OK. I've fixed it. I had to write my own version of the PersistenceContextManager.
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import org.drools.persistence.PersistenceContext;
import org.drools.persistence.jpa.JpaPersistenceContext;
import org.drools.runtime.Environment;
import org.drools.runtime.EnvironmentName;
import org.jbpm.persistence.JpaProcessPersistenceContext;
import org.jbpm.persistence.ProcessPersistenceContext;
import org.jbpm.persistence.ProcessPersistenceContextManager;
public class MultipleUseJpaPersistenceContextManager implements ProcessPersistenceContextManager {
Environment env;
private EntityManagerFactory emf;
private EntityManager appScopedEntityManager;
protected EntityManager cmdScopedEntityManager;
private boolean internalAppScopedEntityManager;
private boolean internalCmdScopedEntityManager;
public MultipleUseJpaPersistenceContextManager(Environment env) {
this.env = env;
this.emf = (EntityManagerFactory) env.get(EnvironmentName.ENTITY_MANAGER_FACTORY);
}
public PersistenceContext getApplicationScopedPersistenceContext() {
checkAppScopedEntityManager();
return new JpaPersistenceContext(appScopedEntityManager);
}
private void checkAppScopedEntityManager() {
if (this.appScopedEntityManager == null) {
// Use the App scoped EntityManager if the user has provided it, and it is open.
this.appScopedEntityManager = (EntityManager) this.env.get(EnvironmentName.APP_SCOPED_ENTITY_MANAGER);
if (this.appScopedEntityManager != null && !this.appScopedEntityManager.isOpen()) {
throw new RuntimeException("Provided APP_SCOPED_ENTITY_MANAGER is not open");
}
if (this.appScopedEntityManager == null) {
internalAppScopedEntityManager = true;
this.appScopedEntityManager = this.emf.createEntityManager();
this.env.set(EnvironmentName.APP_SCOPED_ENTITY_MANAGER, this.appScopedEntityManager);
} else {
internalAppScopedEntityManager = false;
}
}
}
public PersistenceContext getCommandScopedPersistenceContext() {
return new JpaPersistenceContext(this.cmdScopedEntityManager);
}
public void beginCommandScopedEntityManager() {
checkAppScopedEntityManager();
EntityManager cmdScopedEntityManager = (EntityManager) env.get(EnvironmentName.CMD_SCOPED_ENTITY_MANAGER);
if (cmdScopedEntityManager == null
|| (this.cmdScopedEntityManager != null && !this.cmdScopedEntityManager.isOpen())) {
internalCmdScopedEntityManager = true;
this.cmdScopedEntityManager = this.emf.createEntityManager(); // no need to call joinTransaction as it will
// do so if one already exists
this.env.set(EnvironmentName.CMD_SCOPED_ENTITY_MANAGER, this.cmdScopedEntityManager);
cmdScopedEntityManager = this.cmdScopedEntityManager;
} else {
internalCmdScopedEntityManager = false;
}
cmdScopedEntityManager.joinTransaction();
appScopedEntityManager.joinTransaction();
}
public void endCommandScopedEntityManager() {
if (this.internalCmdScopedEntityManager) {
this.env.set(EnvironmentName.CMD_SCOPED_ENTITY_MANAGER, null);
}
}
public void dispose() {
if (this.internalAppScopedEntityManager) {
if (this.appScopedEntityManager != null && this.appScopedEntityManager.isOpen()) {
this.appScopedEntityManager.close();
}
this.internalAppScopedEntityManager = false;
this.env.set(EnvironmentName.APP_SCOPED_ENTITY_MANAGER, null);
this.appScopedEntityManager = null;
}
if (this.internalCmdScopedEntityManager) {
if (this.cmdScopedEntityManager != null && this.cmdScopedEntityManager.isOpen()) {
this.cmdScopedEntityManager.close();
}
this.internalCmdScopedEntityManager = false;
this.env.set(EnvironmentName.CMD_SCOPED_ENTITY_MANAGER, null);
this.cmdScopedEntityManager = null;
}
}
@Override
public ProcessPersistenceContext getProcessPersistenceContext() {
if (cmdScopedEntityManager == null) {
this.emf.createEntityManager();;
}
return new JpaProcessPersistenceContext(cmdScopedEntityManager);
}
}
This version checks that it has a valid appScopedEntityManager and creates one if necessary.
I then make sure this one is used instead of the default one provided by JBPM when creating my knowledgeSession:
Environment env = KnowledgeBaseFactory.newEnvironment();
env.set(EnvironmentName.ENTITY_MANAGER_FACTORY, entityManagerFactory);
InitialContext ctx = new InitialContext();
UserTransaction transactionManager = (UserTransaction) ctx.lookup("java:comp/UserTransaction");
env.set(EnvironmentName.TRANSACTION_MANAGER,
new JtaTransactionManager(transactionManager, null, transactionManager));
env.set(EnvironmentName.PERSISTENCE_CONTEXT_MANAGER,
new MultipleUseJpaPersistenceContextManager(env));
StatefulKnowledgeSession knowledgeSession = JPAKnowledgeService.newStatefulKnowledgeSession(knowledgeBase, null, env);
I hope this helps others.