Creating a Custom HTTP Handler : HTTP Handlers « Development « ASP.NET Tutorial

Create a class that implements the IHttpHandler interface. 
Place this class in the App_Code directory. 

using System;
using System.Web;

namespace HttpExtensions
{
    public class SimpleHandler : IHttpHandler
    {
        public void ProcessRequest(System.Web.HttpContext context)
        {
            HttpResponse response = context.Response;
            response.Write("<html><body><h1>Rendered by the SimpleHandler") ;
            response.Write("</h1></body></html>") ;
        }

        public bool IsReusable
        {
            get {return true;}
        }
    }
}

Configuring a Custom HTTP Handler

<?xml version="1.0"?>
<configuration xmlns="http://schemas.microsoft.com/.NetConfiguration/v2.0">
  <system.web>

    <httpHandlers>
      <add verb="*" path="source.simple" type="SourceHandler"/>
      <add verb="*" path="test.simple" type="SimpleHandler" />

    </httpHandlers>
  </system.web>
</configuration>

9.24.HTTP Handlers
	9.24.1.	Creating HTTP Handlers
	9.24.2.	Creating a Generic Handler
	9.24.3.	HelloWorld HttpHandler (VB)
	9.24.4.	Implementing the IHttpHandler Interface
	9.24.5.	RSS Handler
	9.24.6.	Creating a Custom HTTP Handler
	9.24.7.	Log user in HttpModule
	9.24.8.	Source viewer Http Handler