Google Data Center Efficiency

URL Rewrite Examples

Rewrite Right - Flickr Photo One of the most common Webmaster task is to use mod_rewrite Apache module. It’s a flexible and efficient way to redirect URLs. It is useful to redirect non-functional URLs, moving domain names or renaming directories.

Below is a list of some of the frequently used mod_rewrites.

Note the [R=301] entries for 301 Permanent Redirect directive on the rules. It’s a popular use to preserve SEO rankings of an older site that has been moved to a new one.

Simple redirect:

RewriteRule ^/sub/dir/home.html$ /sub/dir2/page.html [R=301,L]

Redirect http://domain.com to http://www.domain.com. This is especially useful for an SSL certificate that’s already registered to www.domain.com name. Note, the rule captures the query string and redirects with it:

RewriteCond %{HTTP_HOST} ^domain.com$ [NC]
RewriteRule ^(.*)$ http://www.domain.com$1 [R=301,L]

To capture more than one variables in the query string, use the following.

RewriteRule ^([^/]*)/([^/]*)/([^/]*)$ /sub/program.jsp?arg1=$1&arg2=$2&arg3=$3 [L]

For redirects based on the URL’s query string, use QUERY_STRING to capture it for comparison. Note the destination URL may use spaces if enclosed in quotes.

RewriteCond %{QUERY_STRING} ^id=2234$
RewriteRule ^/sub/dir/product.html$ “/sub/dir3/description.html?prodid=vac pro” [L,R=301]

Redirects can also be conditional. For example, redirect everything except with a certain keyword.

RewriteCond %{REQUEST_URI} !/sub/dir/important.html$
RewriteRule ^/sub/dir/.*$ /main/dir/home.html [L,R=301]

With the above rule, it’s possible the original URL may have a query string. To get rid of it, just add “?” to the end of target RewriteRule. For example:

RewriteCond %{REQUEST_URI} !/sub/dir/important.html$
RewriteRule ^/sub/dir/.*$ /main/dir/home.html? [L,R=301]

There are more examples out there. Writing a comprehensive mod_rewrite guide is a full time job, so this list will continue to grow. Here are some other useful references:

Photo Credit: Luke Seeley

Custom 404 Page Using JBOSS

4 Replies

Missing Puzzle Having a custom “page not found”, or 404 page, is an important modification for any website. It’s used to enhance the user experience by presenting an easy to understand message.

Setting up a user friendly error page is simple enough using Apache web server. Just modify the line in httpd.conf and point it to a static HTML document:

ErrorDocument 404 /the404_page.html

With JBOSS (or Tomcat-like Java container) application server, it’s slightly trickier. It has to be handled per web application basis. The change is done on the web.xml file, with these entries:

<web-app>

<error-page>
<error-code>404</error-code>
<location>/the404_page.html</location>
</error-page>

</web-app>

For the root directory, modify the web.xml in the ./deploy/jboss-web.deployer/ROOT.war/WEB-INF directory.

Testing this setup in Firefox and Opera, the custom 404 page will automatically show up properly.

However, with Internet Explorer, a “The Webpage Cannot Be Found” message comes up instead. This is a feature of IE to show Microsoft’s version of a “friendlier error message”. In this case, we want to disable it, so the custom 404 page will show up. It can be done via Internet Options -> Advanced tab :

Update: Microsoft Help & Support site states if the 404 error page is greater than 512 bytes, then IE will not show the friendly message. So the page size must be a bigger one, not just a simple one liner.

Now that the applications are setup to serve up custom error page, here are some examples of beautiful 404 page designs to improve the user experience.

Building IT

Making Sense of Information Technology

Google Data Center Efficiency

URL Rewrite Examples

Custom 404 Page Using JBOSS