uka.transport
Class LayeredObjectSpace

java.lang.Object
  uka.util.IDConstants
      uka.transport.ObjectSpaceAdapter
          uka.transport.LayeredObjectSpace

All Implemented Interfaces:

ObjectSpace, java.io.Serializable

public class LayeredObjectSpace

extends ObjectSpaceAdapter

This class layers an overlay over some original object space. The layered object space behaves like the original space for identifiers that are part of the original object space at the time of the creation of the layerd object space. New identifier assignments are stored in the overlay space.

Note: It is not possible to stack multiple layered object spaces. The original object space must not be a layered object space. This restriction is necessary, because a layerd object space devides the available identifier range into a lower part for the original space and an upper part for the overlay.

See Also:

Serialized Form

Field Summary

private static int	FIRST_OVERLAY_ID
protected ObjectSpace	overlay

Fields inherited from class uka.transport.ObjectSpaceAdapter

original

Fields inherited from class uka.util.IDConstants

FIRST_NEW_ID, FIRST_VALID_ID, INVALID_ID, UNUSED_ID

Constructor Summary

LayeredObjectSpace(ObjectSpace original)

LayeredObjectSpace(ObjectSpace original, ObjectSpace overlay)

Method Summary

void	clear() Clears the object space by removing all identifier assignments.
int	findID(java.lang.Object obj) Same as getID(java.lang.Object), but does not assign the object to this object space, if the object was not yet a member.
int	getID(java.lang.Object obj) Returns the identifier for a given object.
java.lang.Object	getObject(int id) Finds the object for a given identifier.
ObjectSpace	getOverlay()
void	includeID(int id) Make the object that corresponds to the given identifier part of this object space.
boolean	isAccepted(int id) Decides whether an object reference should be blocked during transmission through a MarshalStream/UnmarshalStream pair.
boolean	isIncluded(int id) Decides whether the obect that corresponds to the given identifier is part of this object space.
boolean	isShared(int id)
boolean	isUsed(int id) Checks whether this object space has an object assigned to the given identifier.
void	remove(int id) Removes the given identifer from this object space.
void	resetObject(int id, java.lang.Object obj) Reassigns a new object to an existing identifier.
ObjectSpace	resetOverlay()
void	setObject(int id, java.lang.Object obj) Assigns the given object to an application provided identifier and includes the given object to this object space.
void	setOverlay(ObjectSpace overlay)

Methods inherited from class uka.transport.ObjectSpaceAdapter

getOriginal, getUsedIDs

Methods inherited from class uka.util.IDConstants

isNew, isValid, normalizeID, toggleNew

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

FIRST_OVERLAY_ID

private static final int FIRST_OVERLAY_ID

See Also:

Constant Field Values

overlay

protected ObjectSpace overlay

Constructor Detail

LayeredObjectSpace

public LayeredObjectSpace(ObjectSpace original)

LayeredObjectSpace

public LayeredObjectSpace(ObjectSpace original,
                          ObjectSpace overlay)

Method Detail

setOverlay

public final void setOverlay(ObjectSpace overlay)

resetOverlay

public final ObjectSpace resetOverlay()

getOverlay

public final ObjectSpace getOverlay()

getID

public int getID(java.lang.Object obj)

Description copied from interface: ObjectSpace

Returns the identifier for a given object. If the object was presented to the ObjectSpace the first time, the #isNew method returns true for the resulting identifier.

Specified by:

getID in interface ObjectSpace

Overrides:

getID in class ObjectSpaceAdapter

findID

public int findID(java.lang.Object obj)

Description copied from interface: ObjectSpace

Same as ObjectSpace.getID(java.lang.Object), but does not assign the object to this object space, if the object was not yet a member.

Specified by:

findID in interface ObjectSpace

Overrides:

findID in class ObjectSpaceAdapter

getObject

public java.lang.Object getObject(int id)

Description copied from interface: ObjectSpace

Finds the object for a given identifier.

Specified by:

getObject in interface ObjectSpace

Overrides:

getObject in class ObjectSpaceAdapter

isUsed

public boolean isUsed(int id)

Description copied from interface: ObjectSpace

Checks whether this object space has an object assigned to the given identifier. This is most useful, for traversing a non-contiguous identifier space. ObjectSpace.isUsed(int) returns true for identifier returned from ObjectSpace.getID(java.lang.Object).

Specified by:

isUsed in interface ObjectSpace

Overrides:

isUsed in class ObjectSpaceAdapter

isShared

public boolean isShared(int id)

Specified by:

isShared in interface ObjectSpace

Overrides:

isShared in class ObjectSpaceAdapter

setObject

public void setObject(int id,
                      java.lang.Object obj)

Description copied from interface: ObjectSpace

Assigns the given object to an application provided identifier and includes the given object to this object space.

Specified by:

setObject in interface ObjectSpace

Overrides:

setObject in class ObjectSpaceAdapter

resetObject

public void resetObject(int id,
                        java.lang.Object obj)

Description copied from interface: ObjectSpace

Reassigns a new object to an existing identifier. The effect is the same as removing the identifier first and then reassigning it with ObjectSpace.setObject(int, java.lang.Object). Since ObjectSpace.setObject(int, java.lang.Object) may be overridden in subclasses to handle the first assignment of an identifier especially, ObjectSpace.resetObject(int, java.lang.Object) can be used to avoid additional calls to ObjectSpace.setObject(int, java.lang.Object).

Specified by:

resetObject in interface ObjectSpace

Overrides:

resetObject in class ObjectSpaceAdapter

remove

public void remove(int id)

Description copied from interface: ObjectSpace

Removes the given identifer from this object space. This operation removes the complete binding of the corresponding object to its identifier from this object space. A future call to ObjectSpace.getID(java.lang.Object) with the object corresponding to the given identifier as argument will result in a new identifier.

Specified by:

remove in interface ObjectSpace

Overrides:

remove in class ObjectSpaceAdapter

clear

public void clear()

Description copied from interface: ObjectSpace

Clears the object space by removing all identifier assignments.

Specified by:

clear in interface ObjectSpace

Overrides:

clear in class ObjectSpaceAdapter

includeID

public void includeID(int id)

Description copied from interface: ObjectSpace

Make the object that corresponds to the given identifier part of this object space. An object is part of an object space, if the ObjectSpace.isIncluded(int) method returns true for the corresponding identifier. An object can have an assigned identifier in some object space without being part of that object space.

Specified by:

includeID in interface ObjectSpace

Overrides:

includeID in class ObjectSpaceAdapter

isIncluded

public boolean isIncluded(int id)

Description copied from interface: ObjectSpace

Decides whether the obect that corresponds to the given identifier is part of this object space.

Specified by:

isIncluded in interface ObjectSpace

Overrides:

isIncluded in class ObjectSpaceAdapter

isAccepted

public boolean isAccepted(int id)

Description copied from interface: ObjectSpace

Decides whether an object reference should be blocked during transmission through a MarshalStream/UnmarshalStream pair. If a call to ObjectSpace.isAccepted(int) on the ObjectSpace of the sender-side stream returns false for an object identifier, a reference to the corresponding object is blocked (replaced with null).

Specified by:

isAccepted in interface ObjectSpace

Overrides:

isAccepted in class ObjectSpaceAdapter