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From "Will Hoover" <java.whoo...@gmail.com>
Subject RE: OpenJPA DCN/QCN Caching Support?
Date Mon, 07 Jan 2013 14:00:15 GMT
I wouldn't say it's a make or break feature for using OpenJPA, but it would
be a bonus. I wouldn't mind making a contribution to add this feature. By
the looks of how EclipseLink did things it doesn't seem like it would be too
difficult to implement
(http://dev.eclipse.org/svnroot/rt/org.eclipse.persistence/trunk/foundation/
org.eclipse.persistence.oracle/src/org/eclipse/persistence/platform/database
/oracle/dcn/OracleChangeNotificationListener.java ). I guess there would
have to be some thought/discussion on configuration options. Maybe there
could be an option that would allow control over how stale data is handled
during the L2 window period?

-----Original Message-----
From: Kevin Sutter [mailto:kwsutter@gmail.com] 
Sent: Friday, January 04, 2013 2:25 PM
To: users@openjpa.apache.org
Subject: Re: OpenJPA DCN/QCN Caching Support?

Hi Will,
OpenJPA does support L2 caching.  But, it does not currently support the
"database change notification" as specified in the EclipseLink
documentation.  We are looking at providing this type of notification
support, but there is some concern about the "window" between the time that
the data gets updated in the database and notifying the L2 cache to either
remove or update the contents.  You could argue that any window of time is
better than no automatic notification, but the app still has to know that
they could be processing stale data.  And, closing the window completely may
not actually even be desired since there could be a potential bottleneck at
the notification and processing levels...

It's good to have this conversation though...  Are you indicating this lack
of DCN processing is a make-or-break feature for your usage of OpenJPA?  If
so, would you be interested in helping to develop such a feature?

Thanks,
Kevin

On Fri, Jan 4, 2013 at 1:07 PM, Will Hoover <java.whoover@gmail.com> wrote:

> Does OpenJPA support caching using DCN/QCN similar to EclipseLink?
>
> http://wiki.eclipse.org/EclipseLink/Examples/JPA/DCN
>
> http://wiki.eclipse.org/EclipseLink/UserGuide/JPA/Basic_JPA_Developmen
> t/Cach 
> ing/DatabaseEvents<http://wiki.eclipse.org/EclipseLink/UserGuide/JPA/B
> asic_JPA_Development/Cach%0Aing/DatabaseEvents>
>
>
>


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