Search Engine Optimization(SEO) and URL Rewriting using HTTPModules - Microsoft ASP.NET

Implement IHttpModule interface, which has Initialization(public void Init(HttpApplication context)) methods. In there we attach URL Rewrite method to AuthorizeRequest (for windows authorization)
Note:This is a simplified version. For more information please see references at the end of this post.

namespace Root.Client.SEOHandler
{

public class SEOModule : IHttpModule
{

public void Init(HttpApplication context)
{

context.AuthorizeRequest += new EventHandler(SEOModuleAuthorizeRequest);

}

void SEOModuleAuthorizeRequest(object sender, EventArgs e)
{

HttpApplication app = (HttpApplication)sender;
/* note:
we must implement switches collection in CustomConfiguration as a property. See complete description of how to implement a custom configuration section in web.config please see Adding new section to web.config - Microsoft ASP.NET
*/
List switches =((CustomConfiguration) HttpContext.Current.Cache [“customConfiguration”]).Switches;
for (int i = 0; i < switches.Count; i++)
{

string lookFor = string.Format("{0}/{1}",app.Context.Request.ApplicationPath,switches[i]);
if(string.Compare(lookFor,app.Request.Path)==0)
app.Context.RewritePath(
string.Format(“{0}/{1}”,"required_page.aspx", app.Context.Request.ApplicationPath);

}

}

}

}


Register assembly in web.config
<configuration xmlns="http://schemas.microsoft.com/.NetConfiguration/v2.0">
...

<system.web>
...

<httpModules>

<add name="SEOModule" type="Root.Client.SEOHandler.SEOModule" />
...

</httpModules>
...

</system.web>
...

</configuration>


Reference: URL Rewriting in ASP.NET