Re: Entity manager injection

2007-03-05 Thread Craig L Russell
t;> or entity named in this message. If you are not the intended
>> recipient,
>> and have received this message in error, please immediately return
>> this
>> by email and then delete it.
>>
>> > -Original Message-
>> > From: Matthieu Riou [mailto:[EMAIL PROTECTED]
>> > Sent: Monday, March 05, 2007 8:48 AM
>> > To: Patrick Linskey
>> > Cc: open-jpa-dev@incubator.apache.org
>> > Subject: Re: Entity manager injection
>> >
>> > We're managing our own transactions using our
>> > TransactionManager provided through "openjpa.ManagedRuntime".
>> > So I guess we'll have to go for your second solution. I'll
>> > probably implement a simple ThreadLocal holding the
>> > EntityManager associated with the current tx.
>> >
>> > Btw it's just an idea but wouldn't it be possible for OpenJPA
>> > to handle persistence manager injection even outside of an
>> > EJB container? It seems to me that all the necessary hooks
>> > exist. Just an idea though :)
>> >
>> > Thanks for the help,
>> > Matthieu
>> >
>> >
>> > On 3/5/07, Patrick Linskey <[EMAIL PROTECTED]> wrote:
>> >
>> >   Hi,
>> >
>> >   IIRC, you're doing something like so:
>> >
>> >   @Entity
>> >   public class Foo {
>> >   @PersistenceContext private EntityManager em;
>> >   ...
>> >   }
>> >
>> >   The Java EE spec's support for resource injection does
>> > not apply for
>> >   entity types. So, from an EJB standpoint, you can only
>> > use resource
>> >   injection in session beans and MDBs. You're getting the
>> > NPE because your
>> >   EJB container ignores the @PersistenceContext
>> > annotation on your entity.
>> >   (Note that OpenJPA doesn't do anything at all with
>> > @PersistenceContext
>> >   annotations.)
>> >
>> >   If you were using a session bean, then there are two
>> > possible answers to
>> >   your question:
>> >
>> >   1. If you are managing your own transactions using JTA
>> > and bean-managed
>> >   transactions, then you'd be in good shape using
>> > @PersistenceContext.
>> >
>> >   2. If you are managing your own transactions using the JPA
>> >   EntityTransaction API, then you cannot use
>> > @PersistenceContext to inject
>> >   an EM, but instead must use @PersistenceUnit to inject an
>> >   EntityManagerFactory (or some other EMF lookup means),
>> > and do your own
>> >   lifecycle management.
>> >
>> >   -Patrick
>> >
>> >   --
>> >   Patrick Linskey
>> >   BEA Systems, Inc.
>> >
>> >
>> > __
>> > _
>> >   Notice:  This email message, together with any
>> > attachments, may contain
>> >   information  of  BEA Systems,  Inc.,  its subsidiaries
>> > and  affiliated
>> >   entities,  that may be confidential,  proprietary,
>> > copyrighted  and/or
>> >   legally privileged, and is intended solely for the use
>> > of the individual
>> >   or entity named in this message. If you are not the
>> > intended recipient,
>> >   and have received this message in error, please
>> > immediately return this
>> >   by email and then delete it.
>> >
>> >   > -Original Message-
>> >   > From: Matthieu Riou [mailto: [EMAIL PROTECTED]
>> > <mailto:[EMAIL PROTECTED]> ]
>> >   > Sent: Friday, March 02, 2007 8:32 AM
>> >   > To: open-jpa-dev@incubator.apache.org
>> >   > Subject: Entity manager injection
>> >   >
>> >   > Hi,
>> >   >
>> >   > For ODE we're managing our transactions ourselves. We  
start

>> >   > them and commit
>> >   > them explicitly. By the same token we create the
>> > EntityManagerFactory
>> >   > ourselves. Is there a possibility to use the  
EntityManager

>> >   > injection in the
>> >   > persistent classes in this context or do we have to
>> > implement our own
>> >   > ThreadLocal based thingy to have the EM available in our
>> >   > persistent classes
>> >   > using it?
>> >   >
>> >   > I've tried doing something like:
>> >   >
>> >   > 1. Adding "@PersistenceContext  private EntityManager  
_em;"

>> >   > in a persistence
>> >   > class.
>> >   > 2. Load the persistence class from an EntityManager
>> > created with the
>> >   > factory.
>> >   > 3. Use _em in my persistent class
>> >   >=> NullPointerException
>> >   >
>> >   > Thanks,
>> >   > Matthieu
>> >   >
>> >
>> >
>> >
>> >
>>

Craig Russell
Architect, Sun Java Enterprise System http://java.sun.com/products/ 
jdo

408 276-5638 mailto:[EMAIL PROTECTED]
P.S. A good JDO? O, Gasp!





Craig Russell
Architect, Sun Java Enterprise System http://java.sun.com/products/jdo
408 276-5638 mailto:[EMAIL PROTECTED]
P.S. A good JDO? O, Gasp!



smime.p7s
Description: S/MIME cryptographic signature


Re: Entity manager injection

2007-03-05 Thread Matthieu Riou

Hi Craig,

I plainly understand the rational when your application is living in an EJB
container and relies on session beans. However when you're in a standalone
environment (like Apache Ode is) or only with a servlet container, there are
many cases where you'll want your Entity to know about the EM. It allows you
to have a nice design with some entities being responsible of the lifecycle
of other entities they manage.

For example in Ode the process entity creates and finds process instances,
all the persistence details being hidden behind generic (as non persistence
specific) interfaces.

Thanks a lot for the reply and the clarification,
Matthieu

On 3/5/07, Craig L Russell <[EMAIL PROTECTED]> wrote:


Hi Matthew,

Basically, with JPA we have formalized separation of concerns between
the user's Domain Object Model, represented by Entity, and the user's
Business Object, represented by Session Beans.

There is no need for managing an EntityManager from the Entity
itself. So you should simply remove references to the em in your
Entity classes, and put them instead into your Session Beans.

So injection doesn't work at all for Entity, but works for Session
Beans.

Craig

On Mar 5, 2007, at 9:28 AM, Matthieu Riou wrote:

>> Hmm. I believe that you actually fall into the first category --
>> OpenJPA
>> only uses the ManagedRuntime when it thinks that it's integrating
>> with
>> JTA. It sounds like you're using JTA to control transactions, and
>> plugging into OpenJPA SPIs to tell OpenJPA about how to bind into
>> JTA.
>
>
> I see, so if what JPA needs is just a JTA transaction then yes
> we're in that
> category. So I guess the next question is do you have an idea why
> my entity
> manager is null when I use:
>
> @Entity
> public class Foo {
>   @PersistenceContext private EntityManager em;
>   ...
> }
>
> ?? These 3 links point to the place we initialize the EM factory,
> the EM and
> a the persistence object that uses the EM and would like to use
> injection:
>
> http://svn.apache.org/repos/asf/incubator/ode/trunk/dao-jpa/src/
> main/java/org/apache/ode/dao/jpa/BPELDAOConnectionFactoryImpl.java
> http://svn.apache.org/repos/asf/incubator/ode/trunk/dao-jpa/src/
> main/java/org/apache/ode/dao/jpa/BPELDAOConnectionImpl.java
> http://svn.apache.org/repos/asf/incubator/ode/trunk/dao-jpa/src/
> main/java/org/apache/ode/dao/jpa/ProcessDAOImpl.java
>
> The hooks certainly do exist, for the most part. However, we already
>> have an API-based way to do this --
>> OpenJPAPersistence.getEntityManager(Object). Since injecting an
>> instance's EntityManager not quite the same as what happens with the
>> @PersistenceContext annotation from a Java EE standpoint, I prefer to
>> recommend the proprietary OpenJPA extension API. This makes it more
>> clear where you are depending on OpenJPA-specific features, and
>> avoids
>> any semantic confusion.
>
>
> Makes sense.
>
> Thanks!
> Matthieu
>
>
>
>> -Patrick
>>
>> --
>> Patrick Linskey
>> BEA Systems, Inc.
>>
>> _
>> __
>> Notice:  This email message, together with any attachments, may
>> contain
>> information  of  BEA Systems,  Inc.,  its subsidiaries  and
>> affiliated
>> entities,  that may be confidential,  proprietary,  copyrighted
>> and/or
>> legally privileged, and is intended solely for the use of the
>> individual
>> or entity named in this message. If you are not the intended
>> recipient,
>> and have received this message in error, please immediately return
>> this
>> by email and then delete it.
>>
>> > -Original Message-
>> > From: Matthieu Riou [mailto:[EMAIL PROTECTED]
>> > Sent: Monday, March 05, 2007 8:48 AM
>> > To: Patrick Linskey
>> > Cc: open-jpa-dev@incubator.apache.org
>> > Subject: Re: Entity manager injection
>> >
>> > We're managing our own transactions using our
>> > TransactionManager provided through "openjpa.ManagedRuntime".
>> > So I guess we'll have to go for your second solution. I'll
>> > probably implement a simple ThreadLocal holding the
>> > EntityManager associated with the current tx.
>> >
>> > Btw it's just an idea but wouldn't it be possible for OpenJPA
>> > to handle persistence manager injection even outside of an
>> > EJB container? It seems to me that all the necessary hooks
>> > exist. Just an idea though :)
>> >
>> > Thanks for the help,
>> > Matthieu
>> >

Re: Entity manager injection

2007-03-05 Thread Craig L Russell

Hi Matthew,

Basically, with JPA we have formalized separation of concerns between  
the user's Domain Object Model, represented by Entity, and the user's  
Business Object, represented by Session Beans.


There is no need for managing an EntityManager from the Entity  
itself. So you should simply remove references to the em in your  
Entity classes, and put them instead into your Session Beans.


So injection doesn't work at all for Entity, but works for Session  
Beans.


Craig

On Mar 5, 2007, at 9:28 AM, Matthieu Riou wrote:

Hmm. I believe that you actually fall into the first category --  
OpenJPA
only uses the ManagedRuntime when it thinks that it's integrating  
with

JTA. It sounds like you're using JTA to control transactions, and
plugging into OpenJPA SPIs to tell OpenJPA about how to bind into  
JTA.



I see, so if what JPA needs is just a JTA transaction then yes  
we're in that
category. So I guess the next question is do you have an idea why  
my entity

manager is null when I use:

@Entity
public class Foo {
  @PersistenceContext private EntityManager em;
  ...
}

?? These 3 links point to the place we initialize the EM factory,  
the EM and
a the persistence object that uses the EM and would like to use  
injection:


http://svn.apache.org/repos/asf/incubator/ode/trunk/dao-jpa/src/ 
main/java/org/apache/ode/dao/jpa/BPELDAOConnectionFactoryImpl.java
http://svn.apache.org/repos/asf/incubator/ode/trunk/dao-jpa/src/ 
main/java/org/apache/ode/dao/jpa/BPELDAOConnectionImpl.java
http://svn.apache.org/repos/asf/incubator/ode/trunk/dao-jpa/src/ 
main/java/org/apache/ode/dao/jpa/ProcessDAOImpl.java


The hooks certainly do exist, for the most part. However, we already

have an API-based way to do this --
OpenJPAPersistence.getEntityManager(Object). Since injecting an
instance's EntityManager not quite the same as what happens with the
@PersistenceContext annotation from a Java EE standpoint, I prefer to
recommend the proprietary OpenJPA extension API. This makes it more
clear where you are depending on OpenJPA-specific features, and  
avoids

any semantic confusion.



Makes sense.

Thanks!
Matthieu




-Patrick

--
Patrick Linskey
BEA Systems, Inc.

_ 
__
Notice:  This email message, together with any attachments, may  
contain
information  of  BEA Systems,  Inc.,  its subsidiaries  and   
affiliated
entities,  that may be confidential,  proprietary,  copyrighted   
and/or
legally privileged, and is intended solely for the use of the  
individual
or entity named in this message. If you are not the intended  
recipient,
and have received this message in error, please immediately return  
this

by email and then delete it.

> -Original Message-
> From: Matthieu Riou [mailto:[EMAIL PROTECTED]
> Sent: Monday, March 05, 2007 8:48 AM
> To: Patrick Linskey
> Cc: open-jpa-dev@incubator.apache.org
> Subject: Re: Entity manager injection
>
> We're managing our own transactions using our
> TransactionManager provided through "openjpa.ManagedRuntime".
> So I guess we'll have to go for your second solution. I'll
> probably implement a simple ThreadLocal holding the
> EntityManager associated with the current tx.
>
> Btw it's just an idea but wouldn't it be possible for OpenJPA
> to handle persistence manager injection even outside of an
> EJB container? It seems to me that all the necessary hooks
> exist. Just an idea though :)
>
> Thanks for the help,
> Matthieu
>
>
> On 3/5/07, Patrick Linskey <[EMAIL PROTECTED]> wrote:
>
>   Hi,
>
>   IIRC, you're doing something like so:
>
>   @Entity
>   public class Foo {
>   @PersistenceContext private EntityManager em;
>   ...
>   }
>
>   The Java EE spec's support for resource injection does
> not apply for
>   entity types. So, from an EJB standpoint, you can only
> use resource
>   injection in session beans and MDBs. You're getting the
> NPE because your
>   EJB container ignores the @PersistenceContext
> annotation on your entity.
>   (Note that OpenJPA doesn't do anything at all with
> @PersistenceContext
>   annotations.)
>
>   If you were using a session bean, then there are two
> possible answers to
>   your question:
>
>   1. If you are managing your own transactions using JTA
> and bean-managed
>   transactions, then you'd be in good shape using
> @PersistenceContext.
>
>   2. If you are managing your own transactions using the JPA
>   EntityTransaction API, then you cannot use
> @PersistenceContext to inject
>   an EM, but instead must use @PersistenceUnit to inject an
>   EntityManagerFactory (or some other EMF

Re: Entity manager injection

2007-03-05 Thread Matthieu Riou

Hmm. I believe that you actually fall into the first category -- OpenJPA
only uses the ManagedRuntime when it thinks that it's integrating with
JTA. It sounds like you're using JTA to control transactions, and
plugging into OpenJPA SPIs to tell OpenJPA about how to bind into JTA.



I see, so if what JPA needs is just a JTA transaction then yes we're in that
category. So I guess the next question is do you have an idea why my entity
manager is null when I use:

@Entity
public class Foo {
  @PersistenceContext private EntityManager em;
  ...
}

?? These 3 links point to the place we initialize the EM factory, the EM and
a the persistence object that uses the EM and would like to use injection:

http://svn.apache.org/repos/asf/incubator/ode/trunk/dao-jpa/src/main/java/org/apache/ode/dao/jpa/BPELDAOConnectionFactoryImpl.java
http://svn.apache.org/repos/asf/incubator/ode/trunk/dao-jpa/src/main/java/org/apache/ode/dao/jpa/BPELDAOConnectionImpl.java
http://svn.apache.org/repos/asf/incubator/ode/trunk/dao-jpa/src/main/java/org/apache/ode/dao/jpa/ProcessDAOImpl.java

The hooks certainly do exist, for the most part. However, we already

have an API-based way to do this --
OpenJPAPersistence.getEntityManager(Object). Since injecting an
instance's EntityManager not quite the same as what happens with the
@PersistenceContext annotation from a Java EE standpoint, I prefer to
recommend the proprietary OpenJPA extension API. This makes it more
clear where you are depending on OpenJPA-specific features, and avoids
any semantic confusion.



Makes sense.

Thanks!
Matthieu




-Patrick

--
Patrick Linskey
BEA Systems, Inc.

___
Notice:  This email message, together with any attachments, may contain
information  of  BEA Systems,  Inc.,  its subsidiaries  and  affiliated
entities,  that may be confidential,  proprietary,  copyrighted  and/or
legally privileged, and is intended solely for the use of the individual
or entity named in this message. If you are not the intended recipient,
and have received this message in error, please immediately return this
by email and then delete it.

> -Original Message-
> From: Matthieu Riou [mailto:[EMAIL PROTECTED]
> Sent: Monday, March 05, 2007 8:48 AM
> To: Patrick Linskey
> Cc: open-jpa-dev@incubator.apache.org
> Subject: Re: Entity manager injection
>
> We're managing our own transactions using our
> TransactionManager provided through "openjpa.ManagedRuntime".
> So I guess we'll have to go for your second solution. I'll
> probably implement a simple ThreadLocal holding the
> EntityManager associated with the current tx.
>
> Btw it's just an idea but wouldn't it be possible for OpenJPA
> to handle persistence manager injection even outside of an
> EJB container? It seems to me that all the necessary hooks
> exist. Just an idea though :)
>
> Thanks for the help,
> Matthieu
>
>
> On 3/5/07, Patrick Linskey <[EMAIL PROTECTED]> wrote:
>
>   Hi,
>
>   IIRC, you're doing something like so:
>
>   @Entity
>   public class Foo {
>   @PersistenceContext private EntityManager em;
>   ...
>   }
>
>   The Java EE spec's support for resource injection does
> not apply for
>   entity types. So, from an EJB standpoint, you can only
> use resource
>   injection in session beans and MDBs. You're getting the
> NPE because your
>   EJB container ignores the @PersistenceContext
> annotation on your entity.
>   (Note that OpenJPA doesn't do anything at all with
> @PersistenceContext
>   annotations.)
>
>   If you were using a session bean, then there are two
> possible answers to
>   your question:
>
>   1. If you are managing your own transactions using JTA
> and bean-managed
>   transactions, then you'd be in good shape using
> @PersistenceContext.
>
>   2. If you are managing your own transactions using the JPA
>   EntityTransaction API, then you cannot use
> @PersistenceContext to inject
>   an EM, but instead must use @PersistenceUnit to inject an
>   EntityManagerFactory (or some other EMF lookup means),
> and do your own
>   lifecycle management.
>
>   -Patrick
>
>   --
>   Patrick Linskey
>   BEA Systems, Inc.
>
>
> __
> _
>   Notice:  This email message, together with any
> attachments, may contain
>   information  of  BEA Systems,  Inc.,  its subsidiaries
> and  affiliated
>   entities,  that may be confidential,  proprietary,
> copyrighted  and/or
>   legally privileged, and is intended solely for the use
>

RE: Entity manager injection

2007-03-05 Thread Patrick Linskey
> We're managing our own transactions using our 
> TransactionManager provided through "openjpa.ManagedRuntime". 
> So I guess we'll have to go for your second solution. I'll 
> probably implement a simple ThreadLocal holding the 
> EntityManager associated with the current tx. 

Hmm. I believe that you actually fall into the first category -- OpenJPA
only uses the ManagedRuntime when it thinks that it's integrating with
JTA. It sounds like you're using JTA to control transactions, and
plugging into OpenJPA SPIs to tell OpenJPA about how to bind into JTA.

> Btw it's just an idea but wouldn't it be possible for OpenJPA 
> to handle persistence manager injection even outside of an 
> EJB container? It seems to me that all the necessary hooks 
> exist. Just an idea though :) 

The hooks certainly do exist, for the most part. However, we already
have an API-based way to do this --
OpenJPAPersistence.getEntityManager(Object). Since injecting an
instance's EntityManager not quite the same as what happens with the
@PersistenceContext annotation from a Java EE standpoint, I prefer to
recommend the proprietary OpenJPA extension API. This makes it more
clear where you are depending on OpenJPA-specific features, and avoids
any semantic confusion.

-Patrick

-- 
Patrick Linskey
BEA Systems, Inc. 

___
Notice:  This email message, together with any attachments, may contain
information  of  BEA Systems,  Inc.,  its subsidiaries  and  affiliated
entities,  that may be confidential,  proprietary,  copyrighted  and/or
legally privileged, and is intended solely for the use of the individual
or entity named in this message. If you are not the intended recipient,
and have received this message in error, please immediately return this
by email and then delete it. 

> -Original Message-
> From: Matthieu Riou [mailto:[EMAIL PROTECTED] 
> Sent: Monday, March 05, 2007 8:48 AM
> To: Patrick Linskey
> Cc: open-jpa-dev@incubator.apache.org
> Subject: Re: Entity manager injection
> 
> We're managing our own transactions using our 
> TransactionManager provided through "openjpa.ManagedRuntime". 
> So I guess we'll have to go for your second solution. I'll 
> probably implement a simple ThreadLocal holding the 
> EntityManager associated with the current tx. 
> 
> Btw it's just an idea but wouldn't it be possible for OpenJPA 
> to handle persistence manager injection even outside of an 
> EJB container? It seems to me that all the necessary hooks 
> exist. Just an idea though :) 
> 
> Thanks for the help,
> Matthieu
> 
> 
> On 3/5/07, Patrick Linskey <[EMAIL PROTECTED]> wrote:
> 
>   Hi,
>   
>   IIRC, you're doing something like so:
>   
>   @Entity
>   public class Foo {
>   @PersistenceContext private EntityManager em;
>   ...
>   }
>   
>   The Java EE spec's support for resource injection does 
> not apply for 
>   entity types. So, from an EJB standpoint, you can only 
> use resource
>   injection in session beans and MDBs. You're getting the 
> NPE because your
>   EJB container ignores the @PersistenceContext 
> annotation on your entity. 
>   (Note that OpenJPA doesn't do anything at all with 
> @PersistenceContext
>   annotations.)
>   
>   If you were using a session bean, then there are two 
> possible answers to
>   your question:
>   
>   1. If you are managing your own transactions using JTA 
> and bean-managed 
>   transactions, then you'd be in good shape using 
> @PersistenceContext.
>   
>   2. If you are managing your own transactions using the JPA
>   EntityTransaction API, then you cannot use 
> @PersistenceContext to inject
>   an EM, but instead must use @PersistenceUnit to inject an
>   EntityManagerFactory (or some other EMF lookup means), 
> and do your own
>   lifecycle management.
>   
>   -Patrick
>   
>   --
>   Patrick Linskey
>   BEA Systems, Inc. 
>   
>   
> __
> _
>   Notice:  This email message, together with any 
> attachments, may contain
>   information  of  BEA Systems,  Inc.,  its subsidiaries  
> and  affiliated 
>   entities,  that may be confidential,  proprietary,  
> copyrighted  and/or
>   legally privileged, and is intended solely for the use 
> of the individual
>   or entity named in this message. If you are not the 
> intended recipient, 
>   and have received this message in error, p

Re: Entity manager injection

2007-03-05 Thread Matthieu Riou

We're managing our own transactions using our TransactionManager provided
through "openjpa.ManagedRuntime". So I guess we'll have to go for your
second solution. I'll probably implement a simple ThreadLocal holding the
EntityManager associated with the current tx.

Btw it's just an idea but wouldn't it be possible for OpenJPA to handle
persistence manager injection even outside of an EJB container? It seems to
me that all the necessary hooks exist. Just an idea though :)

Thanks for the help,
Matthieu

On 3/5/07, Patrick Linskey <[EMAIL PROTECTED]> wrote:


Hi,

IIRC, you're doing something like so:

@Entity
public class Foo {
@PersistenceContext private EntityManager em;
...
}

The Java EE spec's support for resource injection does not apply for
entity types. So, from an EJB standpoint, you can only use resource
injection in session beans and MDBs. You're getting the NPE because your
EJB container ignores the @PersistenceContext annotation on your entity.
(Note that OpenJPA doesn't do anything at all with @PersistenceContext
annotations.)

If you were using a session bean, then there are two possible answers to
your question:

1. If you are managing your own transactions using JTA and bean-managed
transactions, then you'd be in good shape using @PersistenceContext.

2. If you are managing your own transactions using the JPA
EntityTransaction API, then you cannot use @PersistenceContext to inject
an EM, but instead must use @PersistenceUnit to inject an
EntityManagerFactory (or some other EMF lookup means), and do your own
lifecycle management.

-Patrick

--
Patrick Linskey
BEA Systems, Inc.

___
Notice:  This email message, together with any attachments, may contain
information  of  BEA Systems,  Inc.,  its subsidiaries  and  affiliated
entities,  that may be confidential,  proprietary,  copyrighted  and/or
legally privileged, and is intended solely for the use of the individual
or entity named in this message. If you are not the intended recipient,
and have received this message in error, please immediately return this
by email and then delete it.

> -Original Message-
> From: Matthieu Riou [mailto:[EMAIL PROTECTED]
> Sent: Friday, March 02, 2007 8:32 AM
> To: open-jpa-dev@incubator.apache.org
> Subject: Entity manager injection
>
> Hi,
>
> For ODE we're managing our transactions ourselves. We start
> them and commit
> them explicitly. By the same token we create the EntityManagerFactory
> ourselves. Is there a possibility to use the EntityManager
> injection in the
> persistent classes in this context or do we have to implement our own
> ThreadLocal based thingy to have the EM available in our
> persistent classes
> using it?
>
> I've tried doing something like:
>
> 1. Adding "@PersistenceContext  private EntityManager _em;"
> in a persistence
> class.
> 2. Load the persistence class from an EntityManager created with the
> factory.
> 3. Use _em in my persistent class
>=> NullPointerException
>
> Thanks,
> Matthieu
>



RE: Entity manager injection

2007-03-05 Thread Patrick Linskey
Hi,

IIRC, you're doing something like so:

@Entity
public class Foo {
@PersistenceContext private EntityManager em;
...
}

The Java EE spec's support for resource injection does not apply for
entity types. So, from an EJB standpoint, you can only use resource
injection in session beans and MDBs. You're getting the NPE because your
EJB container ignores the @PersistenceContext annotation on your entity.
(Note that OpenJPA doesn't do anything at all with @PersistenceContext
annotations.)

If you were using a session bean, then there are two possible answers to
your question:

1. If you are managing your own transactions using JTA and bean-managed
transactions, then you'd be in good shape using @PersistenceContext.

2. If you are managing your own transactions using the JPA
EntityTransaction API, then you cannot use @PersistenceContext to inject
an EM, but instead must use @PersistenceUnit to inject an
EntityManagerFactory (or some other EMF lookup means), and do your own
lifecycle management.

-Patrick

-- 
Patrick Linskey
BEA Systems, Inc. 

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> -Original Message-
> From: Matthieu Riou [mailto:[EMAIL PROTECTED] 
> Sent: Friday, March 02, 2007 8:32 AM
> To: open-jpa-dev@incubator.apache.org
> Subject: Entity manager injection
> 
> Hi,
> 
> For ODE we're managing our transactions ourselves. We start 
> them and commit
> them explicitly. By the same token we create the EntityManagerFactory
> ourselves. Is there a possibility to use the EntityManager 
> injection in the
> persistent classes in this context or do we have to implement our own
> ThreadLocal based thingy to have the EM available in our 
> persistent classes
> using it?
> 
> I've tried doing something like:
> 
> 1. Adding "@PersistenceContext  private EntityManager _em;" 
> in a persistence
> class.
> 2. Load the persistence class from an EntityManager created with the
> factory.
> 3. Use _em in my persistent class
>=> NullPointerException
> 
> Thanks,
> Matthieu
>