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UnitOfWork.javaAPI DocGlassfish v2 API31765Tue May 22 16:54:52 BST 2007oracle.toplink.essentials.sessions

UnitOfWork

public interface UnitOfWork implements Session
Purpose: To allow object level transactions. This class represents the public API of the unit of work and should be used to maintain complete compatibility.

Description: The unit of work is a session that implements all of the normal protocol of a TopLink session. It can be spawned from any other session including another unit of work. Objects can be brought into the unit of work through reading them or through registering them. The unit of work will opperate on its own object space, that is the objects within the unit of work will be clones of the orignial objects. When the unit of work is commited, all changes to any objects registered within the unit of work will be commited to the database. A minimal commit/update will be performed and any foreign keys/circular reference/referencial integrity will be resolved. If the commit to the database is successful the changed objects will be merged back into the unit of work parent session.

Responsibilities:

  • Allow parallel transactions against a session's objects.
  • Allow nested transactions.
  • Not require the application to write objects that is changes, automatically determine what has changed.
  • Perform a minimal commit/update of all changes that occured.
  • Resolve foreign keys for newly created objects and maintain referencial integrity.
  • Allow for the object transaction to use its own object space.

Fields Summary
Constructors Summary
Methods Summary
public voidaddReadOnlyClass(java.lang.Class theClass)
PUBLIC: Adds the given Java class to the receiver's set of read-only classes. Cannot be called after objects have been registered in the unit of work.

public voidaddReadOnlyClasses(java.util.Vector classes)
PUBLIC: Adds the classes in the given Vector to the existing set of read-only classes. Cannot be called after objects have been registered in the unit of work.

public voidassignSequenceNumber(java.lang.Object object)
ADVANCED: Assign sequence number to the object. This allows for an object's id to be assigned before commit. It can be used if the application requires to use the object id before the object exists on the database. Normally all ids are assigned during the commit automatically.

public voidassignSequenceNumbers()
ADVANCED: Assign sequence numbers to all new objects registered in this unit of work, or any new objects reference by any objects registered. This allows for an object's id to be assigned before commit. It can be used if the application requires to use the object id before the object exists on the database. Normally all ids are assigned during the commit automatically.

public voidbeginEarlyTransaction()
PUBLIC: Tell the unit of work to begin a transaction now. By default the unit of work will begin a transaction at commit time. The default is the recommended approach, however sometimes it is neccessary to start the transaction before commit time. When the unit of work commits, this transcation will be commited.

see
#commit()
see
#release()

public voidcommit()
PUBLIC: Commit the unit of work to its parent. For a nested unit of work this will merge any changes to its objects with its parents. For a first level unit of work it will commit all changes to its objects to the database as a single transaction. If successful the changes to its objects will be merged to its parent's objects. If the commit fails the database transaction will be rolledback, and the unit of work will be released. If the commit is successful the unit of work is released, and a new unit of work must be acquired if further changes are desired.

see
#commitAndResumeOnFailure()
see
#commitAndResume()
see
#release()

public voidcommitAndResume()
PUBLIC: Commit the unit of work to its parent. For a nested unit of work this will merge any changes to its objects with its parents. For a first level unit of work it will commit all changes to its objects to the database as a single transaction. If successful the changes to its objects will be merged to its parent's objects. If the commit fails the database transaction will be rolledback, and the unit of work will be released. The normal commit releases the unit of work, forcing a new one to be acquired if further changes are desired. The resuming feature allows for the same unit of work (and working copies) to be continued to be used.

see
#commitAndResumeOnFailure()
see
#commit()
see
#release()

public voidcommitAndResumeOnFailure()
PUBLIC: Commit the unit of work to its parent. For a nested unit of work this will merge any changes to its objects with its parents. For a first level unit of work it will commit all changes to its objects to the database as a single transaction. If successful the changes to its objects will be merged to its parent's objects. If the commit fails the database transaction will be rolledback, but the unit of work will remain active. It can then be retried or released. The normal commit failure releases the unit of work, forcing a new one to be acquired if further changes are desired. The resuming feature allows for the same unit of work (and working copies) to be continued to be used if an error occurs.

see
#commit()
see
#release()

public java.lang.ObjectdeepMergeClone(java.lang.Object rmiClone)
PUBLIC: Merge the attributes of the clone into the unit of work copy. This can be used for objects that are returned from the client through RMI serialization or other serialization mechanisms, because the RMI object will be a clone this will merge its attributes correctly to preserve object identity within the unit of work and record its changes. Everything connected to this object (i.e. the entire object tree where rmiClone is the root) is also merged.

return
the registered version for the clone being merged.
see
#mergeClone(Object)
see
#shallowMergeClone(Object)

public java.lang.ObjectdeepRevertObject(java.lang.Object clone)
PUBLIC: Revert the object's attributes from the parent. This reverts everything the object references.

return
the object reverted.
see
#revertObject(Object)
see
#shallowRevertObject(Object)

public voiddeepUnregisterObject(java.lang.Object clone)
ADVANCED: Unregister the object with the unit of work. This can be used to delete an object that was just created and is not yet persistent. Delete object can also be used, but will result in inserting the object and then deleting it. The method should be used carefully because it will delete all the reachable parts.

public voiddeleteAllObjects(java.util.Collection domainObjects)
PUBLIC: Delete all of the objects and all of their privately owned parts in the database. Delete operations are delayed in a unit of work until commit.

public voiddeleteAllObjects(java.util.Vector domainObjects)
PUBLIC: Delete all of the objects and all of their privately owned parts in the database. Delete operations are delayed in a unit of work until commit.

public java.lang.ObjectdeleteObject(java.lang.Object domainObject)
PUBLIC: Delete the object and all of their privately owned parts in the database. Delete operations are delayed in a unit of work until commit.

public voiddontPerformValidation()
ADVANCED: The unit of work performs validations such as, ensuring multiple copies of the same object don't exist in the same unit of work, ensuring deleted objects are not refered after commit, ensures that objects from the parent cache are not refered in the unit of work cache. The level of validation can be increased or decreased for debugging purposes or under advanced situation where the application requires/desires to violate clone identity in the unit of work. It is strongly suggested that clone identity not be violate in the unit of work.

public voidforceUpdateToVersionField(java.lang.Object cloneFromUOW, boolean shouldModifyVersionField)
ADVANCED: Set optmistic read lock on the object. This feature is overide by normal optimistic lock. when the object is changed in UnitOfWork. The cloneFromUOW must be the clone of from this UnitOfWork and it must implements version locking or timestamp locking. The SQL would look like the followings. If shouldModifyVersionField is true, "UPDATE EMPLOYEE SET VERSION = 2 WHERE EMP_ID = 9 AND VERSION = 1" If shouldModifyVersionField is false, "UPDATE EMPLOYEE SET VERSION = 1 WHERE EMP_ID = 9 AND VERSION = 1"

public oracle.toplink.essentials.changesets.UnitOfWorkChangeSetgetCurrentChanges()
ADVANCED: This method Will Calculate the chages for the UnitOfWork. Without assigning sequence numbers This is a Computationaly intensive operation and should be avoided unless necessary. A valid changeSet, with sequencenumbers can be collected from the UnitOfWork After the commit is complete by calling unitOfWork.getUnitOfWorkChangeSet()

public java.lang.ObjectgetOriginalVersionOfObject(java.lang.Object workingClone)
ADVANCED: Return the original version of the object(clone) from the parent's identity map.

public oracle.toplink.essentials.internal.sessions.AbstractSessiongetParent()
PUBLIC: Return the parent. This is a unit of work if nested, otherwise a database session or client session.

public oracle.toplink.essentials.changesets.UnitOfWorkChangeSetgetUnitOfWorkChangeSet()
ADVANCED: Returns the currentChangeSet from the UnitOfWork. This is only valid after the UnitOfWOrk has commited successfully

public intgetValidationLevel()
ADVANCED: The unit of work performs validations such as, ensuring multiple copies of the same object don't exist in the same unit of work, ensuring deleted objects are not refered after commit, ensures that objects from the parent cache are not refered in the unit of work cache. The level of validation can be increased or decreased for debugging purposes or under advanced situation where the application requires/desires to violate clone identity in the unit of work. It is strongly suggested that clone identity not be violate in the unit of work.

public booleanhasChanges()
ADVANCED: The Unit of work is capable of preprocessing to determine if any on the clone have been changed. This is computationaly expensive and should be avoided on large object graphs.

public booleanisActive()
PUBLIC: Return if the unit of work is active (has not been released).

public booleanisClassReadOnly(java.lang.Class theClass)
PUBLIC: Checks to see if the specified class is read-only or not in this UnitOfWork.

return
true if the class is read-only, false otherwise.

public booleanisNestedUnitOfWork()
ADVANCED: Return if this session is a nested unit of work.

public java.lang.ObjectmergeClone(java.lang.Object rmiClone)
PUBLIC: Merge the attributes of the clone into the unit of work copy. This can be used for objects that are returned from the client through RMI serialization (or another serialization mechanism), because the RMI object will be a clone this will merge its attributes correctly to preserve object identity within the unit of work and record its changes. The object and its private owned parts are merged.

return
the registered version for the clone being merged.
see
#shallowMergeClone(Object)
see
#deepMergeClone(Object)

public java.lang.ObjectmergeCloneWithReferences(java.lang.Object rmiClone)
PUBLIC: Merge the attributes of the clone into the unit of work copy. This can be used for objects that are returned from the client through RMI serialization (or another serialization mechanism), because the RMI object will be a clone this will merge its attributes correctly to preserve object identity within the unit of work and record its changes. The object and its private owned parts are merged. This will include references from this clone to independent objects.

return
the registered version for the clone being merged.
see
#shallowMergeClone(Object)
see
#deepMergeClone(Object)

public java.lang.ObjectnewInstance(java.lang.Class theClass)
PUBLIC: Return a new instance of the class registered in this unit of work. This can be used to ensure that new objects are registered correctly.

public voidperformFullValidation()
ADVANCED: The unit of work performs validations such as, ensuring multiple copies of the same object don't exist in the same unit of work, ensuring deleted objects are not refered after commit, ensures that objects from the parent cache are not refered in the unit of work cache. The level of validation can be increased or decreased for debugging purposes or under advanced situation where the application requires/desires to violate clone identity in the unit of work. It is strongly suggested that clone identity not be violate in the unit of work.

public voidperformPartialValidation()
ADVANCED: The unit of work performs validations such as, ensuring multiple copies of the same object don't exist in the same unit of work, ensuring deleted objects are not refered after commit, ensures that objects from the parent cache are not refered in the unit of work cache. The level of validation can be increased or decreased for debugging purposes or under advanced situation where the application requires/desires to violate clone identity in the unit of work. It is strongly suggested that clone identity not be violate in the unit of work.

public voidprintRegisteredObjects()
PUBLIC: Print the objects in the unit of work.

public java.lang.ObjectrefreshAndLockObject(java.lang.Object object)
PUBLIC: Refresh the attributes of the object and of all of its private parts from the database. The object will be pessimisticly locked on the database for the duration of the transaction. If the object is already locked this method will wait until the lock is released. A no wait option is available through setting the lock mode.

see
#refreshAndLockObject(Object, lockMode)

public java.lang.ObjectrefreshAndLockObject(java.lang.Object object, short lockMode)
PUBLIC: Refresh the attributes of the object and of all of its private parts from the database. The object will be pessimisticly locked on the database for the duration of the transaction.

Lock Modes: ObjectBuildingQuery.NO_LOCK, LOCK, LOCK_NOWAIT

public java.util.VectorregisterAllObjects(java.util.Collection domainObjects)
PUBLIC: Register the objects with the unit of work. All newly created root domain objects must be registered to be inserted on commit. Also any existing objects that will be edited and were not read from this unit of work must also be registered. Once registered any changes to the objects will be commited to the database on commit.

return
is the clones of the original objects, the return value must be used for editing, editing the original is not allowed in the unit of work.

public java.util.VectorregisterAllObjects(java.util.Vector domainObjects)
PUBLIC: Register the objects with the unit of work. All newly created root domain objects must be registered to be inserted on commit. Also any existing objects that will be edited and were not read from this unit of work must also be registered. Once registered any changes to the objects will be commited to the database on commit.

return
is the clones of the original objects, the return value must be used for editing, editing the original is not allowed in the unit of work.

public java.lang.ObjectregisterExistingObject(java.lang.Object existingObject)
ADVANCED: Register the existing object with the unit of work. This is a advanced API that can be used if the application can guarentee the object exists on the database. When registerObject is called the unit of work determines existence through the descriptor's doesExist setting.

return
The clone of the original object, the return value must be used for editing. Editing the original is not allowed in the unit of work.

public java.lang.ObjectregisterNewObject(java.lang.Object newObject)
ADVANCED: Register the new object with the unit of work. This will register the new object without cloning. Normally the registerObject method should be used for all registration of new and existing objects. This version of the register method can only be used for new objects. This method should only be used if a new object is desired to be registered without cloning.

see
#registerObject(Object)

public java.lang.ObjectregisterObject(java.lang.Object domainObject)
PUBLIC: Register the object with the unit of work. All newly created root domain objects must be registered to be inserted on commit. Also any existing objects that will be edited and were not read from this unit of work must also be registered. Once registered any changes to the objects will be commited to the database on commit.

return
the clone of the original object, the return value must be used for editing, ** Editing the original is not allowed in the unit of work. **

public voidrelease()
PUBLIC: Release the unit of work. This terminates this unit of work. Because the unit of work operates on its own object space (clones) no work is required. The unit of work should no longer be used or referenced by the application beyond this point so that it can garbage collect.

see
#commit()

public voidremoveAllReadOnlyClasses()
PUBLIC: Empties the set of read-only classes. It is illegal to call this method on nested UnitOfWork objects. A nested UnitOfWork cannot have a subset of its parent's set of read-only classes.

public voidremoveForceUpdateToVersionField(java.lang.Object cloneFromUOW)
ADVANCED: Remove optimistic read lock from the object See forceUpdateToVersionField(Object)

public voidremoveReadOnlyClass(java.lang.Class theClass)
PUBLIC: Removes a Class from the receiver's set of read-only classes. It is illegal to try to send this method to a nested UnitOfWork.

public voidrevertAndResume()
PUBLIC: Revert all changes made to any registered object. Clear all deleted and new objects. Revert should not be confused with release which it the normal compliment to commit. Revert is more similar to commit and resume, however reverts all changes and resumes. If you do not require to resume the unit of work release should be used instead.

see
#commitAndResume()
see
#release()

public java.lang.ObjectrevertObject(java.lang.Object clone)
PUBLIC: Revert the object's attributes from the parent. This also reverts the object privately-owned parts.

return
the object reverted.
see
#shallowRevertObject(Object)
see
#deepRevertObject(Object)

public voidsetShouldNewObjectsBeCached(boolean shouldNewObjectsBeCached)
ADVANCED: By default new objects are not cached until the exist on the database. Occasionally if mergeClone is used on new objects and is required to allow multiple merges on the same new object, then if the new objects are not cached, each mergeClone will be interpretted as a different new object. By setting new objects to be cached mergeClone can be performed multiple times before commit. New objects cannot be cached unless they have a valid assigned primary key before being registered. New object with non-null invalid primary keys such as 0 or '' can cause problems and should not be used with this option.

public voidsetShouldPerformDeletesFirst(boolean shouldPerformDeletesFirst)
ADVANCED: By default deletes are performed last in a unit of work. Sometimes you may want to have the deletes performed before other actions.

public voidsetShouldThrowConformExceptions(int shouldThrowExceptions)
ADVANCED: Conforming queries can be set to provide different levels of detail about the exceptions they encounter There are two levels: DO_NOT_THROW_CONFORM_EXCEPTIONS = 0; THROW_ALL_CONFORM_EXCEPTIONS = 1;

public voidsetValidationLevel(int validationLevel)
ADVANCED: The unit of work performs validations such as, ensuring multiple copies of the same object don't exist in the same unit of work, ensuring deleted objects are not refered after commit, ensures that objects from the parent cache are not refered in the unit of work cache. The level of validation can be increased or decreased for debugging purposes or under advanced situation where the application requires/desires to violate clone identity in the unit of work. It is strongly suggested that clone identity not be violate in the unit of work.

public java.lang.ObjectshallowMergeClone(java.lang.Object rmiClone)
PUBLIC: Merge the attributes of the clone into the unit of work copy. This can be used for objects that are returned from the client through RMI serialization (or other serialization mechanisms), because the RMI object will be a clone this will merge its attributes correctly to preserve object identity within the unit of work and record its changes. Only direct attributes are merged.

return
the registered version for the clone being merged.
see
#mergeClone(Object)
see
#deepMergeClone(Object)

public java.lang.ObjectshallowRevertObject(java.lang.Object clone)
PUBLIC: Revert the object's attributes from the parent. This only reverts the object's direct attributes.

return
the object reverted.
see
#revertObject(Object)
see
#deepRevertObject(Object)

public voidshallowUnregisterObject(java.lang.Object clone)
ADVANCED: Unregister the object with the unit of work. This can be used to delete an object that was just created and is not yet persistent. Delete object can also be used, but will result in inserting the object and then deleting it. The method will only unregister the clone, none of its parts.

public booleanshouldNewObjectsBeCached()
ADVANCED: By default new objects are not cached until the exist on the database. Occasionally if mergeClone is used on new objects and is required to allow multiple merges on the same new object, then if the new objects are not cached, each mergeClone will be interpretted as a different new object. By setting new objects to be cached mergeClone can be performed multiple times before commit. New objects cannot be cached unless they have a valid assigned primary key before being registered. New object with non-null invalid primary keys such as 0 or '' can cause problems and should not be used with this option.

public booleanshouldPerformDeletesFirst()
ADVANCED: By default all objects are inserted and updated in the database before any object is deleted. If this flag is set to true, deletes will be performed before inserts and updates

public booleanshouldPerformFullValidation()
ADVANCED: The unit of work performs validations such as, ensuring multiple copies of the same object don't exist in the same unit of work, ensuring deleted objects are not refered after commit, ensures that objects from the parent cache are not refered in the unit of work cache. The level of validation can be increased or decreased for debugging purposes or under advanced situation where the application requires/desires to violate clone identity in the unit of work. It is strongly suggested that clone identity not be violate in the unit of work.

public booleanshouldPerformNoValidation()
ADVANCED: The unit of work performs validations such as, ensuring multiple copies of the same object don't exist in the same unit of work, ensuring deleted objects are not refered after commit, ensures that objects from the parent cache are not refered in the unit of work cache. The level of validation can be increased or decreased for debugging purposes or under advanced situation where the application requires/desires to violate clone identity in the unit of work. It is strongly suggested that clone identity not be violate in the unit of work.

public booleanshouldPerformPartialValidation()
ADVANCED: The unit of work performs validations such as, ensuring multiple copies of the same object don't exist in the same unit of work, ensuring deleted objects are not refered after commit, ensures that objects from the parent cache are not refered in the unit of work cache. The level of validation can be increased or decreased for debugging purposes or under advanced situation where the application requires/desires to violate clone identity in the unit of work. It is strongly suggested that clone identity not be violate in the unit of work.

public voidunregisterObject(java.lang.Object clone)
ADVANCED: Unregister the object with the unit of work. This can be used to delete an object that was just created and is not yet persistent. Delete object can also be used, but will result in inserting the object and then deleting it. The method will only unregister private owned parts

public voidvalidateObjectSpace()
ADVANCED: This can be used to help debugging an object-space corruption. An object-space corruption is when your application has incorrectly related a clone to an original object. This method will validate that all registered objects are in a correct state and throw an error if not, it will contain the full stack of object references in the error message. If you call this method after each register or change you perform it will pin-point where the error was made.

public voidwriteChanges()
ADVANCED: Writes all changes now before commit(). The commit process will begin and all changes will be written out to the datastore, but the datastore transaction will not be committed, nor will changes be merged into the global cache.

A subsequent commit (on UnitOfWork or global transaction) will be required to finalize the commit process.

As the commit process has begun any attempt to register objects, or execute object-level queries will generate an exception. Report queries, non-caching queries, and data read/modify queries are allowed.

On exception any global transaction will be rolled marked or marked rollback only. No recovery of this UnitOfWork will be possible.

Can only be called once. It can not be used to write out changes in an incremental fashion.

Use to partially commit a transaction outside of a JTA transaction's callbacks. Allows you to get back any exception directly.

Use to commit a UnitOfWork in two stages.