Month: July 2008

URL rewrite module fully utilizes extensibility of IIS 7.0 configuration system. The rewrite rules are stored in applicationHost.config and web.config files in XML format. This provides a huge benefit of being able to use rich set of IIS 7.0 management tools and API’s for managing and scripting URL rewriter configuration. For example, you can automate any configuration task, including creating, editing and deleting of rewrite rules, by:

• writing .NET code that uses Microsoft.Web.Administration API’s;
• writing JavaScript code;
• using IIS command line tool appcmd.exe;
• using PowerShell provider.

The Configuration Editor, included in the Administration Pack for IIS 7.0, greatly simplifies the process of generating scripts for automating URL rewriter configuration. In this post, I will demonstrate how to use the Configuration Editor to automate configuration of rewrite rules.

IIS.NET team has been very proactive in helping us out with testing of URL rewrite module. In fact, they even agreed to deploy the latest build of the module on the production server that hosts http://www.iis.net. This kind of real-life deployments really helps us validate the features and functionality of the module. And being able to do this validation so early in release cycle gives us a good opportunity to adjust the feature set, re-consider some of the design decisions, or just find some very good bugs.

IIS.NET has URL rewriting requirements, which are typical for large content management systems. The articles on the site are often moved or updated and the old links should continue to work. Or there is a need to have a nice URL (for example – http://www.iis.net/fastcgi) for a page that currently has some meaningless URL (e.g. http://www.iis.net/downloads/default.aspx?tabid=34&g=6&i=1521). IIS.NET has more than a hundred of such URL mappings. Majority of those mappings are static, so there is no need to use regular expression patterns, capture groups, back-references or any other advanced URL rewriting stuff. Rewriting logic is very simple:- for example if input URL is “/php” then rewrite it to “/default.aspx?tabid=50001”. But if we tried to define this logic by creating a rewrite rule per URL mapping we would end up with more than a hundred of rules, which would be evaluated for every request. That would kill the performance of the web site.