Keyvan Nayyeri

It’s obvious that I’m trying to support the wave of NO-WWW! A long time ago I had written a HttpModule to remove “WWW.” from URLs. Last year I wrote a post with some topics for simpler URLs in web applications including an alternative solution to accomplish this task using ISAPI filters in Internet Information Services. Recently I also wrote another post about the issues related to SSL certificates and these extra characters in URLs.

One of the goals that I’m trying to accomplish is collecting all the possible ways to have WWWless URLs in the ASP.NET web applications, and I will keep writing such posts in the future as well. For now, I want to offer the simplest way to accomplish this in ASP.NET and IIS 7.0.

Today I spent some time switching from ISAPI filters to Microsoft URL Rewrite Module for IIS 7.0 and use it as an alternative for ISAPI tasks on Waegis and Nayyeri.NET. As you may know, this module is a very cool addition to the great new features in IIS 7.0 to complement it in one of the most common scenarios which is URL rewriting.

Beside the replacement of URL rewriting mechanism on Waegis (which was previously done with UrlRewriter.NET), I also removed Ionic ISAPI filter to implement Microsoft URL Rewrite module in order to redirect requests to URLs with “WWW.” prefix to the new URLs without it.

Here is the classic configuration of the rule necessary to remove “WWW.” from all the URLs on a domain with a permanent redirect to the new address.

The equivalent manual configuration is this:

But how does it work? First it checks for all the requests defined by the regular expression pattern in <match /> element that includes all the requests.

In the second step it checks the rules defined in <conditions /> section. If these conditions are met, and request has matched the pattern, then it applies the action defined in <action /> element. Here I defined my element as a pattern for HTTP_HOST parameter. When it matches the pattern (so it begins with “WWW.”), it passes the condition.

In the action I use a redirect task to the new URL which is a combination of my domain name and PATH_INFO parameter that yields my desire result. I also use the permanent redirection which is the recommended redirection type for this case.