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Posted to dev@openjpa.apache.org by Todd Nine <to...@spidertracks.com> on 2011/03/08 05:22:28 UTC
Help with Cassandra JPA plugin
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
Re: Help with Cassandra JPA plugin
Posted by Miłosz Tylenda <mt...@o2.pl>.
Hi All,
More on the global sequence subject - you can define such a sequence in persistence.xml like this:
<property name="openjpa.Sequence" value="com.datastax.hectorjpa.sequence.TimeUuid()"/>
Having this, you can annotate your entities with plain @GeneratedValue and your custom sequence will be used.
As Kevin mentioned, OpenJPA does not call allocate(), however you can call it from the application:
OpenJPAEntityManager kem = OpenJPAPersistence.cast(em);
kem.getIdGenerator(TimeUuidEntity.class).allocate(100);
Cheers,
Milosz
Re: Help with Cassandra JPA plugin
Posted by Kevin Sutter <kw...@gmail.com>.
Hi Todd,
Comments below...
On Tue, Mar 8, 2011 at 5:43 PM, Todd Nine <to...@spidertracks.com> wrote:
>
> 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
>
>
Allocate is used for allocating a block of sequences. I believe we only use
this with some databases that could support this functionality. I don't
believe we use allocate() when dealing with custom generators like what you
are trying to use.
>
> 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?
>
Sure, you could, but it would be quite a bit of work... :-) Anything's
possible with enough coding. But, the OpenJPA architecture does not allow
an easy to define plugin for this effort. One thing you might want to
consider is to define your Generator in orm.xml and then just reference it
via your annotations. That might be cleaner for your application.
>
> @Id
> @GeneratedValue(strategy="time-uuid")
> private UUID id;
>
Kevin
>
>
> 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 <to...@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 <to...@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
>
>
>
>
>
>
>
>
>
Re: Help with Cassandra JPA plugin
Posted by Todd Nine <to...@spidertracks.com>.
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 <to...@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
> > <to...@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
> >
> >
> >
> >
> >
> >
> >
> >
>
>
Re: Help with Cassandra JPA plugin
Posted by Kevin Sutter <kw...@gmail.com>.
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 <to...@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 <to...@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
>
>
>
>
>
>
>
>
Re: Help with Cassandra JPA plugin
Posted by Todd Nine <to...@spidertracks.com>.
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 <to...@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
>
>
>
>
>
>
>
>
Re: Help with Cassandra JPA plugin
Posted by Kevin Sutter <kw...@gmail.com>.
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 <to...@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
>
>
>
>
>
>
>