org.omegahat.Environment.Databases
Interface Database

All Superinterfaces:

Activable

All Known Subinterfaces:

BasicFrameInt, DatabaseNotifier, DataFrameInt, TypedDatabaseInt

All Known Implementing Classes:

ObjectDatabase, OrderedTable, AttachableSearchPath, ModelPointDatabase, NamingServiceDatabase, AttachableInterfaceRepository

public interface Database

extends Activable

Interface for object databases

Object databases in Omegahat extend the concept of hash-table databases in Java (e.g.,

See Also:

)

Additional concepts include the notion of attaching/detaching the database from the Omegahat interactive session, the use of listeners to detect events on the database, and a more general attitude to what can be assigned.

Field Summary

static int	ALL
static int	ASSIGN
static int	ATTACH
static int	DETACH This and following fields, down through ALL are used to identify event types for listeners.
static java.lang.String	NULL_ENTRY the constant object stored to correspond to a null assignment.
static int	READ
static int	READ_WRITE database access constants, thinking about a multi-user system.
static int	REMOVE

Fields inherited from interface org.omegahat.Environment.Databases.Activable

ACTIVE, INACTIVE

Method Summary

boolean	assign(java.lang.String name, java.lang.Object obj) assigns obj to the database under name.
boolean	attach(DatabaseCustomer e)
void	clear() remove all the objects from the database.
boolean	detach(DatabaseCustomer e)
boolean	exists(java.lang.String name) does the object exist in the database?
java.lang.Object	get(java.lang.String name) returns the object in the database assigned under the name.
java.lang.String	getName()
java.lang.String[]	objects() the array of object names.
java.lang.Object	remove(java.lang.String name) remove the object from the database
java.lang.String	setName(java.lang.String name)
int	size() what is the size (in bytes?) of the database.

Methods inherited from interface org.omegahat.Environment.Databases.Activable

getState, setState

Field Detail

DETACH

public static final int DETACH

This and following fields, down through ALL are used to identify event types for listeners.

ATTACH

public static final int ATTACH

ASSIGN

public static final int ASSIGN

REMOVE

public static final int REMOVE

ALL

public static final int ALL

READ_WRITE

public static final int READ_WRITE

database access constants, thinking about a multi-user system.

READ

public static final int READ

NULL_ENTRY

public static final java.lang.String NULL_ENTRY

the constant object stored to correspond to a null assignment.

Method Detail

objects

public java.lang.String[] objects()

the array of object names.

get

public java.lang.Object get(java.lang.String name)

returns the object in the database assigned under the name. or null if none.

assign

public boolean assign(java.lang.String name,
                      java.lang.Object obj)
               throws java.lang.Exception

assigns obj to the database under name.

Parameters:

obj - any object, including null

name - a string (preferably non-empty) to locate the object in the database.

remove

public java.lang.Object remove(java.lang.String name)

remove the object from the database

Parameters:

name - any string, matching the one used in a previous assignment.

exists

public boolean exists(java.lang.String name)

does the object exist in the database?

clear

public void clear()

remove all the objects from the database.

size

public int size()

what is the size (in bytes?) of the database.

detach

public boolean detach(DatabaseCustomer e)

attach

public boolean attach(DatabaseCustomer e)

getName

public java.lang.String getName()

setName

public java.lang.String setName(java.lang.String name)