4.8 WFSAsyncDeregister

HRESULT WFSAsyncDeregister( hService, dwEventClass, hWndReg, hWnd, lpRequestID )

Discontinues monitoring of the specified message class(es) (or all classes) from the specified hService, by the specified hWndReg (or all the calling application's hWnd's). The asynchronous version of WFSDeregister.

Parameters HSERVICE hService

Service handle returned by WFSOpen or WFSAsyncOpen. If this value is NULL, and dwEventClass is SYSTEM_EVENTS, the XFS manager deregisters the application for those system events generated by the Manager itself.

DWORD dwEventClass

The class(es) of events from which the application is deregistering. Specified as a bit mask that can be a logical OR of the values for multiple classes. A NULL value requests that all event classes be deregistered from the specified window for this hService.

HWND hWndReg

The window which has been previously registered to receive notification messages, and is now to be deregistered. A NULL value requests that all the application's windows be deregistered from the specified message class(es) for this hService.

HWND hWnd

The window handle which is to receive the completion message for this request.

LPREQUESTID lpRequestID

Pointer to the request identifier for this request (returned parameter).

Mode Asynchronous

Comments See WFSDeregister.

The application must call WFSFreeResult to deallocate the WFSRESULT data structure which is pointed to by the completion message. Note that a WFSRESULT structure may be returned even if the function completes with an error; see Section 3.13.

Messages WFS_DEREGISTER_COMPLETE

Error Codes If the function return is not WFS_SUCCESS, it is one of the following error conditions, indicating that the asynchronous operation was not initiated:

WFS_ERR_CONNECTION_LOST

The connection to the service is lost.

WFS_ERR_INTERNAL_ERROR

An internal inconsistency or other unexpected error occurred in the WOSA/XFS subsystem.

WFS_ERR_INVALID_EVENT_CLASS

The dwEventClass parameter specifies one or more event classes not supported by the service.

WFS_ERR_INVALID_HSERVICE

The hService parameter is not a valid service handle.

WFS_ERR_INVALID_HWND

The hWnd parameter is not a valid window handle.

WFS_ERR_INVALID_HWNDREG

The hWndReg parameter is not a valid window handle.

WFS_ERR_INVALID_POINTER

A pointer parameter does not point to accessible memory.

WFS_ERR_NOT_REGISTERED

The specified hWndReg window was not registered to receive messages for any event classes.

WFS_ERR_NOT_STARTED

The application has not previously performed a successful WFSStartUp.

WFS_ERR_OP_IN_PROGRESS

A blocking operation is in progress on the thread; only WFSCancelBlockingCall and WFSIsBlocking are permitted at this time.

The following error conditions are returned via the asynchronous command completion message, as the hResult from the WFSRESULT structure. Any service-specific errors that can be returned are defined in the specifications for each service class.

WFS_ERR_CANCELED

The request was canceled by WFSCancelAsyncRequest.

WFS_ERR_INTERNAL_ERROR

An internal inconsistency or other unexpected error occurred in the WOSA/XFS subsystem.

See also WFSRegister, WFSClose