27/01/10

Directives may be global/server-wide (server config) directives
    - these apply  across the whole server/web site

Or they may be placed within container directives

e.g. directory level (applies to the directory and all its sub-directories)
    <Directory /users/20120/dtab2/CS2510/htdocs/fr/>
        DefaultLanguage fr
    </Directory>
    
e.g. file level
    <Files *.gif>
        ...
    </Files>
    
e.g. location (i.e. start of a URL)
    <Location /en>
        ...
    </Location>
    
Or they may be place within conditional containers e.g. IfModule
    <IfModule mime_module>
        AddEnecoding x-gzip .gz
    </IfModule>

Directives may also appear in a per-directory configuration file, whose name is usually .htaccess
    - Directives in .htaccess files apply to the directory where the .htacess file lives and all
      its sub-directories
    - Flexibility: unlike changes to httpd.conf, if you change .htacess, you don't need to restart
      server for directives to take effect; makes it possible for people to put .htaccess
      files into their own public_html directories to configure their part of the web site
    - Cost: for each request from the client, server searches for .htaccess files in each
      directory from the root of the filesystem down; also people may put foolish directives
      into these files.
    - If the cost is too high, we can disable by putting directives into httpd.conf
    - E.g. to disallow .htaccess files
        <Directory />
            AllowOverride None
        </Directory>
    - E.g. to disallow at top of the filesystem but allow them lower down (thus reducing the cost)
        <Directory />
            AllowOverride None
        </Directory>
        
        <Directory /users/2012/dtab2/CS2510/htdocs/>
            AllowOverride All
        </Directory>
    - E.g. to allow .htaccess files but only allow them to contain a subset of directives
                <Directory />
            AllowOverride None
        </Directory>
        
        <Directory /users/2012/dtab2/CS2510/htdocs/>
            AllowOverride FileInfo
        </Directory>
        This allows only those that belong to the FileInfo group of directives.