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From Christian Schneider <>
Subject Re: [VOTE] Release Aries JPA 2.0.0
Date Thu, 18 Jun 2015 13:51:47 GMT
The current aries jpa (master) works quite well with updates of the 
persistence unit bundles.
In the 1.x aries jpa I was never able to do a successful update because 
of this issue .

In the new version the EntityManagers are closed after each request. If 
the persistence unit bundle is updated then the old EntityManagerFactory 
is unpublished and closed as soon as all EntityManagers are closed. At 
the same time a new EntityManagerFactory is published that will be 
picked up for any new transactions.
So the implementation should not need Quiesce to be able to cope with 

Additionally we still have the blueprint quiesce which will shut down 
all blueprint services that are the entry point for the acceses to jpa. 
So if you do a blueprint quiesce there should be no open EntityManager 
instances after a short period anyway.

So with those two mechanisms I think there is no need to implement 
Quiesce in aries jpa 2.0 without loosing functionality.
Besides that I have created a 1.x branch. So we will be able to maintain 
the old style bundles if people do not want to switch.

The last argument is that the current implementation largely works 
without proxies of the EMF and EM. So it is a lot easier to understand 
and there is less room for problems. If we would implement Quiesce then 
we probably would have to introduce such proxies again with all the 
problems they bring.


On 18.06.2015 15:19, Jeremy Hughes wrote:
> Hi Sebastian, I guess I wasn't watching when the discussion happened
> in April - sorry about that. We had a discussion before then about the
> quiesce scenario with JPA. I see that the quiesce modules are no
> longer used by JPA. Can you describe how quiesce is now achieved in
> the new implementation. Without it, ie removing something users rely
> on, I'd be a -1 on this release.
> Thanks,
> Jeremy

Christian Schneider

Open Source Architect

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