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From cbeams <cbe...@gmail.com>
Subject Re: JDO 2.1 specification draft can be reviewed...
Date Sat, 04 Aug 2007 22:26:11 GMT

Good question, Michelle.  My first interpretation when reading that  
paragraph is that it would be your latter option, where XML can be  
'mixed in' with annotations, overriding any that already exist on an  
individual basis.  As a user, I would expect this.  It is especially  
important when considering separating out ORM-specific metadata into  
XML.  For example, I would want to be able to specify *what* is  
persistent in annotations, and *how*/*where* it is persisted in XML.

Speaking from my current experience with using 2.1 annotations in a  
large code base, we're putting everything, including ORM metadata in  
annotations.  This is largely to keep things simple.  It's much  
easier for the uninitiated to deal with all the metadata being in  
annotations in the classes they care about than having to know about,  
track down, and understand the package.jdo XML.   However, I can see  
a day coming when we will need to deploy all or part of the code base  
against multiple, somewhat differing data models, and it would be  
nice to be able to override the hard-coded ORM annotations in XML.   
Hopefully that doesn't make for an implementation nightmare :-)

At any rate, thanks for bringing this up.  It'll be nice to have the  
spec be particular on this topic, one way or the other.

- Chris Beams

On Aug 4, 2007, at 2:02 PM, Michelle Caisse wrote:

> Hi Craig,
> Chapter 19 says: "If xml metadata is defined for annotated classes,  
> fields, or properties, xml metadata overrides the annotation." I  
> think there needs to be further discussion about what level the  
> override happens on. Are all of the annotations in the class  
> automatically overriden if there is xml for the class, does the  
> override happen only for annotations for which there is a  
> corresponding xml element, ...?
> -- Michelle
> Craig L Russell wrote:
>> at http://db.apache.org/jdo/documentation.html
>> Check it out, and send comments...
>> 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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