org.apache.derby.iapi.store.access

Interface FileResource

public interface FileResource

Management of file resources within a database. Suitable for jar files, images etc.

A file resource is identified by the pair (name,generationId). Name is an arbitrary String supplied by the caller. GenerationId is a non-repeating sequence number constructed by the database. Within a database a (name,generationId) pair uniquely identifies a version of a file resource for all time. Newer generation numbers reflect newer versions of the file.

A database supports the concept of a designated current version of a fileResource. The management of the current version is transactional. The following rules apply

1. Adding a FileResource makes the added version the current version
2. Removing a FileResource removes the current version of the resource. After this operation the database holds no current version of the FileResoure.
3. Replacing a FileResource removes the current version of the resource.

For the benefit of replication, a database optionally retains historic versions of stored files. These old versions are useful when processing old transactions in the stage.

Field Summary

Fields

Modifier and Type	Field and Description
static java.lang.String	JAR_DIRECTORY_NAME The name of the jar directory

Method Summary

Modifier and Type	Method and Description
long	add(java.lang.String name, java.io.InputStream source) Add a file resource, copying from the input stream.
StorageFile	getAsFile(java.lang.String name, long generationId) Get the StorageFile for a file resource.
char	getSeparatorChar()
void	remove(java.lang.String name, long currentGenerationId) Remove the current generation of a file resource from the database.
void	removeJarDir(java.lang.String f) During hard upgrade to >= 10.9, remove a jar directory (at post-commit time) from the database.
long	replace(java.lang.String name, long currentGenerationId, java.io.InputStream source) Replace a file resource with a new version.

Field Detail

JAR_DIRECTORY_NAME

static final java.lang.String JAR_DIRECTORY_NAME

The name of the jar directory

See Also:

Constant Field Values

Method Detail

add

long add(java.lang.String name,
         java.io.InputStream source)
  throws StandardException

Add a file resource, copying from the input stream. The InputStream will be closed by this method.

Parameters:

name - the name of the file resource.

source - an input stream for reading the content of the file resource.

Returns:

the generationId for the file resource. This quantity increases when you replace the file resource.

Throws:

StandardException - some error occured.

remove

void remove(java.lang.String name,
            long currentGenerationId)
     throws StandardException

Remove the current generation of a file resource from the database.

Parameters:

name - the name of the fileResource to remove.

Throws:

StandardException - some error occured.

removeJarDir

void removeJarDir(java.lang.String f)
           throws StandardException

During hard upgrade to >= 10.9, remove a jar directory (at post-commit time) from the database.

Parameters:

f -

Throws:

StandardException - if an error occurs

replace

long replace(java.lang.String name,
             long currentGenerationId,
             java.io.InputStream source)
      throws StandardException

Replace a file resource with a new version.

The InputStream will be closed by this method.

Parameters:

name - the name of the file resource.

source - an input stream for reading the content of the file resource.

Returns:

the generationId for the new 'current' version of the file resource.

Throws:

StandardException - some error occured.

getAsFile

StorageFile getAsFile(java.lang.String name,
                      long generationId)

Get the StorageFile for a file resource.

Parameters:

name - The name of the fileResource

generationId - the generationId of the fileResource

Returns:

A StorageFile object representing the file.

getSeparatorChar

char getSeparatorChar()

Returns:

the separator character to be used in file names.