Author: Mark Wilson

My ISPs’ Apache servers are configured for index.html and index.htm to be the default documents; however since implementing server side includes in my websites I need index.shtml to be recognised as the default document.

Fortunately, this can be achieved using the following directive in the corresponding .htaccess file:

DirectoryIndex index.shtml index.html index.htm

Microsoft Internet Information Server (IIS) users can find information on setting up default documents in the IIS 6.0 Operations Guide.

One of the features used in my website is custom error pages, which allow errors to be handled using a format that matches other documents on the site.

Apache users can configure custom error messages using .htaccess. Once pages have been created for an error message, include a directive in the .htaccess file as follows:

ErrorDocument error-code document

For example, ErrorDocument 404 /errors/404-notfound.shtml will redirect any page not found (HTTP error 404) errors to display the /errors/404-notfound.shtml document.

Full details for Apache users may be found in the Apache core features documentation.

Microsoft Internet Information Server (IIS) users can find information on configuring custom error messages in the IIS 6.0 Operations Guide.

RFC 2616 details all of all HTTP status (including error) codes.

One of the features used in my website is server side includes (SSI). The SSI code allows my sites to include dynamic information which would otherwise require scripting that may not function correctly with certain browsers.

SSI is pretty simple. Apache users need to edit the .htaccess file in their web root directory to allow SSI, adding the following lines:

Options Includes
AddType text/html .shtml

AddHandler server-parsed .shtml

Some of these may not be necessary if they have been set at a higher level in the Apache configuration by the ISP or server administrator – for full details, see the Apache Tutorial: Introduction to Server Side Includes.

Microsoft Internet Information Server (IIS) users can find information on using server side include directives in the IIS 6.0 Operations Guide.

Once enabled, pages which call the server-based code should be named .shtml (or whatever file extension is defined in the configuration). Because my ISP has configured its servers for the default web page to be called index.htm or index.html, it was also necessary to change the default documents for the website.

One use of SSI to reuse common HTML code (e.g. headers, menus, etc.), but another useful application is to report document information (e.g. date last modified). There are many references on the Internet for SSI options, but one of the most useful is Craig McFetridge’s SSI page on the Carleton University website, with another being the one found on the ThinkQuest Amazing HTML website.

A few weeks back, I updated two websites (which run on my ISPs’ Apache servers) to use various features which improve the experience for users of the site. These features include:

• Server side includes (SSI).
• Changing the default web page.
• Providing custom error messages.
• Redirecting clients where pages have changed.
• Preventing listing the contents of certain directories.
• Denying access to certain files.

All of these features (and more) may be controlled on an Apache server using a file called .htaccess, which is intended for users who do not have access to the server configuration to make configuration changes on a per-directory basis.

In general, where access to the server configuration is available, then changes should be made at the server level; however in a hosted environment, .htaccess allows content providers to make their own configuration without affecting other users of the server.

Administrators should be made aware that enabling .htaccess on a server does incur a performance hit as Apache will look in every directory on the path for an .htaccess file, and will load the file, whether or not the directives contained within .htaccess are relevant to the HTTP request. For this reason, some ISPs may prohibit the use of .htaccess.

Microsoft Internet Information Server (IIS) does not have an equivalent to .htaccess and all configuration must be carried out using the various IIS administration tools (along with an appropriate organisational security model).

Links
Apache Tutorial: .htaccess files
Comprehensive guide to .htaccess