In our web application, we have a facade EJB which in turn calls multiple EJBs to perform a business function. The flow is like :
SLSB facade -> invokes ejb1, ejb2, ejb 3 etc -> invoke JPA layer
In each of the ejbs in the business layer, i inject entity manager using #PersistenceContext.
A simplified version of the code is as below:
#Stateless
public class facade{
#EJB
private EJB1 ejb1;
#EJB
private EJB2 ejb2;
#EJB ejb3;
private EJB3 ejb3;
public void performAction(..) {
// invoke method on ejb1
// invoke method on ejb2
// invoke method on ejb3
}
}
#Stateless
public class EJB1 implements IEjb1 {
#PersistenceContext(unitName = "pu")
private EntityManager entityManager;
#TransactionAttribute(TransactionAttributeType.REQUIRED)
public xxxEntity insert(xxxEntity entity) throws AppException {
// code for persisting the entity
}
}
#Stateless
public class EJB2 implements IEjb2 {
#PersistenceContext(unitName = "pu")
private EntityManager entityManager;
#TransactionAttribute(TransactionAttributeType.REQUIRED)
public yyyEntity insert(yyyEntity entity) throws AppException {
// code for persisting the entity
}
}
The application is deployed on Glassfish and uses JTA transaction. Since this is container managed PC, will the same persistence context be propagated to all EJBs? Will they run in the same transaction (reusing the transaction started in EJB1)? Is there a way to verify if the same transaction is used by all EJBs (same transaction id?)
By default all ejbs (1,2,3) will participate in the one, same transaction that is started by facade ejb. You would need to define different transaction attribute for them to use different transactions (e.g. REQIRES_NEW to create new transaction).
If you really need transaction id, you could try to inject TransactionSynchronizationRegistry into your bean like this
#Resource
TransactionSynchronizationRegistry registry;
// and then get key
...
registry.getTransactionKey()
See TransactionSynchronizationRegistry and Container-Managed Transactions
Related
I'm trying to do this.
public class MyEntityListener {
#PrePersist
private void onPrePersist(final Object object) {
// set object with value fetched via onPostConstruct
}
#PostConstruct
private void onPostConstruct() {
// fetch some value using entityManager
}
#PersistenceContext
private EntityManager entityManager;
}
When I persist and instance via EJB, the entityManager is different instance from that of the EJB.
onPrePersist is executed (before or) regardless of postConstruct.
Is this normal?
I am a long time Seam user who tries to move to Java EE7, JSF2.2 and CDI now.
In Seam you tend to use EntityManagers with extended scope most of the time (in the Seam Conversation Scope). You don't get any LIEs on Ajax request etc.
I am trying to do it in a similar way with Java EE7 and CDI but somehow the injected EntityManager is only transaction scoped. When I get a ajax request in the entities that were loaded before are not managed anymore.
I am using the new javax.faces.view.ViewScoped and javax.transactional.Transactional on my CDI bean.
My Producer:
#PersistenceContext(unitName = "primary", type = PersistenceContextType.EXTENDED)
private EntityManager entityManager;
#Produces
#Default
#Dependent
public EntityManager getEntityManager() {
return entityManager;
}
And my CDI bean:
#Named
#ViewScoped
#Transactional
public class TestBean implements Serializable{
/**
*
*/
private static final long serialVersionUID = 1L;
#Inject
EntityManager entityManager;
Logger log = Logger.getLogger(TestBean.class);
private TestEntity lastTest = null;
public void testAdd(){
TestEntity test = new TestEntity();
test.setVal("Test "+System.currentTimeMillis());
entityManager.persist(test);
entityManager.flush();
log.infov("Created test entity {0}", test);
lastTest = test;
}
public void testRead(){
List<TestEntity> test = entityManager.createQuery("select t from TestEntity t").getResultList();
for(TestEntity t: test){
log.infov("Found {0} managed {1}",t,entityManager.contains(t));
}
if(lastTest!=null){
log.infov("Last Test {0} managed {1}",lastTest,entityManager.contains(lastTest));
}
}
So when I first call testAdd() via Ajax it creates a new test entity. When I then call testRead() it gets all test entities and checks that the last created test entity is still managed (which it should if it is an EntityManager with an extended persistent context). But entityManager.contains(lastTest) always returns false.
What am I doing wrong?
I believe I can't use #PersistenceContext directly in the CDI bean. So how do I get the desired (Seam like) behaviour?
When you specify that an injected EntityManager is an extended persistence context, all object instances remain managed. Extended persistence contexts can only be used within Stateful session beans.
This is according to JBOSS documentation: https://docs.jboss.org/ejb3/app-server/tutorial/extended_pc/extended.html.
Consider packaging your insert/update/delete operations into EJBs while simple read from database can be through CDI beans. But more complex operations involving multiple reads and writes as well as transaction should be within EJBs.
I read a lot about the possibility of injection with jax rs 2.0 and in particular with jersey.
I even read that ejb injection is expected in jax rs 2.0 spec. But i still haven't found a unique solution among the variety of posts i read over the net.
In my use case i'm working with:
WildFly 9.0 and Jersey 2.x
I have a webapplication exposing my REST services and importing a jar implementing my model data.
This is the CDI approach:
#RequestScoped
#Path("/myPath")
public class ModelRetriever {
#Context
SecurityContext securityContext;
#Inject
private IMyModel MyModel;
#Path("{i}")
#GET
#Produces("application/json")
public Response countries(#PathParam("i") String countryId)
throws JSONException, Failure, IOException {
MyModel.doSomething();
}
This is my IMyModel interface
public interface IKasPrincipal extends Principal {
public void doSomething();
}
And this is MyModel implementation:
#RequestScope
public class MyModelImpl implements IMyModel {
public void doSomehting() {
doSomething();
}
}
Another method i tried is to use EJB injection changing my previous annotations like this:
#Stateless
#Path("/myPath")
public class ModelRetriever {
#EJB
private IMyModel MyModel;
#Path("{i}")
#GET
#Produces("application/json")
public Response countries(#PathParam("i") String countryId)
throws JSONException, Failure, IOException {
MyModel.doSomething();
}
This is my IMyModel interface
#Local
public interface IKasPrincipal extends Principal {
public void doSomething();
}
And this is MyModel implementation:
#Stateless
public class MyModelImpl implements IMyModel {
public void doSomehting() {
doSomething();
}
}
i get a null object using EJB approach and i get this exception using CDI
Caused by: org.glassfish.hk2.api.UnsatisfiedDependencyException: There was no object available for injection at SystemInjecteeImpl(requiredType=IMyModel,parent=ModelRetriever,qualifiers={},position=-1,optional=false,self=false,unqualified=null,616459318)
at org.jvnet.hk2.internal.ThreeThirtyResolver.resolve(ThreeThirtyResolver.java:75)
at org.jvnet.hk2.internal.ClazzCreator.resolve(ClazzCreator.java:211)
at org.jvnet.hk2.internal.ClazzCreator.resolveAllDependencies(ClazzCreator.java:234)
So is there anything i'm missing?
see other Stack Overflow related posts:
Dependency injection with Jersey 2.0
HK2 Jersey EJB 3 injection
The problem you are having is that HK2 does not know about anything that was not registered directly into it, and HK2 tries to to satisfy all dependency in your Jersey aware class.
I has this issue a while back. Then I discovered that Jersey uses HK2 internally. HK2 is a JSR-330 implementation (CDI).
One would think that a open-source project would declares it's CDI beans and use them regardless of the CDI implementation, but it looks like its not that way.
see : https://java.net/jira/browse/JERSEY-1933
see : https://hk2.java.net/integration.html
You can register your components into HK2...
see : https://jersey.java.net/documentation/latest/ioc.html
For all I know, you cannot inject CDI components (or anything else, as EJB) into Jersey's classes using your own (or your container's) CDI implementation, unless you use Glassfish (which personally I would never use) which in turn uses HK2 as its CDI implementation.
To me, this is a major draw back. But the only(?) draw back of Jersey.
-Maybe I missed something (which is very possible)
-Maybe this is a trick from Oracle so that you can't use Jersey in, let's say, your Websphere app which uses OpenWeb Beans as CDI implementation.
-Maybe they hardwired it to HK2, and just don't care that Jersey can't be used as a drop in component in your application, which relies on CDI or EJB
I'm not aware of why #EJB not worked, but, you can use #Produces/#Disposes bean.
#ApplicationScoped // or some other scoped
public class MyModelProducer {
#Produces public MyModel produceMyModel() {
}
public void disposeMyModel#Disposes final MyModel model) {
}
}
I am working with JPA 2.1 (EclipseLink 2.5.1) and JBoss 7.1.
I've define very simple JPA entities:
#Entity
#Table(name="APLICACIONES_TB")
public class Aplicacion implements Serializable {
#Id
#Column(name="COD_APLICACION_V")
private long codAplicacionV;
#Column(name="APLICACION_V")
private String aplicacionV;
#OneToMany(mappedBy="aplicacion")
private Collection<Prestacion> prestaciones;
... getters and setters
}
#Entity
#Table(name="PRESTACIONES_TB")
public class Prestacion implements Serializable {
#Id
#Column(name="COD_PRESTACIONES_V")
private String codPrestacionesV;
#Column(name="DESCRIPCION_V")
private String descripcionV;
#ManyToOne(fetch=FetchType.LAZY)
#JoinColumn(name = "COD_APLICACION_V")
private Aplicacion aplicacion;
... getters and setters ...
}
I have developed a staless EJB that executes a query to obtain some "Aplicacion" entities.
#Stateless
#LocalBean
public class DocuEJB implements DocuEJBLocal
{
#PersistenceContext(name="DocuEjb", type=PersistenceContextType.TRANSACTION)
private EntityManager em;
public Prestacion getResult(String name)
{
return em.createNamedQuery("ExampleQueryName", Prestacion.class).getSingleResult();
}
}
Because I'm working with JSF 2.1 the EJB is being injected in a managed bean:
#ManagedBean(name = "ManagedBean")
#RequestScoped
public class ManagedBean
{
#EJB DocuEJB docuEjb;
public String doSomething()
{
Prestacion entity = docuEjb.getResult("egesr");
if (entity != null)
{
// It should return null because 'entity' should be detached
Aplicacion app = entity.getAplicacion();
// but 'app' entity is not null, ¿why not?
System.out.println (app.getCodAplicacionV());
}
}
}
Lazy loading is not working even when lazy loading has been defined for 'aplicacion' field on 'Prestacion' entity. The code posted before should return a NullPointerException in the next line:
System.out.println (app.getCodAplicacionV());
because 'app' entity is detached and lazy loading has been configured.
Why is not working lazy loading?
Thanks
Try to add #Transactional on doSomething(), I think that your transaction manager is not well configured.
You can see here the official spring documentation. In any case, can you add your spring configurations, so that we can better help you. :)
I don't think the behavior your encounter is abnormal or your question should state it clearly:
EJB are by default transactional
Your JSF inject an EJB, with #EJB, and I guess JBoss can create a java reference and not a proxy
The entity is being managed because the transaction is not done, it will finish when doSomething ends.
Your entity is then loaded into the EntityManager, and lazy loading works because there is a context to it.
You would call em.evict(entity) with the result your are getting, this would probably fails because the entity would not be managed any more.
I'm a novice.
Does Jersey and EJB hold the same EntityManager scope?
Should I have to pass the EntityManager to EJB for same persistence context?
The primary target usage is JTA.
#Stateless
class MyEJB {
public MyEntity find(Long id) {
...
}
#PersistenceContext;
EntityManager entityManager;
}
class MyResource {
#GET
#Path("/myentity/{id}");
public MyEntity get(#PathParam("id") final long id) {
final MyEntity found = myEjb.find(id);
// is found's state detached?
// should I have to reattach?
found.setDate(new Date());
return found;
}
#EJB
private MyEjb myEjb;
#PersistenceContext;
EntityManager entityManager;
}
Does Jersey and EJB hold the same EntityManager scope?
Should I have to pass the EntityManager to EJB for same persistence context?
I don't think that your wording is correct, but they can share the same EntityManager instance, and you have chosen the right way (through injection). Have a look at this chapter of the Java EE 6 Tutorial:
To obtain an EntityManager instance, inject the entity manager into the application component:
#PersistenceContext
EntityManager em;
So, once again, your approach is correct. With regards to the questions in the code comments: the fact that MyEntity is attached or detached, it depends on the implementation of the find method in your EJB. If you do the following, it will be attached:
public MyEntity find(Long id) {
return entityManager.find(MyEntity.class, id);
}
Finally, doing this way, if you have chosen JTA to use container managed transactions, the transactions will be automatically bounded with the natural boundaries of MyBean's methods. In order to have JTA transactions, you have to use this line in persistence.xml file:
<persistence-unit name="em" transaction-type="JTA">