How to use Optimistic Locking in Toplink

Hi!
Iam using Toplink for O/R mapping, and for each table
iam using one TimeStamp field, and i specified that
field as Locking filed, by using the Loking option, and checked the TimeStampLocking option.
Now my question is do i need to update the Timestamp filed
each time if i create a new record and while modify an existing record.
And also do i need to compare the Timestamp for the record which client as read previousley to the TimeStamp in the database for the record manullay lik
suppose t1 is the timeStamp, which i got from the client,
and t2 is the timestamp which i read from the Database.
Now my question is, is it necessary to compare the timestamp.

Once optimistic locking has been configured TopLink will manage the updating and comparing of the OptimisticLocking value. There is no requirement for you to manage this value.
--Gordon

Similar Messages

Hello anyone know how to use the locked iphone outside USA

hello anyone know how to use the locked AT&T iphone 5 outside US. I'll go to Japan. Don't know if the phone can be used there.any idea will be appreciated.

You'll need to get it unlocked by ATandT to avoid paying huge roaming costs.
See: http://www.att.com/esupport/article.jsp?sid=KB414532&cv=820

Query using Optimistic Locking

Hello all ,
"With optimistic locking, a resource is not actually locked when it is first is accessed by a transaction."
Is optimistic locking used for banking applications ??
Please share your ideas , share your ideas.Thanks in advance.

Can optimistic locking be used for banking applications? Sure. Is it always appropriate for every possible banking related application? No.
You'll need to be a lot more specific about your application's requirements before we can say anything with much specificity. In general, banking or non-banking, OLTP applications ought to be using optimistic locking and any application that uses pessimistic locking needs to be careful not to hold locks across user interaction events (i.e. don't allow a user to lock a row and then head out to lunch without releasing the lock).
Justin

What is the use for lock object and how to use the lock objects

Hi Guru's,
I am new to ABAP .Can you please clarify the that what is the use of lock object and how to use the loct object .what is use of the Deque & Enque function modules .

hi ,
below are some minfo about lock objects :
Lock Objects
These types of objects are used for locking the access to database records in table. This mechanism is used to enforce data integrity that is two users cannot update the same data at the same time. With lock objects you can lock table-field or whole table.
In a system where many users can access the same data, it becomes necessary to control the access to the data. In R/3 system this access control is built-in on database tables. Developers can also lock objects over table records.
To lock an object you need to call standard functions, which are automatically generated while defining the lock object in ABAP/4 dictionary. This locking system is independent of the locking mechanism used by the R/3 system. This mechanism also defines LUW i.e. Logical Unit of Work. Whenever an object is locked, either by in built locking mechanism or by function modules, it creates corresponding entry in global system table i.e. table is locked. The system automatically releases the lock at the end of transaction. The LUW starts when a lock entry is created in the system table and ends when the lock is released.
Creating Lock Objects
Lock object is an aggregated dictionary object and can be defined by using the following steps:
o From initial data dictionary screen, enter the name for the object, Click Lock object radiobutton and then click on Create. The system displays a dialog box for Maintain Lock Objects screen
o Enter short text as usual and the name for primary table.
-Save
-Select Tables option
From this screen you can:
Select secondary tables, if any, linked by foreign key relationship.
Fields for the lock objects. This option allows you to select fields for objects (R/3 system allows locking up to record level). Lock object argument are not selected by user but are imposed by the system and includes all the primary keys for the table.
1) Exclusive lock: The locked data can only be displayed or edited by a single user. A request for another exclusive lock or for a shared lock is rejected.
2) Shared lock: More than one user can access the locked data at the same time in display mode. A request for another shared lock is accepted, even if it comes from another user. An exclusive lock is rejected.
3) Exclusive but not cumulative: Exclusive locks can be requested several times from the same transaction and are processed successively. In contrast, exclusive but not cumulative locks can be called only once from the same transaction. All other lock requests are rejected.
Also, last but not the least, locking the object is logical (locking with any enqueue ) .so, you have to use the lock object while trying to access from second program .
reward if helpful ,
Regards,
Ranjita

How to use REF cursor with toplink

Hi,
I have a stored proc has a out variable which is a REF CURSOR.
How to read my cursor with toplink?

I have got it. Here is the solution.
          UnitOfWork uow= dbSession.acquireUnitOfWork();
          StoredProcedureCall call = new StoredProcedureCall();
          call.setProcedureName("smart.getCompanyStruct");
          call.addNamedArgument("xnrid");
          call.useNamedCursorOutputAsResultSet("cpy");
          DataReadQuery query = new DataReadQuery();
          query.setCall(call);
          Vector parameters = new Vector();
          query.addArgument("xnrid");
          parameters.add(new Long(5009L));
          Vector obj = (Vector) uow.executeQuery(query, parameters);
Vector contains result ser of the cursor
Gurcan

How to use Native SQL in Toplink

I am using toplink in my project, can you please some one help me how to create native sql using toplink.
I have seen EntityManager interface having method createNativeQuery, but how to create instance of EntityManager

import javax.persistence.EntityManager;within class, place
protected EntityManager entityManager;of course make it public, private, whatever you need.
Then, in your method
entityManager.createNativeQuery(....);R. Grimes

How to use aggregate function with Toplink

Hi
My question is how can I get the following select when using Toplink-EJB.3:
SELECT MAX(fieldname) FROM tablename;
Thanasi

Hi KAVI PRIYA,
if date is not in cannonical format, how can we change it in BI publisher, then how to calcualte minimum and as well as maximum.
please advise me,
Thanks,
Sri

How to use join queries with toplink

Hi there
I'm using toplink within the JDeveloper 10.1.3.3. with great success.
Now, I need to query multiple tables using a join SQL.
How do you configure toplink now without creating database views?
I could not find an easy with within the JDev IDE or from google search.
Any help please?
Thanks
Henkie

In a TopLink query you can query across any relationship to another object. You can also join or batch read the object's relationship using the ObjectLevelReadQuery and ReadAllQuery API (see TopLink documentation).
You can also map a class to multiple tables.
-- James : http://www.eclipselink.org

HT3965 how to use cap locks on keyboard

How does one find/use the caplocks function on the iPhone keyboard? I've enabled the caplocks feature, but cannot find a key to turn caplocks on.

Doubble tap the shift key fast and when it gets blue you should type ALL caps. Then when you want to take it of just tap it once so it goes back to lowercase letters.

How to use master locks in a process chain with planning sequence

Hi,
when I start a process chain which contains a planning sequence there is no master lock set. The chain stops and I get the message "Data in InfoProvider XYZ is locked by user TIMMAY". What can i do to enable the master locks?
Thanks for your help!

Hello,
When a planning sequence is triggered via process chain system first first tries to set a normal lock and if this is possible, these selections are stored as master locks and then the normal locks are released.
In your case if some data is already locked by another user the lock conflict will occur in teh first step only where system tries to create a normal lock before creating master locks.
If Administrator wants to trigger the process chain he should ask other users to come out of the planning layouts so that all the locks are released and then trigger the chain and after this the system will set the master locks. Packaging in planning sequence process type won't help in setting master locks even if the data is locked by other user.
Also, after master locks are deleted in RSPLSE, the transaction data remains protected by normal data locks during runtime. Nevertheless, without master locks it is no longer guaranteed that parts of planning sequences can be carried out without encountering lock conflicts with other users.
Regards,
Deepti

Toplink Optimistic Locking not working with Session Bean facade.

I am working on Oracle JDeveloper v 10.1.2 and connecting to an Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - 64bit
The application is based on J2EE architecture and the technology stack uses Struts for presentation/controller framework, Stateless Session EJBs as session facade for custom business services, Simple java classes for the business services, Toplink implementation of DAO layer, Domain objects are mapped to database tables using Toplink Workbench that ships with JDeveloper. The transaction is managed by the session bean and hence the toplink session is configured to use external transaction controller and a named datasource as follows.
<session xsi:type="server-session">
<name>DBSession</name>
<server-platform xsi:type="oc4j-1012-platform"/>
<event-listener-classes/>
<logging xsi:type="toplink-log">
<log-level>fine</log-level>
<file-name>D:/ToplinkLog.log</file-name>
</logging>
<primary-project xsi:type="xml">META-INF/toplink-descriptor.xml</primary-project>
<login xsi:type="database-login">
<platform-class>oracle.toplink.platform.database.oracle.Oracle10Platform</platform-class>
<external-connection-pooling>true</external-connection-pooling>
<external-transaction-controller>true</external-transaction-controller>
<sequencing>
<default-sequence xsi:type="native-sequence">
<name>Native</name>
<preallocation-size>1</preallocation-size>
</default-sequence>
</sequencing>
<datasource>jdbc/ORADS</datasource>
</login>
</session>
We intend to use Optimistic Locking based on Timestamp-version locking through an audit field "last_modification_date" of type java.sql.Timestamp. The corresponding database field is also of type Timestamp(6). We are not storing the version in cache.
The problem we are facing is as follows.. we have an edit screen from where user can edit values for a domain object which are then persisted using Toplink...we expect Toplink to check the database record version (modification_date timestamp) before it applies the update. In DAO implementation, we register the object in a unitOfWork, then set the modified values, however we leave the modification_date (version field) unedited. Now when the application is running, on edit, an exception is thrown by the Session bean before ending the transaction.
com.evermind.server.rmi.OrionRemoteException: Transaction was rolled back: Error in transaction: java.lang.NullPointerException
     at TrackingMediator_StatelessSessionBeanWrapper2.editOverheadExpenditure(TrackingMediator_StatelessSessionBeanWrapper2.java:1597)
     at com.enbridge.dsm.web.action.TrackingPortfolioAction.editOverheadExpenditure(TrackingPortfolioAction.java:264)
     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
     at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java)
     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
     at java.lang.reflect.Method.invoke(Method.java)
     at org.apache.struts.actions.DispatchAction.dispatchMethod(DispatchAction.java:278)
     at com.enbridge.dsm.web.shared.BaseAction.execute(BaseAction.java:90)
     at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:465)
     at com.enbridge.dsm.web.shared.DSMPojoRequestProcessor.process(DSMPojoRequestProcessor.java:182)
     at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1425)
     at com.sourcebeat.strutslive.common.SLActionServlet.process(SLActionServlet.java:44)
     at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:525)
     at javax.servlet.http.HttpServlet.service(HttpServlet.java:760)
     at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
     at com.evermind.server.http.ResourceFilterChain.doFilter(ResourceFilterChain.java:65)
     at oracle.security.jazn.oc4j.JAZNFilter.doFilter(Unknown Source)
     at com.evermind.server.http.EvermindFilterChain.doFilter(EvermindFilterChain.java:16)
     at com.enbridge.dsm.web.shared.security.SecurityFilter.doFilter(SecurityFilter.java:142)
     at com.evermind.server.http.ServletRequestDispatcher.invoke(ServletRequestDispatcher.java:645)
     at com.evermind.server.http.ServletRequestDispatcher.forwardInternal(ServletRequestDispatcher.java:322)
     at com.evermind.server.http.HttpRequestHandler.processRequest(HttpRequestHandler.java:790)
     at com.evermind.server.http.HttpRequestHandler.run(HttpRequestHandler.java:270)
     at com.evermind.server.http.HttpRequestHandler.run(HttpRequestHandler.java:112)
     at com.evermind.util.ReleasableResourcePooledExecutor$MyWorker.run(ReleasableResourcePooledExecutor.java:192)
     at java.lang.Thread.run(Thread.java:534)
     Nested exception is:
java.lang.NullPointerException
     at oracle.jdbc.driver.PhysicalConnection.commit(PhysicalConnection.java:1190)
     at com.evermind.sql.FilterConnection.commit(FilterConnection.java:209)
     at com.evermind.sql.DriverManagerXAConnection.commit(DriverManagerXAConnection.java:203)
     at com.evermind.server.TransactionEnlistment.commit(TransactionEnlistment.java:251)
     at com.evermind.server.ApplicationServerTransaction.singlePhaseCommit(ApplicationServerTransaction.java:745)
     at com.evermind.server.ApplicationServerTransaction.commit(ApplicationServerTransaction.java:690)
     at com.evermind.server.ApplicationServerTransaction.end(ApplicationServerTransaction.java:1035)
     at TrackingMediator_StatelessSessionBeanWrapper2.editOverheadExpenditure(TrackingMediator_StatelessSessionBeanWrapper2.java:1593)
     at com.enbridge.dsm.web.action.TrackingPortfolioAction.editOverheadExpenditure(TrackingPortfolioAction.java:264)
     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
     at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java)
     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
     at java.lang.reflect.Method.invoke(Method.java)
     at org.apache.struts.actions.DispatchAction.dispatchMethod(DispatchAction.java:278)
     at com.enbridge.dsm.web.shared.BaseAction.execute(BaseAction.java:90)
     at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:465)
     at com.enbridge.dsm.web.shared.DSMPojoRequestProcessor.process(DSMPojoRequestProcessor.java:182)
     at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1425)
     at com.sourcebeat.strutslive.common.SLActionServlet.process(SLActionServlet.java:44)
     at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:525)
     at javax.servlet.http.HttpServlet.service(HttpServlet.java:760)
     at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
     at com.evermind.server.http.ResourceFilterChain.doFilter(ResourceFilterChain.java:65)
     at oracle.security.jazn.oc4j.JAZNFilter.doFilter(Unknown Source)
     at com.evermind.server.http.EvermindFilterChain.doFilter(EvermindFilterChain.java:16)
     at com.enbridge.dsm.web.shared.security.SecurityFilter.doFilter(SecurityFilter.java:142)
     at com.evermind.server.http.ServletRequestDispatcher.invoke(ServletRequestDispatcher.java:645)
     at com.evermind.server.http.ServletRequestDispatcher.forwardInternal(ServletRequestDispatcher.java:322)
     at com.evermind.server.http.HttpRequestHandler.processRequest(HttpRequestHandler.java:790)
     at com.evermind.server.http.HttpRequestHandler.run(HttpRequestHandler.java:270)
     at com.evermind.server.http.HttpRequestHandler.run(HttpRequestHandler.java:112)
     at com.evermind.util.ReleasableResourcePooledExecutor$MyWorker.run(ReleasableResourcePooledExecutor.java:192)
     at java.lang.Thread.run(Thread.java:534)
Note that the exception is thrown at the time when the session bean is about to commit the transaction. i.e. the DAO code did not throw any exception and was able to check the optimistic locking and submit the update transaction.
I am not able to understand why is the the EJB throwing this weird error with Optimistic locking implementation. The application is working fine when the optimistic locking is disabled.
I am facing another problem due to this problem... since the session bean throws this exception after exiting the bean implemented method, when trying to commit the transaction, I am not able to mark the session context to setRollbackOnly. Hence if I continue on to another transaction by navigating to another screen in the application, mysteriously the previous transaction gets committed!!... again... weird...

I am using JDBC driver version 10.1.2.
I saw this additional error message in JDeveloper console, which for some reason was not logged to my log4j log file... if it helps...
06/09/22 18:32:10 Thr[thread 6]-TransactionEnlistment.TransactionEnlistment.Caught forgetandRollback XAException e null
Here are the logs from my Toplink log file....
[TopLink Info]: 2006.09.22 06:31:46.546--ServerSession(989)--Thread(Thread[HttpRequestHandler-86,5,main])--TopLink, version: Oracle TopLink - 10g Release 3 (10.1.3.0.0) (Build 060118)
[TopLink Info]: 2006.09.22 06:31:46.578--ServerSession(989)--Thread(Thread[HttpRequestHandler-86,5,main])--Server: Oracle Application Server Containers for J2EE 10g (10.1.2.0.0)
[TopLink Config]: 2006.09.22 06:31:46.593--ServerSession(989)--Connection(991)--Thread(Thread[HttpRequestHandler-86,5,main])--connecting(DatabaseLogin(
     platform=>Oracle10Platform
     user name=> ""
     connector=>JNDIConnector datasource name=>jdbc/ORADS
[TopLink Config]: 2006.09.22 06:31:47.484--ServerSession(989)--Connection(1432)--Thread(Thread[HttpRequestHandler-86,5,main])--Connected: jdbc:oracle:thin:@10.210.16.37:1521:orabld
     User: APP_USR
     Database: Oracle Version: Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - 64bit Production
With the Partitioning, OLAP and Data Mining options
     Driver: Oracle JDBC driver Version: 10.1.0.3.0
[TopLink Config]: 2006.09.22 06:31:47.500--ServerSession(989)--Connection(1433)--Thread(Thread[HttpRequestHandler-86,5,main])--connecting(DatabaseLogin(
     platform=>Oracle10Platform
     user name=> ""
     connector=>JNDIConnector datasource name=>jdbc/ORADS
[TopLink Config]: 2006.09.22 06:31:47.500--ServerSession(989)--Connection(1434)--Thread(Thread[HttpRequestHandler-86,5,main])--Connected: jdbc:oracle:thin:@10.210.16.37:1521:orabld
     User: APP_USR
     Database: Oracle Version: Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - 64bit Production
With the Partitioning, OLAP and Data Mining options
     Driver: Oracle JDBC driver Version: 10.1.0.3.0
[TopLink Info]: 2006.09.22 06:31:47.671--ServerSession(989)--Thread(Thread[HttpRequestHandler-86,5,main])--DBSession login successful
[TopLink Fine]: 2006.09.22 06:31:47.703--ServerSession(989)--Connection(1554)--Thread(Thread[HttpRequestHandler-86,5,main])--select * from user_role ur, app_resource ar, role_resource rr where rr.APP_RESOURCE_ID = ar.APP_RESOURCE_ID and rr.USER_ROLE_ID = ur.USER_ROLE_ID
[TopLink Fine]: 2006.09.22 06:31:49.937--ServerSession(989)--Connection(10245)--Thread(Thread[HttpRequestHandler-86,5,main])--SELECT * FROM PROGRAM_SUB_CAT
[TopLink Fine]: 2006.09.22 06:31:50.015--ServerSession(989)--Connection(10332)--Thread(Thread[HttpRequestHandler-86,5,main])--SELECT PROGRAM_ID, CREATED_BY_USERID FROM (SELECT CREATED_BY_USERID, ROWNUM PROGRAM_ID FROM (SELECT DISTINCT(CREATED_BY_USERID) CREATED_BY_USERID, 1 AS PROGRAM_ID FROM PROGRAM))
(I only see my application specific queries after this... no exceptions or debug logs)... as I said before.. the application gives exception in the session bean at the time of commit, and there's no exception raised from Toplink code in DAO...

Em.merge does not throw Optimistic Lock Exception

Hello,
we are using Optimistic Lock Exception in a stateful bean managed transaction.
I am wondering that there is no Optimistic Lock Exception is thrown after em.merge
The Optimistic Lock Exception is primary thrown on em.flush - is this right?
A similar problem is described on
http://www.nabble.com/Optimistic-Lock-Exception-expected-td22742662.html#a22742662
See serveroutput: The EclipseLink-5006-Exception is thrown after an em.flush
14:03:11,657 INFO [STDOUT] updateItem
14:03:11,657 INFO [STDOUT] [EL Finest]: 2009-04-09 14:03:11.657--UnitOfWork(14218007)--Thread(WorkerThread#0[192.168.1.217:4518])--Merge clone with references com.tup.model.Person@131a24c
14:03:11,657 INFO [STDOUT] merged
14:03:11,657 INFO [STDOUT] [EL Finest]: 2009-04-09 14:03:11.657--UnitOfWork(14218007)--Thread(WorkerThread#0[192.168.1.217:4518])--Execute query UpdateObjectQuery(com.tup.model.Person@196649c)
14:03:11,657 INFO [STDOUT] [EL Fine]: 2009-04-09 14:03:11.657--ClientSession(21268424)--Connection(25845065)--Thread(WorkerThread#0[192.168.1.217:4518])--UPDATE mku_person_ver SET first_name = ? WHERE ((ID = ?) AND (((last_name = ?) AND (first_name = ?)) AND (version = ?)))
bind => [Bernd 982, 5, Kuls, Bernd 98, 2009-04-09 13:12:15.0]
14:03:11,672 INFO [STDOUT] [EL Warning]: 2009-04-09 14:03:11.672--UnitOfWork(14218007)--Thread(WorkerThread#0[192.168.1.217:4518])--Exception [EclipseLink-5006] (Eclipse Persistence Services - 1.1.0.r3634): org.eclipse.persistence.exceptions.OptimisticLockException
Exception Description: The object [com.tup.model.Person@196649c] cannot be updated because it has changed or been deleted since it was last read.
Class> com.tup.model.Person Primary Key> [5]
14:03:11,688 INFO [STDOUT] [EL Warning]: 2009-04-09 14:03:11.688--UnitOfWork(14218007)--Thread(WorkerThread#0[192.168.1.217:4518])--javax.persistence.OptimisticLockException: Exception [EclipseLink-5006] (Eclipse Persistence Services - 1.1.0.r3634): org.eclipse.persistence.exceptions.OptimisticLockException
Exception Description: The object [com.tup.model.Person@196649c] cannot be updated because it has changed or been deleted since it was last read.
Class> com.tup.model.Person Primary Key> [5]
14:03:11,688 INFO [STDOUT] OptimisticLockException throws MyApplicationException
14:03:11,688 INFO [STDOUT] MyApplicationException
14:03:11,735 INFO [STDOUT] [EL Finer]: 2009-04-09 14:03:11.735--UnitOfWork(14218007)--Thread(WorkerThread#0[192.168.1.217:4518])--TX afterCompletion callback, status=ROLLEDBACK
14:03:11,750 INFO [STDOUT] [EL Finer]: 2009-04-09 14:03:11.75--UnitOfWork(14218007)--Thread(WorkerThread#0[192.168.1.217:4518])--release unit of work
14:03:11,750 INFO [STDOUT] [EL Finer]: 2009-04-09 14:03:11.75--ClientSession(21268424)--Thread(WorkerThread#0[192.168.1.217:4518])--client released
14:03:11,750 ERROR [BMTInterceptor] BMT stateful bean 'ModelFacade' did not complete user transaction properly status=STATUS_MARKED_ROLLBACK
And by this Exception the transaction's status is set to status=STATUS_MARKED_ROLLBACK.
The transaction can no longer be used.
I want to use this transaction further and wrap the OptimisticLockException into an MyApplicationException
(see serveroutput).
But no change!
Any Ideas ?
Regards,
Martin Kubitza
T&P Bochum/Germany

Hi,
are you using JPA or TopLink ? Check if there is another exception thrown that produces the error. You can try and catch (Exception ex), which will catch them all. if this works the obviously you don't catch the right exception
I found a post saying that: "If you trying commit directly after persist w/o doing an explicit
flush then OptimisticLocking Exception maybe nested inside
RollBackException. What is the top most error on stack? You can catch
javax.persistence.PersistenceException and try to do this kind of
error translation
public static void getThrowable(javax.persistence.PersistenceException
perex, int code) {
boolean updateError = false ;
boolean deleteError = false ;
KentException kentex = null ;
Throwable th = null ;
if( perex instanceof org.apache.openjpa.persistence.RollbackException) {
th = perex.getCause();
if(th instanceof OptimisticLockException) {
updateError = true ;
if(perex instanceof OptimisticLockException ){
updateError = true ;
th = perex ;
if(perex instanceof org.apache.openjpa.persistence.EntityNotFoundException) {
deleteError = true ;
th = perex ;
http://n2.nabble.com/OptimisticLockException-confusion.-td210621.html
Frank

Optimistic Locking fails when version field is part of a Aggregate

I'm trying to persist a Mapped Object using 9.0.3 Toplink.
The object uses optimistic locking while the Timestamp versioning field is part of an Aggreate Descriptor. This works well in the Workbench (does not complain).
Unfortunally it does not work whenever I use the UnitOfWork to register and commit the chances.
Sample code:
Object original;
UnitOfWork unitOfWork = ...
Object clone =   unitOfWork.registerExistingObject(original);
clone.setBarcode("bliblalbu");
unitOfWork.commit();This throws an nasty OptimisticLockException, complaining about a missing versioning field:
LOCAL EXCEPTION STACK:
EXCEPTION [TOPLINK-5004] (TopLink - 9.0.3 (Build 423)): oracle.toplink.exceptions.OptimisticLockException
EXCEPTION DESCRIPTION: An attempt was made to update the object [BusinessObject:{id:12382902,shorttext:null,barcode:bliblablu,ownerLocation:null,IdEntryName:0,idCs:20579121}], but it has no version number in the identity map.
It may not have been read before the update was attempted.
CLASS> de.grob.wps.domain.model.BusinessObjectBO PK> [12382902]
     at oracle.toplink.exceptions.OptimisticLockException.noVersionNumberWhenUpdating(Unknown Source)
     at oracle.toplink.descriptors.VersionLockingPolicy.addLockValuesToTranslationRow(Unknown Source)
     at oracle.toplink.internal.queryframework.DatabaseQueryMechanism.updateObjectForWrite(Unknown Source)
     at oracle.toplink.queryframework.WriteObjectQuery.executeCommit(Unknown Source)
     at oracle.toplink.internal.queryframework.DatabaseQueryMechanism.executeWrite(Unknown Source)
     at oracle.toplink.queryframework.WriteObjectQuery.execute(Unknown Source)
     at oracle.toplink.queryframework.DatabaseQuery.execute(Unknown Source)
     at oracle.toplink.publicinterface.Session.internalExecuteQuery(Unknown Source)
     at oracle.toplink.publicinterface.UnitOfWork.internalExecuteQuery(Unknown Source)
     at oracle.toplink.publicinterface.Session.executeQuery(Unknown Source)
     at oracle.toplink.publicinterface.Session.executeQuery(Unknown Source)
     at oracle.toplink.internal.sessions.CommitManager.commitAllObjects(Unknown Source)
     at oracle.toplink.publicinterface.Session.writeAllObjects(Unknown Source)
     at oracle.toplink.publicinterface.UnitOfWork.commitToDatabase(Unknown Source)
     at oracle.toplink.publicinterface.UnitOfWork.commitRootUnitOfWork(Unknown Source)
     at oracle.toplink.publicinterface.UnitOfWork.commitAndResume(Unknown Source)
     at de.grob.wps.dwarf.domainstore.toplink.ToplinkTransaction.commit(ToplinkTransaction.java:60)
     at de.grob.wps.dwarf.domainstore.toplink.ToplinkPersistenceManager.commit(ToplinkPersistenceManager.java:396)
     at de.grob.wps.dwarf.domainstore.toplink.ToplinkPersistenceManagerTest.testPersistSerializableWithBusinessObjects(ToplinkPersistenceManagerTest.java:87)
     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
     at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
     at java.lang.reflect.Method.invoke(Method.java:324)
     at junit.framework.TestCase.runTest(TestCase.java:154)
     at junit.framework.TestCase.runBare(TestCase.java:127)
     at junit.framework.TestResult$1.protect(TestResult.java:106)
     at junit.framework.TestResult.runProtected(TestResult.java:124)
     at junit.framework.TestResult.run(TestResult.java:109)
     at junit.framework.TestCase.run(TestCase.java:118)
     at junit.framework.TestSuite.runTest(TestSuite.java:208)
     at junit.framework.TestSuite.run(TestSuite.java:203)
     at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:392)
     at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:276)
     at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:167)So what can I to fix this problem? BTW the Object I try to persists has been read from database and the IDE debugger shows what that the aggregate object contains java.sql.Timestamp instances.

Sorry guys. My debugger fooled me. The locking field wasn't initialized in the database. This caused the problem which is fixed now.
Thx anyway.
Bye
Toby

Regd using of lock object in an abap program

Hi all,
     i have created an lock object but doesnot know how to use that lock object in an abap program. can anyone guide me how to use lock object in an abap program.

check this sample for Production Order.
<b>* Lock request for order
call function 'ENQUEUE_ESORDER'
exporting
   aufnr                = p_aufnr
exceptions
   foreign_lock         = 1
   system_failure       = 2
   others               = 3
if sy-subrc <> 0.
message id sy-msgid type sy-msgty number sy-msgno
         with sy-msgv1 sy-msgv2 sy-msgv3 sy-msgv4.
endif.</b>
Regards
Prabhu

High concurrency optimistic locking

Hi there,
We have an EJB method that roughly does the following; we have a number of buckets that may or may not be full. If one or more are not full we want it to find the one with the most space available and add the item there. Our main problem here is that this method can be called upwards of 1000 times per second and we're now looking for an efficient way to solve the concurrency issue of two different calls both thinking bucket X has space left even though one of the two calls will fill it up :
THREAD 1 : findEmptyBucket() returns BUCKET1 (1 SPOT LEFT)
THREAD 2 : findEmptyBucket() returns BUCKET1 (1 SPOT LEFT)
THREAD 1 : addItemToBucket(BUCKET1) <- FULL NOW
THREAD 2 : addItemToBucket(BUCKET1) <- WRONG
Since only optimistic locking is available in the spec for some reason I think the "EJB3" approach is basically (pseudoish) :
while(!succeeded) {
    try {
        Bucket b = findEmptyBucket(...); // Will throw OptimisticLockException?
        addItemToBucket(b, item);
        succeeded = true;
    catch(OptimisticLockException e) {}
} This seems horribly inefficient for a call that is almost guaranteed to require dozens of retries during peak hours. Is there any way to optimize this in such a way that we don't have to use optimistic locking? We're trying to solve this without using vendor specific solutions but EJB3 seems to lack the necessary functionality. Suggestions definitely welcome, evne if they are "that's the only way to do it" ;)
Thanks!

I think the OptimisticLockingException is thrown after-the-fact. So, if the addItemToBucket() method does a commit (flush), it will generate the exception rather than the find method. Otherwise, if there is no explicit commit call, the exception will be thrown when the EJB method that holds the while loop returns.
If performance is critical, maybe a Stateful SessionBean with a Stateless Facade would work better. Create a Stateless SessionBean with an addItem() method and a reference to a single stateful bean. The implementation of the stateful session bean would be something like the following standalone program. The stateful bean would have an addItem() method too, but would keep track of a pool of resources internally.
class ItemBucket { Item i; }
class Item { String data; }
class NoBucketsAvailableException extends Exception {}
public class bucket {
    final static int POOL_SIZE = 4;
    ItemBucket[] bucketPool = new ItemBucket[POOL_SIZE];
    Object[] bucketLocks = new Object[POOL_SIZE];
    void initBucketPool() {
     for(int i=0; i<POOL_SIZE; i++) {
         bucketPool[i] = new ItemBucket();
         bucketLocks[i] = new Object();
    void addItemToEmptyBucket(Item _i) throws NoBucketsAvailableException {
     int i=0;
     for(; i<POOL_SIZE; i++) {
         if( bucketPool.i == null ) { // possible empty bucket
          synchronized(bucketLocks[i]) {
          if( bucketPool[i].i == null ) { // double checked locking
               bucketPool[i].i = _i;
     if( i >= POOL_SIZE) { throw new NoBucketsAvailableException(); }
public static void main(String[] args) {
     bucket app = new bucket();
     app.initBucketPool();
     Item item = new Item();
     item.data = "test";
     try {
     app.addItemToEmptyBucket(item);
     catch(NoBucketsAvailableException exc) {}

How to use Optimistic Locking in Toplink

Similar Messages

Maybe you are looking for