IWMSDataSourcePlugin::OpenDataContainer
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IWMSDataSourcePlugin::OpenDataContainer
The server calls the OpenDataContainer method to open or create a data container.
Syntax
HRESULT OpenDataContainer( IWMSCommandContext* pCommandContext, IWMSContext* pUserContext, IWMSContext* pPresentationContext, LPWSTR pszContainerName, DWORD dwFlags, IWMSBufferAllocator* pBufferAllocator, IWMSDataSourcePluginCallback* pCallback, QWORD qwContext );
Parameters
pCommandContext
[in] Pointer to an IWMSCommandContext interface that specifies the request command context.
pUserContext
[in] Pointer to an IWMSContext interface that specifies the user context.
pPresentationContext
[in] Pointer to an IWMSContext interface that specifies the presentation context.
pszContainerName
[in] Pointer to a null-terminated string containing the name of the container to be opened.
dwFlags
[in] DWORD containing a member of the WMS_DATA_CONTAINER_OPEN_FLAGS enumeration type that indicates the type of access requested. This must be a bitwise OR of one or more of the following values.
| Values | Description |
| WMS_DATA_CONTAINER_READ_ACCESS | The server requested read access. |
| WMS_DATA_CONTAINER_WRITE_ACCESS | The server requested write access. |
| WMS_DATA_CONTAINER_CREATE_NEW_CONTAINER | The server requested that a new data container be created. |
| WMS_DATA_CONTAINER_ALLOW_BUFFER_IO | The buffered data does not need to be page-aligned. |
| WMS_DATA_CONTAINER_SHARED_SOURCE | The server requested that the data container be used for a shared resource such as a broadcast. If the plug-in determines that the data path must not be shared, it can return COMADMIN_E_PRIVATE_ACCESSDENIED when it calls IWMSDataSourcePluginCallback::OnOpenDataContainer. |
pBufferAllocator
[in] Pointer to an IWMSBufferAllocator interface that can be used by the data source plug-in to allocate additional buffers for reading or writing data.
pCallback
[in] Pointer to an IWMSDataSourcePluginCallback interface. The plug-in calls IWMSDataSourcePluginCallback::OnOpenDataContainer to return a result to the server.
qwContext
[in] QWORD containing a value defined by the server to identify which OpenDataContainer request the plug-in is responding to when it calls IWMSDataSourcePluginCallback::OnOpenDataContainer. The plug-in must pass this value back unaltered.
Return Values
If the method succeeds, the plug-in must return S_OK. To report an error, the plug-in can return any HRESULT other than S_OK. If the plug-in uses the IWMSEventLog interface to log error information directly to the Windows Event Viewer, it is recommended that it return NS_E_PLUGIN_ERROR_REPORTED. Typically, the server attempts to make plug-in error information available to the server object model, the Windows Event Viewer, and the troubleshooting list in the details pane of the Windows Media Services MMC. However, if the plug-in uses the IWMSEventLog interface to send custom error information to the Windows Event Viewer, returning NS_E_PLUGIN_ERROR_REPORTED stops the server from also logging to the event viewer. For more information about retrieving plug-in error information, see Identifying Plug-in Errors.
Remarks
If the server requests that the data container be used for a shared broadcast by sending WMS_DATA_CONTAINER_SHARED_SOURCE in the dwFlags parameter when it calls OpenDataContainer, and the plug-in determines that the source cannot be shared, the plug-in can return COMADMIN_E_PRIVATE_ACCESSDENIED to the server in the hr parameter of IWMSDataSourcePluginCallback::OnOpenDataContainer. The COMADMIN_E_PRIVATE_ACCESSDENIED error is defined in the WinError.h file. A plug-in can decide that a source must not be shared if, for example, a distribution connection requires authentication or the content must be personalized for a specific end user. When the server receives this error, it deletes the shared data path and creates an on-demand (non-shared) data path instead.
Example Code
HRESULT STDMETHODCALLTYPE
CDataSourcePlugin::OpenDataContainer(
IWMSCommandContext *pCommandContext,
IWMSContext *pUserContext,
IWMSContext *pPresentationContext,
LPWSTR pszContainerName,
DWORD dwFlags,
IWMSBufferAllocator *pBufferAllocator,
IWMSDataSourcePluginCallback *pCallback,
QWORD qwContext)
{
HRESULT hr = S_OK;
CDataContainer *pDataContainer = NULL;
pDataContainer = new CDataContainer;
hr = pDataContainer->Initialize(
pUserContext,
pszContainerName,
dwFlags,
pBufferAllocator,
this,
pCallback,
qwContext
);
if ( FAILED( hr ) ) goto EXIT;
EXIT:
if( NULL != pDataContainer )
{
pDataContainer->Release();
pDataContainer = NULL;
}
return( hr );
}
HRESULT CDataContainer::Initialize(
IWMSContext *pUserContext,
LPWSTR pszContainerName,
DWORD dwFlags,
IWMSBufferAllocator *pBufferAllocator,
CSDKSampleStorageSystem *pOwnerStorageSystem,
IWMSDataSourcePluginCallback *pCallback,
QWORD qwContext)
{
HRESULT hr = S_OK;
DWORD dwSDKSampleStorageSystemFlags = 0;
CHAR *pResult = NULL;
DWORD cbDriveNameLen = 0;
BOOL fSuccess = TRUE;
DWORD dwOpenStyle = 0;
CHAR *pszSDKSampleStorageSystemPathname = NULL;
DWORD dwFileAccess = 0;
DWORD dwSizeHigh = 0, dwError = 0, dwSizeLow = 0;
int cchNeeded = WideCharToMultiByte(
CP_ACP,
0,
pszContainerName,
-1,
NULL,
0,
NULL,
NULL);
if( 0 >= cchNeeded )
{
hr = HRESULT_FROM_WIN32( GetLastError() );
goto EXIT;
}
m_pszPathName = new CHAR[ cchNeeded ];
int cchConverted = WideCharToMultiByte(
CP_ACP,
0,
pszContainerName,
-1,
m_pszPathName,
cchNeeded,
NULL,
NULL);
if( cchConverted != cchNeeded )
{
delete [] m_pszPathName;
m_pszPathName = NULL;
hr = E_UNEXPECTED;
goto EXIT;
}
m_pOwnerStorageSystem = pOwnerStorageSystem;
pOwnerStorageSystem->AddRef();
if ( dwFlags & WMS_DATA_CONTAINER_CREATE_NEW_CONTAINER )
dwOpenStyle = OPEN_ALWAYS;
else
dwOpenStyle = OPEN_EXISTING;
dwFileAccess = GENERIC_READ;
if ( ( dwFlags & WMS_DATA_CONTAINER_WRITE_ACCESS )
|| ( dwFlags & WMS_DATA_CONTAINER_CREATE_NEW_CONTAINER ) )
dwFileAccess |= GENERIC_WRITE;
pszSDKSampleStorageSystemPathname = m_pszPathName + URL_SCHEME_LENGTH;
m_hFile = CreateFileA(
pszSDKSampleStorageSystemPathname,
dwFileAccess,
FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE,
NULL,
dwOpenStyle,
dwSDKSampleStorageSystemFlags,
NULL);
if ( INVALID_HANDLE_VALUE == m_hFile )
{
hr = HRESULT_FROM_WIN32( GetLastError() );
goto EXIT;
}
else
{
DWORD dwFileType = GetFileType( m_hFile );
if( FILE_TYPE_DISK != dwFileType )
{
hr = HRESULT_FROM_WIN32( ERROR_FILE_NOT_FOUND );
goto EXIT;
}
}
dwSizeLow = GetFileSize( m_hFile, & dwSizeHigh ) ;
if( ( dwSizeLow == 0xFFFFFFFF ) &&
( ( dwError = GetLastError() ) != NO_ERROR ) )
{
hr = HRESULT_FROM_WIN32( dwError );
goto EXIT;
}
m_qwFileSize = MAKEQWORD( dwSizeLow, dwSizeHigh );
EXIT:
if( FAILED(hr) && ( INVALID_HANDLE_VALUE != m_hFile ) )
{
CloseHandle( m_hFile );
m_hFile = INVALID_HANDLE_VALUE;
}
if ( NULL != pCallback )
{
pCallback->OnOpenDataContainer( hr, this, qwContext );
hr = S_OK;
}
return( hr );
}
Requirements
Header: datacontainer.h.
Library: WMSServerTypeLib.dll.
Platform: Windows Server 2003, Enterprise Edition; Windows Server 2003, Datacenter Edition; Windows Server 2008.
See Also
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