Re: [eclipselink-users] Overwrite session manager settings

[James Sutherland <jamesssss@xxxxxxxxx>]

Reads will normally use the login information from the EntityManagerFactory. 
This is because the shared cache should use a common login.  You can do this
however using the property,

"eclipselink.jdbc.exclusive-connection.mode"="Always"

See,
http://www.eclipse.org/eclipselink/api/1.1/org/eclipse/persistence/config/PersistenceUnitProperties.html#EXCLUSIVE_CONNECTION_MODE

You can also disable the shared cache using,

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

Or disable on a per class basis.


Jaka Jančar wrote:
> 
> 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
>>>>>
> 
> 
> 


-----
---
http://wiki.eclipse.org/User:James.sutherland.oracle.com James Sutherland 
http://www.eclipse.org/eclipselink/
 EclipseLink ,  http://www.oracle.com/technology/products/ias/toplink/
TopLink 
Wiki:  http://wiki.eclipse.org/EclipseLink EclipseLink , 
http://wiki.oracle.com/page/TopLink TopLink 
Forums:  http://forums.oracle.com/forums/forum.jspa?forumID=48 TopLink , 
http://www.nabble.com/EclipseLink-f26430.html EclipseLink 
Book:  http://en.wikibooks.org/wiki/Java_Persistence Java Persistence 
-- 
View this message in context: http://www.nabble.com/Overwrite-session-manager-settings-tp22606192p22849307.html
Sent from the EclipseLink - Users mailing list archive at Nabble.com.