Download Part I

ULI101 – XHTML Basics (Part I)
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Internet / Web Concepts
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Brief History
TCP/IP
Web Servers / Web Browsers
URL
HTTP / HTML
Internet - History
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Computers were not always set-up to form networks
Critical Periods:
 1957 – USSR launches Sputnik I & II launches
(starting the “space-race” between USSR & USA)
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1958 – U.S. government developed 2 agencies to keep up
with technologies:
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NASA (National Aeronautics and Space Administration)
ARPA (Advanced Research Projects Agency)
This agency’s purpose was to allow U.S. technology to “keepup” with the USSR.
Internet - History
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ARPAnet (Late 60s)
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Network of computers to keep computer networks operational in case
of Nuclear war. Also allow communication among defense research
scientists.
Allows for “packet-switching”
Known as the ancestor to the “Internet”
ARPAnet lead to a development of many other key
technologies such as:
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Telnet (1970).
FTP (1972)
E-mail standard (using “@” symbol after username - 1973)
TCP/IP (1977)
Internet - History
TCP/IP
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(Transmission Control Protocol / Internet Protocol)
Considered to be the basic communication
language of the Internet.
TCP/IP is a two-layer Program:
Higher Layer:
TCP
Lower Layer:
IP
Manages the assembling or file into packets that are
transmitted over the Internet and received by a TCP
layer that resembles the packets into the original
message.
Handles the address portion of each package so that
it gets to the right destination. Each gateway
computer on the network check this address to see
where to forward message
Internet - History
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National Science Foundation (NSF)
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In the mid 1980s, the National Science Foundation (NSF) funded the
purchase of 5 supercomputers, to be located in different parts of the
United States.
The NSFnet was formed to link these supercomputers and allow
institutions in other parts of the country to access and share the costly
machines. This was to be the first backbone of the Internet.
Network Access Points (NAPs)
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In the mid 90s, as commercial interest in the Internet increased, the
NSFnet was replaced by a backbone of commercial networks,
connected by Network Access Points (NAPs).
World Wide Web - History
Critical Periods:
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80s – Networks in widespread use, but although hyperlinks
existed, they were not consistently applied.
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Tim Berners-Lee (considered to be the father of the World Wide Web)
developed method to allow fellow CERN employees to communicate
and share ideas via hyperlinks.
This lead to the development of:
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HTTP Server / FTP Server
Hypertext Transfer Protocol (HTTP)
Hypertext Markup Language (HTML)
Uniform Resource Locator (URL)
Line-mode browser
The World Wide Web (www) is a subset of the Internet. The www
amounts to text documents that are stored on computers. The
www are all the resources on the Internet that use HTTP.
World Wide Web - History
Critical Periods:
 90s – Tim Berners-Lee made these key technologies
available to the public via download. Allowed CERN to
release code and technology to the public domain.
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1993 – First graphical web browser called Mosaic created
by Marc Andreesen while working for NCSA.
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Mosaic was originally created for the X-window platform.
Release of Mosiac browser triggered interest in the World Wide
Web.
1994 – Marc Andreesen left NCSA to form Netscape
Communication Corporation with Jim Clark.
Web Concepts
The Internet
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The Internet is a global communications network consisting of thousands of
networks typically interconnected by fiber optic cabling.
The World Wide Web (WWW)
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The World Wide Web The Web is a conglomeration of what amounts to text
documents, stored on computers on the Internet, and available for examination
by users of the Internet, anywhere in the world.
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The World Wide Web is all the resources and users on the Internet that are using
what is known as the Hypertext Transfer Protocol (HTTP). According to Tim Berners-Lee:
“The World Wide Web is the universe of network-accessible information, an embodiment of
human knowledge."
Web Concepts
Web Browser
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A Web browser is a program (Netscape or Microsoft Internet Explorer)
that allows you to view information on the World Wide Web in a graphical
format. The standard for Web browsers is that they interpret HTML
(Hypertext Markup Language) documents, at the very least.
Web Concepts
Web Server
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A web server program uses a client/server model that makes use of the
World Wide Web’s Hypertext Transfer Protocol (HTTP) to serve files that
form Web pages to Web users.
Web server
hosts the pages,
scripts,
programs, and
multimedia files
via HTTP
Server-Side
Client-Side
Web Server
Web Pages
Internet
Web
Browser
Note: The two leading Web Servers are:
• Apache (Unix, Linux, Windows)  most widely used
• MS Internet Information Server (MS-Windows)
Web Concepts
HTML
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Considered basically as a document language – mainly to design and display data (e.g. text,
links, images) in a browser.
HTML was one of the first simple-to-use languages derived from a more complex and harderto-learn language developed earlier called SGML (Standardized General Markup Language).
Appearance (in web browser)
code
<html>
<head>
<title>Sample Title Name</title>
</head>
<body>
Information to be displayed
</body>
</html>
Tags can be used to enhance
the display of text on the web
browser. Links can be created
to connect to other web pages.
Web Concepts
Domain Name Server (DNS)
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Static IP addresses are shown in groups of numbers separated by
periods (eg. 123.123.23.2)
Since static IP addresses are hard to remember, a Domain Name
can be associated with a static IP address
www.tucows.com
Last element indicates type of website.
Indicates the
protocol – in this
case, the
world wide web.
Middle element indicates name
of server.
Note: A domain name always goes from general
information on the right to specific information on the left
Web Concepts
Domain Name Server (DNS)
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The last element in the DNS can relate to many things such as
commercial site, organization, government (even country).
A present, there are over 200 recognized country domains.
Below is a chart of commonly recognized domain names
Domain
.com
.edu
.gov
.mil
.net
.org
Description
Commercial
Educational institute
Government
Military
ISP
Non-profit organization
Domain
.ae
.am
.ar
.br
.ca
.uk
.us
Description
United Arab Emirates
Armenia
Argentina
Brazil
Canada
United Kingdom
United States
Web Concepts
Universal Resource Locator (URL)
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Considered to be the website address.
Also referred to as URI (Uniform Resource Indicator)
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Various formats for a URL/URI include:
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Protocol://domainname
(e.g. Webpage)
Protocol://domainname:port
(e.g. Streaming audio)
Protocol://domainname:port/uri (e.g. .Net applications)
Web Concepts
Web Developer Tools
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There are many tools that a web developer can use to create web pages:
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Graphical Web Authoring Applications (e.g. Dreamweaver)
Graphical Editing Applications (e.g. Paintshop Pro, GIMP, etc)
Other tools (SSH, FTP, etc…)
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In this course, you will be required to use only a text editor (like vi, nled,
pico, etc…) to create or edit your web pages. (i.e. graphical authoring
applications are not allowed).
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You will have an account on a server called Matrix to practice and work
on web page assignments.