org.odmg
Interface Database

All Known Implementing Classes:

DatabaseImpl

public interface Database

The interface for interacting with an ODMG database. Databases must be opened before starting any transactions that use the database and closed after ending these transactions.

A database application generally begins processing by accessing one or more critical objects and proceeding from there. These objects are root objects, because they lead to interconnected webs of other objects. The ability to name an object (using method bind) and retrieve it later by that name (using method lookup facilitates this start-up capability. A name is not explicitly defined as an attribute of an object. Naming an object also makes it persistent.

There is a single flat name scope per database; thus all names in a particular database are unique.

Version:

ODMG 3.0

Author:

David Jordan (as Java Editor of the Object Data Management Group)

Field Summary

static int	NOT_OPEN The database is not open.
static int	OPEN_EXCLUSIVE The database is open for exclusive access.
static int	OPEN_READ_ONLY The database is opened for read-only access.
static int	OPEN_READ_WRITE The database is opened for reading and writing.

Method Summary

void	bind(Object object, String name) Associate a name with an object and make it persistent.
void	close() Close the database.
void	deletePersistent(Object object) Deletes an object from the database.
Object	lookup(String name) Lookup an object via its name.
void	makePersistent(Object object) Make a transient object durable in the database.
void	open(String name, int accessMode) Open the named database with the specified access mode.
void	unbind(String name) Disassociate a name with an object

Field Detail

NOT_OPEN

static final int NOT_OPEN

The database is not open.

See Also:

Constant Field Values

OPEN_READ_ONLY

static final int OPEN_READ_ONLY

The database is opened for read-only access.

See Also:

Constant Field Values

OPEN_READ_WRITE

static final int OPEN_READ_WRITE

The database is opened for reading and writing.

See Also:

Constant Field Values

OPEN_EXCLUSIVE

static final int OPEN_EXCLUSIVE

The database is open for exclusive access.

See Also:

Constant Field Values

Method Detail

open

void open(String name,
          int accessMode)
          throws ODMGException

Open the named database with the specified access mode. Attempts to open a database when it has already been opened will result in the throwing of the exception DatabaseOpenException. A DatabaseNotFoundException is thrown if the database does not exist. Some implementations may throw additional exceptions that are also derived from ODMGException.

Parameters:

name - The name of the database.

accessMode - The access mode, which should be one of the static fields: OPEN_READ_ONLY, OPEN_READ_WRITE, or OPEN_EXCLUSIVE.

Throws:

ODMGException - The database could not be opened.

close

void close()
           throws ODMGException

Close the database. After you have closed a database, further attempts to access objects in the database will cause the exception DatabaseClosedException to be thrown. Some implementations may throw additional exceptions that are also derived from ODMGException.

Throws:

ODMGException - Unable to close the database.

bind

void bind(Object object,
          String name)
          throws ObjectNameNotUniqueException

Associate a name with an object and make it persistent. An object instance may be bound to more than one name. Binding a previously transient object to a name makes that object persistent.

Parameters:

object - The object to be named.

name - The name to be given to the object.

Throws:

ObjectNameNotUniqueException - If an attempt is made to bind a name to an object and that name is already bound to an object.

lookup

Object lookup(String name)
              throws ObjectNameNotFoundException

Lookup an object via its name.

Parameters:

name - The name of an object.

Returns:

The object with that name.

Throws:

ObjectNameNotFoundException - There is no object with the specified name.

See Also:

ObjectNameNotFoundException

unbind

void unbind(String name)
            throws ObjectNameNotFoundException

Disassociate a name with an object

Parameters:

name - The name of an object.

Throws:

ObjectNameNotFoundException - No object exists in the database with that name.

makePersistent

void makePersistent(Object object)

Make a transient object durable in the database. It must be executed in the context of an open transaction. If the transaction in which this method is executed commits, then the object is made durable. If the transaction aborts, then the makePersistent operation is considered not to have been executed, and the target object is again transient. ClassNotPersistenceCapableException is thrown if the implementation cannot make the object persistent because of the type of the object.

Parameters:

object - The object to make persistent.

deletePersistent

void deletePersistent(Object object)

Deletes an object from the database. It must be executed in the context of an open transaction. If the object is not persistent, then ObjectNotPersistent is thrown. If the transaction in which this method is executed commits, then the object is removed from the database. If the transaction aborts, then the deletePersistent operation is considered not to have been executed, and the target object is again in the database.

Parameters:

object - The object to delete.