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Date: Thu, 7 Jul 2011 11:42:55 -0500
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Subject: Re: Audit log with OpenJPA
From: Rick Curtis <curtisr7@gmail.com>
To: users@openjpa.apache.org
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Perhaps you could use a separate PU for your audit logging? That should be
safe to use inside of a lifecycle callback.

On Thu, Jul 7, 2011 at 11:36 AM, Bengt Rodehav <bengt@rodehav.com> wrote:

> Jari,
>
> Yes an asynchronous queue is definitely an option. I've actually used that
> approach before. It makes a lot of sense when trying to achieve high
> throughput since the audit logging can then be done on lower priority.
>
> I was however hoping to be able to use JPA for this since a queue increases
> the complexity significantly (also regarding testing).
>
> Thanks,
>
> /Bengt
>
> 2011/7/7 Jari Fredriksson <jarif@iki.fi>
>
> > 7.7.2011 14:05, Bengt Rodehav kirjoitti:
> > > I'm using OpenJPA for persistence and would like to audit log any
> changes
> > > made to my entities. I serialize the objects to JSON (with Gson) and
> > store
> > > them in a separate table in the database. Since the audit log needs to
> > have
> > > the correct id's, the audit logging must take place after the entity
> has
> > > been persisted.
> > >
> > > I was hoping I could use the @PostPersist and @PostUpdate life cycle
> > > callbacks for this. I do seem to have the right information available
> and
> > > the serialization works fine but I don't know how I can persist my
> audit
> > log
> > > entries at this point. From what I've read, I'm not allowed to use the
> > > entity manager in a "Post" lifecycle callback which of course makes
> this
> > > hard.
> > >
> > > What do you recommend? Is there a good place in JPA/OpenJPA where I
> > > automatically can trigger the storing of an audit log entry as
> described
> > > above. Of course I can move this logic up from the persistence layer to
> a
> > > place where I can first have the entity manager persist my entity and
> > then
> > > explicitly call another service to do the audit log. However, this is a
> > > pretty general mechanism that I would like to have automatic support
> for
> > in
> > > my framework which is why I would like to have it pushed down into the
> > > persistence layer.
> > >
> > > Any ideas?
> > >
> >
> > I have not done anything like this, but some kind of queue and a
> > separate processor for that queue might be a solution.
> >
> > Maybe some message queue? Or a singleton Hashtable containing entries,
> > and a separate thread for persisting these to database.
> >
> > Something like that.
> >
> >
> >
> > --
> >
> > AWAKE! FEAR! FIRE! FOES! AWAKE!
> >        FEAR! FIRE! FOES!
> >                AWAKE! AWAKE!
> >                -- J. R. R. Tolkien
> >
> >
>


-- 
*Rick Curtis*

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