Mapping for a Vista application and legacy driver

Important

This article contains information that applies to obsolete Windows operating systems.

This section shows the mapping used when a Windows Vista application needs to work with a legacy driver. The following tables describe how the WIA compatibility layer maps legacy transfer messages and data flow to Windows Vista transfer messages and data flow.

Callback transfers

This table shows the mapping of a legacy driver's callback transfer messages to the messages sent to a Windows Vista application.

Legacy driver transfer message	Windows Vista Application message (after compatibility layer conversion)
IT_MSG_DATA	IStream::Seek,IStream::Write, and WIA_TRANSFER_MSG_STATUS all ORed together.
IT_MSG_STATUS	WIA_TRANSFER_MSG_STATUS
IT_MSG_DATA_HEADER	Ignored. This message is only sent by the service, not by the driver, and will never be sent during this type of transfer.
IT_MSG_NEW_PAGE	Ignored. This message should never be received during this type of transfer. A legacy driver would only send this during a multi-page transfer with TYMED_CALLBACK or TYMED_MULTIPAGE_CALLBACK that's not exposed to a Windows Vista application. The compatibility layer only does multi-page transfers with TYMED_MULTIPAGE_FILE. For TYMED_FILE transfers, the application will always receive one page at a time.
IT_MSG_TERMINATION	This message is only sent by the service, not by the driver. The compatibility layer sends WIA_TRANSFER_MSG_END_OF_STREAM and WIA_TRANSFER_MSG_END_OF_TRANSFER instead.
IT_MSG_FILE_PREVIEW_DATA	Ignored. The IStream transfer model doesn't support out-of-band data.
IT_MSG_FILE_PREVIEW_DATA_HEADER	Ignored. The IStream transfer model doesn't support out-of-band data.

File transfers

This table shows the mapping of a legacy driver's file transfer messages to the messages sent to a Windows Vista application.

Legacy driver transfer message	Windows Vista Application message (after compatibility layer conversion)
IT_MSG_DATA	Ignored. This message should never be sent during a file transfer.
IT_MSG_STATUS	WIA_TRANSFER_MSG_STATUS
IT_MSG_DATA_HEADER	Ignored. This message is only sent by the service (not by the driver) and will never be sent during this type of transfer.
IT_MSG_NEW_PAGE	Ignored. This message should never be received during this type of transfer. A legacy driver would only send this during a multi-page transfer with TYMED_CALLBACK or TYMED_MULTIPAGE_CALLBACK that's not exposed to a Windows Vista application. The compatibility layer, however, only does multi-page transfers with TYMED_MULTIPAGE_FILE. For TYMED_FILE transfers, the driver will always receive one page at a time.
IT_MSG_TERMINATION	This message is only sent by the service (not by the driver). The compatibility layer will instead send WIA_TRANSFER_MSG_END_OF_STREAM and WIA_TRANSFER_MSG_END_OF_TRANSFER.
IT_MSG_FILE_PREVIEW_DATA	Ignored. The new transfer model doesn't support for out-of-band data.
IT_MSG_FILE_PREVIEW_DATA_HEADER	Ignored. The new transfer model doesn't support for out-of-band data.

For more information on the legacy transfer messages, see the IWiaMiniDrvCallBack interface.

For more information on the TYMED constants, see Understanding TYMED.