Hi Craig,
I was already afraid that "create a persistent instance" might only
apply to the PM cache, not the datastore (but only after second read).
However, would you say that JPOX is not JDO2 compliant if it created
missing instances in the datastore anyway? Will there be a test in the
TCK2 that expects an exception to be thrown if a detached instances does
not exist in the datastore?
And, most of all, what sense would it make to forbid the creation of
missing detached instances in the datastore? There is lots of
application for that behaviour, and at least I don't know of any problem
with it.
Regards,
Jörg
Craig L Russell schrieb:
Hi Jörg,
On Mar 9, 2006, at 1:43 AM, Jörg von Frantzius wrote:
Craig L Russell schrieb:
Also I find it confusing that the method most prominently used for
inserting new objects shouldn't do so for detached instances.
There is a bunch of history that you should look at, most of which
is in the jdo-dev archives. Bottom line, we used to have a different
API, attachCopy, but we looked at what it had to do for transient
and detached instances and decided that it wasn't worth making a
different API for attaching detached instances.
That particular behaviour of attachCopy() wasn't really specified,
but it was pleasant JPOX-specific behaviour, if I remember correctly.
I saw the discussion and I didn't see where inserting the instances
would be forbidden by the spec, and still I don't see where it says
that, especially in the light of 12.6.7. Please excuse my ignorance,
where does it say that?
<spec>
These methods make transient instances persistent and apply detached
instance changes
to the cache.
...
For a detached instance, they locate or create a persistent
instance with the same JDO identity as the detached instance, and
merge the persistent
state of the detached instance into the persistent instance. Only the
state of persistent fields
is merged.
</spec>
This means that if there is already a persistent instance in the cache
with the same object id as the detached instance, the detached state
will be merged. If there is not a persistent instance in the cache, a
cache instance is created and the detached state is merged with the
persistent instance.
But there is no creation aspect of makePersistent on a detached instance.
Craig
Regards,
Craig
Craig
On Mar 8, 2006, at 7:14 AM, Erik Bengtson wrote:
Hi,
What happens when we invoke makePersistent on a detached instance
that was
deleted by another isolated process? I suspect that we raise an
exception
instead of reinserting it for a second time. Is that right?
Maybe this can be clarified in the spec.
Regards,
Craig Russell
Architect, Sun Java Enterprise System
http://java.sun.com/products/jdo
408 276-5638 mailto:[EMAIL PROTECTED]
P.S. A good JDO? O, Gasp!
Craig Russell
Architect, Sun Java Enterprise System http://java.sun.com/products/jdo
408 276-5638 mailto:[EMAIL PROTECTED]
P.S. A good JDO? O, Gasp!
Craig Russell
Architect, Sun Java Enterprise System http://java.sun.com/products/jdo
408 276-5638 mailto:[EMAIL PROTECTED]
P.S. A good JDO? O, Gasp!
