Craig L Russell schrieb:
Hi Jörg,
It seems we have these alternatives:
[ ] 1. Remove attribute dependent-element from element collection and
element array and use attribute dependent on element field to describe
this.
[ ] 2. Disallow use of attribute dependent on element field for
collection and array type fields (throw an exception if the user
specifies a value for the attribute dependent).
[ ] 3. Allow use of attribute dependent-element in element collection
and element array and allow use of attribute dependent on element
field but require that they not both be specified.
[ ] 4. Allow use of attribute dependent-element in element collection
and element array and allow use of attribute dependent on element
field but require that if they are both specified, they be the same
value.
[ ] 5. Ignore use of attribute dependent on element field for
collection and array type fields.
If you have a strong preference please vote. My favorite is
2. This makes it clear where the dependency needs to be declared. The
only issue that I can see is for object databases where the field
level dependent actually does refer to the collection itself. But I
cannot see that there is a need to allow non-dependent collection
instances of dependent references.
I second number 2. Also because we still have dependent-key and
dependent-value to be declared somewhere for map fields, and I find it
good to have that declared in the same manner as for collection and
array fields. I find throwing of an exception also better than just
issuing warnings that can get lost among other output, as a simple
mistake can lead to loss of data here.
Craig
On Jan 27, 2006, at 7:30 AM, Jörg von Frantzius wrote:
Please see my comments below on how JPOX will treat dependent vs.
element-dependent on collection fields. Please reply if you have
objections!
Craig L Russell schrieb:
Hi Jörg,
On Nov 3, 2005, at 1:49 AM, Jörg von Frantzius wrote:
Hello,
the specification currently is somewhat confusing where it defines
the meta-data attributes "dependent" and "element-dependent".
Concerning "dependent" it says:
"The dependent attribute indicates that the field contains a
reference that is to be deleted
The reference is the object that is referenced by the field. I'll
try to clarify this in the spec.
from the datastore if the referring instance in which the field is
declared is deleted, or if the
referring field is nullified."
Now does that mean that really the *reference* is to be deleted
(which seems kinda natural to me), or rather the object being
referred to? Probably the latter?
Yes.
For collection fields, there is the additional "dependent-element"
attribute of the "collection" tag. Wouldn't it be enough to have
"dependent" on the field level?
We try to make the field metadata refer to behavior of the field
itself, and put the behavior of multi-valued field types (array,
collection, map) in separate metadata to better match the semantics
of Collection versus Element.
We could make it illegal to specify dependent on field types of
array, collection, and map...
Or what does it mean if the user specifies 'dependent="false"' with
nested 'element-dependent="true"', or vice-versa?
See above.
JPOX will ignore any "dependent" attribute setting on Collection
fields, so only the "element-dependent" attribute will be of meaning
for Collection fields.
Experts, any opinion on this subject?
Craig
Thanks for any explanations,
Jörg
--__________________________________________________________
Dipl.-Inf. Jörg von Frantzius | artnology GmbH
| Milastr. 4
Tel +49 (0)30 4435 099 26 | 10437 Berlin
Fax +49 (0)30 4435 099 99 | http://www.artnology.com
_______________________________|__________________________
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!
--__________________________________________________________
Dipl.-Inf. Jörg von Frantzius | artnology GmbH
| Milastr. 4
Tel +49 (0)30 4435 099 26 | 10437 Berlin
Fax +49 (0)30 4435 099 99 | http://www.artnology.com
_______________________________|__________________________
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!
--
__________________________________________________________
Dipl.-Inf. Jörg von Frantzius | artnology GmbH
| Milastr. 4
Tel +49 (0)30 4435 099 26 | 10437 Berlin
Fax +49 (0)30 4435 099 99 | http://www.artnology.com
_______________________________|__________________________
