- The WWW is made up of
two types of computer programs
:
- Web Servers
(e.g., Apache - click here )
- The Web Server stores web pages in a directory
- Web Clients
(e.g., Firefox -
click here ,
Internet Explorer -
click here )
- Web clients are computer programs used to receive webpages and display (render) them
- Web Servers
(e.g., Apache - click here )
- Website/Webpages:
- In fact, THIS WEB PAGE is written in HTML....
A web site is nothing more (and nothing less) than a collection of computer files (= webpages)...
These computer files (webpages) are written in a special language called HTML (Hyper Text Markup Language)
- Structure of the World Wide Web (WWW):
- Webpage:
- web page = an
HTML file
- HTML file = a file written in the HTML language
- web page = an
HTML file
- HTML "markup" language:
- HTML uses
tags to
specify how
an item in a file
is to be displayed
- Example:
<B> xxxxxx </B> text is bolded <I> xxxxxx </I> text is italized <B><I> xxxxxx </I></B> text is bolded and italized
- HTML uses
tags to
specify how
an item in a file
is to be displayed
- The
primary function
of a Web server:
- Deliver (= transmit)
HTML files
(= web pages) inside a special
"Document Root" directory
to
clients
- The Document root
is usually named htdocs
- The Document Root directory contain sub-directory that contain the user web sites (files in HTML).
- The Document root
is usually named htdocs
- Deliver (= transmit)
HTML files
(= web pages) inside a special
"Document Root" directory
to
clients
- Secondary
service (extensions)
of a Web server:
- execute ("sanctified") programs stored in some special directory
This special directory contains pre-approved programs (i.e., virus-free) that can be executed by the Web server.
- A special Web server
has been set up in support for the
CS377
course in
teaching web access of database
holland.mathcs.emory.edu
- CS377 students:
- Every student in the cs377 course has a web site at this web server
- Accessing your own
web site on
holland.mathcs.emory.edu:
ssh -X yourID@holland.mathcs.emory.edu cd ~/public_htmlHTML files stored in the directory ~/public_html can be served by the webserver at holland.mathcs.emory.edu.
- Example:
- I have the following HTML file
in
~cs377001/public_html/intro/hello1.html
<html> <head> <title> CS377 Hello page </title> </head> <body> <UL> <H2> Hello world ! </H2> </UL> </body> </html>
The URL of this web page is:
http://holland.mathcs.emory.edu/~cs377001/intro/hello1.html
- You can also click on the following
hyperlink to access the "Hello page" of cs377001:
Explanation:
- When you click on the:
http://holland.mathcs.emory.edu/~cs377001/intro/hello1.html link,
the browser sends the HTTP request message to holland.mathcs.emory.edu requesting the webpage "hello1.html" from user cs377001:
- The file
/home/cs377001/public_html/intro/hello1.html
is then
returned (in an HTML message)
by the web server:
- The Web browser receives the
file
/home/cs377001/public_html/intro/hello1.html
and
then "renders" the
file content
in the browser's window:
- I have the following HTML file
in
~cs377001/public_html/intro/hello1.html