The Objective Toolkit Asynchronous Pluggable Protocol (referred to as APP) ATL Object allows you to add a COM object that implements the IInternetProtocol and IInternetProtocolInfo interfaces required for implementing any custom APP.

The ATL Object Wizard provides a very convenient way to insert the Objective Toolkit APP ATL Object into any ATL project. The inserted object provides default features like parsing and validating the supplied URL, spawning a worker thread to perform asynchronous data fetch, and the ability to abort the operation gracefully. The COM object contains an implementation object to which it delegates all of the function calls. Subclassing the implementation object will provide you virtual notifications and allow you to customize the default behavior.

Pluggable protocol handlers can be used to handle a custom Uniform Resource Locator (URL) protocol scheme or to filter data for a designated MIME type.

The ability to handle a custom URL protocol scheme using a pluggable protocol handler gives developers the ability to implement new or custom protocol schemes for Internet Explorer 4.0 (and later) and for applications using URL monikers. Existing protocol schemes, such as HTTP and FTP, are handled by the default pluggable protocol handler included with Internet Explorer.

For more information take a look at the documentation available at MSDN (http://msdn.microsoft.com).