On 20/02/2006, at 12:17 PM, Andrus Adamchik wrote:
> On Feb 19, 2006, at 9:38 PM, Ashley Aitken wrote:
>
>> This is a very interesting direction for Cayenne and I wish you
>> all well.
>
> For now we are building a JPA facade. We'll see if that's going to
> become a "direction" ;-) The spec is rather narrow in scope,
> concentrating on object *relational* mapping. Cayenne does more
> than that.
Sure, I understand. I guess session management, transactions etc.
are out of scope.
>> 1. Do you see the Cayenne Developer GUI tool being able to be
>> used with JPA
>
> Absolutely. Although I have no concrete strategy regarding the
> Modeler and JPA, I don't see the Modeler going away. Also with
> CAY-455 we'll have a translator between Cayenne and JPA mapping
> formats - a good start for integrating with the Modeler.
That's great. I don't think the "Java world" really gets how much
easier a modelling tool can make this stuff (at least for me, it's
easier to think about a mapping within a modelling tool).
>> 2. I thought JPA required POJO persistence? Doesn't Cayenne
>> require inheritance from a base class ...
>
> Not a problem for two reasons:
>
> 1. JPA defines ClassTransformer interface for runtime class
> enhancement JDO-style. So we can make a DataObject out of a POJO
> when we want.
I'm (definitely) not an expert, and I don't know for sure, but I
don't believe JDO implementations used run-time enhancements to add
inheritance. I thought they were still mostly reflection-based but
with enhancements to help detect dirty objects etc.
How would "adding inheritance and code" at run-time work if the POJO
already inherits from other (non-persistent classes)? I guess you
could walk the hierarchy but wouldn't that change the non-persistent
classes? Again, I am not sure, but it seems problematic to use
inheritance.
> 2. Latest 1.2 milestones more and more rely on the new
> org.objectstyle.cayenne.property.ClassDescriptor interface, making
> common superclass less crucial. If we have to get rid of it, we can
> probably do it now.
Now that approach would obviously work, but I would think it would be
a big (good) change for Cayenne.
-- Ashley Aitken Perth, Western Australia mrhatken at mac dot com Skype Name: MrHatken (GMT + 8 Hours!)
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