org.ceryle.xnode.providers
Class FileSystemProvider

java.lang.Object
  org.ceryle.xnode.providers.AbstractXNodeStoreProvider
      org.ceryle.xnode.providers.FileSystemProvider

All Implemented Interfaces:

XNodeStoreProvider

public class FileSystemProvider
extends AbstractXNodeStoreProvider
implements XNodeStoreProvider

Implements the XNodeStoreProvider API for an XNodeStore, using the local file system as the storage. This can actually coexist with the BerkeleyDBProvider as it uses a 'db' directory within the default 'storage' directory as the root of the directory tree.

The XNode Implementation (the package org.ceryle.xnode.*, both its source code and documentation), are released under the Apache 2.0 License. For more details, check the LICENSE file contained with the distribution, or see The Ceryle Project for more information. It is distributed with no warranty.

Since:

XNode 1.2

Version:

$Id: FileSystemProvider.java,v 1.2 2007-06-15 15:46:27 altheim Exp $

Author:

Murray Altheim

Field Summary

static String

FILE_EXT The file extension for stored files.

Fields inherited from class org.ceryle.xnode.providers.AbstractXNodeStoreProvider

Filesep, m_homepath, m_storage, m_storagepath, m_xns, mh

Constructor Summary

FileSystemProvider()

Method Summary

void	closeDatabase(String did) Close the Database backing the XNodeCollection having ID did.
void	deleteContent(String did, String rid) Permanently deletes the key/data pair (database record) matching the key String rid from the Database with ID did.
void	deleteDatabase(String did) Remove the Database backing the XNodeCollection having ID did.
String	getContent(String did, String rid) The method that does the actual work of retrieving the contents in the record with key String rid (record ID) from the Database with ID did.
int	getContentSize(String did, String rid) Returns the record storage size of the document in the Database with ID did for the data matching the key String rid (record ID).
Object	getDatabase(String did) Return the Database backing the XNodeCollection having ID did.
List	getDatabaseIndex() Returns the List of existing Database IDs.
List	getDocumentIndex(String did) Returns the document index for the Database with key did, sorted, created from the Database.
boolean	hasContent(String did, String rid) Returns true if the Database with ID did contains data matching the key String rid (record ID).
boolean	hasDatabase(String did) Returns true if there is an existing Database with key did.
void	initialize(XNodeStore xnodestore) Initializes the XNodeStoreProvider provided its parent XNodeStore.
void	putContent(String did, String rid, String content, boolean overwrite) The method that does the actual work of storing the String content in the Database db using the key String rid (record ID).
void	start() Start the database service.
void	stop() Shuts down the database service.

Methods inherited from class org.ceryle.xnode.providers.AbstractXNodeStoreProvider

error, isLoadedDatabase, message, optimize, setPaths, storageExists, warning, writeXNodeToDatabase

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.purl.xnode.XNodeStoreProvider

isLoadedDatabase, optimize, storageExists, writeXNodeToDatabase

Field Detail

FILE_EXT

public static final String FILE_EXT

The file extension for stored files. The value is ".xml".

See Also:

Constant Field Values

Constructor Detail

FileSystemProvider

public FileSystemProvider()

Method Detail

initialize

public void initialize(XNodeStore xnodestore)
                throws XNodeStoreProviderException

Initializes the XNodeStoreProvider provided its parent XNodeStore. Calling this method subsequently throws an XNodeStoreProviderException.

Specified by:

initialize in interface XNodeStoreProvider

Overrides:

initialize in class AbstractXNodeStoreProvider

Parameters:

xnodestore - the parent XNodeStore.

Throws:

XNodeStoreProviderException - if any error occurs while initializing the provider.

start

public void start()
           throws XNodeStoreProviderException

Start the database service. If already started, this has no effect.

Does nothing in this class.

(This is an XNodeStoreProvider API method)

Specified by:

start in interface XNodeStoreProvider

Specified by:

start in class AbstractXNodeStoreProvider

Throws:

XNodeStoreProviderException - if unable to start the database.

stop

public void stop()
          throws XNodeStoreProviderException

Shuts down the database service. If already stopped, this has no effect.

Does nothing in this class.

(This is an XNodeStoreProvider API method)

Specified by:

stop in interface XNodeStoreProvider

Specified by:

stop in class AbstractXNodeStoreProvider

Throws:

XNodeStoreProviderException - if an error occurs while stopping the database.

getDatabase

public Object getDatabase(String did)
                   throws XNodeStoreProviderException

Return the Database backing the XNodeCollection having ID did. This will create the database if it does not already exist.

If did equals the root ID ("db"), use that as the base name, otherwise the root should be added as part of the path , e.g., "db/did".

(This is an XNodeStoreProvider API method)

Specified by:

getDatabase in interface XNodeStoreProvider

Specified by:

getDatabase in class AbstractXNodeStoreProvider

Parameters:

did - the ID of the Database

Returns:

null.

Throws:

XNodeStoreProviderException - if any error occurs while getting or creating the Database.

hasDatabase

public boolean hasDatabase(String did)
                    throws XNodeStoreProviderException

Returns true if there is an existing Database with key did. This directly queries the stored databases (as directories) from the file system.

(This is an XNodeStoreProvider API method)

Specified by:

hasDatabase in interface XNodeStoreProvider

Specified by:

hasDatabase in class AbstractXNodeStoreProvider

Parameters:

did - the ID of the Database to query.

Returns:

true if the Database exists.

Throws:

XNodeStoreProviderException - if any error occurs while querying.

getDatabaseIndex

public List getDatabaseIndex()
                      throws XNodeStoreProviderException

Returns the List of existing Database IDs. This directly queries the stored databases (as directories) from the file system, not the XNodeCollections that are their registries. This returns an empty List rather than null if there are no collections. It does not include the root Database ("db") in the list.

(This is an XNodeStoreProvider API method)

Specified by:

getDatabaseIndex in interface XNodeStoreProvider

Specified by:

getDatabaseIndex in class AbstractXNodeStoreProvider

Returns:

an immutable List of the Database IDs (as Strings).

Throws:

XNodeStoreProviderException - if any error occurs while building the index.

closeDatabase

public void closeDatabase(String did)
                   throws XNodeStoreProviderException

Close the Database backing the XNodeCollection having ID did. If a Database matching the ID does not exist or is not loaded, nothing happens. This is only used for implementations that require housekeeping upon closing a database.

In this class this method does nothing.

Specified by:

closeDatabase in interface XNodeStoreProvider

Specified by:

closeDatabase in class AbstractXNodeStoreProvider

Parameters:

did - the ID of the Database to close.

Throws:

XNodeStoreProviderException - if any error occurs while closing the Database.

deleteDatabase

public void deleteDatabase(String did)
                    throws XNodeStoreProviderException

Remove the Database backing the XNodeCollection having ID did.

This will ignore requests to delete the root directory ("db").

(This is an XNodeStoreProvider API method)

Specified by:

deleteDatabase in interface XNodeStoreProvider

Specified by:

deleteDatabase in class AbstractXNodeStoreProvider

Parameters:

did - the ID of the Database to delete.

Throws:

XNodeStoreProviderException - if any error occurs while removing the Database.

putContent

public void putContent(String did,
                       String rid,
                       String content,
                       boolean overwrite)
                throws XNodeStoreProviderException

The method that does the actual work of storing the String content in the Database db using the key String rid (record ID). The boolean overwrite is used as a failsafe to keep from accidentally overwriting an existing record — if true, throws an exception if the record already exists.

(This is an XNodeStoreProvider API method)

Specified by:

putContent in interface XNodeStoreProvider

Specified by:

putContent in class AbstractXNodeStoreProvider

Parameters:

did - the ID of the Database

rid - the ID of the record

content - the content String.

overwrite - when true permit the overwrite of previous content.

Throws:

XNodeStoreProviderException - if any error occurs while putting the content into the Database.

hasContent

public boolean hasContent(String did,
                          String rid)
                   throws XNodeStoreProviderException

Returns true if the Database with ID did contains data matching the key String rid (record ID). This returns false under all other circumstances.

(This is an XNodeStoreProvider API method)

Specified by:

hasContent in interface XNodeStoreProvider

Specified by:

hasContent in class AbstractXNodeStoreProvider

Parameters:

did - the ID of the Database

rid - the ID of the record

Returns:

true if a record matching the key 'id' exists.

Throws:

XNodeStoreProviderException - if an error occurs retrieving the content.

getContentSize

public int getContentSize(String did,
                          String rid)

Returns the record storage size of the document in the Database with ID did for the data matching the key String rid (record ID). This may be used as an alternative to hasContent(String,String) since it does basically the same function but returns a more useful value. This returns -1 if the document doesn't exist, and returns a -2 if either of the parameters is null or an error occurs, rather than throwing an exception.

(This is an XNodeStoreProvider API method)

Specified by:

getContentSize in interface XNodeStoreProvider

Specified by:

getContentSize in class AbstractXNodeStoreProvider

Parameters:

did - the ID of the Database

rid - the ID of the record

Returns:

the size of the record matching the key 'id'; -1 if it doesn't exist; -2 upon error.

getContent

public String getContent(String did,
                         String rid)
                  throws XNodeStoreProviderException

The method that does the actual work of retrieving the contents in the record with key String rid (record ID) from the Database with ID did.

(This is an XNodeStoreProvider API method)

Specified by:

getContent in interface XNodeStoreProvider

Specified by:

getContent in class AbstractXNodeStoreProvider

Parameters:

did - the ID of the Database

rid - the ID of the record

Returns:

a String representation of the data, or null if unavailable.

Throws:

XNodeStoreProviderException - if an error occurs retrieving the content.

deleteContent

public void deleteContent(String did,
                          String rid)
                   throws XNodeStoreProviderException

Permanently deletes the key/data pair (database record) matching the key String rid from the Database with ID did.

(This is an XNodeStoreProvider API method)

Specified by:

deleteContent in interface XNodeStoreProvider

Specified by:

deleteContent in class AbstractXNodeStoreProvider

Parameters:

did - the ID of the Database

rid - the ID of the record

Throws:

XNodeStoreProviderException - if an error occurs deleting the key/data pair.

getDocumentIndex

public List getDocumentIndex(String did)
                      throws XNodeStoreProviderException

Returns the document index for the Database with key did, sorted, created from the Database. Returns an empty List rather than null.

(This is an XNodeStoreProvider API method)

Specified by:

getDocumentIndex in interface XNodeStoreProvider

Specified by:

getDocumentIndex in class AbstractXNodeStoreProvider

Parameters:

did - the ID of the Database.

Returns:

a List containing the IDs of the XNodes in this XNodeCollection.

Throws:

XNodeStoreProviderException - if an error occurs obtaining the document index.

Since:

XNode 1.2