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From Craig L Russell <Craig.Russ...@Sun.COM>
Subject VOTE: Dependent and element-dependent
Date Mon, 30 Jan 2006 00:16:31 GMT
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.

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:Craig.Russell@sun.com
>> 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:Craig.Russell@sun.com
P.S. A good JDO? O, Gasp!


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