IIS Aid

Yes I know I've already written a guide for using ISAPI Rewrite to generate clean URL's with Drupal, however Helicon have taken a vastly different approach with the release of ISAPI Rewrite 3 to the extent where it is more than likely your ISAPI Rewrite 2.x rules will not work with it. The reason for this is that Helicon have restructured ISAPI Rewrite so that it now uses the same syntax as the popular Mod Rewrite module for the Apache web server. Why they have done this after having established a solid product over the last 5 years is anyones guess, but I'd say it has a lot to do with the fact the ISAPI Rewrite support forums are swamped with "how do I convert these .htaccess rules to ISAPI Rewrite" style questions. So lets take a look.

Helicon have done a comprehensive job with implementing the Mod Rewrite structure into ISAPI Rewrite 3, but as there are several Mod Rewrite directives that are tied directly to the Apache architecture they haven't been able to implement everything. You can find more information on ISAPI Rewrite 3 compatibility with Apache here. Fortunately this has no effect for us with Drupal as all the rewrite rules used here can be used directly. And I do mean directly.

If you have purchased the full version of ISAPI Rewrite 3, then there is little for you do to as ISAPI Rewrite 3 should be able to read the rules from the Drupal .htaccess file directly. Although I have purchased the full version myself, I am yet to make the upgrade from 2.x as I don't feel I've done enough testing with it yet. I will update this section with any tips and tricks I might discover after I have made the upgrade myself.

For those of us unable to shell out the $99USD for a license to get the full version of ISAPI Rewrite, then there is still the option of using the Lite version which is free to use. The Lite version of ISAPI Rewrite has most of the functionality of the full version, but as you might expect is operating with a few limitations of which the biggest one being it only supports a single global level httpd.conf file. This in nothing new as this limitation has always existed in the Lite version and in no way means that you can't get all the functionality you need for creating clean URL's for Drupal. All we need to do here is transpose the .htaccess rules along with a few other tricks over to the global httpd.conf

Step 1 - Transpose your .htaccess rules

First step after installing ISAPI Rewrite 3.x Lite is to open your httpd.conf file which stores all the global level rules which is located in your ISAPI Rewrite installation directory. Once opened, enter the following;

If you installed Drupal in the root of your website and it is the only website to be server on this server, then all you need to do from here is save the file and move onto step 4. However, if you have installed Drupal into a sub directory and/or have several websites on your server and only want these rules applied to your Drupal site then you'll need to read on through steps 2 and 3.

Step 2 - Adding a rule for sub directory Drupal installations

If you have installed Drupal into a sub directory off your website root, then you'll need to make a small modification to the RewriteBase directive as shown below;

This example assumes you have installed into a sub directory called drupal. If you have installed into another directory simple exchange "drupal" in the RewriteBase rule with the name of the directory you installed into.

Step 3 - Rewriting only for specific domains

One of the biggest limitations of the Lite version of ISAPI Rewrite is that you have only one global configuration file which is applied to all your websites. This meaning that any other websites on your server not using Drupal will have these rules applied to them which could very well break them. The work around to this is to use the RewriteCond directive to specify which hosts these rules should be applied for as shown below;

This example assumes that you only want these rules to apply to www.example.com and example.com. Simply exchange this domain name for the one you installed Drupal on and you should find that your Drupal rules are only applied to this domain.

Step 4 - Configuring settings.php

The final step is to tell Drupal to turn on Clean URL's. This is a little more complicated for IIS users than it is for Apache users as Drupal uses the REQUEST_URI server variable to check for clean url compatibility. The problem is that while Apache supports the modification of server variables, IIS does not. So no matter what URL rewriting tool you use for IIS, it is never going to pass the clean url test from the Drupal admin control panel.

There are two ways in which you can get around this though. First is to manually override the Clean URL test by setting the following directive in your settings.php file for your site;

$conf['clean_url'] = 1; // 1 enables, 0 clears clean_url

The other way is to use the HTTP_X_REWRITE_URL variable that ISAPI Rewrite 3.x uses for Apache compatibility. This requires you to add the following to your settings.php file;

The advantage of using this method is that Drupal will now pass the clean url test, so you can enable/disable clean url's from the Drupal admin panel rather than having to comment out the the manual override setting.

That's it. You should now have clean URL's with you Drupal installation using ISAPI Rewrite 3.x. If you have any comments, questions or other feedback please feel free to leave a post in the comments section here or in the forums.