Chip,
I think we are in violent agreement. My understanding is that future EJB
specs will tighten down CMP w/regard to dependent objects.
Also there is a new group rising from the ashes of ODMG which address object
persistence services (both OR mapping and ODBMS). A future where EJB layers
on top of a standard Java object persistence specification is likely.
Regards,
-Chris.
> -----Original Message-----
> From: Chip Wilson [SMTP:[EMAIL PROTECTED]]
> Sent: Tuesday, December 14, 1999 9:09 AM
> To: [EMAIL PROTECTED]
> Subject: Re: Persisting Dependant Data
>
> Hi Chris,
>
> I agree that there is no standard way to implement CMP. I'm not convinced
> that
> the spec should specify a standard way to accomplish this. This seems to
> me to
> be an area for product differentiation in the functionality dimension.
>
> The flexibility Tom didn't want to lose was not the ability to change
> application servers, but rather the ability to change datasources without
> impacting his entity bean code. I think a good CMP implementation, even
> if
> proprietary, could offer this kind of flexibility, arguably making it
> superior
> to BMP with regard to this one feature.
>
> On the other hand, it doesn't seem hard to implement a BMP framework that
> would
> allow you to change datasources without affecting the entity beans, so I
> could
> make the case that a good BMP implementation could offer this flexibility
> as
> well.
>
> In an exchange I had with Tom off the list, we discussed this further and
> I
> encouraged him, as I do everyone, to implement entity beans using BMP
> until
> better implementations of CMP are available. If an app server provided
> all of
> the complex mappings necessary to map a domain model to a relational
> database, I
> would not rule out CMP merely because it was proprietary and non-portable
> to
> other app servers.
>
> I would think that the most we could hope for from future specs would be a
> portable way of specifying the meta data for mapping the domain objects to
> a
> given dB schema.
>
> --Chip
>
> Chris Raber wrote:
>
> > Chip,
> >
> > I agree with your sentiment. However, there is no standard way for a CMP
> > implementation to provide the functionality you suggest (the spec
> doesn't
> > deal with this), so you are no better off using a CMP implementation
> than
> > using BMP and an OR tool.
> >
> > -Chris.
> >
> >
> > > The flexibility you gained came from using CMP. The fact that you had
> to
> > > hand-code the persistence of dependant objects came from using a poor
> > > implementation of CMP.
>
> Original Post:
>
> >
> > > > What i have been doing thus far is
> > > > adding the persistence code to the entity bean and let it control
> the
> > > > dependant object. Is this the right way of doing things?
> > > >
> > > > The thing that i don't like about that approach is that the Order
> bean
> > > has
> > > > the flexibility of having its data source changed without impact to
> the
> > > > component. If the component now contains hand coded persistance
> code, it
> > > > then become unportable. I would be very keen on knowing how is the
> best
> > > way
> > > > to approach this common problem.
> > > >
> > > > thanks in advance.
> > > > Tom << File: Card for Chip Wilson >>
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