Lab - Web

1. web page
   • How to set up and maintain Web pages
   • put home page in: $HOME/public_html/index.html
   • visible at: http://student.computing.dcu.ie/~username/
   • More on student.computing.dcu.ie

2. student.computing.dcu.ie
   • Linux cluster
   • It has access to your home directories (on shared / distributed file system).
     e.g. your web dir, which it can put online:

      /users/mse1/USERNAME/public_html 
      /users/gdf1/USERNAME/public_html 
     

   • It also has its own web dir, which is something like:

       /htdocs  
       /srv/www/htdocs  
       /local/apache/htdocs  
       etc.
     

     On Linux PC login (with distributed file system) you cannot see this dir.
     But on ssh direct login to student.computing.dcu.ie you can see it.

   
   

   URL	maps to this file	on this filesystem
   http://student.computing.dcu.ie/	/local1/apache2/htdocs/index.html	non-shared (can see it through ssh)
   http://student.computing.dcu.ie/STRING/	/local1/apache2/htdocs/STRING/index.html	non-shared (can see it through ssh)
   http://student.computing.dcu.ie/~STRING/	/users/group/STRING/public_html/index.html	shared

   
   

3. More on the tilde convention:
   • Can use it at command-line:
     cd ~/bin is same as cd $HOME/bin
   • www.computing (also here) is running Solaris. Uses similar tilde convention for user web pages.

   
   

4. two web servers, two file systems:

   URL	server IP	server OS	result
   http://student.computing.dcu.ie/~STUDENT/	136.206.11.245	Linux	Works. STUDENT files are on Linux file system.
   http://student.computing.dcu.ie/~STAFF/	136.206.11.245	Linux	Fails. STAFF files are on Solaris file system. Linux server cannot access Solaris file system. Linux command-line cannot access Solaris file system.

   URL	server IP	server OS	result
   http://www.computing.dcu.ie/~STAFF/	136.206.11.240	Solaris	Works. STAFF files are on Solaris file system.
   http://www.computing.dcu.ie/~STUDENT/	136.206.11.240	Solaris	Fails. STUDENT files are on Linux file system. This fails, even though Solaris server can access Linux file system. Solaris command-line can access Linux file system. (*)

   (*) Solaris command-line can access Linux file system:
   When I am logged into Solaris machines, I can access Linux dirs:

    /users/mse1 
    /users/gdf1 
   

   Like the HTTP server, I am now "other" not "group".
   So I can't do an ls, but I can access file if I know its name:
   cat USER/public_html/index.html

   
   

5. Exercise:
   • Make web page
   • make it link to sub-page, which links back to main page
   • chmod -r and see it is now invisible
   • chmod +r and see it is visible

6. Exercise:
   • Make offline web page (not in your public_html).
   • Accessible via file:///
   • It embeds image of Shakespeare found in my directory (embed path to my image, not a copy).