Sure (since both you and Meeraj asked)...
Basically, I think the use cases are pretty much the same for JPA,
Hibernate, or JDO (not surprisingly): an application developer wants
to use a strongly-typed O/R mapper to persist data used within a
service or composite implementation. They should be able to use any
of the JPA annotations to inject an entity manager onto a service
instance:
public class FooImpl extends Foo {
@PersistenceUnit(name="example")
protected EntityManager entityManager;
}
Hibernate would work the same way, except inject a Session. This
would basically be an example of the "layering" approach to Java C&I
that we have discussed in the spec group. Under the covers, Tuscany
is managing instances of EntityManagerFactory as system services and
there is an annotation extension which is responsible for performing
the injection of EntityManager instances (non-thread-safe) onto
component implementation instances.
I would expect developers to use this approach when:
- writing in Java or perhaps a "Java-friendly" language such as
Groovy (obviously!)
- they don't need to perform batch-oriented operations (JDBC is
better for that)
- they want to manipulate data in an O-O fashion as opposed to in a
loosely typed way or something like active record
- they don't want to use declarative services, or they are not suited
for an application's needs
- they just like JPA or Hibernate for whatever reason
From a non-technical perspective, this helps to embrace several
communities by showing how their technologies are relevant in an SCA
environment.
Jim
On Oct 2, 2006, at 8:00 AM, scabooz wrote:
Hi Jim,
This is the first time I've seen this topic discussed on the list.
Apologies
if I've missed it previously. Can you illuminate some of your
thinking behind it? I'm interested in understanding the use cases you
might be thinking of supporting, from at least the
perspective of the app developer.
thanks
Dave Booz
----- Original Message ----- From: "Jim Marino"
<[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Monday, October 02, 2006 3:24 AM
Subject: EJB3 (JPA) support
Hi,
I checked in a skeleton of EJB3 persistence support (using
OpenJPA) that will leverage the system service work I just did.
If anyone is interested in helping with this or adding in
Hibernate support let me know. We may want to look at providing a
generic EJB3 JPA extension, although I'm not sure how much common
code would exist across implementations.
Jim
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