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

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

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

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.");
}
Compile the project.


Deploy the Handler
Create a new directory named Handler under the C:\Inetpub\Wwwroot directory.
Create a subdirectory named Bin in the newly created Handler directory. The resultant path is C:\Inetpub\Wwwroot\Handler\Bin.
Copy MyHandler.dll from your project's Bin\Debug directory to the C:\Inetpub\Wwwroot\Handler\Bin directory.
Follow these steps to mark the new Handler directory as a Web application:
Open Internet Services Manager.
Right-click the Handler directory, and then click Properties.
On the Directory tab, click Create.
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.
Right-click on the Handler Web application, and then click Properties.
On the Directory tab, click Configuration.
Click Add to add a new mapping.
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
In the Extension text box, type .sync.
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.
Click OK to close the Application Configuration and the Handler Properties dialog boxes.
Close Internet Services Manager.


Configure the System
In the C:\Inetpub\Wwwroot\Handler directory, create a new file named Web.config.
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:///Handler/Default.sync). You should receive the following results:
Hello from custom handler.