11:49 p.m.
Sure!
Drools does JPA persistence using this set of managers:
https://github.com/droolsjbpm/drools/blob/master/drools-persistence-jpa/s...
https://github.com/droolsjbpm/drools/blob/master/drools-persistence-jpa/s...
and JTA transaction management using:
https://github.com/droolsjbpm/drools/blob/master/drools-persistence-jpa/s...
As you can see in JpaPersistenceContext, Drools only has support for
persisting this set of entities: SessionInfo & WorkItemInfo
JBPM has its own persistence management implemented in this classes:
https://github.com/droolsjbpm/jbpm/blob/master/jbpm-persistence-jpa/src/m...
https://github.com/droolsjbpm/jbpm/blob/master/jbpm-persistence-jpa/src/m...
So JBPM can persist ProcessInstanceInfo entities but there's no support for
JTA transactions, the code doesn't join a current JTA transaction, it even
doesn't use transactions at all.
The problem arises when using Hibernate as EntityManager for persistence
and running in a fireUntilHalt loop, given the lack of transactions support
in JBPM, when a processinstance gets created and JBPM tries to persist it
Hibernate delays the insertion as there is no transaction involved, then
the primary key stays null and so the NPE.
Alberto R. Galdo
argaldo(a)gmail.com
On Mon, Mar 19, 2012 at 22:34, Marco Rietveld <mrietvel(a)redhat.com> wrote:
Sorry, to be clear: a github link to the code you quoted is what I
was
after.
03/19/2012 10:33 PM, Marco Rietveld:
Alberto,
Sorry to hear that the bug isn't fixed.
Could you clarify what you mean by these points?
- Drools and JBPM have different persistence managers.
- Drools uses JTA for persistence and JBPM does not.
I was pretty sure you could specify a JTA data source in the
persistence.xml that jBPM uses.
As for the persistence managers, what do you mean exactly?
Also, if you could maybe give me a github link referring to the code
you're using, that would be great.
(Just to make sure, you are referring to jbpm *5*, right?)
Thanks,
Marco
03/19/2012 06:23 PM, Alberto R. Galdo:
I'm afraid this bug is not resolved and doesn't have nothing to do with
lazy evaluation.
We've been able to get to the source of the problem and this are the facts:
- Drools and JBPM have different persistence managers.
- Drools uses JTA for persistence and JBPM does not.
- When any JPA enabled object is persisted in Drools, a transaction
begins, it's EntityManager ( Hibernate ) joins the transaction and the
entity gets persisted.
- When any JPA enabled object ( in this case a ProcessInstanceInfo ) is
persisted in JBPM, there are no transactions involved, and so the
EntityManager ( Hibernate ) decides to delay the insert ( queuing it as
there's no transaction in progress ). Then the processId never gets updated
and the NPE arises.
The problem here seems to be that both Drools and JBPM manage persistence
in different and incompatible ways. We've been able to modify
jbpm-persistence-jpa to open a JTA transaction before persisting
ProcessInstanceInfo, getting the EntityManager joining that transaction and
using the current Bitronix implementation already running in Drools ( to
assist persistence for their objects ) .. like so:
public void setKnowledgeRuntime(InternalKnowledgeRuntime kruntime) {
this.kruntime = kruntime;
Environment env = kruntime.getEnvironment();
Object tm = env.get( EnvironmentName.TRANSACTION_MANAGER );
if (!(tm instanceof javax.transaction.TransactionManager)) {
try {
// get Bitronix instance inside ...
java.lang.reflect.Field field =
tm.getClass().getDeclaredField("tm");
// who says private in Java is really private ... xD
field.setAccessible(true);
tm = field.get(tm);
} catch (Exception e){
e.printStackTrace();
}
}
this.txm = new JtaTransactionManager( env.get(
EnvironmentName.TRANSACTION ), env.get(
EnvironmentName.TRANSACTION_SYNCHRONIZATION_REGISTRY ), tm );
}
public void addProcessInstance(ProcessInstance processInstance) {
ProcessInstanceInfo processInstanceInfo = new ProcessInstanceInfo(
processInstance, this.kruntime.getEnvironment() );
ProcessPersistenceContext context =
((ProcessPersistenceContextManager) this.kruntime.getEnvironment().get(
EnvironmentName.PERSISTENCE_CONTEXT_MANAGER
)).getProcessPersistenceContext();
this.txm.begin();
context.persist( processInstanceInfo );
this.txm.commit();
I think we can agree that the previous lines of code are not the most
elegant solution ( at least not for me ).
So, Is there any timeline for merging DROOLS and JBPM 5 persistence
managers?
If someone gives me advice and architectural hints ( and if it is doable
in a reasonable ammount of time ) I would be eager to submit a patch for
this ....
Alberto R. Galdo
argaldo(a)gmail.com
On Wed, Mar 14, 2012 at 13:56, Alberto R. Galdo <argaldo(a)gmail.com> wrote:
> Great news!
>
> We were in the process of debugging JBPM trying to find the source of the
> bug ... and maybe days away from the solution ...
>
> Is there any bug report in Jira and/or a patch we can apply without
> having to wait for the next release so we can quick-patch our systems?
>
>
> Alberto R. Galdo
> argaldo(a)gmail.com
>
>
>
> On Wed, Mar 14, 2012 at 13:09, Marco Rietveld <mrietvel(a)redhat.com>wrote:
>
>>
>> Hi Alberto,
>>
>> This is a bug that has been fixed in jBPM. It had to do with lazy
>> initialization of a JPAProcessInstanceManager field.
>>
>> We'll be releasing a new jBPM version sometime soon (synchronous with
>> Drools, I think). The bug is fixed in there.
>>
>> Regards,
>> Marco
>>
>> 03/08/2012 11:32 AM, Alberto R. Galdo:
>>
>> Hi,
>>
>> We're running an application that uses Drools + JBPM 5 + Drools
>> integration our set-up can be seen as:
>>
>> Some rule fires and creates a JBPM process ( a fact gets inserted
>> into drools using
>> "kcontext.getKnowledgeRuntime().startProcess("testProcess")"
). We have a
>> problem with the persistence of this processes. Persistence is implemented
>> with JPA and JTA. Our application runs with fireUntilHalt() and when a
>> process is launched from the consequence of any of the rules the
>> persistence of the process fails. If the application runs with
>> fireAllRules(), the persistence works like a charm.
>>
>> The error shown is as follow:
>>
>> Exception in thread "Thread-5" Exception executing consequence for
>> rule "Run Process" in com.sample: java.lang.NullPointerException
>> at
>>
org.drools.runtime.rule.impl.DefaultConsequenceExceptionHandler.handleException(DefaultConsequenceExceptionHandler.java:39)
>> at
>> org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:1101)
>> at
>> org.drools.common.DefaultAgenda.fireNextItem(DefaultAgenda.java:1029)
>> at
>> org.drools.common.DefaultAgenda.fireUntilHalt(DefaultAgenda.java:1229)
>> at
>>
org.drools.common.AbstractWorkingMemory.fireUntilHalt(AbstractWorkingMemory.java:754)
>> at
>>
org.drools.common.AbstractWorkingMemory.fireUntilHalt(AbstractWorkingMemory.java:730)
>> at
>>
org.drools.command.runtime.rule.FireUntilHaltCommand$1.run(FireUntilHaltCommand.java:50)
>> at java.lang.Thread.run(Thread.java:662)
>> Caused by: java.lang.NullPointerException
>> at
>>
org.jbpm.persistence.processinstance.JPAProcessInstanceManager.addProcessInstance(JPAProcessInstanceManager.java:44)
>> at
>>
org.jbpm.process.instance.AbstractProcessInstanceFactory.createProcessInstance(AbstractProcessInstanceFactory.java:36)
>> at
>>
org.jbpm.process.instance.ProcessRuntimeImpl.startProcess(ProcessRuntimeImpl.java:182)
>> at
>>
org.jbpm.process.instance.ProcessRuntimeImpl.createProcessInstance(ProcessRuntimeImpl.java:154)
>> at
>>
org.jbpm.process.instance.ProcessRuntimeImpl.startProcess(ProcessRuntimeImpl.java:135)
>> at
>>
org.jbpm.process.instance.ProcessRuntimeImpl.startProcess(ProcessRuntimeImpl.java:130)
>> at
>>
org.drools.common.AbstractWorkingMemory.startProcess(AbstractWorkingMemory.java:1074)
>> at
>>
org.drools.impl.StatefulKnowledgeSessionImpl.startProcess(StatefulKnowledgeSessionImpl.java:301)
>> at
>> com.sample.Rule_Run_Process.defaultConsequence(Rule_Run_Process.java:9)
>> at
>> com.sample.Rule_Run_ProcessDefaultConsequenceInvoker.evaluate(Unknown
>> Source)
>> at
>> org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:1091)
>> ... 6 more
>> The problem is in this function:
>> public void addProcessInstance(ProcessInstance processInstance) {
>> ProcessInstanceInfo processInstanceInfo = new
>> ProcessInstanceInfo( processInstance, this.kruntime.getEnvironment() );
>> ProcessPersistenceContext context
>> = ((ProcessPersistenceContextManager)
>> this.kruntime.getEnvironment()
>> .get( EnvironmentName.PERSISTENCE_CONTEXT_MANAGER ))
>> .getProcessPersistenceContext();
>> // @PrePersist added to ProcessInstanceInfo because of this
>> context.persist( processInstanceInfo );
>> ((org.jbpm.process.instance.ProcessInstance)
>> processInstance).setId( processInstanceInfo.getId() );
>> processInstanceInfo.updateLastReadDate();
>> internalAddProcessInstance(processInstance);
>> }
>> We think after that persist sentence, the entity manager would have
>> to run a flush sentence for the process instance is inserted into database
>> and get the ID.
>> Greets.
>>
>>
>> _______________________________________________
>> rules-users mailing
listrules-users@lists.jboss.orghttps://lists.jboss.org/mailman/listinfo/rules-users
<https://lists.jboss.org/mailman/listinfo/rules-users>
>>
>>
>>
>> --
>> jBPM/Drools developer
>> Utrecht, the Netherlands
>>
>>
>
--
jBPM/Drools developer
Utrecht, the Netherlands
--
jBPM/Drools developer
Utrecht, the Netherlands