org.dspace.core

Interface DBConnection<T>

Type Parameters:

T - type of the persistence provider's session object.

All Known Implementing Classes:

HibernateDBConnection

public interface DBConnection<T>

Interface representing a persistence provider "session". Implementations will wrap something like a JPA EntityManager or a Hibernate Session. The terms "database" and "connection" are historic and have no direct relationship to a JDBC Connection or even a connection pool.

This class should only be accessed by an enclosing Context object.

Note that the user's HTTPSession is an unrelated concept.

Author:

kevinvandevelde at atmire.com

Method Summary

Modifier and Type	Method and Description
void	closeDBConnection() Close this session: close DBMS connection(s) and clean up resources.
void	commit() Commit the open transaction.
long	getCacheSize() How many entities are cached in this session?
DatabaseConfigVO	getDatabaseConfig() Identify certain characteristics of the DBMS being used to support persistence.
DataSource	getDataSource() The JDBC DataSource used by this session.
T	getSession() Access to the underlying persistence provider's session object.
String	getType() Some description of the DBMS used to persist entities.
boolean	isOptimizedForBatchProcessing() Has this session been configured for large batches? Typically this means that automatic flushing of updates to the database is suppressed, and thus one must take care to flush manually (or commit) at appropriate times.
boolean	isSessionAlive()
boolean	isTransActionAlive()
<E extends ReloadableEntity> E	reloadEntity(E entity) Reload a DSpace object from the database.
void	rollback() Roll back the open transaction.
void	setConnectionMode(boolean batchOptimized, boolean readOnlyOptimized) Configure the connection for special uses.
void	shutdown() Close all sessions.
<E extends ReloadableEntity> void	uncacheEntity(E entity) Remove a DSpace object from the session cache when batch processing a large number of objects.

Method Detail

getSession

T getSession()
      throws SQLException

Access to the underlying persistence provider's session object.

Returns:

the provider's session object for this connection.

Throws:

SQLException - passed through.

isTransActionAlive

boolean isTransActionAlive()

Returns:

true if this session has an uncommitted transaction.

isSessionAlive

boolean isSessionAlive()

Returns:

true if the session is open, false if it has been closed.

commit

void commit()
     throws SQLException

Commit the open transaction.

Throws:

SQLException - passed through.

rollback

void rollback()
       throws SQLException

Roll back the open transaction.

Throws:

SQLException - passed through.

closeDBConnection

void closeDBConnection()
                throws SQLException

Close this session: close DBMS connection(s) and clean up resources.

Throws:

SQLException - passed through.

shutdown

void shutdown()

Close all sessions. Release all associated resources (cache, DBMS connections, etc.) To be used only when exiting the application.

getType

String getType()

Some description of the DBMS used to persist entities.

Returns:

Brand, version, dialect, etc. Implementation specific.

getDataSource

DataSource getDataSource()

The JDBC DataSource used by this session. Think carefully before using.

Returns:

the source of DBMS connections.

getDatabaseConfig

DatabaseConfigVO getDatabaseConfig()
                            throws SQLException

Identify certain characteristics of the DBMS being used to support persistence.

Returns:

a collection of DBMS, database and connection information.

Throws:

SQLException - passed through.

setConnectionMode

void setConnectionMode(boolean batchOptimized,
                       boolean readOnlyOptimized)
                throws SQLException

Configure the connection for special uses.

Parameters:

batchOptimized - if true, optimize for batch use. Typically this means suppressing automatic flushing of updates, thus requiring manual flushing at appropriate points in the process.

readOnlyOptimized - if true, optimize for read-only use. Typically this suppresses all updating.

Throws:

SQLException

isOptimizedForBatchProcessing

boolean isOptimizedForBatchProcessing()

Has this session been configured for large batches? Typically this means that automatic flushing of updates to the database is suppressed, and thus one must take care to flush manually (or commit) at appropriate times.

Returns:

true if configured for batch.

getCacheSize

long getCacheSize()
           throws SQLException

How many entities are cached in this session?

Returns:

number of cached entities.

Throws:

SQLException - passed through.

reloadEntity

<E extends ReloadableEntity> E reloadEntity(E entity)
                                     throws SQLException

Reload a DSpace object from the database. This will make sure the object is valid and stored in the cache. The returned object should be used henceforth instead of the passed object.

Type Parameters:

E - type of entity

Parameters:

entity - The DSpace object to reload

Returns:

the reloaded entity.

Throws:

SQLException - passed through.

uncacheEntity

<E extends ReloadableEntity> void uncacheEntity(E entity)
                                         throws SQLException

Remove a DSpace object from the session cache when batch processing a large number of objects.

Objects removed from cache are not saved in any way. Therefore, if you have modified an object, you should be sure to commit() changes before calling this method.

Type Parameters:

E - Type of entity

Parameters:

entity - The DSpace object to decache.

Throws:

SQLException