IUnknown for MAPI
4/8/2010
The MAPI IUnknown methods for the Windows Mobile Messaging Application Programming Interface (CE MAPI) manages the existence of a CE MAPI interface object through its own version of the AddRef, Release, and QueryInterface methods.
The standard IUnknown method with Windows Mobile (versions 5.0 and later) corresponds with the standard COM IUnknown interface.
Note
The QueryInterface method is not implemented on many of the CE MAPI interfaces for Pocket PC 2002 and later, and for Smartphone 2002 and later. To determine whether the platform supports this interface, see Determining Supported COM APIs.
Methods in Vtable Order
| IUnknown methods | Description |
|---|---|
Returns a pointer to a specified interface. |
|
Increments the reference count for an interface on an object. |
|
Decrements the reference count for the calling interface on an object. |
Remarks
All CE MAPI interfaces use COM, and therefore inherit MAPI IUnknown. However, the QueryInterface method of many CE MAPI interfaces returns an error indicating that the method is not implemented (E_NOTIMPL).
The AddRef and Release methods are always implemented on CE MAPI interfaces.
Requirements
| Header | unknwn.h |
| Windows Embedded CE | Windows CE 3.0 and later |
| Windows Mobile | Pocket PC 2002 and later, Smartphone 2002 and later |