Using IIS URL Rewrite module instead of Global.asax for complex redirect rules

Question

We have a legacy ASP.NET website in which complex redirect rules are coded in Global.asax. Actually this logic processes requests with several optional or variable parts like

{http|https}://[www.]ourdomain.com/[Home/]Products/old-product-name/page.aspx

and redirects them to

https://ourdomain.com/new-product-name/

Theoretically this logic can be rewritten with a set of rules for the IIS URL rewrite module. I am considering this approach for two reasons. First, this should simplify the redirect logic as it will be written as a set of declarative rules. Second, we need to add more and more redirect rules, and it will be simpler to do this in the format of the URL Rewrite rules.

The question: does it make sense to rewrite our redirect logic with the URL Rewrite module? Can it lead to performance degrade and the like? Or maybe, the best way to do what we need is to use Global.asax together with the URL Rewrite rules, coding complex rules in Global.asax and using URL Rewrite for simple redirects?

Answer 1

As long as your rules can be expressed as regular expressions for the paths, combined with conditions related to headers, server variables, etc. they can be rewritten as URL Rewrite rules. Obviously you can't have any specific application data linked to the rules (those should be included in your app, probably in the global.asax file or in an HTTPModule.

You'll get better performance, they will be independent of the application code or technology, will be easier to maintain and you'll have extra features such as internal rewrites of the requests instead of redirections (for example to expose friendly URLs but use "ugly" ones internally), redirection maps that you can manage separately, and many more.