Mike,
This is not what the spec says in section "2.1.5 Embeddable Classes":
"The access type for an embedded object is
determined by the access type of the entity in which it is embedded."
There is nothing else in the spec that states otherwise (I searched
for embeddable), so the only option to support a mixed access type
correctly will be to introduce a product-specific annotation which
will make it absolutely clear that a developer uses a product-specific
feature.
thanks,
-marina
Mike Keith wrote On 08/09/06 12:23,:
> Right. The combination of access types is undefined,
> but an embeddable and an entity are two separate
> classes and putting annotations on an embedded object
> has nothing to do with combining access types with the
> entity. They are completely separate objects and do not
> share, merge or combine persistent state.
>
> We actually did have technical reasons for not supporting
> different access types in inheritance hierarchies, and this
> was the reason why the limitation exists. The confusion factor
> went up significantly when we tried to define the rules for
> how field and property mappings were defaulted in an entity
> hierarchy with and without mapped superclasses.
>
> I agree that in the next release we will need to clarify.
> I also do not want to alienate features that make perfect sense
> and are essentially just miswordings of the spec. Non-portability
> is one thing, making them appear wrong is another.
>
> -Mike
>
>
>>-----Original Message-----
>>From: Linda.Demichiel_at_Sun.COM
>>[mailto:Linda.Demichiel_at_Sun.COM]On Behalf
>>Of Linda DeMichiel
>>Sent: Wednesday, August 09, 2006 2:23 PM
>>To: Mike Keith
>>Cc: Sanjeeb Kumar Sahoo; persistence_at_glassfish.dev.java.net
>>Subject: Re: code review for issue #831
>>
>>
>>
>>The spec is very consistent in treating the combination of
>>access types as undefined. The fact that it *could* work
>>does not make it any less undefined, or the spec any more
>>or less 'incorrect'. We didn't have any technical reasons
>>for not supporting different access types in mapped superclasses
>>either.
>>
>>At any rate, I do think we should look at clarifying this
>>in a future release, systematically with the other cases
>>for which more flexibility makes sense.
>>
>>Linda
>>
>>
>>Mike Keith wrote:
>>
>>
>>>The section in 2.1.1 applies to entity/class hierarchies and not
>>>really to embeddables. There is no technical reason to disallow
>>>an embeddable having a different access type from its owning entity
>>>since there is no conflict between it and the owning class
>>>(like there is in entity hierarchies where fields/properties are
>>>inherited). The problem was in the wording of that one line that
>>>discusses how the access type should be defined for an embeddable
>>>in the absence of metadata (since there is no PK and hence no
>>>requirement for there to be any metadata at all).
>>>
>>>Sahoo once asked me whether something like the following code
>>>would work:
>>>
>>>@Entity class Building {
>>> @Id int id;
>>> @Embedded Address address;
>>>}
>>>@Entity class Person {
>>> @Id int getId() { ... }
>>> @Embedded public Address getAddress() { ... }
>>> ...
>>>}
>>>@Embeddable class Address {
>>> String street;
>>> String city;
>>> String getStreet() { ... };
>>> String getCity() { ... };
>>> ...
>>>}
>>>
>>>The answer that I gave was that it would work fine and that
>>>to map the column names, etc, @AttributeOverride annotations
>>>should be used on the entities.
>>>
>>>The example should be able to work just as well, though, if the
>>>address were annotated, as in:
>>>
>>>@Embeddable class Address {
>>> @Column(name="STR")
>>> String street;
>>> String city;
>>> ...
>>>}
>>>
>>>This would simply mean that the embedded object is just being
>>>accessed using field access, which neither concerns nor affects
>>>the owning entity. In reality I can't even think of a really good
>>>use case for overriding the access type of an embedded
>>
>>object to match
>>
>>>the entity that happens to be pointing to it.
>>>
>>>The *only* reason why the above example might not be permitted is
>>>because of the one incorrectly worded line in the spec that
>>
>>I pointed
>>
>>>out. As it is there does not need to be any vendor-specific
>>
>>annotations,
>>
>>>since just annotating the class is the obvious way to do this.
>>>
>>>-Mike
>>>
>>>
>>>
>>>>-----Original Message-----
>>>>From: Linda.Demichiel_at_Sun.COM
>>>>[mailto:Linda.Demichiel_at_Sun.COM]On Behalf
>>>>Of Linda DeMichiel
>>>>Sent: Wednesday, August 09, 2006 12:13 AM
>>>>To: Sanjeeb Kumar Sahoo
>>>>Cc: Mike Keith; persistence_at_glassfish.dev.java.net
>>>>Subject: Re: code review for issue #831
>>>>
>>>>
>>>>Sahoo,
>>>>
>>>>I agree with your assessment in your earlier email.
>>>>As stated in section 2.1.5, the access type for an embedded
>>>>object is determined by the access type of the entity in which
>>>>it is embedded, and as stated in section 2.1.1, the behavior
>>>>is unspecified if mapping annotations are applied to both
>>>>persistent fields and properties or if the XML descriptor
>>>>specifies use of different access types within a class hierarchy.
>>>>Specifying a different access type in an embeddable class than
>>>>in the entity which embeds it is undefined, and the verifier
>>>>should flag this case. Defined behavior exists only for the
>>>>case where a single access type applies for an entire entity
>>>>hierarchy.
>>>>
>>>>In the next rev of the spec, we can look at whether or not
>>>>we should define annotations on embeddables that imply a
>>>>different access type to be 'overriding' (and if so, whether
>>>>for the embedded class as a whole or for a specific field
>>>>or property). If we do so, we should do this more generally
>>>>(i.e., also handle the cases of subclasses defining different
>>>>access types as well).
>>>>
>>>>In the mean time, if it is important to support a vendor-specific
>>>>mixing of access types, we should use a product-specific annotation
>>>>for that purpose.
>>>>
>>>>-Linda
>>>>
>>>>
>>>>
>>>>Sanjeeb Kumar Sahoo wrote:
>>>>
>>>>
>>>>
>>>>>Mike,
>>>>>
>>>>>If that was the intent, then why should an application be
>>>>
>>>>non-portable
>>>>
>>>>
>>>>>if it uses different access-type in the embeddable? Or are we also
>>>>>missing a line like this in that same section of the spec:
>>>>
>>>>/a portable
>>>>
>>>>
>>>>>app should not use access-type that is different from the enclosing
>>>>>entity class./
>>>>>
>>>>>More over, were similar lines missing for MappedSuperclass?
>>>>
>>>>How about
>>>>
>>>>
>>>>>mixed access-type in an entity hierarchy?
>>>>>
>>>>>Thanks,
>>>>>Sahoo
>>>>>Mike Keith wrote:
>>>>>
>>>>>
>>>>>
>>>>>>// /When there is no metadata specified for an embedded
>>
>>object, the
>>
>>>>>>access type for an embedded object *is* determined by the
>>>>
>>>>access type
>>>>
>>>>
>>>>>>of the entity in which it is embedded./
>>>>>>
>>>>>> -----Original Message-----
>>>>>> *From:* Mike Keith [mailto:michael.keith_at_oracle.com]
>>>>>> *Sent:* Tuesday, August 08, 2006 1:45 PM
>>>>>> *To:* Sanjeeb Kumar Sahoo; persistence_at_glassfish.dev.java.net;
>>>>>> Linda DeMichiel
>>>>>> *Subject:* RE: code review for issue #831
>>>>>>
>>>>>> The intent was never to disallow a vendor form doing
>>>>
>>>>so on their
>>>>
>>>>
>>>>>> own. Our wording in the first section might have
>>>>>> been better stated as:
>>>>>>
>>>>>> -----Original Message-----
>>>>>> *From:* Sanjeeb.Sahoo_at_Sun.COM
>>>>>> [mailto:Sanjeeb.Sahoo_at_Sun.COM]*On Behalf Of
>>>>
>>>>*Sanjeeb Kumar Sahoo
>>>>
>>>>
>>>>>> *Sent:* Tuesday, August 08, 2006 1:27 PM
>>>>>> *To:* persistence_at_glassfish.dev.java.net; Mike
>>
>>Keith; Linda
>>
>>>>>> DeMichiel
>>>>>> *Subject:* Re: code review for issue #831
>>>>>>
>>>>>> Hi Gordon,
>>>>>>
>>>>>> Thanks for reviewing. Are there any other comments?
>>>>>>
>>>>>> I totally agree with you that an embeddable should
>>>>
>>>>be allowed
>>>>
>>>>
>>>>>> to have its own access-type and that would have given more
>>>>>> options to the user, but unfortunately, the expert group
>>>>>> ignored this point when it was raised. More over,
>>>>
>>>>the spec is
>>>>
>>>>
>>>>>> *very very* confusing on this subject. In 2.1.5, it says:
>>>>>> /The access type for an embedded object *is*
>>>>
>>>>determined by the
>>>>
>>>>
>>>>>> access type of the entity in which it is embedded./
>>>>>> (Note, it says *is determined by* as opposed to *can be
>>>>>> determined*.). Yet, *orm_1_0.xsd* allows an
>>>>
>>>>access-type to be
>>>>
>>>>
>>>>>> specified for an embeddable, there by *contradicting* the
>>>>>> previous rule. Moreover, only non-portable
>>
>>applications can
>>
>>>>>> have different access-type for an embeddable as
>>>>
>>>>the spec says
>>>>
>>>>
>>>>>> the following in section #10.1.5.2:
>>>>>> /Portable applications must not specify the access
>>>>
>>>>attribute
>>>>
>>>>
>>>>>> if mapping annotations have been applied
>>>>>> to the fields or properties of the embeddable class or the
>>>>>> entity with which it is associated and the value
>>>>>> differs from the access type defined by means of
>>>>
>>>>annotations.
>>>>
>>>>
>>>>>> Portable applications must not use more than one
>>>>
>>>>access type
>>>>
>>>>
>>>>>> within an entity hierarchy.
>>>>>> /
>>>>>> So, until it is officially clarified in the spec,
>>>>
>>>>I think, we
>>>>
>>>>
>>>>>> *must not* use annotations in embeddable class to
>>
>>determine
>>
>>>>>> access-type. I am also not in favor of allowing
>>>>
>>>>access-type of
>>>>
>>>>
>>>>>> an embeddable to be overridden in orm.xml unless
>>
>>we support
>>
>>>>>> the same extension for MappedSuperclass. Are you
>>>>
>>>>proposing to
>>>>
>>>>
>>>>>> support this for MappedSuperclass as well? Looking at the
>>>>>> code, I think, supporting this for
>>
>>MappedSuperclass will be
>>
>>>>>> tougher than that for Embeddable.
>>>>>>
>>>>>> Thanks,
>>>>>> Sahoo
>>>>>>
>>>>>> Gordon Yorke wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>>> Hello Sahoo,
>>>>>>> I have reviewed your code and have a suggestion. The
>>>>>>>Access Type of the Embeddable should still be determined based on
>>>>>>>annotations or XML (XML can define access type directly). This
>>>>>>>allows users to specify the access type of the
>>
>>Embeddable. If the
>>
>>>>>>>access type is not available from the Embeddable then use
>>>>
>>>>the access
>>>>
>>>>
>>>>>>>type of the parent. The specification states that the
>>
>>access type
>>
>>>>>>>can be 'determined' from that of the parent but is not
>>>>
>>>>mandated to be
>>>>
>>>>
>>>>>>>that of the parent( Mike, is that not the intention of the
>>>>>>>specification?) This would give users much more flexibility for
>>>>>>>sharing Embeddables.
>>>>>>> Also based on how TopLink treats Embeddable
>>
>>mappings we
>>
>>>>>>>could, in the future, support a different access type for
>>>>
>>>>each target
>>>>
>>>>
>>>>>>>of an Embeddable mapping if the AccesType of the
>>>>
>>>>Embeddable was not
>>>>
>>>>
>>>>>>>supplied by the user.
>>>>>>> --Gordon
>>>>>>>
>>>>>>> -----Original Message-----
>>>>>>> From: Sanjeeb.Sahoo_at_Sun.COM
>>>>
>>>>[mailto:Sanjeeb.Sahoo_at_Sun.COM]On
>>>>
>>>>
>>>>>>>Behalf Of
>>>>>>> Sanjeeb Kumar Sahoo
>>>>>>> Sent: Monday, August 07, 2006 9:00 AM
>>>>>>> To: Tom Ware
>>>>>>> Cc: persistence_at_glassfish.dev.java.net
>>>>>>> Subject: code review for issue #831
>>>>>>>
>>>>>>>
>>>>>>> Hi Tom,
>>>>>>>
>>>>>>> Attached here with the suggested fix for
>>>>>>>
>>>>
>>>>https://glassfish.dev.java.net/issues/show_bug.cgi?id=831 .
>>>>
>>>>
>>>>>>> The jar file contains modified sources in new folder,
>>>>>>>original sources
>>>>>>> in orig folder and differences in diffs folder.
>>>>>>> Please review them. I have update issue tracker with the
>>>>>>>details.
>>>>>>>
>>>>>>> Tests run:
>>>>>>> entity-persistence-tests(all of them passed)
>>>>>>> JPA TCK v1.0: 3 tests failed but they fail on a clean
>>>>>>>workspace as well
>>>>>>> (Yes, I have run those 3 tests in a clean
>>>>
>>>>workspace and they
>>>>
>>>>
>>>>>>>failed).
>>>>>>> So, my changes are not causing those failures.
>>>>>>>
>>>>>>> Appreciate a quick reply.
>>>>>>>
>>>>>>> Thanks,
>>>>>>> Sahoo
>>>>>>>
>>>>>>>
>>>>>>
>>>>>>