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Re: [eclipselink-users] Spring: Attempting to execute an operation on a closed EntityManager.
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Hi,
I ran my following code under concurrent access scenario, without any
issue so far.
Note: - 1. JTA transactions as shown below
<bean id="entityManager"
class="org.springframework.jndi.JndiObjectFactoryBean">
<property name="jndiName">
<value>java:comp/env/claimProcessing/EntityManager</value>
</property>
<property name="resourceRef">
<value>true</value>
</property>
…….
2. I also used very strickt isolation level - ISOLATION_SERIALIZABLE
3. I think template usage or annotation should yeild same results
public class GenericDAOJPAImpl<T extends Persistable> extends JpaDaoSupport
implements GenericDAO<T> {
public void create(final T t) {
Object retVal= getJpaTemplate().execute(new JpaCallback() {
public Object doInJpa(EntityManager em)
throws PersistenceException {
em.persist(t);
return null;
}
});
}
@SuppressWarnings("unchecked")
public T update(final T t) {
T retVal= (T) getJpaTemplate().execute(new JpaCallback() {
public Object doInJpa(final EntityManager em)
throws PersistenceException {
T updatedValue = em.merge(t);
return updatedValue;
}
});
return retVal;
}
--- ---- ---- ----- ----- ---- ----
Alejandro de Brito Fontes wrote:
>
> Hi Tim,
> The pure JPA setup that you can find in examples works fine, until
> you stress the DAO with multiples simultaneous clients. In my case I
> receive errors when trying to save/delete data. This is related with
> the fact that the EntityManager defined in the DAO's is the same for
> all the references:
>
> http://static.springframework.org/spring/docs/2.0.x/api/org/springframework/orm/jpa/JpaTemplate.html#method_summary
> " NOTE: JpaTemplate mainly exists as a sibling of JdoTemplate and
> HibernateTemplate, offering the same style for people used to it. For
> newly started projects, consider adopting the standard JPA style of
> coding data access objects instead, based on a "shared EntityManager"
> reference injected via a Spring bean definition or the JPA
> PersistenceContext annotation. (Using Spring's
> SharedEntityManagerBean / PersistenceAnnotationBeanPostProcessor, or
> using a direct JNDI lookup for an EntityManager on a Java EE 5 server.)"
>
> This is way I prefer the JpaTemplate in which I inject the
> EntityManagerFactory (this generates a new instance of EntityManager
> by each DAO).
> To avoid the lazy initialization problem only use
> OpenEntityManagerInView if you are creating an Web Application
>
> Here is an example of the generic dao and one example:
>
> @Repository
> public class GenericDaoJPAImpl<T, PK extends Serializable> extends
> JpaDaoSupport implements GenericDao<T, PK> {
>
> private Class<T> cPersistentT;
>
> @Autowired
> private EntityManagerFactory emf;
>
> @SuppressWarnings("unchecked")
> public GenericDaoJPAImpl(final Class<T> cType) {
> this.cPersistentT = (Class<T>) ((ParameterizedType)
> getClass().getGenericSuperclass()).getActualTypeArguments()[0];
> }
>
> @PostConstruct
> private void postConstruct() {
> setEntityManagerFactory(emf);
> }
>
> @Transactional(propagation = Propagation.REQUIRED)
> public void delete(final T oEntity2Remove) {
> getJpaTemplate().remove(oEntity2Remove);
> flush();
> }
>
> @Transactional
> public void delete(final PK oID) {
> T instanceToRemove = getJpaTemplate().find(cPersistentT, oID);
> getJpaTemplate().remove(instanceToRemove);
> flush();
> }
>
> @SuppressWarnings("unchecked")
> public List<T> findAll() {
> return getJpaTemplate().find("select objects from " +
> cPersistentT.getSimpleName() + " objects");
> }
>
> public T findById(PK oID) {
> return getJpaTemplate().find(getPersistentClass(), oID);
> }
>
> @Transactional(propagation = Propagation.REQUIRED)
> public void flush() {
> getJpaTemplate().flush();
> }
>
> public Class<T> getPersistentClass() {
> return cPersistentT;
> }
>
> @Transactional(propagation = Propagation.REQUIRED)
> public T save(T oInstance) {
> T oReturn = getJpaTemplate().merge(oInstance);
> flush();
> return oReturn;
> }
> }
>
> @Repository
> public class ExampleDaoImpl extends GenericDaoJPAImpl<Example, Long>
> implements I ExampleDao {
>
> public ExampleDaoImpl() {
> super(Example.class);
> }
> }
>
> With this example you need Java 1.6 o 1.5 with the JSR-250 jar (for
> the @PostConstruct annotation).
>
>
> On 26-09-2008, at 11:48, Tim Hollosy wrote:
>
>> Thanks Shaun,
>> I've completely given up on tomcat at this point, I'll be in an OC4J
>> environment in production anyway.
>>
>> The problem I'm running into now is there are about 4,000 ways to use
>> JPA in Spring:
>>
>> I can get things to work if I use their JpaDaoSupport class, however I
>> would prefer a more "pure" method....which just happened to FINALLY
>> work as I typed this, that method was using the @PersistenceContext
>> annotation to inject an EntityManager.
>>
>> Unfortunately, now that it works I have no idea why :) I do see now
>> that AspectJ is reporting it's doing stuff, so I think my problems
>> before might have been with weaving on some level.
>>
>> I think part of the problems I was dealing with was two-fold: My Lack
>> of any real understanding on the Spring Framework and lack of any real
>> examples.
>>
>> Once I take the time now to analyze what's going on I'll try to remedy
>> the latter.
>>
>> If anyone can impart some best practices for using Eclipselink with
>> Spring 2.5 I'd be all ears in the mean time.
>>
>> ./tch
>>
>>
>>
>> On Fri, Sep 26, 2008 at 11:24 AM, Shaun Smith
>> <shaun.smith@xxxxxxxxxx> wrote:
>>> Hi Tim,
>>>
>>> If you're using Spring with EclipseLink you must copy
>>> spring-tomcat-weaver.jar into $CATALINA_HOME/server/lib see the
>>> Spring
>>> Manual for details. Tomcat absolutely will not support dynamic
>>> weaving in
>>> Spring (or anything else for that matter) unless you use a
>>> technique like
>>> this. You didn't mention you did this so don't think you did.
>>> Once you
>>> have this in place and you've setup your Spring config properly,
>>> Spring will
>>> do @PersistenceContext injection. Take a look at the TopLink
>>> Essentials JPA
>>> version of the Spring PetClinic for an example.
>>>
>>> Shaun
>>>
>>> Tim Hollosy wrote:
>>>
>>> So no luck em.isOpen returns true.
>>>
>>> I can't get my friggin AspectJ Weaver to output anything even
>>> though I
>>> have an aop.xml like this:
>>>
>>> <!DOCTYPE aspectj PUBLIC
>>> "-//AspectJ//DTD//EN" "http://www.eclipse.org/aspectj/dtd/
>>> aspectj.dtd">
>>> <aspectj>
>>> <weaver options="-debug -verbose -showWeaveInfo
>>> -
>>> XmessageHandlerClass:org
>>> .springframework.aop.aspectj.AspectJWeaverMessageHandler">
>>> <include within="com.redacted.*"/>
>>> </weaver>
>>> <aspects>
>>> <aspect
>>> name
>>> =
>>> "org
>>> .springframework.transaction.aspectj.AnnotationTransactionAspect"/>
>>> </aspects>
>>> </aspectj>
>>>
>>>
>>> BUT, doing some more reading about weaving I see: at
>>> http://wiki.eclipse.org/EclipseLink/Examples/JPA/Tomcat_Web_Tutorial#Limitations_to_JPA
>>>
>>> As Tomcat is not a JEE5 compatible server, there are some
>>> limitiations to
>>> JPA.
>>>
>>> * No dynamic weaving (instrumentation) - static weaving of
>>> entities is still available via EclipseLink
>>> * No @EJB injection of a session bean (containing the
>>> EntityManager) is available - use the persistence factory and manager
>>> directly
>>> * No @PersistenceContext injection of a container managed
>>> persistence unit is available - use
>>> Persistence.createEntityManagerFactory(JTA_PU_NAME)
>>>
>>>
>>> Does that mean i can't use the @PersistenceContext annotation with
>>> EclipseLink in Tomcat 6???
>>>
>>> I'm confused as to weather Tomcat 6 supports LTW or not, since there
>>> are instructions all over for getting it to weave with Spring...
>>>
>>> I may set up an OC4J Instance and see if I have better luck, but
>>> right
>>> now I'm confused as all get out.
>>>
>>> ./tch
>>>
>>>
>>>
>>> On Fri, Sep 26, 2008 at 6:58 AM, Tim Hollosy <hollosyt@xxxxxxxxx>
>>> wrote:
>>>
>>>
>>> Mohsen,
>>> I didn't actually call isOpen, I instead inspected it with the
>>> debugger, and noticed the isOpen boolean was true. I'll try your
>>> obvious suggestion when I get in to the office this morning.
>>>
>>> My hunch is something odd is going on with weaving, so I'm going to
>>> put some weaving logging in as well.
>>>
>>>
>>> I guess this is just growing pains and it doesn't always help when I
>>> choose bleeding edge -- pure annotations & eclipselink for my first
>>> foray into Spring -- but I just can't stand XML, so I've made my bed
>>> :)
>>>
>>> Thanks
>>>
>>> ./tch
>>>
>>>
>>>
>>> On Fri, Sep 26, 2008 at 6:54 AM, Mohsen Saboorian
>>> <mohsens@xxxxxxxxx> wrote:
>>>
>>>
>>> I didn't test it with EclipseLink, but with Hibernate session is
>>> closed after transaction is committed, and it produces a lot of
>>> frustrations with lazy loading, since you usually need to fetch a
>>> list
>>> after a transaction is committed.
>>>
>>> Spring provides a OpenSessionInViewFilter to work around this. It
>>> keeps session open durig a request life-cycle.
>>>
>>> How did you verified that EM is open? EM.isOpen()?
>>>
>>> Mohsen.
>>>
>>> On Thu, Sep 25, 2008 at 9:58 PM, Tim Hollosy <hollosyt@xxxxxxxxx>
>>> wrote:
>>>
>>>
>>> I'm hoping some Spring gurus can help me out, whenever I try to
>>> execute a query I get the error: Attempting to execute an operation
>>> on
>>> a closed EntityManager.
>>>
>>> I'm using Spring 2.5 + Tomcat6.
>>>
>>> The weird thing is find's work fine. I'm launching tomcat with the
>>> spring-aspects.jar for weaving. I'm new to this whole spring web
>>> stuff
>>> so I am probably missing something, but the only thing I could find
>>> online was to make sure I have the @Transactional annotations used
>>> everywhere in my DAO class, which I do.
>>>
>>> If I run in the debugger it looks like the EM is open as well, so I'm
>>> kind of stumped. I suspect some weaving shenanigans, but I'm too much
>>> of a neophyte at this right now to debug much more.
>>>
>>> Many thanks :)
>>>
>>> Here's my config:
>>>
>>> applicationcontext.xml;
>>> <context:component-scan base-package="com.redacted" />
>>>
>>> <tx:annotation-driven mode="aspectj"/>
>>>
>>> <bean id="transactionManager"
>>> class="org.springframework.orm.jpa.JpaTransactionManager"
>>> p:entityManagerFactory-ref="entityManagerFactory"/>
>>>
>>> <bean id="dataSource"
>>> class="org.apache.commons.dbcp.BasicDataSource">
>>> <property name="driverClassName"
>>> value="oracle.jdbc.OracleDriver" />
>>> <property name="url"
>>> value="jdbc:oracle:thin:@redacted:1521:redacted" />
>>> <property name="username" value="redacted" />
>>> <property name="password" value="redacted" />
>>> </bean>
>>>
>>> <bean id="jpaAdapter"
>>> class
>>> ="org.springframework.orm.jpa.vendor.EclipseLinkJpaVendorAdapter">
>>> <property name="databasePlatform"
>>> value
>>> ="org.eclipse.persistence.platform.database.oracle.OraclePlatform"
>>> />
>>> <property name="showSql" value="true" />
>>> </bean>
>>>
>>>
>>> <bean id="loadTimeWeaver"
>>> class
>>> =
>>> "org
>>> .springframework
>>> .instrument.classloading.InstrumentationLoadTimeWeaver"/>
>>>
>>> <bean id="entityManagerFactory"
>>> class
>>> =
>>> "org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
>>> <property name="persistenceUnitName" value="ProofOConcept"/>
>>> <property name="dataSource" ref="dataSource"/>
>>> <property name="jpaVendorAdapter" ref="jpaAdapter"/>
>>> <property name="loadTimeWeaver" ref="loadTimeWeaver"/>
>>>
>>> </bean>
>>>
>>> <util:list id="annotatedClasses">
>>> <value>com.redacted.*</value>
>>> </util:list>
>>>
>>>
>>> Here's my DAO class:
>>>
>>> import java.util.List;
>>>
>>> import javax.persistence.EntityManager;
>>> import javax.persistence.PersistenceContext;
>>> import javax.persistence.Query;
>>>
>>> import org.eclipse.persistence.jpa.JpaEntityManager;
>>> import org.eclipse.persistence.jpa.JpaHelper;
>>> import org.springframework.stereotype.Repository;
>>> import org.springframework.transaction.annotation.Transactional;
>>>
>>> @Transactional
>>> @Repository
>>> public class BasicDao {
>>>
>>> @PersistenceContext(unitName = "ProofOConcept")
>>> private EntityManager em;
>>>
>>> @Transactional(readOnly = true)
>>> public <T> T find(Class<T> entityClass, Object primaryKey) {
>>> T result = em.find(entityClass, primaryKey);
>>>
>>> return result;
>>> }
>>>
>>>
>>>
>>> @Transactional(readOnly = true)
>>> public <T> List<T> selectAll(Class<T> clazz) {
>>> JpaEntityManager jpaEm =
>>> JpaHelper.getEntityManager(em);
>>> Query query = jpaEm.createQuery(null, clazz);
>>> return (List<T>) query.getResultList();
>>> }
>>>
>>> }
>>>
>>>
>>>
>>>
>>>
>>>
>>> ./tch
>>> _______________________________________________
>>> eclipselink-users mailing list
>>> eclipselink-users@xxxxxxxxxxx
>>> https://dev.eclipse.org/mailman/listinfo/eclipselink-users
>>>
>>>
>>>
>>> _______________________________________________
>>> eclipselink-users mailing list
>>> eclipselink-users@xxxxxxxxxxx
>>> https://dev.eclipse.org/mailman/listinfo/eclipselink-users
>>>
>>>
>>>
>>> _______________________________________________
>>> eclipselink-users mailing list
>>> eclipselink-users@xxxxxxxxxxx
>>> https://dev.eclipse.org/mailman/listinfo/eclipselink-users
>>>
>>>
>>> --
>>>
>>>
>>>
>>> Shaun Smith | Principal Product Manager, TopLink | +1.905.502.3094
>>> Oracle Fusion Middleware
>>> 110 Matheson Boulevard West, Suite 100
>>> Mississauga, Ontario, Canada L5R 3P4
>>>
>>> _______________________________________________
>>> eclipselink-users mailing list
>>> eclipselink-users@xxxxxxxxxxx
>>> https://dev.eclipse.org/mailman/listinfo/eclipselink-users
>>>
>>>
>> _______________________________________________
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>> eclipselink-users@xxxxxxxxxxx
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>
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>
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