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From Ilan Kirsh <ki...@objectdb.com>
Subject Re: The Future of JDO
Date Fri, 06 Oct 2006 00:55:56 GMT
I found now an interesting poll at http://www.java.net/pub/pq/122. The 
results should be taken suspiciously of course, but it seems that JDO still 
has some hope as it is. However, probably by extending JPA as Hibernate and 
TopLink do it has much better chances. I agree that the big question is 
whether the effort worth it. I hope it does.

----- Original Message ----- 
From: "David Jordan" <davejrdn@bellsouth.net>
To: "Ilan Kirsh" <kirsh@objectdb.com>
Cc: "Andy Jefferson" <andy@jpox.org>; <jdo-dev@db.apache.org>; "JDO Expert 
Group" <jdo-experts-ext@sun.com>
Sent: Friday, October 06, 2006 1:32 AM
Subject: Re: The Future of JDO

> I am not at all opposed to what Andy has suggested. I guess the big 
> question is whether JDO offers enough beyond JPA that makes this  effort 
> worthwhile, versus everyone just doing JPA.
> On Oct 5, 2006, at 7:17 PM, Ilan Kirsh wrote:
>> My personal feeling after reading the JPA spec and two books on
>> EJB 3 / JPA is that JPA is not so weak. It has an excellent query
>> language and API that  is very similar to JDO (but more compact).
>> I highly recommend reading "Pro EJB 3 - Java Persistence API" /
>> Apress (despite statements such as "as a result JDO spent most of
>> its time in the persistence underground" and "the writing was on the
>> wall for JDO" - which are very natural for the two authors that work
>> for Oracle).
>> Anyway, I do think that JPA has good chances to succeed. It does
>> take time to achieve a critical mass of implementations and users but
>> it seems that JPA is on the right track. If it succeeds we should be
>> ready. Therefore, I think that Andy's list looks very good as a base
>> for JDO 2.1.
>> Ilan
>>> Totally agree. I would think of the following items
>>> 1. "persistence.xml". I see no real reason not to allow  specification 
>>> of
>>> classes to be persisted using persistence.xml as an additional way of
>>> creating the PMF.
>>> 2. Persistence API. There are not many differences between JPA and  JDO 
>>> methods
>>> so what you propose should be straightforward. Those JDO 
>>> implementations that
>>> have/are implementing JPA will know that it is simply putting a  wrapper
>>> around their existing JDO method. Why not include in 2.1?
>>> 3. Query Language. JPQL can be made available via the query  "language" 
>>> flag in
>>> the existing API (so we add "javax.jdo.query.JPQL" or something as  a 
>>> valid
>>> value). OK the JDO implementation (if supporting this language)  will 
>>> have to
>>> add a new query language but the hook is there. Could be an  optional 
>>> feature
>>> in JDO 2.1 ?
>>> 4. Types. Mandate support for Enums, Calendar when running under  Java5, 
>>> so all
>>> types that JPA supports are there. Why not include in 2.1?
>>> 5. Annotations. The donated JDO2 annotations need splitting between
>>> persistence annotations, and ORM. Looking through the JPA  annotations 
>>> some
>>> time ago, it wasn't clear that we can just take theirs and add  others 
>>> due to
>>> too many missing concepts. What the JDO(3) spec could do is  firstly 
>>> define
>>> the precedence of annotations and metadata (to match the JPA spec
>>> definition), and secondly define how JPA annotations can be used  by a 
>>> JDO3
>>> implementation. In addition provide JDO2/3 annotations to allow finer
>>> definition.
>>> -- 
>>> Andy

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