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From Craig L Russell <Craig.Russ...@Sun.COM>
Subject Re: JDO TCK Conference Call Friday, June 16, 9 am PST
Date Sun, 18 Jun 2006 20:49:47 GMT
Hi Andy,

On Jun 18, 2006, at 10:59 AM, Andy Jefferson wrote:

>> We need more documentation to make JDO more accessible.
>> One option is to use EJB3 annotations for metadata. JPOX.
>
>> The JPOX community is looking for more members, and so is
>> the Apache JDO project. We need to brainstorm how to get
>> the two communities to work closer together.
>
> Hi,
>
> whilst implementing annotations for JPOX I find that I need to  
> implement some of
> my own to map those JDO2 attributes that JPA1 doesnt have :-). Only  
> covered the
> class-level annotations so far but I have
> detachable
> requires-extent
> identity-type
>
> I've implemented these as JPOX annotations, but it would make sense  
> (to me) to
> have these as part of Apache JDO (in some way). Clearly this would  
> open up the
> issue of annotations in JDO. To quote from the JDO2 spec
> <spec>
> Metadata annotations for persistence are being developed in JSR  
> 220. When that speci-
> fication is final, an update to the JDO specification to specify  
> support for the
> annota-
> tions will be made.
> </spec>
> We're at this point aren't we ? ;-)

Yes, we are. With both 243 and 220 approved, we have achieved the  
milestone called out here.

>  Is there any interest in standardising these
> in a JDK1.5 part of Apache JDO (since the spec already defines what  
> the
> attributes are, and its just a case of having an associated  
> annotation for them,
> and using the JPA annotation where there is one).

We should have a discussion about how to add JDK 1.5 support to JDO  
2.0.1. I'd like consensus on how we do the following:

1. Add annotations to persistence capable classes. I think there are  
at least three alternatives here:

1a. Use the 220 annotations including the package names and add JDO- 
specific annotations to them.

1b. Use just the 220 annotation names but repackage them from  
javax.persistence to javax.jdo.annotations or something similar. This  
would give us the opportunity (and the danger) of redefining the  
semantics of some of the annotations without conflicting with the 220  
spec. For example, we could redefine the default behavior of fetching  
relationship fields from eager to lazy, which cannot be done with 1a.

1c. Completely redefine annotations to align completely with JDO xml  
metadata. With this approach, you would not be able to take advantage  
of tools that generate 220 annotations.

2. Add support for enums and highly concurrent collections.

3. Change signatures of interface methods to be 1.5 friendly. For  
example, the signatures of the makePersistent methods should be  
changed to:

<T> T makePersistent(T pc);
<T> Collection<T> makePersistent(Collection<T> pcs);
<T> T[ ] makePersistent(T[ ] pcs);

4. Distribute multiple jar files that represent the 1.5 interfaces.  
The interfaces that are 1.5-specific cannot be packaged in a jar file  
with the 1.3 declarations of the interfaces. Right now, the jar is  
named:
javax.jdo/jars/jdo2-api-2.0.jar. What needs to change for 1.5?  
Perhaps javax.jdo/jars/jdo2-1.5-api-2.0.1.jar would work.

> The other issue is whether
> OpenJPA has already done this - but then thats also a part of  
> Apache so you'll be
> more familiar with that than me :-)

There is nothing yet checked into the OpenJPA repository that would  
inform our decision here.

Craig

>
> Comments?
>
> --
> Andy
>

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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