SCN versus EJB 3 @Version for optimistic locking

Does anyone have an opinion on using the standard
EJB3 @Version annotation and column compared to using
the Oracle SCN?
Could there advantages in using the SCN over an
explicit version column?
Is there anyway to use the SCN as the version column
with EJB3?
Are they mutually exclusive solutions to the
problem?
Any ideas?
Thanks
MichaelI have a similar question.
1) Has anyone answered the prior question?
2) I had a Java EJB3 Developer tried to use ora_rowscn in Hibernate, but he said it failed, and his reason was this ora_rowscn column must be write/update-able and that is not possible. I am not sure if it is Hibernate limitation or its configuration.
3) Can Oracle's TopLink product (the licensed and/or free version) utilize ora_rowscn column for version, thereby avoiding the need for an extra column for version ?
Any other way to avoid using an additional version column for supporting EJB3 / JPA applications?
Thanks.
Mitesh

Similar Messages

10g Locks Up when selecting database field for optimistic locking

As the subject says, when I attempt to select the database field for optimistic locking, JDeveloper locks up and I have to kill it with the task manager.
Should I post problems with TopLink in 10g in this forum or the TopLink forum?

I finally hit this StackOverflowError again. This happens sometimes when I select the Locking tab on a class where the locking field has already been selected. Here is the top of the stack trace:
java.lang.StackOverflowError
     at java.util.TreeMap$KeyIterator.next(TreeMap.java:1047)
     at java.util.TreeMap.buildFromSorted(TreeMap.java:1588)
     at java.util.TreeMap.buildFromSorted(TreeMap.java:1534)
     at java.util.TreeMap.addAllForTreeSet(TreeMap.java:1492)
     at java.util.TreeSet.addAll(TreeSet.java:247)
     at java.util.TreeSet.<init>(TreeSet.java:138)
     at oracle.toplink.workbench.model.desc.MWClassDescriptor.getAssociatedTablesCopy(MWClassDescriptor.java:377)
     at oracle.toplink.workbench.model.desc.MWClassDescriptor.getSecondaryTablesCopy(MWClassDescriptor.java:698)
     at oracle.toplink.workbench.model.desc.MWClassDescriptor.hasMultipleTables(MWClassDescriptor.java:796)
     at oracle.toplink.workbench.ui.labels.DatabaseFieldLabel.isMultiTable(DatabaseFieldLabel.java:120)
     at oracle.toplink.workbench.ui.labels.DatabaseFieldLabel.installUI(DatabaseFieldLabel.java:93)
     at oracle.toplink.uitools.cell.BasicLabel.prepareLabel(BasicLabel.java:953)
     at oracle.toplink.uitools.cell.BasicLabel.getListCellRendererComponent(BasicLabel.java:611)
     at oracle.toplink.uitools.plaf.basic.BasicListChooserUI$RendererWrapper.getListCellRendererComponent(BasicListChooserUI.java:1104)
     at javax.swing.plaf.basic.BasicListUI.updateLayoutState(BasicListUI.java:1147)
     at javax.swing.plaf.basic.BasicListUI.maybeUpdateLayoutState(BasicListUI.java:1097)
     at javax.swing.plaf.basic.BasicListUI$ListSelectionHandler.valueChanged(BasicListUI.java:1465)
     at javax.swing.DefaultListSelectionModel.fireValueChanged(DefaultListSelectionModel.java:187)
     at javax.swing.DefaultListSelectionModel.fireValueChanged(DefaultListSelectionModel.java:167)
     at javax.swing.DefaultListSelectionModel.fireValueChanged(DefaultListSelectionModel.java:214)
     at javax.swing.DefaultListSelectionModel.changeSelection(DefaultListSelectionModel.java:402)
     at javax.swing.DefaultListSelectionModel.changeSelection(DefaultListSelectionModel.java:411)
     at javax.swing.DefaultListSelectionModel.setSelectionInterval(DefaultListSelectionModel.java:435)
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     at javax.swing.JComboBox.fireItemStateChanged(JComboBox.java:1161)
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...

Error in Update Process for optimistic locking

Hello,
I tried to create a tabular form according to this How-To:
http://www.oracle.com/technology/products/database/application_express/howtos/tabular_form.html
which worked fine until I tried to implement the optimistic locking.
I use the same update process:
declare
l_cks wwv_flow_global.vc_arr2;
j pls_integer := 1;
begin
-- Get original MD5 checksum
select wwv_flow_item.md5(job,mgr,hiredate,sal,comm,deptno) cks
BULK COLLECT INTO
l_cks
from emp;
-- Compare the original checksum, l_cks,
-- with submitted checksum, htmldb_application.g_fcs.
-- If they are different, raise an error.
for i in 1..l_cks.count
loop
if htmldb_application.g_fcs(i) != l_cks(i) then
rollback;
raise_application_error(
          -20001,
     'Current version of data in database has changed '||
          'since user initiated update process.');
return;
end if;
end loop;
but as soon as I try to apply the changes in the update process I get an error message saying: PLS-00503: RETURN statement required for this return from function
So, if i delete the row with the "return;" statement, I get no error anymore, but when I test the optimistic locking I get an error as soon as I try to update a row in the first place.
What am I doing wrong?
Johnny
P.S. : I am using Apex 1.6

Hi Ant, of course......here is the customized pl/sql block I use:
declare
l_cks wwv_flow_global.vc_arr2;
j pls_integer := 1;
begin
-- Get original MD5 checksum
select wwv_flow_item.md5(partition,desig) cks
BULK COLLECT INTO
l_cks
from UNITS;
-- Compare the original checksum, l_cks,
-- with submitted checksum, htmldb_application.g_fcs.
-- If they are different, raise an error.
for i in 1..l_cks.count
loop
if htmldb_application.g_fcs(i) != l_cks(i) then
rollback;
raise_application_error(-20001,'Current version of data in database has changed ' || 'since user initiated update process.');
-- return;
end if;
end loop;
-- update UNITS
for i in 1..htmldb_application.g_f08.count
loop
if htmldb_application.g_f08(i) is not null then
update UNITS
set report_id = :P2_REPORT_ID,
partition = htmldb_application.g_f10(i),
desig = htmldb_application.g_f11(i)
where unit_id = htmldb_application.g_f08(i);
else
if htmldb_application.g_f10(i) is not null then
insert into UNITS
(report_id,
partition,
desig)
values
(:P2_REPORT_ID,
htmldb_application.g_f10(i),
htmldb_application.g_f11(i));
end if;
end if;
end loop;
end;
Thanks
Johnny

Optimistic locking/ data concurrency and consistency

Hi,
When creating a tabular form using wizard, apex creates its own processes for optimistic locking. But when creating a form on a table, it doesn't create the processes. I suppose I need to create them manually.
Can anybody show me the steps?
Thanks!

Scott,
Thanks once again.
2 things:
My understanding is that I can't change the error message, and that if I want to customize the error message, I need to create my own process for checksum. Is this true? If so, what is the easiest way of doing this?
I realized it returns an error message and the changes the user made gets lost if he went out for lunch and somebody else made an update on that record. What can I do so the user doesn't lose the data?
Thanks,

Charged twice for Slider Lock to be upgraded to paid version but application not downloaded

I was on BB Applications and decided to buy the paid version of the slider lock, I used my credit card to buy this application, now my credit card has been charged twice for this application and all I have got is an error message stating that there was an internal error and so I should try again later, I have already tried twice, each time you try, your credit card gets charged and you get the error message.The support website for slider lock is : www.getempower.com and it is a product by Ajani Infotech Private Ltd , and so i tried contacting them and sent them e-mails but all in vain it seems as I did not get any response from anywhere and also even after being charged twice for the same application, did not get anything from the company. Can someone please forward this matter to the concerned authorities and can i get the paid version and also refund for the money charged in access?
Please reply back on my mail : Removed personal information to comply with Community Guidelines and Terms and Conditions of Use.
Awiting your reply,
Anuj Malik

Hello!
I have found your case and appears one of our teams from corporate has been trying to contact you for the past 2 days with the provided contact # we have on file. If there is a alternate phone # we can reach you to resolve this issue, please send me a private message with that number. Thanks!

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

Production version with status " locked for any use" being considered

Dear All,
while creating integration model for PDS , materials with production version locked for any use are being considered. Can any body put some light on it.
My requirement is that in creation of integration model it should not take production version which are locked for use.
Regards
Arun Negi

Check OSS Note 854561 - PDS does not recognize any locked production version in R/3
"Symptom
If a production version is locked in the R/3 System, this change is not transferred to the related production data structure (PDS) in APO. The PDS is therefore still used as a source in APO in the plan explosion. This causes errors during planning and results in terminations when an order is converted and subsequently transferred to the R/3 system."
https://websmp130.sap-ag.de/sap(bD1lbiZjPTAwMQ==)/bc/bsp/spn/sapnotes/index2.htm?numm=854561
Manish
Edited by: Manish Kumar Rathi on Oct 10, 2008 11:46 AM

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...

Orion-ejb-jar.xml for oc4j and xdoclet

Does anybody try to use xdoclet to generate orion-ejb-jar.xml with ejb relation?
Could somebody show me any example of definition relation for xdoclet and orion-ejb-jar.xml? (@orion:persistence...)
thanks for any advice... :-)
Zajo

Hello,
The warning message looks to be unrelated to the java.lang.IllegalArgumentException error. The warning states that optimistic locking cannot be migrated to the toplink-ejb-jar.xml file; this is stated in chapter 7 of the TopLink developer's guide at
http://download-west.oracle.com/otn_hosted_doc/toplink/1013/MAIN/_pdf/b13593_v1_01.pdf
The exception though seems to indicate that your orion-ejb-jar.xml contains EJBs mapped to the same table that are not related through EJB inheritance. I do it all the time with POJOs so this will work in TopLink, but you will need a support case to help get your project migrated if this is the case.
Best Regards,
Chris Delahunt

ChangeFields optimistic locking

I am trying to use optmistic locking without changing my database schema by using the descriptor.useChangedFieldsLocking() on my EJB descriptor. Two clients try to do the following.
1) Query the shallow properties of the EJB (no getters called for unary or collection relationships).
2) Edit some of that simple data
3) Submit their changes
The optimistic locking works okay when just the shallow properties are being retrieved. If a client tries to submit when someone else has already done so, an OptimisticLockException is thrown which is the desired result.
However, if I wish to traverse one of the relationships on the EJB when it is first queried (by calling a getter for a collection for example) the following happens: When the second client attempts to load and edit this EJB the transaction times out with a deadlock exception.
I want to traverse relationships for display purposes in this case but in the furture will want to edit something in that relationship with ChangedFieldsLocking also set.
If anyone could tell me why the second client's transaction times out when it asks for the EJB I would be very grateful.
Regards
James.

Thanks for the reply.
After further investigation I have found that it's nothing to do with the locking (since I can switch it off and still have the problem) but may be a problem with OC4J (or how I am using it). The situation is as follows:
1) Client A starts a transaction
2) Client A asks for ejb1
3) Client A asks for ejb1.collection()
4) Client A asks for ejb1.collection(i).someMethod()
5) Client A uses the result of someMethod()
(transaction is still open)
6) Client B starts a transaction
7) Client B asks for ejb1
8) Client B asks for ejb1.collection()
9) Client B asks for ejb1.collection(i).someMethod()
10) Client B uses the result of someMethod()
The server hangs on step 9 and never enters someMethod() (the first line is debug and I never see it). Eventually it tells me that the transaction has timed out with a deadlock exception.
The following comes from the output of a ctrl-break at the point of hanging (someMethod() is getTitle() in this example) :
"HttpRequestHandler-22629000" prio=5 tid=0x434DE690 nid=0xab4 in Object.wait() [4400f000..4400fd8c]
at java.lang.Object.wait(Native Method)
- waiting on <08FC9AC8> (a com.evermind.server.ThreadState)
at com.evermind.server.ejb.AbstractEJBObject.startCall(AbstractEJBObject.java:226)
- locked <08FC9AC8> (a com.evermind.server.ThreadState)
at PersonNamesRemote_EntityBeanWrapper79.getTitle(PersonNamesRemote_EntityBeanWrapper79.java:3227)
at uk.co.corelogic.framework.common.ejb.entity.PeopleEJB.toBean(PeopleEJB.java:1800)
at PeopleRemote_EntityBeanWrapper60.toBean(PeopleRemote_EntityBeanWrapper60.java:1742)
at uk.co.corelogic.framework.common.ejb.session.FrameworkManager.retrieve(FrameworkManager.java:142)
I am using OC4J 9.0.4, Toplink 9.0.3.3. I have Toplink configured to generate BMP Entity beans.
My entity bean deployment descriptor has <reentrant>False</reentrant> but <reentrant>True</reentrant> makes no difference. It also has <trans-attribute>Required</trans-attribute> for everything which should be okay and trying <trans-attribute>Supports</trans-attribute> just causes null pointers to be thrown all over the place.
I will post this message on the OC4J forum too but would appreciate a reply if you have any ideas.
Thanks.
James.

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) {}

Aggregate-collection-mapping combined with optimistic-locking

I've tried to set up an aggregate-collection-mapping and everything seems to be okay. But one thing still lacks: use this aggregate-collection in combination with optimistic-locking. Defining to use optimistic-locking (exactly: timestamp locking) doesn't work. The generated sql-statement doesn't have the wanted timestamp field. Any idea is recommend.

Hi,
Aggregate collection mappings do support optimistic locking. You MUST map and store the version value in the object, not the cache. Aggregate objects are not cache independently of their parents so cannot store their version value in the cache.
Make sure that you have:
- provided a direc-to-field (non-readonly) mapping for the version field
- define the locking policy to store the version value in the object, not the cache
Example:
     descriptor.descriptorIsAggregateCollection();
     descriptor.useTimestampLocking("VERSION", false);
     // SECTION: DIRECTTOFIELDMAPPING
     DirectToFieldMapping directtofieldmapping3 = new DirectToFieldMapping();
     directtofieldmapping3.setAttributeName("version");
     directtofieldmapping3.setIsReadOnly(false );
     directtofieldmapping3.setFieldName("VERSION");
     descriptor.addMapping(directtofieldmapping3);

Optimistic Lock with Parent and Child relationships

Hi,
I just have a question regarding optimistic locking. We have a scenario
where a parent object has many child objects. Both the parent and the
child objects have a jdolockx column in the database/jdo file.
It appears that whenever you add a new child to the parent the parent's
optimistic lock counter is also updated.
eg
parent.getChildren().add(child);
child.setParent(parent);
Why does this occur? There is no change made to the database table for
the parent, except for the jdolockx column. Is there something that I can
do to stop the lock count from incrementing when I child is added?
We have a scenario where we have many threads of execution wishing to add
children to a single parent. The parent itself isnt modified but this
operation fails due to the parent lock counter being incremented.
Any help would be appreciated
Thanks
Luke

There is state image indicator in Kodo 3 which has more locking options
beyond a simple number:
http://solarmetric.com/Software/Documentation/3.0.1/docs/ref_guide_mapping_versionind.html#state-image
In addition, you can plug your own version indicator.
Our default optimistic locking avoids the problem of users having no
idea what is -actually- in the collection/set at any given time.
Inconsistencies can occur at the datastore level (user 1 adds
object a to collection, user 2 removes a, user 1 adds object b... which
should actually be in the DB? {a,b} or or {a}? This is one of the
many ways in which not tracking changes to a collection/set can be
hazardous).
On locking exceptions, errors could be handled in some appropriate
function (i.e. refresh, re-apply changes if applicable/safe,
and commit).
Luke wrote:
Hi,
I just have a question regarding optimistic locking. We have a scenario
where a parent object has many child objects. Both the parent and the
child objects have a jdolockx column in the database/jdo file.
It appears that whenever you add a new child to the parent the parent's
optimistic lock counter is also updated.
eg
parent.getChildren().add(child);
child.setParent(parent);
Why does this occur? There is no change made to the database table for
the parent, except for the jdolockx column. Is there something that I can
do to stop the lock count from incrementing when I child is added?
We have a scenario where we have many threads of execution wishing to add
children to a single parent. The parent itself isnt modified but this
operation fails due to the parent lock counter being incremented.
Any help would be appreciated
Thanks
Luke
Steve Kim
[email protected]
SolarMetric Inc.
http://www.solarmetric.com

Access to optimistic lock revision number

We have an existing schema that includes a REVISION column. The current JDBC
code base increments the revision number each time an object is updated.
Ideally I would like to use this same field for Kodo's optimistic locking
mechanism and let Kodo manage the field. The problem is that we need
(read-only) access to the revision value for other purposes. Is there a way
to get this value? I'm okay with using a Kodo-specific API.
Thanks,
Tom

Sadly, the mechanism for doing this isn't very well-documented, so here
goes:
import com.solarmetric.kodo.runtime.*;
PersistenceManagerImpl pm = (PersistenceManagerImpl) pman;
StateManagerImpl sm = pm.getState (persistentObject);
Object version = sm.getVersion ();
This object is a Number when used with our JDBC back-end.
-Patrick
On Sat, 02 Aug 2003 09:26:47 -0700, thomasrlandon wrote:
We have an existing schema that includes a REVISION column. The current JDBC
code base increments the revision number each time an object is updated.
Ideally I would like to use this same field for Kodo's optimistic locking
mechanism and let Kodo manage the field. The problem is that we need
(read-only) access to the revision value for other purposes. Is there a way
to get this value? I'm okay with using a Kodo-specific API.
Thanks,
Tom--
Patrick Linskey
SolarMetric Inc.

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

SCN versus EJB 3 @Version for optimistic locking

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