# Using the Container’s Functionality

The previous sections have described some of the necessary caller-side support that an ActiveX Control must have in order to access certain features of its container. The following table describes a control’s usage of container-side interfaces and when such usage would occur.

Interface | Container Object | Usage
IOleClientSite | Site | Controls that implement IOleObject call IOleClientSite methods as part of the standard OLE embedding protocol, specifically the methods SaveObject, ShowObject, OnShowWindow (only if a separate-window activation state is supported), RequestNewObjectLayout, and GetContainer (if communication with other controls is desired). The GetMoniker method is only used when the control can be linked to externally, that is, the control is not marked with OLEMISC_CANTLINKINSIDE.
IOleInPlaceSite | Site | Controls that have an in-place activate and possibly a UI active state will call IOleInPlaceSite methods (generally all of them with the exception of ContextSensitiveHelp) as part of the standard OLE in-place activation protocol.
IAdviseSink | Site | Control calls OnDataChange if the control supports IDataObject, OnViewChange if the control supports IViewObject2, and OnClose, OnSave, and OnRename if the control supports IOleObject.
IOleControlSite | Site | If supported, control calls OnControlInfoChanged when mnemonics change, LockInPlaceActive and TransformCoords if events are fired (the latter method is only used if coordinates are passed as event arguments), OnFocus and TranslateAccelerator if the control has a UI active state, and GetExtendedControl if the control wants to look at extended-control (container-owned) properties.
IDispatch (ambient properties) | Site | Used to access ambient properties.
IPropertyNotifySink | Varies | A control must generate OnChanged and OnRequestEdit for any control properties that are marked as [bindable] and [request], respectively.
Other event sink interfaces | Varies | A control that has outgoing interfaces other than IPropertyNotifySink will be handed other interface pointers of the correct IID to the control’s IConnectionPoint::Advise implementations (which are usually found in sub-objects of the control). A control always knows how to call its own event interfaces since the control defines those interfaces.
IOleInPlaceFrame | Frame | Used when a control has an in-place UI active state that requires frame-level tools or menu items.
IOleInPlaceUIWindow | Document | Used only when a control has an in-place UI active state that requires document-level or pane-level UI tools. This is rare.