com.webobjects.eocontrol
Class EOGlobalID

java.lang.Object
  |
  +--com.webobjects.eocontrol.EOGlobalID

All Implemented Interfaces:

Cloneable, Serializable

Direct Known Subclasses:

EOKeyGlobalID, EOTemporaryGlobalID

public abstract class EOGlobalID

extends Object

implements Serializable, Cloneable

An EOGlobalID is a compact, universal, identifier for a persistent object. This forms the basis for uniquing in the Enterprise Objects Framework. An EOGlobalID uniquely identifies the same object or record both between EOEditingContexts in a single application, and in multiple applications (as in distributed systems). EOGlobalID is an abstract class, declaring only the methods needed for identification. A concrete subclass must define appropriate storage for identifying values (such as primary keys), as well as an initialization or creation method to build IDs.

Temporary Identifiers

EOEditingContexts and other object stores support the insertion of new objects without established IDs, creating temporary IDs that get replaced with permanent ones as soon as the new objects are saved to their persistent stores. The temporary IDs are instances of the EOTemporaryGlobalID class.

When an EOObjectStore saves these newly inserted objects, it must replace the temporary IDs with persistent ones. When it does this, it must post a GlobalIDChangedNotification announcing the change so that observers can update their accounts of which objects are identified by which global IDs. The notification's userInfo dictionary contains a mapping from the temporary IDs (the keys) to their permanent replacements (the values).

See Also:

GlobalIDChangedNotification, EOTemporaryGlobalID, EOObjectStore, Serialized Form

Field Summary

static String

GlobalIDChangedNotification Posted whenever EOTemporaryGlobalIDs are replaced by permanent EOGlobalIDs.

Constructor Summary

EOGlobalID()

Method Summary

Object	clone() EOGlobalID's implementation simply returns a reference to the receiver (this).
abstract boolean	equals(Object object) Compares the receiver to object.
abstract int	hashCode() Provides an appropriate hash code useful for storing the receiver in a hash-based data structure.
boolean	isTemporary() If the receiver is temporary (that is, most likely an instance of EOTemporaryGlobalID), this method returns true; false otherwise.

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Field Detail

GlobalIDChangedNotification

public static final String GlobalIDChangedNotification

Posted whenever EOTemporaryGlobalIDs are replaced by permanent EOGlobalIDs. The notification contains:

Notification Object	null
Userinfo	A mapping from the temporary IDs (keys) to permanent IDs (values)

Constructor Detail

EOGlobalID

public EOGlobalID()

Method Detail

clone

public Object clone()

EOGlobalID's implementation simply returns a reference to the receiver (this).

Overrides:

clone in class Object

Returns:

an Object reference to the receiver

equals

public abstract boolean equals(Object object)

Compares the receiver to object. If the contents of object are equal to the contents of the receiver, this method returns true. If not, it returns false. Two data objects are equal if they hold the same number of bytes, and if the bytes at the same position in the objects are the same.

Overrides:

equals in class Object

Parameters:

object - input object against which the receiver is compared

Returns:

true if the objects are equal; false otherwise

hashCode

public abstract int hashCode()

Provides an appropriate hash code useful for storing the receiver in a hash-based data structure.

Overrides:

hashCode in class Object

Returns:

hash code int useful for storing the receiver in a hash-based data structure

isTemporary

public boolean isTemporary()

If the receiver is temporary (that is, most likely an instance of EOTemporaryGlobalID), this method returns true; false otherwise. See the class description for more information on temporary IDs. Note that EOGlobalID's implementation simply returns false.

Returns:

true if the globalID is temporary

See Also:

EOGlobalID, EOTemporaryGlobalID