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IUnknown for MAPI

The IUnknown interface for the Windows Mobile Messaging Application Programming Interface (MAPI) manages the existence of a MAPI object through the AddRef and Release methods.

Note   To conserve memory on mobile devices, the QueryInterface method is not implemented on many Windows Mobile-based MAPI interfaces for Windows Mobile 2002 and Windows Mobile 2003.

Methods in Vtable Order

IUnknown methods Description
QueryInterface Returns a pointer to a specified interface.
AddRef Increments the reference count for an interface on an object.
Release Decrements the reference count for the calling interface on an object.

Remarks

All Windows Mobile-based MAPI interfaces use COM and therefore inherit IUnknown. However, to conserve memory on Windows Mobile 2002 and Windows Mobile 2003 devices, the QueryInterface method of many Windows Mobile-based MAPI interfaces returns an error indicating that the method is not implemented (E_NOTIMPL). However, the AddRef and Release methods are always implemented on Windows Mobile-based MAPI interfaces.

Requirements

Smartphone: Windows Mobile 2002 and later
OS Versions: Windows CE 3.0 and later
Header: unknwn.h

See Also

MAPI Interfaces

Messaging

Last updated on Friday, April 22, 2005

© 2005 Microsoft Corporation. All rights reserved.

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