally in a style sheet document
 Used mainly to separate presentation from the structure
of a page
 Presentation – “looks” of a page
 Structure – “meaning” of a page’s content
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JavaScript
 Developed by Netscape
 Has become almost as popular as HTML
 Has nothing to do with the Java Programming Language
 But Netscape licensed the name from Sun Microsystems in
hopes of increasing acceptance of the new scripting
protocol
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Web Application
 An application on Web sites that delivers dynamic data
using:
 DHTML
 Database – stores data for future retrieval and update
 Server-side scripting – such as like Active Server Pages
(ASP), Java Server Pages (JSP), ASP.NET, ColdFusion, PHP, etc
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