The CVssWriter class is an abstract base class that defines the interface by which a writer synchronizes its state with VSS and other writers.
Every writer must instantiate an object derived from CVssWriter.
Objects derived from CVssWriter must supply implementations for all of the CVssWriter's pure virtual methods.
A writer can override one or all of CVssWriter's virtual methods.
A writer terminates its participation by calling CVssWriter::Unsubscribe.
The CVssWriter base class is responsible for the life cycle of interfaces passed to event handlers. This includes the following:
- The instance of the IVssWriterComponents interface passed to:
- The instance of the IVssCreateWriterMetadata interface passed to CVssWriter::OnIdentify.
CVssWriter has these types of members:
|AreComponentsSelected||Indicates whether a requester supports selecting individual components to be backed up or backs up entire volumes.|
|GetBackupType||Indicates the type of backup to be performed.|
|GetContext||Returns the context of the current shadow copy operation.|
|GetCurrentLevel||Returns the current application level.|
|GetCurrentSnapshotSetId||Returns the unique identifier of the current shadow copy set.|
|GetCurrentVolumeArray||Returns an array of the names of the original volumes belonging to the shadow copy set.|
|GetCurrentVolumeCount||Returns the number of volumes in the shadow copy set.|
|GetRestoreType||During file restoration, indicates the type of restore under way.|
|GetSnapshotDeviceName||Returns the volume name of the shadow copy of the specified volume.|
|IsBootableStateBackedUp||Indicates whether the bootable state will be backed up.|
|IsPartialFileSupportEnabled||Indicates if partial file support is enabled or disabled.|
|IsPathAffected||Indicates whether a specific directory or file is included in the current shadow copy set.|
|SetWriterFailure||Method used by a writer to set an error code when it encounters a problem with participating in a VSS operation.|
|OnAbort||Writer-implemented method called in response to the Abort event.|
|OnFreeze||Writer-implemented method called in response to a Freeze event.|
|OnPrepareSnapshot||Writer-implemented method called in response to the PrepareForSnapshot event.|
|OnThaw||Writer-implemented method called in response to the Thaw event.|
|~CVssWriter||Destructor for the CVssWriter class object.|
|OnBackupComplete||Writer-overridable method called during the BackupComplete event.|
|OnBackupShutdown||Writer-overridable method called during the BackupShutdown event.|
|OnIdentify||Writer-overridable method called during the Identify event.|
|OnPostRestore||Writer-overridable method called during the PostRestore event.|
|OnPostSnapshot||Writer-overridable method called during the PostSnapshot event.|
|OnPrepareBackup||Writer-overridable method called during the PrepareForBackup event.|
|OnPreRestore||Writer-overridable method called during the PreRestore event.|
|OnBackOffIOOnVolume||This method is reserved for future use.|
|OnContinueIOOnVolume||This method is reserved for future use.|
|OnVSSApplicationStartup||This method is reserved for future use.|
|OnVssShutdown||This method is reserved for future use.|
|CVssWriter||Constructor for the CVssWriter class object.|
|Initialize||Initializes a CVssWriter object and allows a writer application to interact with VSS.|
|Subscribe||Subscribes the writer to VSS.|
|Unsubscribe||Unsubscribes the writer from VSS.|
|InstallAlternateWriter||This method is reserved for future use.|
Minimum supported client
|Windows XP [desktop apps only]|
Minimum supported server
|Windows Server 2003 [desktop apps only]|