Enables interfaces that are usually synchronous to function asynchronously.

IAsyncOperation Members

EndOperation	Notifies the data object that that asynchronous data extraction has ended.
GetAsyncMode	Called by a drop target to determine whether the data object supports asynchronous data extraction.
InOperation	Called by the drop source to determine whether the target is extracting data asynchronously.
SetAsyncMode	Called by a drop source to specify whether the data object supports asynchronous data extraction.
StartOperation	Called by a drop target to indicate that asynchronous data extraction is starting.

Remarks

This interface is primarily exported by the data objects used with drag-and-drop and Clipboard operations. Typically, such operations are synchronous. However, if data rendering will be time-consuming, IAsyncOperation can be used to allow data extraction to take place on a background thread. See the Dragging and Dropping Shell Objects Asynchronously section of Handling Shell Data Transfer Scenarios for a detailed discussion of how to use this interface.

IAsyncOperation is an optional interface that is implemented by a data object. It allows the drop target to negotiate with the drop source to extract data from the data object asynchronously.

Drop sources and targets use this interface when they wish to have a lengthy data extraction process handled by a background thread.

Interface Information

Minimum DLL Version	shell32.dll version 5.0 or later
Custom Implementation	Yes
Inherits from	IUnknown
Header	shlobj.h
Minimum operating systems	Windows 2000, Windows Me