I also read your blog, and it sounds very interesting.
Just a quick question (probably should've done so on the blog though):
Does it hold that after getting a book and author from the results that:
aBook.getAuthor() == anAuthor
and/or
aBook.getAuthor().equals(anAuthor)
?
Martijn
On 8/27/06, Igor Vaynberg <[EMAIL PROTECTED]> wrote:
> another interesting problem i find with identity in full blown orms is that
> it can cause a nasty cascade of loading object graph when using "business"
> identity instead of db identity.
>
> if you have school->semester->class relationships and you do not want to
> depend on db identity which is the "recommended" way most likely you will
> have
>
> class.equals(class other) {
> this.name.equals(other.name)&&this.semester.equals(other.semster); }
> semester.equals(semester other) {
> this.code.equals(other.code)&&this.school.equals( other.school); }
>
> so now every time you equals/hashcode a class you load the semester and the
> school. given they they are loaded-by-id and might be in 2nd level
> cache....but still. this is the kind of troubles you always have when
> working on such a highly abstracted level that doesnt always map properly to
> the bare metal.
>
>
> -Igor
>
>
> On 8/26/06, Geoff hendrey <[EMAIL PROTECTED]> wrote:
> > Sure - but honestly I don't want to convince anyone
> > they need Shades.
> >
> > One problem I found with JDO was that the
> > PersistenceManager was not serializable. Another is
> > that detachment had to be handled explicitely.
> >
> > In Shades all pojo's are inherently detached. Change
> > tracking is automagic. The DatabaseSession is
> > ultra-leightweight and totally appropriate for keeping
> > in a Session.
> >
> > A big innovation in Shades is how identity is handled
> > - that really solved a lot of problems for me related
> > to change of identity within transactions. Identity is
> > a much more fluid concept in Shades, due to the
> > dynamic ORMapping interface, which you can even
> > implement on the fly as an anonynmous inner class.
> >
> > To be clear, I found ways to make JDO work just fine
> > with Wicket. Certainly JDO was a huge step forward in
> > making it easier to use Pojo-based frameworks like
> > Wicket.
> >
> > I blogged a bit on my motivation for Shades:
> > http://notskateboarding.blogspot.com/
> >
> > -geoff
> >
> >
> >
> > --- Igor Vaynberg < [EMAIL PROTECTED]> wrote:
> >
> > > i glanced over the code - but i dont get it after
> > > the first glance. perhaps
> > > you can explain what difficulties you hit when using
> > > wicket and an orm to
> > > help us better understand.
> > >
> > > seems to me like you are trying to work with a ui
> > > connected to a persistence
> > > layer - without a service layer in between. have you
> > > seen databinder which
> > > glues wicket and hibernate together?
> > >
> > > also your point about wicket and tapestry - wicket
> > > is much more flexible
> > > because it has IModel which gives you an extra layer
> > > of indirection that can
> > > hide a lot of orm logic and make the code
> > > cleaner/easier.
> > >
> > > -Igor
> > >
> > >
> > > On 8/26/06, Geoff hendrey <[EMAIL PROTECTED]>
> > > wrote:
> > > >
> > > > Hi All,
> > > >
> > > > I was one of the early users of Wicket before 1.0.
> > > I
> > > > did a lot of work to use Wicket with my JDO
> > > > implementation JDOMax (no longer supported). In
> > > the
> > > > process I learned a lot about why it is harder
> > > than it
> > > > has to be to use many ORM frameworks with Wicket
> > > and
> > > > Tapestry.
> > > >
> > > > I'm a member of JSR 243 Java Data Objects Experts
> > > > Group, and I advocated hard within that spec for
> > > the
> > > > "fixing" of the JDO spec with regard to
> > > > non-transaction-write behavior, along with Eric
> > > Samson
> > > > and others. The JDO group was receptive, having
> > > > gotten similar feedback from Howard Lewis Ship of
> > > > Tapestry. I believe this change will benefit
> > > Wicket
> > > > users, and make it much easier to use JDO 2.0 than
> > > JDO
> > > > 1.1, from Wicket.
> > > >
> > > > However, I still wasn't satisfied that it was
> > > "easy"
> > > > to do ORM from Wicket or Tapestry. So I started a
> > > new
> > > > project, based on what I learned -- it's a better
> > > way
> > > > to do ORM -- I call it Shades. Following the
> > > wicket
> > > > style,Shades works without any XML configuration.
> > > >
> > > > Rather than make this any longer-winded, I thought
> > > I
> > > > would just begin passing back some code, showing
> > > the
> > > > Library sample application using Shades. The
> > > attached
> > > > zipfile is just the "library" folder from the
> > > wicket
> > > > sample applications. EditBook.java and
> > > > LibrarySession.java have been altered to use
> > > Shades
> > > > for database access. LibraryORMDictionary.java is
> > > the
> > > > only new file required.
> > > >
> > > > Please let me know what you think. Also, I do not
> > > have
> > > > a website for Shades yet but I hope to find the
> > > right
> > > > venue for open sourcing the code soon. (see
> > > attached
> > > > zip file 'library.zippo' with library-example
> > > directory)
> > > >
> > > >
> > >
> >
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