title: How to create and add custom httpHandler to existing IIS WebSite
body: <p>I need to add a custom httpHandler to an existing IIS WebSite. I have a Windows Server 2012 R2 with IIS and in IIS i have a WebSite which runs an ASP.NET solution where i have no access to the sources. The ApplicationPool is configured to run with .Net 4.0 and in Integrated Mode.</p>
  
  <p>We want to develop a custom httpHandler as .dll and register this within the WebSite under Handler Mappings. To do so we have created in Visual Studio 2015 a new Dynamic Linked Libary project with the following code:</p>
  
  <pre><code>using System;
  using System.Collections.Generic;
  using System.IO;
  using System.Linq;
  using System.Web;
  
  namespace MinimalStandaloneHttpHandler
  {
      public class Class1 : IHttpHandler
      {
          public Class1()
          {
  
          }
  
          public void ProcessRequest(HttpContext context)
          {
              HttpRequest Request = context.Request;
              HttpResponse Response = context.Response;
              // This handler is called whenever a file ending 
              // in .sample is requested. A file with that extension
              // does not need to exist.
  
              context.Server.Transfer("http://www.google.com", false);
          }
  
          public bool IsReusable
          {
              // To enable pooling, return true here.
              // This keeps the handler in memory.
              get { return false; }
          }
  
      }
  }
  </code></pre>
  
  <p>We have compiled it and the went to IIS -> WebSite -> Handler Mappings -> Add Wildcard Script Map.</p>
  
  <p>Here we added "*" as Request Path, the full path to the .dll and a friendly name. Under Handler Mappings -> My Handler -> Right click -> Request Restrictions -> Mapping -> Unchecked "Invoke handler only if request is mapped to:".</p>
  
  <p>The handler is now listed under the enabled handlers. Now the web.config got modified:</p>
  
  <pre><code>&lt;configuration&gt;
      &lt;system.webServer&gt;
          &lt;handlers&gt;
              &lt;add name="asdasd" path="*" verb="*" modules="IsapiModule" scriptProcessor="C:\inetpub\wwwroot\WebSiteStaticTest\MinimalStandaloneHttpHandler.dll" resourceType="File" requireAccess="None" preCondition="bitness32" /&gt;
          &lt;/handlers&gt;
      &lt;/system.webServer&gt;
  &lt;/configuration&gt;
  </code></pre>
  
  <p>But when we execute the page on the website the handler does not seem to work, cause we are not getting redirected to Google. What is wrong here?</p>