Use the Add Managed Handler and Edit Managed Handler dialog boxes to add new or edit existing managed code handlers on the Web server. Managed handlers are written in managed code and respond to specific requests on the Web server. For example, the PageHandlerFactory-Integrated handler mapping specifies that the System.Web.UI.PageHandlerFactory handler process requests for .aspx files.
By default, when you add a managed handler, the handler will run only in application pools configured to use Integrated mode. However, if you want to run the handler in application pools configured to use ISAPI mode, you must add the handler to the <httphandlers> section in System.web from a tool such as Appcmd.exe.
UI Element List
Type a file name extension or file name with an extension for which you want the handler to process requests. For example, if you want the handler to process all requests made for files with the extension .abc, enter *.abc; or if you want the handler to run all requests made for a specific file, type the file name and its extension, such as Myfile.abc.
Type the type name of the managed handler, such as System.Web.Handlers.
When you add a managed handler, make sure that the assembly to which the class belongs is registered in the system.web/compilation section of your Web.config file. Otherwise you must type the assembly qualified class name of the managed handler. If the class is defined in the App_Code or bin directory you can specify just the class name.
Type a descriptive friendly name for the handler mapping.
Opens the Request Restrictions dialog box from which you can specify additional, optional restrictions for the mapping.