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FaxExtUnregisterForEvents function (faxext.h)

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The FaxExtUnregisterForEvents callback function unregisters the fax extension DLL for notifications about configuration data changes related to a specific device and GUID.

Syntax

DWORD FaxExtUnregisterForEvents(
  HANDLE hNotification
);

Parameters

hNotification

Type: HANDLE

Specifies a HANDLE that indicates the registration handle from which the caller wishes to unregister.

The handle must be the return value from a previous call to the FaxExtRegisterForEvents function.

Return value

Type: DWORD

If the function succeeds, the return value is ERROR_SUCCESS.

If the function fails, the return value is a nonzero error code defined in WinError.h. You can call the Win32 FormatMessage function specifying the FORMAT_MESSAGE_FROM_SYSTEM flag to retrieve a generic description of the error.

The FaxExtUnregisterForEvents function can return the following error codes.

Return code Description
ERROR_SUCCESS
 The unregistration process succeeded.
ERROR_NOT_FOUND
 The registration handle specified by the hNotification parameter was not found.
ERROR_INVALID_PARAMETER
 The hNotification parameter is invalid.
ERROR_NOT_ENOUGH_MEMORY
 Not enough memory is available to complete the operation.
ERROR_GEN_FAILURE
 An internal failure at the fax server prevents access to the data.
ERROR_SHUTDOWN_IN_PROGRESS
 The server is shutting down.
ERROR_BUSY
 The server cannot process a request for notifications while it is sending a notification about a data change. You should try calling the function at a later time.

Remarks

When the fax extension calls this fax service callback function, it must use the function pointer exposed by the fax service when the service calls the FaxExtInitializeConfig function.

The fax extension can call the FaxExtUnregisterForEvents function to stop receiving notifications about device configuration data changes. An extension registers for notifications by calling the fax service's callback function FaxExtRegisterForEvents.

The fax service passes a pointer to the FaxExtUnregisterForEvents callback function when the fax service calls the FaxExtInitializeConfig function. The PFAX_EXT_UNREGISTER_FOR_EVENTS data type is a pointer to a FaxExtUnregisterForEvents function.

Requirements

Requirement Value
Minimum supported client Windows XP [desktop apps only]
Minimum supported server Windows Server 2003 [desktop apps only]
Target Platform Windows
Header faxext.h

See also

FaxExtInitializeConfig

FaxExtRegisterForEvents