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From "Ricardo Andere de Mello" <wyt...@gmail.com>
Subject Re: Historical Session
Date Mon, 21 May 2007 22:16:49 GMT
yes.... this look something simple, but it is not...
see, objects exists in time, so for example, they are not deleted, they are
"finalized".
the worst part are the relationships, because they are historical too...
basically you have a start and end date for that object, and the object with
end date null is the actual object.
everytime you modify an object you clone it, set the end date of the old,
and set the start date of the new.
imagine now that "A" points to "B". both are historical objects. if "B" is
modified, a new historical object is created. "A" should point to the new
"B", not the old one. so you must have a "historical id" or a "historical id
object" to point at, that is common to all "B".

[]s, gandhi

2007/5/21, Marc Prud'hommeaux <mprudhom@apache.org>:
>
>
> Something like: "select x from Employee x as x was on January 1, 2002"
>
>
>
> On May 21, 2007, at 11:01 AM, Kevin Sutter wrote:
>
> > Sorry to show my ignorance, but what are "historical objects"?
> > Thanks!
> >
> > Kevin
> >
> > On 5/18/07, Ricardo Andere de Mello <wytwyg@gmail.com> wrote:
> >>
> >> ok, I'm sending this message to netmind list too, so they can
> >> answer my
> >> next
> >> question too:
> >>
> >> * Maybe this is a silly question, but is it possible to place
> >> netmind's
> >> beankeeper historical structure between OpenJPA and the database
> >> backstore?
> >>
> >> I dont think *any* serious commercial application can avoid
> >> historical
> >> objects.
> >> I think netmind's beankeeper is a great thing, and JPA is a good
> >> standard.
> >> Mixing both projects would be very cool. ;-)
> >>
> >> []s, gandhi
> >>
> >>
> >> 2007/5/18, Marc Prud'hommeaux <mprudhom@apache.org>:
> >> >
> >> >
> >> > Sadly, no. We don't have any built-in support for historical
> >> support
> >> > at this time, although we have thought for a long time that this
> >> > would be a great feature to have.
> >> >
> >> > You can, of course, do it yourself manually with a bunch of
> >> > persistent Date fields, but I agree that this is pretty
> >> cumbersome to
> >> > have to manage yourself.
> >> >
> >> >
> >> >
> >> > On May 18, 2007, at 11:27 AM, Ricardo Andere de Mello wrote:
> >> >
> >> > > Does OpenJPA have something similar to TopLink's "AsOfClause" ?
> >> > >
> >> > > I've been working for some time with OJB and Hibernate, and I'm
> >> > > work a lot
> >> > > with historical objects.
> >> > > It really sucks to manage lots of classes to build a historical
> >> > > structure of
> >> > > objects and object relations.
> >> > >
> >> > > Netminds beankeeper does a great job about this, but I'd like to
> >> > > adhere to
> >> > > JPA...
> >> > >
> >> > > Any idea of implementing historical objects AND RELATIONS,
> >> inside JPA?
> >> > >
> >> > > --
> >> > > Ricardo Andere de Mello
> >> > > Presidente do Quilombo Digital
> >> > > 55 (11) 3271-7928 / 55 (11) 9917-7722
> >> >
> >> >
> >>
> >>
> >> --
> >> Ricardo Andere de Mello
> >> Presidente do Quilombo Digital
> >> 55 (11) 3271-7928 / 55 (11) 9917-7722
> >>
>
>


-- 
Ricardo Andere de Mello
Presidente do Quilombo Digital
55 (11) 3271-7928 / 55 (11) 9917-7722

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