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From Todd Nine <t...@spidertracks.com>
Subject Re: Help with Cassandra JPA plugin
Date Tue, 08 Mar 2011 23:43:59 GMT
Awesome.  Thanks for the help Kevin.  I have a couple of follow up
questions.


 Allocate doesn't appear to do anything in your test custom sequence
either.  Is there any way to get the Open JPA framework to invoke it
without allocating during the "next" call? 
https://fisheye6.atlassian.com/browse/~br=trunk/openjpa/trunk/openjpa-persistence-jdbc/src/test/java/org/apache/openjpa/persistence/generationtype/CustomSeq.java?r=777135&r=757278


As per this example
https://fisheye6.atlassian.com/browse/~br=trunk/openjpa/trunk/openjpa-persistence-jdbc/src/test/java/org/apache/openjpa/persistence/generationtype/GeneratedValues.java?r=777135

We're doing the same thing.  Is it possible to register the sequence
generator we create globally with the Open JPA framework so that users
can simply use the annotations like this without the need to declare a
@SequenceGenerator?


@Id
@GeneratedValue(strategy="time-uuid")
private UUID id;


Thanks,
Todd



On Tue, 2011-03-08 at 17:21 -0600, Kevin Sutter wrote:

> Hi Todd,
> Okay, now I understand your question.  I should read more
> closely...  :-)
> 
> Looking at your code, nothing is jumping out at me as being incorrect.
> You have implemented the Seq interface, and it looks like you have
> designated the sequenceName correctly.  We have a junit test case that
> does something very similar.  This test is also testing out UUID
> generation, so that might be of interest as well.
> 
> Check this out for an example:
> https://fisheye6.atlassian.com/browse/~br=trunk/openjpa/trunk/openjpa-persistence-jdbc/src/test/java/org/apache/openjpa/persistence/generationtype/TestGeneratedValues.java?hb=true
> 
> https://fisheye6.atlassian.com/browse/~br=trunk/openjpa/trunk/openjpa-persistence-jdbc/src/test/java/org/apache/openjpa/persistence/generationtype/GeneratedValues.java?r=777135
> 
> https://fisheye6.atlassian.com/browse/~br=trunk/openjpa/trunk/openjpa-persistence-jdbc/src/test/java/org/apache/openjpa/persistence/generationtype/CustomSeq.java?r=777135&r=757278
> 
> Also, our UUID generation does lock and synchronize to protect certain
> code paths.  You'll probably need to do something similar.  Here's an
> example of our code:
> https://fisheye6.atlassian.com/browse/~br=trunk/openjpa/trunk/openjpa-lib/src/main/java/org/apache/openjpa/lib/util/UUIDGenerator.java?r=777135&r=757278&r=792592
> 
> Good luck,
> Kevin
> 
> 
> On Tue, Mar 8, 2011 at 2:46 PM, Todd Nine <todd@spidertracks.com>
> wrote:
> 
>         Hey Kevin,
>           Thanks for the reply.  To be clear, I'm not actually
>         creating a JDO plugin.  Rather I'm migrating what I've done
>         from JDO to JPA.  The demand for JPA is much greater in the
>         community, and we would prefer to use it here as well.   My
>         biggest hurdle is finding good developer documentation to
>         allow me to create the best plugin possible using open JPA.
>         If you can give me any guidance on the issues below for a JPA
>         only implementation, I would really appreciate it.
>         
>         Thanks,
>         
>         Todd
>         
>         
>         
>         
>         
>         
>         On Tue, 2011-03-08 at 13:58 -0600, Kevin Sutter wrote:
>         
>         > Some general comments...  Extending the OpenJPA kernel for
>         > JDO is definitely doable.  The original code base (BEA's
>         > Kodo) had a JDO personality, but it was never contributed to
>         > the OpenJPA project.  At least for a period of time (I don't
>         > know if it still is), BEA and then Oracle continued to
>         > support this JDO personality internally.  So, I know it's a
>         > doable endeavor...
>         > 
>         > The other bit of news is that our own Craig Russell is a bit
>         > of JDO expert...  :-)  And, he might even know a thing or
>         > two about the JDO personality.
>         > 
>         > Good luck,
>         > Kevin
>         > 
>         > On Mon, Mar 7, 2011 at 10:22 PM, Todd Nine
>         > <todd@spidertracks.com> wrote:
>         > 
>         >         Hi guys,
>         >          I've previously developed a JDO plugin for
>         >         Cassandra using
>         >         Datanucleus.  I'm now helping the datastax guys
>         >         develop the JPA plugin
>         >         using open JPA.  I'm having some trouble I would use
>         >         a hand with from
>         >         developers.
>         >         
>         >         Current version 2.1.0
>         >         
>         >         
>         >         Issue 1:  Defining an identity generator at the
>         >         plugin level.
>         >         
>         >         
>         >         Most of our users will want a TimeUUID generated as
>         >         the default entity
>         >         Id.  We do not want to do this as a string, but
>         >         rather want to use the
>         >         actual UUID object.  As you can see from my code
>         >         here, I'm defining the
>         >         generator at the entity level.  Since this will be a
>         >         default use case
>         >         for a lot of our users, I want to make it a standard
>         >         part of our plugin.
>         >         
>         >         https://github.com/riptano/hector-jpa/blob/master/src/test/java/com/datastax/hectorjpa/bean/TimeUuidEntity.java
>         >         
>         >         and
>         >         
>         >         https://github.com/riptano/hector-jpa/blob/master/src/main/java/com/datastax/hectorjpa/sequence/TimeUuid.java
>         >         
>         >         
>         >         
>         >         Issue 2:  Allocate is never invoked on my sequence
>         >         generator, I'm
>         >         assuming this is due to incorrect setup that will be
>         >         resolved in issue
>         >         1.
>         >         
>         >         
>         >         Issue 3: Do I need to synchronize the next call
>         >         internally in my
>         >         Sequence generator?  Given the high throughput of
>         >         our JPA clients, I
>         >         don't want to accidentally return the same UUID to
>         >         multiple callers.
>         >         
>         >         
>         >         Thanks,
>         >         
>         >         
>         >         
>         >         --
>         >         todd
>         >         SENIOR SOFTWARE ENGINEER
>         >         
>         >         todd nine| spidertracks ltd |  117a the square
>         >         po box 5203 | palmerston north 4441 | new zealand
>         >         P: +64 6 353 3395
>         >         E: todd@spidertracks.co.nz W: www.spidertracks.com
>         >         
>         >         
>         >         
>         >         
>         >         
>         >         
>         > 
>         > 
> 
> 

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