ISCPSecureExchange3::TransferContainerDataOnClearChannel method (mswmdm.h)

Article
04/02/2021

The TransferContainerDataOnClearChannel method transfers container file data to the content provider through the clear channel. The content provider breaks down the container internally and reports which parts of the content are available as they are extracted from the container.

This method is identical to ISCPSecureExchange::TransferContainerData except that the parameters passed to this method are not encrypted. Consequently this method is more efficient.

Syntax

HRESULT TransferContainerDataOnClearChannel(
  IMDSPDevice    *pDevice,
  BYTE           *pData,
  DWORD          dwSize,
  IWMDMProgress3 *pProgressCallback,
  UINT           *pfuReadyFlags
);

Parameters

pDevice

Pointer to a device object.

pData

Pointer to a buffer holding the current data being transferred from the container file.

dwSize

Contains the number of bytes in the buffer.

pProgressCallback

Progress callback on which the content provider can report progress of any steps that it might need to carry out. The step will be identified by the EventId parameter of IWMDMProgress3 methods.

pfuReadyFlags

Flag indicating which parts of the container file are ready to be read. This parameter is included in the output message authentication code. The following flags indicate what is ready.

Value	Meaning
WMDM_SCP_TRANSFER_OBJECTDATA	Data of the object is available by calling the GetObjectDataOnClearChannel method.
WMDM_SCP_NO_MORE_CHANGES	The content provider has determined that it requires no further processing and/or modification of the file being transferred. Windows Media Device Manager can directly transfer the remainder of the file to the device.

Return value

If the method succeeds, it returns S_OK. If the method fails, it returns an HRESULT error code.

Return code	Description
WMDM_E_NOT_CERTIFIED	The caller is not authorized to use this interface.
WMDM_E_NORIGHTS	The caller does not have the rights required to perform the requested operation.
WMDM_E_MAC_CHECK_FAILED	The message authentication code is not valid.
S_FALSE	The method failed. Terminate interaction with the content provider.
E_INVALIDARG	A parameter is invalid or is a NULL pointer.
E_FAIL	An unspecified error occurred.

Remarks

Windows Media Device Manager calls this method repeatedly, transferring data from the container file to the content provider. Windows Media Device Manager eventually calls this method with dwSize set to zero to indicate that it has no more data to transfer. As the content provider collects the data and extracts the various objects from it, it reports back to Windows Media Device Manager which objects, if any, are available after each call. If no objects are available, the content provider returns S_OK with the pfuReadyFlags parameter set to zero. When the content provider has determined that it requires no further processing and/or modification of the file being transferred, the flag WMDM_SCP_NO_MORE_CHANGES is returned. Windows Media Device Manager can then directly transfer the remainder of the file to the device.

Object data is transferred from the content provider by calling the GetObjectDataOnClearChannel method. Windows Media Device Manager calls GetObjectDataOnClearChannel repeatedly until it returns zero in the third parameter, pdwsize.

The ISCPSecureExchange::TransferComplete (or TransferCompleteForDevice if a session is active) method is called by Windows Media Device Manager to signal the end of a data transfer.

Windows Media Device Manager passes the application-provided progress callback to the content provider in the pProgressCallback parameter. The content provider can use this parameter to provide progress notification for any steps that it needs to carry out. The step itself is identified by EventId, which is the first parameter of the methods of IWMDMProgress3. A specific content provider implementation will define EventId values for applications to use.

This method is identical to ISCPSecureExchange::TransferContainerData except that the parameters passed to this method are not encrypted. Consequently this method is more efficient.

Requirements

Requirement	Value
Target Platform	Windows
Header	mswmdm.h
Library	Mssachlp.lib