JDO vs JPA for Java on Google App Engine

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+18 Q:

JDO vs JPA for Java on Google App Engine

I want to develop my project on Google App Engine with Struts2. For the database I have two options JPA and JDO. Will you guys please suggest me on it? Both are new for me and I need to learn them. So I will be focused on one after your replies.

Thanks.

+14 A:

JPA is Sun's standard for persistence, JDO is IMHO dying (actually, it's dead but still moving). In other words, JPA seems to be a better investment on the long term. So I guess I'd choose JPA if both were new to me.

Pascal Thivent 2009-09-13 17:20:09

+1 I agree with that opinion.

KLE 2009-09-13 19:53:02

JDO is not dying, and is targetted at a different audience. Please do check your facts. JDO has had JDO 2.1, JDO 2.2 and now JDO 2.3. JDO is datastore independent. JPA is targetted solely for RDBMS. Fact

DataNucleus 2009-09-14 16:59:06

Well, I don't think we can say that JDO adoption is a success, no matter how much versions there are. Open your eyes, JDO could have billions of versions, nobody is using it anyway (and please, don't tell me JDO will reborn thanks to GAE). Then, if JPA is targeted solely for RDBMS, explain me why we can use this API with Google's BigTable? Thanks.

Pascal Thivent 2009-09-14 17:22:14

As JPA is backed by SUN. So for its standardization, I decided to go for it. I wonder why GAE put people to think between JDO and JPA. A religious matter it could be.

Tahir Akram 2009-12-05 18:25:47

+10 A:

The GAE/J google group has several posts about this very thing. I'd do a search on there and look at people's opinions. You will get a very different message to the opinions expressed above. Also focus on the fact that BigTable is not an RDBMS. Use the right tool for the job

DataNucleus 2009-09-14 17:01:08

Why does the Google App Engine supports JPA for its BigTable datastore using the datanucleus-appengine plugin (quoting http://www.datanucleus.org/products/accessplatform/appengine/support.html) if it's a total mistake? Can you elaborate on this?

Pascal Thivent 2009-09-14 17:15:56

JPA support on non-RDBMS datastores involves making compromises on the API and query language. Many things don't fit so aren't supported since they are RDBMS-specific (significant parts of JPQL for example, or many JPA annotations, etc). Consequently you cannot have full portability across datastores, and so any argument for using JPA on BigTable being a straight copy across for what you'd use for an RDBMS store is false.

DataNucleus 2009-09-14 17:23:52

For JDO on the other hand the query language (JDOQL) has no RDBMS-specific components, and metadata is database neutral on the whole with RDBMS-specific components separated out cleanly. Consequently you do have portability between datastores. The JDO API allows use of a native query language for each datastore where required.

DataNucleus 2009-09-14 17:25:50

I never said that you can use the full JPA API but, to me, this won't prevent you from reusing your JPA knowledge so it's just not a valid reason for not using JPA. And BTW, portability accross datastores **doesn't happen in real life**.

Pascal Thivent 2009-09-14 17:30:46

Whatever I say you're not going to agree so it is pointless the discussion, nor necessary of bold type. Yes portability across datastores does happen since I've got clients doing just that. As always people should decide things for themselves based on their project needs, which is what we say in the DataNucleus docs. --Andy (DataNucleus)

DataNucleus 2009-09-14 17:32:43

Andy, could you give an example or 2 of BigTable features that are not available with JPA? Even example of the feature that is possible with JPA but awkwardly would work...

grigory 2009-09-16 16:18:07

Use of JDO is so demotivating and depressing. In Stargate Atlantis there was a scene of Gen Oneil whacking golf balls into the ocean and I am imagining JDO as those golf balls.

Blessed Geek 2010-01-14 00:21:23

Always nice when someone comes in with an intelligent comment with a nice coherent argument :-) So nothing to say then. ok

DataNucleus 2010-01-14 08:17:58

I love how with GAE/J you can't use @Id as primary keys if you want to persist multiple different objects in a single transaction - you have to use Google's non-portable @Key instead.

Chris Kaminski 2010-07-28 15:26:25

+7 A:

Just saw this comparison between JPA and JDO by DataNucleus themselves:- http://www.datanucleus.org/products/accessplatform/jdo%5Fjpa%5Ffaq.html An eye-opener.

Vinod 2009-10-13 12:59:04

This Datanucleus' manifesto seems to be very pro-JDO. All their statements seem critical of JPA and defensive of JDO and yet I find using JPA a happier activity than using JDO.

Blessed Geek 2010-01-14 00:38:41

DataNucleus supports both JDO and JPA, and we actually just included most of JPA2 in DN 2.0. We promote both, unlike all other persistence solutions, and let users choose. If you think there are factual errors in any coverage of JDO or JPA we would welcome your input. If part of a political agenda on your behalf then you're best advised to keep your feelings to yourself

DataNucleus 2010-01-16 10:08:38

http://google.com/trends?q=jdo,+jpa

matt b 2010-03-31 15:05:53

Try EclipseLink. It's the upcoming JPA 2.0's reference implementation.

Zoltan 2009-10-13 13:01:16

How can you try EclipseLink when the poster asked about GAE/J ? EclipseLInk supports persistence to RDBMS. This is not an RDBMS

DataNucleus 2010-01-16 09:49:36

+5 A:

I'm a happy user of JDO. Keep up the good work guys.

Manfred 2010-01-28 17:06:58

+1 A:

JPA is the way to go as it seems to be pushed as a standardized API and has recently got momentum in EJB3.0.. JDO seems to have lost the steam.

prateek mathur 2010-06-05 09:30:46

+2 A:

Go JDO. Even if you don't have experience in it, it is not hard to pick up, and you will have a new skill under your belt!

corydoras 2010-07-15 00:33:48

+2 A:

GAE/J is slated to add MYSQL before the end of the year.

Peace, Scott

stanlick 2010-08-18 16:30:36

Do you have a source for this?

Taylor Leese 2010-08-18 16:55:05

Downvoted because I don't think this is true, can't find any info online to support it, and there's no evidence provided with the post.

Steve Armstrong 2010-09-01 15:26:36

The roadmap mentions a full featured SQL database is in the works http://code.google.com/appengine/business/roadmap.html

Ashwin Prabhu 2010-09-17 12:56:06

ansaurus

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JDO vs JPA for Java on Google App Engine

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