Hi Kevin /Jeremy,
Thanks for your replies.
In the code that you mention, I would have to follow a pattern like this...
MYEjb {
EntityManager em = null;
InitialContext ctx = new InitialContext();
em = (EntityManager)ctx.lookup("java:comp/env/MyPCJndi");
public void mymethodwhichneedsacachevalue() {
Cache.getValue(key, manager); // the manager is passed to
the cache. Don't want this
}
}
CachePOJO {
public String getValue(String key, EntityManager manager) {
//singleton...uses manager to initialize from database for the
first time....
}
}
What I really want is
CachePOJO {
private void initialize() {
InitialContext ctx = new InitialContext();
Entitymanger mgr = ctx.lookup(jndinameofmgr);
//use mgr to load values from DB.
}
}
Yes, the cache is accessed from an EJB, but I don't want to be passing the
manager around. In fact, I have this pattern problem repeatedly because we
have DAO classes that always now need to get initialized with the manager
which is passed from the EJB class (session facade). I end up having to pass
my entitymanager around.
In a previous project with hibernate, I remember being able to get the
sessions directly from the container using JNDI and they would be bound to a
transaction if there was one existing. I want to be able to work with a
similar pattern but stumble since the only place I am able to get a manager
from right now is inside an EJB which I then have to pass around to lower
layers.
Thanks in advance.
Devu.
Jeremy, I don't have an option to go to WAS 7 right now, I will have to live
with the fix packs. Will try out the method in Kevin's link.
Kevin Sutter wrote:
>
> Devu213,
> Besides Jeremy's references below, I want to be aware of WebSphere's
> support
> of OpenJPA. I started to cover this the WebSphere and Java Persistence
> blog
> [1], but to cover your specific situation... You are correct that the
> version shipped with the WebSphere EJB3 Feature Pack was OpenJPA 1.0.
> But,
> we have created a service stream for this release in OpenJPA (1.0.x). If
> any problems are discovered in the 1.0 release, then we can fix them in
> OpenJPA 1.0.x. This updated version of OpenJPA will then get picked up
> for
> WebSphere iFixes and FixPacks. So, you are not "stuck" with OpenJPA 1.0.
> It will get updated just like the rest of your WebSphere offering as
> additional FixPacks are applied.
>
> WebSphere v7 shipped a version of 1.2 OpenJPA. This version will get
> supported via the 1.2.x branch of OpenJPA. You could follow Jeremy's
> references below to use this newer version of OpenJPA with the EJB3
> Feature
> Pack, but then you no longer have access to the WebSphere extensions that
> sit on top of the OpenJPA binaries. It is an option though.
>
> Good luck,
> Kevin
>
> [1]
> http://webspherepersistence.blogspot.com/2008/09/support-for-openjpa.html
>
>
> On Mon, Jan 12, 2009 at 10:42 AM, Jeremy Bauer <techhu...@gmail.com>
> wrote:
>
>> Hi devu213,
>> To use JNDI to lookup an EM or EMF in WebSphere app server you can define
>> a
>> class level annotation (or via XML in your ejb module deployment
>> descriptor)
>> on your session bean or servlet and use the "name" attribute to specify
>> the
>> JNDI name. For example:
>>
>> @Stateless
>> @PersistenceContext(unitName="MyPC", name="MyPCJndi")
>> public class JPABean implements JPALocal, JPARemote {
>> ...
>> @Resource SessionContext sessionCtx;
>>
>> public void beanMethod() {
>>
>> // 1) Lookup via comp/env namespace of the initial/current context
>> EntityManager em = null;
>> InitialContext ctx = new InitialContext();
>> em = (EntityManager)ctx.lookup("java:comp/env/MyPCJndi");
>>
>> // or 2) Use direct lookup from the injected session ctx of the session
>> bean
>> em = (EntityManager)sessionCtx.lookup("MyPCJndi");
>>
>> }
>>
>> Looking up an EntityManagerFactory via @PersistenceUnit works similarly.
>>
>> Notice though, that lookup is via the ENC of the EJB. I don't know
>> how/if
>> global JNDI can be used to get a factory. (Anyone?) So, if you initialize
>> your POJO cache within the context of the EJB, the lookup will work. If
>> you
>> need to initialize the cache outside of a container,
>> Persistence.createEntityManagerFactory should work for you. I'd verify
>> that
>> all of your jars specified in your jar-file entry are available on the
>> classpath of your application. You may need to add the jars to the class
>> path entry in the manifest of your module.
>>
>> Here's an IBM infocenter document that explains how to configure an
>> alternate persistence provider[1]. The key items when using an alternate
>> version of OpenJPA is to make sure you've included all the necessary
>> OpenJPA
>> jars in your application or via shared library and the application
>> classloader is configured to load PARENT_LAST. This allows the OpenJPA
>> jars
>> provided by the application (or shared lib) to be loaded before those
>> provided by the app server.
>>
>> [1]
>>
>> http://publib.boulder.ibm.com/infocenter/wasinfo/v6r1/index.jsp?topic=/com.ibm.websphere.ejbfep.multiplatform.doc/info/ae/ae/tejb_jpa3rdparty.html
>>
>> Hope this helps,
>> -Jeremy
>>
>> On Sat, Jan 10, 2009 at 4:25 AM, devu213 <devusm...@gmail.com> wrote:
>>
>> >
>> > Hi Kevin,
>> >
>> > Thanks for taking interest despite this being a Websphere question.
>> Here
>> is
>> > the information that might help:
>> >
>> > 1. Yes am using the EJB3 featurepack. My server is at version 6.1.0.17
>> with
>> > EJB and Webservices FP installed.
>> > 2. The code snippet Persistence.createEntityManager() works on
>> stand-alone
>> > even with the jar tags(but fails in the container).
>> > 3. I am using the openJPA shipped with Websphere.
>> >
>> > Having given you the above it looks from your answer that I have erred
>> by
>> > not stating my question properly. The issue is, I don't know what name
>> is
>> > used to bind the factory and the manager. So the issue is not that I'm
>> not
>> > able to lookup but that I don't know the JNDI name to look up and so
>> > haven't
>> > even tried it. Somehow, I did not find any documentation on the
>> Websphere
>> > sites or google.
>> >
>> > Also on similar lines, I would like to see some documentation on how to
>> > override the default openJPA shipped with WAS because I want to be able
>> to
>> > use the latest version but the one being picked up by the classloader
>> is
>> > always the 1.0 version.
>> >
>> > Thanks in advance.
>> >
>> >
>> >
>> > Kevin Sutter wrote:
>> > >
>> > > Hi devu213,
>> > > Just to clarify... Are you using the EJB3 Feature Pack on top of
>> > > WebSphere
>> > > v6.1. Are you using the version of OpenJPA that ships with the
>> Feature
>> > > Pack, or something newer? It sounds like you are using
>> container-managed
>> > > persistence (ie. the injection support), so it sounds like you are
>> using
>> > > the
>> > > EJB3 Feature Pack. But, I just want to make sure.
>> > >
>> > > With the EJB3 Feature Pack, the JNDI lookup of an EntityManager
>> should
>> > > work
>> > > as well as the injection support. You mention that you are getting a
>> SAX
>> > > parser error with your persistence.xml file. Do you get any parsing
>> > > errors
>> > > when running OpenJPA standalone? Or, is all of your testing within a
>> > > container? Can you provide more details on the specific parsing
>> errors
>> > > you
>> > > are getting?
>> > >
>> > > You should also be able to use application-managed persistence within
>> the
>> > > Container.
>> > >
>> > > Off the top of my head, I'm not aware of any problems with what you
>> are
>> > > attempting. Unfortunately, I can't highlight anything you're doing
>> > > incorrectly. If you can provide some additional details, maybe we
>> can
>> > > help
>> > > get you running.
>> > >
>> > > FYI... Just a reminder. This forum is for questions and issues
>> specific
>> > > to
>> > > OpenJPA. Since some of us are intimate with WebSphere, we attempt to
>> > help
>> > > with related WebSphere questions. In this particular case, it sounds
>> > like
>> > > you might be hitting a problem with the EJB Container within
>> WebSphere.
>> > > We
>> > > can help with the triage of this case, but we won't be able to
>> resolve
>> > the
>> > > problem with OpenJPA (if it turns out to be a problem with the
>> > Container).
>> > >
>> > > Thanks,
>> > > Kevin
>> > >
>> > > On Wed, Jan 7, 2009 at 2:40 AM, devu213 <devusm...@gmail.com> wrote:
>> > >
>> > >>
>> > >> Hi,
>> > >>
>> > >> I need to lookup an entitymanager using JNDI on websphere 6.1. My
>> > >> persistence.xml is configured to use JPA. Although I use injection
>> > (which
>> > >> works) in almost all cases, I have a case where I would like the use
>> of
>> > >> entitymanager in a POJO and therefore would like to get it from JNDI
>> > >> directly.
>> > >>
>> > >> The case is I have a cache which should be initialized with values
>> from
>> > >> the
>> > >> database the first time it is accessed. The cache class is a POJO
>> class.
>> > >>
>> > >> I don't seem to find any documentation regarding this. Is this a
>> > >> websphere
>> > >> limitation ? Also, currently this class is trying to create a
>> factory
>> of
>> > >> its
>> > >> own within the container using
>> > >> Persistence.createEntityManagerFactory(unitname) but that fails as
>> for
>> > >> some
>> > >> reason a SAX exception is thrown during parsing Persistence.xml file
>> at
>> > >> the
>> > >> point where it tries to load the jar files containing the various
>> entity
>> > >> classes.
>> > >>
>> > >> So my second question is, is there some sort of restriction on the
>> use
>> > of
>> > >> Persistence.createEntityManager() inside the container?
>> > >>
>> > >> Have uploaded the class as well as the persistence.xml file.
>> > >> http://n2.nabble.com/file/n2121433/ParamValuesCache.java
>> > >> ParamValuesCache.java
>> > http://n2.nabble.com/file/n2121433/persistence.xml
>> > >> persistence.xml
>> > >> --
>> > >> View this message in context:
>> > >>
>> >
>> http://n2.nabble.com/Entitymanager-lookup-using-JNDI-on-webshpere-tp2121433p2121433.html
>> > >> Sent from the OpenJPA Users mailing list archive at Nabble.com.
>> > >>
>> > >>
>> > >
>> > >
>> >
>> > --
>> > View this message in context:
>> >
>> http://n2.nabble.com/Entitymanager-lookup-using-JNDI-on-webshpere-tp2121433p2137356.html
>> > Sent from the OpenJPA Users mailing list archive at Nabble.com.
>> >
>> >
>>
>
>
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