org.clapper.curn
Class DataPersister

java.lang.Object
  org.clapper.curn.DataPersister

Direct Known Subclasses:

XMLDataPersister

public abstract class DataPersister
extends java.lang.Object

Persists data to the curn persistent data store, whatever that may be.

Version:

$Revision: 6498 $

Nested Class Summary

static interface

DataPersister.LoadedDataHandler Used to define a callback for handling loaded data.

Constructor Summary

protected

DataPersister()

Method Summary

void	addPersistentDataClient(PersistentDataClient client) Register a PersistentDataClient object with this registry.
protected abstract void	doLoad(DataPersister.LoadedDataHandler loadedDataHandler) The actual load method; only called if the object is enabled.
protected abstract void	endLoadOperation() Called at the end of the load operation to close files, clean up, etc.
protected abstract void	endSaveOperation() Called at the end of the actual save operation to flush files, clean up, etc.
abstract void	init(CurnConfig curnConfig) Called when the DataPersister is first instantiated.
protected abstract boolean	isEnabled() Determine whether the data persister subclass is enabled or not (i.e., whether or not metadata is to be loaded and saved).
void	loadData(FeedCache feedCache) Load the cache and metadata.
void	saveData(FeedCache feedCache) Save the feed metadata.
protected abstract void	saveExtraMetadata(java.util.Collection<PersistentMetadataGroup> metadata) Save any extra metadata (i.e., metadata that isn't attached to a specific feed or a specific item).
protected abstract void	saveFeedData(PersistentFeedData feedData) Save the data for one feed, including the items.
protected abstract void	startLoadOperation() Called at the beginning of the load operation to initialize the load.
protected abstract void	startSaveOperation() Called at the beginning of the actual save operation to initialize the save, etc.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

DataPersister

protected DataPersister()

Method Detail

saveData

public final void saveData(FeedCache feedCache)
                    throws CurnException

Save the feed metadata. The configuration is passed in, so that the persister can obtain, from the configuration, whatever data it needs to find the persisted metadata to read.

Parameters:

feedCache - FeedCache object to save

Throws:

CurnException - on error

loadData

public void loadData(FeedCache feedCache)
              throws CurnException

Load the cache and metadata.

Parameters:

feedCache - the FeedCache object to fill

Throws:

CurnException - on error

addPersistentDataClient

public final void addPersistentDataClient(PersistentDataClient client)

Register a PersistentDataClient object with this registry. When data for that client is read, this object will call the client's process methods. When it's time to save the metadata, this object will call the client's get methods. Multiple PersistentDataClient objects may be registered with this object.

Parameters:

client - the PersistentDataClient object

init

public abstract void init(CurnConfig curnConfig)
                   throws CurnException

Called when the DataPersister is first instantiated. Useful for retrieving configuration values, etc.

Parameters:

curnConfig - the configuration

Throws:

CurnException - on error

isEnabled

protected abstract boolean isEnabled()

Determine whether the data persister subclass is enabled or not (i.e., whether or not metadata is to be loaded and saved). The configuration usually determines whether or not the data persister is enabled.

Returns:

true if enabled, false if disabled.

startLoadOperation

protected abstract void startLoadOperation()
                                    throws CurnException

Called at the beginning of the load operation to initialize the load.

Throws:

CurnException - on error

endLoadOperation

protected abstract void endLoadOperation()
                                  throws CurnException

Called at the end of the load operation to close files, clean up, etc.

Throws:

CurnException - on error

doLoad

protected abstract void doLoad(DataPersister.LoadedDataHandler loadedDataHandler)
                        throws CurnException

The actual load method; only called if the object is enabled.

Parameters:

loadedDataHandler - object to receive data as it's loaded

Throws:

CurnException - on error

startSaveOperation

protected abstract void startSaveOperation()
                                    throws CurnException

Called at the beginning of the actual save operation to initialize the save, etc.

Throws:

CurnException - on error

endSaveOperation

protected abstract void endSaveOperation()
                                  throws CurnException

Called at the end of the actual save operation to flush files, clean up, etc.

Throws:

CurnException - on error

saveFeedData

protected abstract void saveFeedData(PersistentFeedData feedData)
                              throws CurnException

Save the data for one feed, including the items.

Parameters:

feedData - the feed data to be saved

Throws:

CurnException - on error

saveExtraMetadata

protected abstract void saveExtraMetadata(java.util.Collection<PersistentMetadataGroup> metadata)
                                   throws CurnException

Save any extra metadata (i.e., metadata that isn't attached to a specific feed or a specific item).

Parameters:

metadata - the collection of metadata items

Throws:

CurnException - on error