Package org.opencms.db.storage

Interface I_CmsStorage

All Superinterfaces:

AutoCloseable

All Known Subinterfaces:

I_CmsDbStorage, I_CmsEnumerableStorage

All Known Implementing Classes:

CmsDbStorage, CmsDbStorage, CmsDbStorage, CmsDbStorage, CmsDbStorage, CmsDbStorage, CmsDbStorage, CmsDbStorage, CmsFsStorage, CmsS3Storage

public interface I_CmsStorage
extends AutoCloseable

Storage backend interface for the OpenCms deduplicating media storage engine (DMSE).

This interface abstracts the physical storage of binary resource content in database, file system or S3-compatible backends. Content is addressed by its SHA-512 hash.

See Also:

• CmsStorageManager

Method Summary

Modifier and Type	Method	Description
default void	close()	Closes this storage backend and releases associated resources.
void	deleteContent(CmsDbContext dbc, String hash)	Deletes the content from the storage if applicable.
String	getStorageIdentifier()	Returns the stable storage identifier stored in the VFS content tables.
byte[]	loadContent(CmsDbContext dbc, String hash)	Loads the actual binary content.
default void	loadContentFrom(CmsDbContext dbc, String hash, I_CmsFileContentStreamHandler handler)	Loads the actual binary content and passes it to the given input stream handler.
default void	loadContentTo(CmsDbContext dbc, String hash, OutputStream out)	Loads the actual binary content into the given output stream.
void	storeContent(CmsDbContext dbc, String hash, byte[] content)	Stores the given content.
void	validateAvailable(CmsDbContext dbc)	Validates that the storage backend is available for read and write operations.

Method Details

close

default void close()
            throws Exception

Closes this storage backend and releases associated resources.

Specified by:

close in interface AutoCloseable

Throws:

Exception - if closing the storage backend fails

deleteContent

void deleteContent(CmsDbContext dbc,
 String hash)
            throws Exception

Deletes the content from the storage if applicable.

Parameters:

dbc - the database context

hash - the SHA-512 content hash

Throws:

Exception - if the deletion in the external storage fails

getStorageIdentifier

String getStorageIdentifier()

Returns the stable storage identifier stored in the VFS content tables.

The identifier is the configured backend id, for example media or archive. The database storage uses the reserved backend id db. The identifier must not depend on mutable connection details such as paths, endpoints, or bucket names.

Returns:

the stable storage identifier

loadContent

byte[] loadContent(CmsDbContext dbc,
 String hash)
            throws Exception

Loads the actual binary content.

Parameters:

dbc - the database context

hash - the SHA-512 content hash

Returns:

the actual binary file content

Throws:

Exception - if the content cannot be retrieved

loadContentFrom

default void loadContentFrom(CmsDbContext dbc,
 String hash,
 I_CmsFileContentStreamHandler handler)
                      throws Exception

Loads the actual binary content and passes it to the given input stream handler.

This default implementation keeps custom storage implementations source compatible by falling back to loadContent(CmsDbContext, String).

Parameters:

dbc - the database context

hash - the SHA-512 content hash

handler - the stream handler

Throws:

Exception - if the content cannot be retrieved or handled

loadContentTo

default void loadContentTo(CmsDbContext dbc,
 String hash,
 OutputStream out)
                    throws Exception

Loads the actual binary content into the given output stream.

This default implementation keeps custom storage implementations source compatible by falling back to loadContent(CmsDbContext, String).

Parameters:

dbc - the database context

hash - the SHA-512 content hash

out - the output stream to write to

Throws:

Exception - if the content cannot be retrieved or written

storeContent

void storeContent(CmsDbContext dbc,
 String hash,
 byte[] content)
           throws Exception

Stores the given content.

Parameters:

dbc - the database context

hash - the SHA-512 content hash

content - the actual binary data to store

Throws:

Exception - if the storage operation fails

validateAvailable

void validateAvailable(CmsDbContext dbc)
                throws Exception

Validates that the storage backend is available for read and write operations.

This method is called during startup for configured storage backends. Implementations should perform a lightweight roundtrip which verifies the required prerequisites for storing content.

Parameters:

dbc - the database context

Throws:

Exception - if the storage backend is not available