IWMSDataSourcePlugin::OpenDirectory
.gif)
| Previous | Next |
IWMSDataSourcePlugin::OpenDirectory
The OpenDirectory method opens a directory data container.
Syntax
HRESULT OpenDirectory( 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 contains a command context.
pUserContext
[in] Pointer to an IWMSContext object that contains a user context.
pPresentationContext
[in] Pointer to an IWMSContext interface that contains a presentation context.
pszContainerName
[in] Pointer to a null-terminated string containing the directory name that the server resolved from the requested URL. This includes the scheme type, as in file://C:\wmpub\wmroot\.
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 has requested read access. |
| WMS_DATA_CONTAINER_WRITE_ACCESS | The server has requested write access. |
| WMS_DATA_CONTAINER_CREATE_NEW_CONTAINER | The server has requested that a new data container be created. |
| WMS_DATA_CONTAINER_ALLOW_BUFFER_IO | Buffered data does not need to be page-aligned. |
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::OnOpenDirectory to return a result to the server.
qwContext
[in] QWORD containing a value defined by the server to identify which OpenDirectory request the plug-in is responding to when it calls IWMSDataSourcePluginCallback::OnOpenDirectory. 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.
Example Code
HRESULT STDMETHODCALLTYPE
CDataSourcePlugin::OpenDirectory(
IWMSCommandContext *pCommandContext,
IWMSContext *pUserContext,
IWMSContext *pPresentationContext,
LPWSTR pszContainerName,
DWORD dwFlags,
IWMSBufferAllocator *pBufferAllocator,
IWMSDataSourcePluginCallback *pCallback,
QWORD qwContext
)
{
HRESULT hr = S_OK;
CDirectoryImpl *pDirectory = NULL;
// TODO: Allocate a CDirectoryImpl object. The
// CDirectoryImpl object is user-defined
// and implements the IWMSDirectory interface.
// pDirectory points to the object.
hr = pDirectory->Initialize(
pUserContext,
pszContainerName,
this,
pCallback,
qwContext
);
if (FAILED(hr)) goto EXIT;
hr = pDirectory->Release();
if (FAILED(hr)) goto EXIT;
EXIT:
// TODO: Release temporary objects.
return( hr );
}
// Create a CDirectory object and a method, Initialize(), to
// enumerate the files in a directory and store information
// about them in a linked list of CDirectoryInfo objects. The
// CDirectory and CDirectoryInfo objects are user-defined, and
// the CDirectory object implements the IWMSDirectory interface.
CDirectory::Initialize(
IWMSContext *pUserContext,
LPWSTR pszContainerName,
CNTFSStorageSystem *pOwnerStorageSystem,
IWMSDataSourcePluginCallback *pCallback,
QWORD qwContext
)
{
HRESULT hr = S_OK;
HRESULT hr = S_OK;
WCHAR *pszNtfsPathname;
size_t sFileName;
DWORD dwFileAttributes;
DWORD dwIndex;
HANDLE hFileEnum = INVALID_HANDLE_VALUE;
BOOL fSuccess = FALSE;
WIN32_FIND_DATA FileInfo;
// Parse the path name to remove the scheme type and
// use the GetFileAttributes() function to determine
// whether the path identifies a directory.
pszNtfsPathname = pszContainerName + URL_SCHEME_LENGTH;
dwFileAttributes = GetFileAttributes( pszNtfsPathname );
if( !( FILE_ATTRIBUTE_DIRECTORY & dwFileAttributes ) )
{
hr = HRESULT_FROM_WIN32( ERROR_DIRECTORY );
}
// Add the global wildcard character '*' to the end
// of the directory name.
sFileName = wcslen( pszNtfsPathname );
pSearchDirName = new WCHAR[ sFileName + 8 ];
pSearchDirName[sFileName] = '*';
pSearchDirName[sFileName + 1] = '\0';
// Find the first entry in the directory.
hFileEnum = FindFirstFileW( m_pSearchDirName, &FileInfo );
dwIndex = 0;
fSuccess = TRUE;
while ( TRUE )
{
// TODO: Determine whether you have reached the end of
// the directory items. If so, break.
// If the directory item is empty or '.' or '..' or a hidden file,
// skip it, get the next file and start the loop again.
if( ( '\0' == FileInfo.cFileName[0] )
|| ( ( '.' == FileInfo.cFileName[0] )
&& ('\0' == FileInfo.cFileName[1] ) )
|| ( ( '.' == FileInfo.cFileName[0] )
&& ( '.' == FileInfo.cFileName[1] )
&& ( '\0' == FileInfo.cFileName[2] ) )
|| ( FileInfo.dwFileAttributes & FILE_ATTRIBUTE_HIDDEN ) )
{
fSuccess = FindNextFileW( hFileEnum, &FileInfo );
continue;
}
// TODO: Retrieve information about each file, such as
// the name and size, and save it in a linked list of
// user-defined CDirectoryInfo objects. In this example,
// the CDirectoryInfo class contains four data members
// that save information about a file:
// CDirectoryInfo()
// {
// m_cRef = 1; // Reference count.
// m_pszwName = NULL; // File name.
// m_qwSize = 0; // File size.
// m_pNext = NULL; // Pointer to next CDirectoryInfo.
// }
// Increment the index and find the next file.
dwIndex++;
fSuccess = FindNextFileW( hFileEnum, &FileInfo );
}
// Callback to the server.
hr = pCallback->OnOpenDirectory( hr, this, qwContext );
if (FAILED(hr)) goto EXIT;
// Because errors are passed through the callback, return S_OK.
return( S_OK );
EXIT:
// TODO: Release temporary objects.
}
Requirements
Header: datacontainer.h.
Library: WMSServerTypeLib.dll.
Platform: Windows Server 2003, Enterprise Edition; Windows Server 2003, Datacenter Edition; Windows Server 2008.
See Also
| Previous | Next |