Marcel,
You'll find the answers here in the email thread.
You'll probably need to have a hashtable to lookup
the corresponding EMF by PU name in your case.
Also, you do not need javaee.jar - all javax.persistence
classes and xml schemas are packaged together into
toplink-essentials.jar. The same is true if you access
this jar from a GlassFish installation.
regards,
-marina
Tom Ware wrote On 04/17/06 12:25,:
> Currently a new instance of EntityManagerFactory will be created each
> time this method is called. A fair amount of the work related to
> creating an EntityManagerFactory, however, only needs to occur the first
> time an EntityManagerFactory is created for a persistence unit.
>
> -Tom
>
>
>
> Marina Vatkina wrote:
>
>
>>Tom,
>>
>>Calling Persistence.createEntityManagerFactory(pu) is accessing PU outside
>>a container. Will this call create a new EMF every time?
>>
>>thanks,
>>-marina
>>
>>Tom Ware wrote:
>>
>>
>>
>>>Hi Marcel,
>>>
>>>I'll handle question #2. I'll let the folks that work on the container
>>>answer the other ones.
>>>
>>>#2 The javaagent is used to allow us to do dynamic weaving of domain
>>>classes that use fetch=LAZY for OneToOne and ManyToOne mappings. Those
>>>classes are weaved to contain som TopLink-specific data structures that
>>>allow us to provide LAZY loading of those relationships. If you do not
>>>want to (or cannot use the agent), a flag can be provided in the
>>>properties of your persitence unit to avoid the weaving. The property
>>>"toplink.weaving" can be set to "false". This will disable the
>>>weaving. The consequences of setting this property is that the LAZY
>>>hint will not be observed for OneToOne and ManyToOne relationships and
>>>they will be loaded EAGERly.
>>>
>>>-Tom
>>>
>>>Marcel Overdijk wrote:
>>>
>>>
>>>
>>>
>>>>Hi,
>>>>
>>>>I'm adding JPA support to a framework and have some questions.
>>>>Currently I'm using the Toplink Essentials and javaee.jar from
>>>>GlassFish M6.
>>>>
>>>>1. The javaee.jar contains more then only the persistence related
>>>>classes and therefor is 1mb big. Is there a official Sun jar
>>>>downloadable containing only persistence classes. In Spring 2.0
>>>>distribution a persistence.jar (58kb) is included. I can use this but
>>>>I don't know the origin of it.
>>>>
>>>>2. In the persistence example on the GlassFish page the
>>>>toplinks-essentials-agent.jar is used in combination with -javaagent
>>>>(SE example). What does the toplink-essentials-agent do? If I just put
>>>>toplink-essentials and javaee.jar on the classpath everything seems to
>>>>work fine. Is there any drawback?
>>>>
>>>>3. When I want to get an EntityManager based on an persistence unit
>>>>Name I don't know at compile time. The only option (I believe) is to
>>>>create an emf first:
>>>>String pu = "some dynamic pu name";
>>>>Persistence.createEntityManagerFactory(pu);
>>>>However to create a emf each time is expensive. I could keep a
>>>>reference to a pu once created.
>>>>But what I'm wondering is how JEE 5 containers handle this. Do they
>>>>create subsequent emf's or are they smart that they know it was
>>>>already created in a previous call?
>>>>
>>>>Hope you can hekp me on this.
>>>>
>>>>Regards,
>>>>Marcel Overdijk
>>>>
>>>>
>>>>
>>>>
>>>>