Re: POJO question

From: Michael Engelhart (moosebrookfar..mail.com)
Date: Thu Mar 10 2005 - 11:15:13 EST

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    Hi Andrus,

    Thanks for the quick response. As I mentioned I'm not really
    familiar with serialization code but that being said I'd be more then
    happy to look into writing something like this if someone could point
    me in the right direction. Is there anything similar going on in the
    current codebase that could be used as a sample of what needs to be
    done to accomplish this?

    Michael
    On Thu, 10 Mar 2005 09:54:31 -0500 (EST), Andrus Adamchik
    <andru..bjectstyle.org> wrote:
    > Michael,
    >
    > All we need here is an alternative serialization mechanism for the case
    > when DataObjects are crossing a certain boundary. You will pass around
    > CayenneDataObject subclasses, but this shouldn't bother you as long as
    > they are fully inflated and don't require a DataContext to read
    > properties. The actual serialization mechanism can be optimized so that
    > there is not much overhead.
    >
    > So I don't see much drawback in using Cayenne over just POJO in this case
    > .... other than we need to create and test a serializer. I'll need maybe a
    > few hours to write it... the question is when I get those few hours to
    > spare :-)
    >
    > On the long run we should investigate adding support for serialization
    > delegate to CayenneDataObject so that those private write/readObject can
    > still be customized.
    >
    > Andrus
    >
    >
    > > Hi -
    > >
    > > I've been using Cayenne for a few days now in a test to port a new
    > > prototype project to use Cayenne from Hibernate. There's one nagging
    > > concern I have so far in my trials. My persistent objects are used in
    > > many circumstances that have nothing to do with their persistent
    > > quality . They were just POJO's that I pass around to other classes
    > > that need to access their data fields. Much of what is done in my
    > > system is read only from a persistence standpoint. But what feels weird
    > > is the sense that what I'm passing to my other classes is not really a
    > > POJO and that if I'm not careful, the data I need to access in another
    > > class is not going to be there (i.e. Hollow state). With Hibernate for
    > > example, once the object has been retrieved I am
    > > confident that what I'm passing around isn't going to magically become
    > > disconnected from a DataContext or the like. Also much of this is
    > > distributed data where it's being serialized through JMS message
    > > queue's on possibly remote application servers. I realize there's
    > > overhead but I can't really gauge how much more there is with Cayenne
    > > vs. a POJO. Obviously inherting from a subclass adds size to the
    > > serialized objects as well but I'm not familiar enough with things like
    > > CayenneDataObject and the intricacies of serialization to know how much.
    > >
    > > Is this is just something I'm going to have to get used to or is
    > > Cayenne not really what I'm looking for in the sense that 90% of what
    > > I'm doing is read-only database queries. The persistent objects also
    > > need to be changed inside the application but in general they won't need
    > > to be committed back to the database. The changes will usually happen
    > > to fields inside the subclass of the persistent objects but these fields
    > > can't be transient because they need to be serialized through the JMS
    > > message queues as well.
    > >
    > > So am I barking up the wrong tree with Cayenne? Part of my concern is
    > > just being new to a large framework but I don't want to spend time
    > > learning something like Cayenne if it's going to cause me more code
    > > maintenance headaches then another framework (hibernate - which I
    > > don't particularly care for, or another ORM framework).
    > >
    > > Thanks for any advice
    > >
    > > Michael
    >
    >



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