Which redirection is better - web.config or global.asax

I need to redirect some of the older pages in my application to new pages. I thought urlMapping in web.config is the efficient way to achieve this. But there is also another开发者_开发百科 way to redirect using global.asax. Which one is the efficient way for this. At what point in request execution does this asax and config file comes into the picture?

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If I were mapping existing pages to new ones I would keep the old pages in place and flush a 301 permanent redirect to the client. This will preserve SEO, assuming this is a public site.

 Response.StatusCode = 301;
 Response.Status = "301 Moved Permanently";
 Response.RedirectLocation = location; // static, configuration, or database
 Response.End();

Overall I would go with rerouting instead of rewriting. Two great links for this are:

• Chris Cavanagh - ASP.NET Routing… Goodbye URL rewriting?
• Phil Haack - Using Routing With WebForms

For an overview of some different approaches prior to rerouting check out Scott Gu's Tip/Trick: Url Rewriting with ASP.NET

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Use the URL Rewrite ISAPI filter to do the redirect - it is lower level and will run first, so you don't take a hit on the asp.net engine.

The page I linked also mentions ASP.NET Routing, the differences between them and how to choose between the two.

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Here is one of way to write redirect by HttpHandler.

http://www.developerfusion.com/article/4643/implementing-http-handlers-in-aspnet/