I have a WebSphere ESB 7.5 hosting a web service (inside a mediation module).
The data from the web service should be stored to a DB. DB access should be performed via JPA.
I would like to utilize JPA with WebSphere's container-managed transactions (so JPA just replaces plain SQL calls and that's it). I don't want to generate an EJB from this tutorial. This seems unnecessary for my case.
Is it possible? Any code example?
There is nothing in the JPA specification that mandates it be used in an application container or via EJB's. But, as to your second condition, container managed transactions are defined at the level of the container, and more specifically, they are only valid for use in entity beans. So, your options are to use:
JPA + non-entity beans + user transactions
JPA + entity beans + container managed transaction.
I am using Glassfish server. It seems that the #LocalBean is getting initialized at server startup. For other beans they are correctly initialized on look up. Is this the correct behaviour for LocalBean ?
There is no rule saying that #LocalBean should be eagerly initialized and others should not. It's left to the container provider to decide when particular bean should be initialized.
The only case you have control over when bean is initialized is to use #Singleton EJB with #Startup annotation. This will force container provider to create an instance of the singleton bean during server startup. This is a good place to put your initialization logic within.
The behavior you've observed might be correct in case of Glassfish but I would not relay on it because other container providers might choose different approach.
I've been working on a web application, deployed on Tomcat 7, which use EclipseLink JPA to handle the persistence layer.
Everything works fine in a test environment but we're having serious issues in the production environment due to a firewall cutting killing inactive connections. Basically if a connection is inactive for a while a firewall the sits between the Tomcat server and the DB server kill it, with the result of leaving "stale" connections in the pool.
The next time that connection is used the code never returns, until it gets a "Connection timed out" SQLException (full ex.getMessage() below).
EL Fine]: 2012-07-13
18:24:39.479--ServerSession(309463268)--Connection(69352859)--Thread(Thread[http-bio-8080-exec-5,5,main])--
MY QUERY REPLACED TO POST IT TO SO [EL Config]: 2012-07-13
18:40:10.229--ServerSession(309463268)--Connection(69352859)--Thread(Thread[http-bio-8080-exec-5,5,main])--disconnect
[EL Info]: 2012-07-13
18:40:10.23--UnitOfWork(1062365884)--Thread(Thread[http-bio-8080-exec-5,5,main])--Communication
failure detected when attempting to perform read query outside of a
transaction. Attempting to retry query. Error was: Exception
[EclipseLink-4002] (Eclipse Persistence Services -
2.3.0.v20110604-r9504): org.eclipse.persistence.exceptions.DatabaseException Internal
Exception: java.sql.SQLException: Eccezione IO: Connection timed out
I already tried several configuration in the persistence.xml, but since I have no access to the firewall configuration I had no luck with these methods. I also tried to use setCheckConnections()
ConnectionPool cp = ((JpaEntityManager)em).getServerSession().getDefaultConnectionPool();
cp.setCheckConnections();
cp.releaseConnection(cp.acquireConnection());
I managed to solve the issue in a test script using testOnBorrow, testWhileIdle and other features that are avalaible from DBCP Apache Commons. I'd like to know how to override the EclipseLink internal connection pool to use a custom connection pool so that I can provide an already configured pool, based on DBCP rather than just configuring the internal one using persistence.xml.
I know I should provide a SessionCustomizer, I'm uncertain which one is the correct pattern to use. Basically I would like to preserve the performance of DBCP in a JPA-like way.
I'm deploying on Tomcat 7, I know that if I switch to GF I won't have this problem, but for a matter of consistency with other webapp on the same server I'd prefere to stay on Tomcat.
What you want is definitely possible, but you might be hitting the limits of the "do it yourself" approach.
This is one of the more difficult things to explain, but there are effectively two ways to configure your EntityManagerFactory. The "do it yourself" approach and the "container" approach.
When you call Persistence.createEntityManagerFactory it eventually delegates to this method of the PersistenceProvider interface implemented by EclipseLink:
EntityManagerFactory createEntityManagerFactory(String emName, Map map)
The deal here is EclipseLink will then take it upon itself to do all the work, including its own connection creation and handling. This is the "do it yourself" approach. I don't know EclipseLink well enough to know if there is a way to feed it connections using this approach. After two days on Stackoverflow it doesn't seem like anyone else has that info either.
So here is why this "works in GF". When you let the container create the EntityManagerFactory for you by having it injected or looking it up, the container uses a different method on the PersistenceProvider interface implemented by EclipseLink:
EntityManagerFactory createContainerEntityManagerFactory(PersistenceUnitInfo info, Map map)
The long and short of it is that this PersistenceUnitInfo is an interface that the container implements and has these two very key methods on it:
public DataSource getJtaDataSource();
public DataSource getNonJtaDataSource();
With this mode EclipseLink will not try to do its own connection handling and will simply call these methods to get the DataSource from the container. This is really what you need.
There are two possible approaches you could take to solving this:
You could attempt to instantiate the EclipseLink PersistenceProvider implementation yourself and call the createContainerEntityManagerFactory method passing in your own implementation of the PersistenceUnitInfo interface and feed the DBCP configured DataSource instances into EclipseLink that way. You would need to parse the persistence.xml file yourself and feed that data in through the PersistenceUnitInfo. As well EclipseLink might also expect a TransactionManager, in which case you'll be stuck unless you hunt down a TransactionManager you can add to Tomcat.
You could use the Java EE 6 certified version of Tomcat, TomEE. DataSources are configured in the tomee.xml, created using DBCP with full support for all the options you need, and passed to the PersistenceProvider using the described createContainerEntityManagerFactory call. You then get the EntityManagerFactory injected via #PersistenceUnit or look it up.
If you do attempt to use TomEE, make sure your persistence.xml is updated to explicitly set transaction-type="RESOURCE_LOCAL" because the default is JTA. Even though it's non-compliant to use JTA with the Persistence.createEntityManagerFactory approach, there aren't any persistence providers that will complain and let you know you're doing something wrong, they treat it as RESOURCE_LOCAL ignoring the schema. So when you go to port your app to an actual certified server, it blows up.
Another note on TomEE is that in the current release, you'll have to put your EclipseLink libs in the <tomcat>/lib/ directory. This is fixed in trunk, just not released yet.
I'm not sure how useful these slides will be without the explanation that goes along with them, but the second part of this presentation is a deep dive into how container-managed EntityManager's work, specifically with regards to connection handling and transactions. You can ignore the transaction part as you aren't using them and already have an in production you're not likely to dramatically change, but it might be interesting for future development.
Best of luck!
I need to be able to circumvent the whole deployer malarkey and programmatically register/unregister (dependency-less) POJOs as services in JBoss.
Currently I'm dynamically creating an MBean interface and registering this with the JBoss MBeanServer, and then registering local/remote with Jndi.
This works ok (I can have a standard service from a vanilla SAR reference one of these service POJOs with the #EJB annotation) - however the container seems to leaves stale references behind as after calling unbind() and unregisterMBean().
Obviously I'm missing something by not dealing with the container in a way it expects, but what am I missing? Or is there an easier way (can't see much in the way of an API)?
thanks.
I'm working with EJBs...I do the following and I don't know why the injected EntityManager is not working as one might expect.
EJB1 calls a method on EJB2 that writes to the DB.
when EJB2 returns EJB1 sends a message to a MDB.
MDB calls EJB3 that reads the DB and does some work.
My problem is that the EntityManager injected in all 3 EJBs with #PersistenceContext is not working properly. Calling persist() in EJB2 is not being reflected on the EntityManager injected in EJB3.
What might be wrong?
Hope I made my problem clear enough.
now working with Container managed transactions.
My problem is that the EntityManager injected in all 3 EJBs with #PersistenceContext is not working properly. Calling persist() in EJB2 is not being reflected on the EntityManager injected in EJB3.
In a Java EE environment, the common case is to use a Transaction-Scoped Container-Managed entity manager. And with such an entity manager, the persistence context propagates as the JTA transaction propagates.
In your case, I suspect you're using a REQUIRES_NEW transaction attribute for the method of EJB3. So:
when invoking EJB3#bar(), the container will suspend the transaction started for EJB2#foo() and start a new transaction
when invoking the entity manager from EJB3#bar(), a new persistence context will be created.
since the transaction started for EJB2#foo() has not yet committed, changes aren't "visible" to the new persistence context.
PS: Are you really creating new threads? If yes, little reminder: this is forbidden by the EJB spec.