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From David Jordan <davej...@bellsouth.net>
Subject Re: The Future of JDO
Date Fri, 06 Oct 2006 21:22:47 GMT

But suppose a large percentage of the JPA implementations also  
provided JDO support...
Suppose all 15 JDO implementations also started supporting JPA,  
therefore the market would have 15 or so JPA implementations. You  
probably would not see too many new JPA implementations, new vendors  
that had not supported JDO. With 15 JPA implementations out there,  
potential new JPA vendors would decide there were more than enough  
JPA implementations available, they would not pursue it.
If 90% of those JPA vendors also supported JDO, and JDO had a truly  
transparent superset API over JPA, then JDO would be positioned quite  
well....    Just a thought...


On Oct 6, 2006, at 11:03 AM, Ilan Kirsh wrote:

> Hi Eric,
>
> No doubt that currently most people are using Hibernate and using  
> its old
> API. A visit in Hibernate forums can also confirm this (compare the  
> traffic
> in the main forum to the traffic in the EJB3 forum). However, this  
> might be
> because JPA is still young and many people are working on existing  
> systems.
> An happy user do not look for changes. Therefore, the results of  
> your survey
> also make sense. I also feel that current ObjectDB users are happy  
> with the
> JDO API and will not switch to anything else.
>
> However, we should try to look what happens in new projects. If I  
> had to
> start a new project using Hibernate, I would probably be using the  
> JPA API
> (where possible) to remain unlocked to Hibernate. Many people take  
> this
> exact decision these days. This is today when there are 3 JPA
> implementations. I believe that in a short time (1-2 years) there  
> may be
> 8-10 JPA implementations and then such a decision will be almost a  
> must.
>
> You write that you see a real value in going in this direction. I  
> agree that
> the real value is more regarding developers that do not use JDO  
> today (which
> unfortunately are the majority) rather than regarding  the current JDO
> users.
>
> Regards,
>
> Ilan
>
> ----- Original Message ----- From: "Eric Samson"  
> <eric.samson@xcalia.com>
> To: "Ilan Kirsh" <kirsh@objectdb.com>; "Andy Jefferson"  
> <andy@jpox.org>;
> <jdo-dev@db.apache.org>; "JDO Expert Group" <jdo-experts-ext@sun.com>
> Sent: Friday, October 06, 2006 4:25 PM
> Subject: RE: The Future of JDO
>
>
> Hi all
>
> When I talk to prospects, customers, journalists, etc. I always  
> introduce
> JPA as a subset of JDO, which is true in terms of concepts.
> I think there is a real value in aligning JDO on JPA where possible
> (annotations, APIs, etc.) or at least in making JPA features as  
> optional in
> JDO (QL).
>
> I agree with David when he says that JPA is not so popular and most  
> people
> still use raw proprietary Hibernate.
>
> We recently ran a survey among our users: most of them don't even  
> require us
> to support JPA, and they won't move to JPA when will support it.  
> They are
> simply happy with JDO and want us to continue to support it.
>
> Best Regards,
> ....: Eric Samson, Founder & CTO, Xcalia
> Service your Data!
>
> -----Message d'origine-----
> De : Ilan Kirsh [mailto:kirsh@objectdb.com]
> Envoyé : vendredi 6 octobre 2006 01:17
> À : Andy Jefferson; jdo-dev@db.apache.org; JDO Expert Group
> Objet : Re: The Future of JDO
>
> 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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