Package org.dspace.storage.bitstore.service

Interface BitstreamStorageService

All Known Implementing Classes:

BitstreamStorageServiceImpl

public interface BitstreamStorageService

Stores, retrieves and deletes bitstreams.

Presently, asset stores are specified in dspace.cfg. Since Java does not offer a way of detecting free disk space, the asset store to use for new bitstreams is also specified in a configuration property. The drawbacks to this are that the administrators are responsible for monitoring available space in the asset stores, and DSpace (Tomcat) has to be restarted when the asset store for new ('incoming') bitstreams is changed.

Mods by David Little, UCSD Libraries 12/21/04 to allow the registration of files (bitstreams) into DSpace.

Cleanup integration with checker package by Nate Sarr 2006-01. N.B. The dependency on the checker package isn't ideal - a Listener pattern would be better but was considered overkill for the purposes of integrating the checker. It would be worth re-considering a Listener pattern if another package needs to be notified of BitstreamStorageManager actions.

Version:

$Revision$

Author:

Peter Breton, Robert Tansley, David Little, Nathan Sarr

Method Summary

Modifier and Type	Method	Description
void	cleanup(boolean deleteDbRecords, boolean verbose)	Clean up the bitstream storage area.
Bitstream	clone(Context context, Bitstream bitstream)	Clone the given bitstream to a new bitstream with a new ID.
Map	computeChecksum(Context context, Bitstream bitstream)
Long	getLastModified(Bitstream bitstream)	Gets the last modified timestamp of the the given bitstream's content, if known.
boolean	isRegisteredBitstream(String internalId)	Does the internal_id column in the bitstream row indicate the bitstream is a registered file
void	migrate(Context context, Integer assetstoreSource, Integer assetstoreDestination, boolean deleteOld, Integer batchCommitSize)	Migrate all the assets from assetstoreSource to assetstoreDestination
void	printStores(Context context)	Print out (log/out) a listing of the assetstores configured, and how many assets they contain
UUID	register(Context context, Bitstream bitstream, int assetstore, String bitstreamPath)	Register a bitstream already in storage.
InputStream	retrieve(Context context, Bitstream bitstream)	Retrieve the bits for the bitstream with ID.
UUID	store(Context context, Bitstream bitstream, InputStream is)	Store a stream of bits.

Method Detail

store

UUID store(Context context,
           Bitstream bitstream,
           InputStream is)
    throws SQLException,
           IOException

Store a stream of bits.

If this method returns successfully, the bits have been stored, and RDBMS metadata entries are in place (the context still needs to be completed to finalize the transaction).

If this method returns successfully and the context is aborted, then the bits will be stored in the asset store and the RDBMS metadata entries will exist, but with the deleted flag set.

If this method throws an exception, then any of the following may be true:

• Neither bits nor RDBMS metadata entries have been stored.
• RDBMS metadata entries with the deleted flag set have been stored, but no bits.
• RDBMS metadata entries with the deleted flag set have been stored, and some or all of the bits have also been stored.

Parameters:

context - The current context

bitstream - The bitstream to store

is - The stream of bits to store

Returns:

The ID of the stored bitstream

Throws:

IOException - If a problem occurs while storing the bits

SQLException - If a problem occurs accessing the RDBMS

register

UUID register(Context context,
              Bitstream bitstream,
              int assetstore,
              String bitstreamPath)
       throws SQLException,
              IOException,
              AuthorizeException

Register a bitstream already in storage.

Parameters:

context - The current context

bitstream - The bitstream to register

assetstore - The assetstore number for the bitstream to be registered

bitstreamPath - The relative path of the bitstream to be registered. The path is relative to the path of ths assetstore.

Returns:

The ID of the registered bitstream

Throws:

SQLException - If a problem occurs accessing the RDBMS

IOException - if IO error

AuthorizeException - Exception indicating the current user of the context does not have permission to perform a particular action.

computeChecksum

Map computeChecksum(Context context,
                    Bitstream bitstream)
             throws IOException

Throws:

IOException

isRegisteredBitstream

boolean isRegisteredBitstream(String internalId)

Does the internal_id column in the bitstream row indicate the bitstream is a registered file

Parameters:

internalId - the value of the internal_id column

Returns:

true if the bitstream is a registered file

retrieve

InputStream retrieve(Context context,
                     Bitstream bitstream)
              throws SQLException,
                     IOException

Retrieve the bits for the bitstream with ID. If the bitstream does not exist, or is marked deleted, returns null.

Parameters:

context - The current context

bitstream - The bitstream to retrieve

Returns:

The stream of bits, or null

Throws:

IOException - If a problem occurs while retrieving the bits

SQLException - If a problem occurs accessing the RDBMS

cleanup

void cleanup(boolean deleteDbRecords,
             boolean verbose)
      throws SQLException,
             IOException,
             AuthorizeException

Clean up the bitstream storage area. This method deletes any bitstreams which are more than 1 hour old and marked deleted. The deletions cannot be undone.

Parameters:

deleteDbRecords - if true deletes the database records otherwise it only deletes the files and directories in the assetstore

verbose - verbosity flag

Throws:

IOException - If a problem occurs while cleaning up

SQLException - If a problem occurs accessing the RDBMS

AuthorizeException - Exception indicating the current user of the context does not have permission to perform a particular action.

clone

Bitstream clone(Context context,
                Bitstream bitstream)
         throws SQLException,
                IOException,
                AuthorizeException

Clone the given bitstream to a new bitstream with a new ID. Metadata of the given bitstream are also copied to the new bitstream.

Parameters:

context - DSpace context object

bitstream - the bitstream to be cloned

Returns:

id of the clone bitstream.

Throws:

SQLException - if database error

IOException - if IO error

AuthorizeException - if authorization error

printStores

void printStores(Context context)
          throws SQLException

Print out (log/out) a listing of the assetstores configured, and how many assets they contain

Parameters:

context - The relevant DSpace Context.

Throws:

SQLException - if database error

migrate

void migrate(Context context,
             Integer assetstoreSource,
             Integer assetstoreDestination,
             boolean deleteOld,
             Integer batchCommitSize)
      throws IOException,
             SQLException,
             AuthorizeException

Migrate all the assets from assetstoreSource to assetstoreDestination

Parameters:

context - The relevant DSpace Context.

assetstoreSource - source assetstore

assetstoreDestination - destination assetstore

deleteOld - whether to delete files from the source assetstore after migration

batchCommitSize - batch size

Throws:

IOException - A general class of exceptions produced by failed or interrupted I/O operations.

SQLException - An exception that provides information on a database access error or other errors.

AuthorizeException - Exception indicating the current user of the context does not have permission to perform a particular action.

getLastModified

@Nullable
Long getLastModified(Bitstream bitstream)
              throws IOException

Gets the last modified timestamp of the the given bitstream's content, if known.

Parameters:

bitstream - the bitstream.

Returns:

the timestamp in milliseconds, or null if unknown.

Throws:

IOException - if an unexpected io error occurs.