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Re: [eclipselink-users] Overwrite session manager settings
"jdbc:mysql://host/ global" specified in persistence.xml for both persistence units? Each persistence unit *must* have connection string (or data source) because the session underneath the factory is connected before createEMF method returns.
----- Original Message ----- From: "Jaka Jančar" <jaka@xxxxxxxxx> 
To: "EclipseLink User Discussions" <eclipselink-users@xxxxxxxxxxx>
Sent: Thursday, April 02, 2009 2:47 PM
Subject: Re: [eclipselink-users] Overwrite session manager settings


The connection string (JDBC_URL) is not the same, that's why it
puzzles me. The host however is.

The steps that I do are:
 - clusterEMF = createEMF("ClusterPU", JDBC_URL="jdbc:mysql://host/
global"...)
 - clusterEMF.createEM() and do some work with it

 - instanceEMF = createEMF("InstancePU", NO JDBC URL!)
   (will have to disable shared caches here like you told me)
 - instanceEM = instanceEMF.createEM(JDBC_URL="jdbc:mysql://host/
instance_<N>"...)
 - instanceEM.find(Foo.class, id)

At the last step, I get the error "Table 'global.foo' doesn't exist".
Database "global"?! From clusterEMF?!

Reading the docu, I would think that each EMF (server session) has its
own connection pool and it's own cache. Is that not correct?

I understand that, as you told me, I will have to isolate caches of
EMs of the second EMF. But I still don't understand how a completely
unrelated URL from another EMF was used and I would very much like to
know that.

Regards,
 Jaka

On 2. Apr 2009, at 16:46, Andrei Ilitchev wrote:
You must use some connections in the second EMF, I am assuming that connection string is the same as in the first EMF.
Eclipselink uses by default shared cache for all objects it handles, so consider defining the separate cache for the classes you will handle in EM created with connection strings. Defining of non-shared caches is done when EMF is created by passing the properties to createEMF (or specifying the properties in persistence.xml): 

//for each class that requires isolated cache

"eclipselink.cache.shared.myPackage.MyClass" "false"
//alternatively you can use a single property in case all classes require isolated cache 

"eclipselink.cache.shared.default" "false"

To createEM along with a new connection properties, pass:
"eclipselink.jdbc.exclusive-connection.mode" "Isolated"


----- Original Message ----- From: "Jaka Jančar" <jaka@xxxxxxxxx>
To: "EclipseLink User Discussions" <eclipselink-users@xxxxxxxxxxx>
Sent: Thursday, April 02, 2009 7:42 AM
Subject: Re: [eclipselink-users] Overwrite session manager settings


Hi Tom,

I'm having a problem with this approach: the wrong connections are
being used for the persistence units.

I have two Persistence Units defined in persistence.xml: ClusterPU and
InstancePU. The EMF for ClusterPU is created normally, supplying JDBC
data and not overriding it in createEM(). The EMF for InstancePU is
created without supplying JDBC data and setting it each time in
createEM().

After the EMFs are created, I create an EM for ClusterPU, the pool is
initialized and all works fine for ClusterPU.

The problem is with InstancePU (the one with per-EM JDBC parameters):

If I save an entity (instanceEm.persist(entity)) a new connection is
established and all works fine. However if I try to load an entity
(instanceEm.find(entityClass, entityId)), a connection from ClusterPU
will be used, instead of a new one being created, which is completely
incorrect!

Any ideas?

Jaka


On 19. Mar 2009, at 20:39, Jaka Jančar wrote:


Hmm... this is awesome, I'll check it out.

Hibernate does not support this at all, btw :)

Jaka

On 19. Mar 2009, at 19:50, Tom Ware wrote:


Hi Jaka,
I just spoke to a colleague and he mentioned that the behavior is exposed through properties.
The key is to create a working EntityManagerFactory with the strategy listed below. (i.e. Provide working connection information at the creation of the EMF)
Once you have done that, you can create EntityManagers with alternate connection information using the properties in org.eclipse.persistence.config.EntityManagerProperties. Note: They are the same strings as the ones you use for EntityManagerFactory creation. The limitation here is that you must connect to a database that uses the same EclipseLink DatabasePlatform.
Once again, the recommended approach for most applications is to use the settings in EntityManagerFactory. The additional functionality is available for applications that have more complicated connection requirements. 

-Tom

Jaka Janc(ar wrote:

Tom,
is it possible to specify the database server on an EntityManager basis? In other words, what can you do if you want to connect to loads of different hosts, but don't want to recreate EntityManagerFactory for each one (since that takes ages). 
Jaka
On 19. Mar 2009, at 19:23, Tom Ware wrote:

Hi Phil,
In EclipseLink, EntityManagerFactory holds the object that controls database connections. As a result you need to provide the database properties to the EntityManagerFactory at creation time. (In the bootstrap API, a Map can be provided to the Persistence.createEntityManagerFactory(String, Map) method.)
If you need to regulate these things on an EntityManager basis, there is some EclipseLink specific API that can be used to do that, but for most people, the general API is sufficient. 

-Tom

Philipp Kursawe wrote:
Is it possible to overwrite the settings made in the persistence.xml when creating the EntityManager using an EntityManagerFactory.create(Map)? 
It seems like that the properties I am handing in are not valued.
Is it in any other way possible to set certain persistence.xml values from within the program? I mean I cannot seriously be asked to put login credentials inside a JAR? I would like the user to configure those values and feed them to EclipseLink programmatically not from the persistence.xml. 
Thanks for your help!
Phil
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