How To Create an ASP.NET HTTP Handler by Using Visual C# .NET

Implement the Handler

1. Open Microsoft Visual Studio .NET. In Visual C# .NET, create a new Class Library project named MyHandler.
2. Set a reference to the System.Web.dll assembly.
3. Add the following directive to the class:

   using System.Web;
        

4. Rename the class SyncHandler.cs, and then change the class definition to reflect this.
5. Implement the IHttpHandler interface. Your class definition should appear as follows:

   public class SyncHandler : IHttpHandler
        

6. Implement the IsReusable property and the ProcessRequest method of the IHttpHandler interface. Because this is a synchronous handler, return False for the IsReusable property so that the handler is not pooled.

   public bool IsReusable
   {
      get {return false;}
   }
   
   public void ProcessRequest(HttpContext context)
   {
      context.Response.Write("Hello from custom handler.");
   }
        

7. Compile the project.

Deploy the Handler

1. Create a new directory named Handler under the C:\Inetpub\Wwwroot directory.
2. Create a subdirectory named Bin in the newly created Handler directory. The resultant path is C:\Inetpub\Wwwroot\Handler\Bin.
3. Copy MyHandler.dll from your project's Bin\Debug directory to the C:\Inetpub\Wwwroot\Handler\Bin directory.
4. Follow these steps to mark the new Handler directory as a Web application:
   1. Open Internet Services Manager.
   2. Right-click the Handler directory, and then click Properties.
   3. On the Directory tab, click Create.
5. Follow these steps to create an application mapping for the handler. For this handler, create a mapping to the Aspnet_isapi.dll file for the *.sync extension. Whenever a .sync file is requested, the request is routed to ASP.NET, and ASP.NET executes the code in the handler.
   1. Right-click on the Handler Web application, and then click Properties.
   2. On the Directory tab, click Configuration.
   3. Click Add to add a new mapping.
   4. In the Executable text box, type the following path: Microsoft Windows 2000:
      C:\WINNT\Microsoft.NET\Framework\<version#>\Aspnet_isapi.dll
      Microsoft Windows XP:
      C:\WINDOWS\Microsoft.NET\Framework\<version#>\Aspnet_isapi.dll
   5. In the Extension text box, type .sync.
   6. Make sure that the Check that file exists check box is cleared, and then click OK to close the Add/Edit Application Extension Mapping dialog box.
   7. Click OK to close the Application Configuration and the Handler Properties dialog boxes.
6. Close Internet Services Manager.

Configure the System

1. In the C:\Inetpub\Wwwroot\Handler directory, create a new file named Web.config.
2. Add the following code to Web.config:

   <configuration>
      <system.web>
         <httpHandlers>
            <add verb="*" path="*.sync" type="MyHandler.SyncHandler, MyHandler" />
         </httpHandlers>
      </system.web>
   </configuration>
         

   In the verb="*" attribute, we instruct the handler to process a request that uses any verb (for example, POST, HEAD, GET, and so on). If you want this handler to process only the POST request, change this to verb="POST".
   
   In the path="*.sync" attribute, we instruct the handler to process any incoming requests for files with the .sync extension.
   
   In the type="MyHandler.SyncHandler, MyHandler" attribute, we instruct the handler that processes the request to implement in the MyHandler.SyncHandler namespace, and this class resides in the MyHandler assembly.

Test the Module

To test a handler, a page does not need to exist in the file system. For example, request the Default.sync file in the Handler Web application (http://<ComputerName>/Handler/Default.sync). You should receive the following results:

Hello from custom handler.