Lab - Web

• Background pages
  • How to set up and maintain Web pages
  • Coding a webpage with HTML tags

• The two addresses:
  • Linux file system address: $HOME/public_html/index.html
  • Web address (URL): https://student.computing.dcu.ie/~username/

• student.computing.dcu.ie
  • Runs Linux
  • This has access to your home directories (on shared / distributed file system).

• Mapping of URLs to files:

  URL	maps to this file
  https://student.computing.dcu.ie/	/var/www/html/index.html
  https://student.computing.dcu.ie/CompuTY/index.html	/var/www/html/CompuTY/index.html
  https://student.computing.dcu.ie/mhumphrysdculab/	/var/www/html/mhumphrysdculab/index.html (does not exist)
  https://student.computing.dcu.ie/~mhumphrysdculab/	/users/tutors/mhumphrysdculab/public_html/index.html

  
  

• www.computing.dcu.ie
  • or just computing.dcu.ie
  • Runs Linux
  • Accesses a different file system.
  • Server home page https://www.computing.dcu.ie/ is a redirect to the main university site. The server is there just to host user pages.
  • My home page https://www.computing.dcu.ie/~humphrys/ is also a redirect to my own site.

• Tilde convention:
  • Comes from Unix command-line. Means home:
    cd ~/bin is same as cd $HOME/bin
  • student.computing.dcu.ie and www.computing.dcu.ie both use tilde convention for user web pages.

  
  

• Two web servers:

  URL	server IP	server OS	result
  https://student.computing.dcu.ie/~STUDENT/	136.206.218.15	Linux	Works.
  https://student.computing.dcu.ie/~STAFF/	136.206.218.15	Linux	Fails. Can't access other file system.

  URL	server IP	server OS	result
  https://www.computing.dcu.ie/~STAFF/	136.206.217.26	Linux	Works.
  https://www.computing.dcu.ie/~STUDENT/	136.206.217.26	Linux	Fails. Can't access other file system.

• Try the servers with a userid that exists (but is on the other system) v. a userid that does not exist at all. See what the error messages are.

Exercise 1

1. Make a web page:

   cd
   cd public_html
   gedit index.html &
   

2. Put some HTML in it.
3. View it as: https://student.computing.dcu.ie/~username/

4. Make another page p2.html
5. Make index.html link to p2.html
6. Make p2.html link back to index.html
7. View both pages through the browser.

Exercise 2

1. Insert an img tag in page to display an image
2. First include a remote picture e.g. Mona Lisa at Wikimedia Commons
3. Then copy the image to your own public_html
4. Then make img point to that.

Look at some tags

title 
h1, h2, h3 
p, br, hr 
a, img
ol, ul, li

b, i
center 

pre