# IDataAdviseHolder::Advise

Creates a connection between an advise sink and a data object for receiving notifications.

HRESULT Advise(

IDataObject * pDataObject, | //Pointer to the data object for which notifications are requested
FORMATETC * pFormatetc, | //Pointer to the description of data to the advise sink
DWORD advf, | //Flags that specify how the notification takes place
IAdviseSink * pAdvSink, | //Pointer to the advise sink requesting notification
DWORD * pdwConnection | //Pointer to the connection token
); |

Parameters

pDataObject
  [in] Pointer to the IDataObject interface on the data object for which notifications are requested. If data in this object changes, a notification is sent to the advise sinks that have requested notification.
pFormatetc
  [in] Pointer to the specified format, medium, and target device that is of interest to the advise sink requesting notification. For example, one sink may want to know only when the bitmap representation of the data in the data object changes. Another sink may be interested in only the metafile format of the same object. Each advise sink is notified when the data of interest changes. This data is passed back to the advise sink when notification occurs.
advf
  [in] Contains a group of flags for controlling the advisory connection. Valid values are from the enumeration ADVF. However, only some of the possible ADVF values are relevant for this method. The following table briefly describes the relevant values; a more detailed description can be found in the description of the ADVF enumeration.

  ADVF Value | Description
  ADVF_NODATA | Asks that no data be sent along with the notification.
  ADVF_ONLYONCE | Causes the advisory connection to be destroyed after the first notification is sent. An implicit call to IDataAdviseHolder::Unadvise is made on behalf of the caller to remove the connection.
  ADVF_PRIMEFIRST | Causes an initial notification to be sent regardless of whether or not data has changed from its current state.
  ADVF_DATAONSTOP | When specified with ADVF_NODATA, this flag causes a last notification with the data included to be sent before the data object is destroyed. When ADVF_NODATA is not specified, this flag has no effect.

pAdvSink
  [in] Pointer to the IAdviseSink interface on the advisory sink that receives the change notification.
pdwConnection
  [out] Pointer to a DWORD token that identifies this connection. The calling object can later delete the advisory connection by passing this token to IDataAdviseHolder::Unadvise. If this value is zero, the connection was not established.

Return Values

This method supports the standard return value E_INVALIDARG, as well as the following:

S_OK
  The advisory connection was created.

Remarks

Through the connection established through this method, the advisory sink can receive future notifications in a call to IAdviseSink::OnDataChange.

An object issues a call to IDataObject::DAdvise to request notification on changes to the format, medium, or target device of interest. This data is specified in the pFormatetc parameter. The DAdvise method is usually implemented to call IDataAdviseHolder::Advise to delegate the task of setting up and tracking a connection to the advise holder. When the format, medium, or target device in question changes, the data object calls IDataAdviseHolder::SendOnDataChange to send the necessary notifications.

The established connection can be deleted by passing the value in pdwConnection in a call to IDataAdviseHolder::Unadvise.

See also

ADVF, CreateDataAdviseHolder, FORMATETC, IDataAdviseHolder::Unadvise, IDataObject::DAdvise