Meeraj,
I think there are strong possible synergies between the two technologies:
* JPA can lend a full O/R capability to SDO
* SDO can bring a superior "disconnected" capability to JPA via its
change summary
The RDB DAS provides an implicit one-to-one mapping from tables to
DataObjects but JPA provides a complete and standard O/R mapping. JPA
provides some features for disconnected data but I believe they fall far
short of SDO's capabilities.
--
Kevin
Meeraj Kunnumpurath wrote:
Kevin,
I remember an email a while ago from Jim (I think) about SDO and JPA
addressing orthogonal problem spaces. Apart from that, to be honest, I
haven't put much thought into it. However, it would be great if you
could pls shed your thoughts on the synergies between the two.
Thanks
Meeraj
-----Original Message-----
From: Kevin Williams [mailto:[EMAIL PROTECTED]
Sent: 31 October 2006 18:15
To: [email protected]
Subject: Re: JPA Integration
You may have thought of this already but it would be good to
consider how SDO might play with this JPA integration.
--
Kevin
Meeraj Kunnumpurath wrote:
Hi,
I have made a start on JPA integration. Haven't got to do
much because
of the build problems. The current home is
sca/services/persistence/common.
Anyway, this is a brief highlight of my thinking ...
1. Support injection of entity manager factory and entity manager
instances using PersistenceUnit and PersistenceContext
annotations on
member fields.
2. For entity manager factory instances, the unitName attribute is
introspected at the component load time and scans all the available
persistence.xml for matching unit name.
3. The JPA provider API is used for creating the entity
manager factory.
4. Entity manager factory is caches somewhere (System composite)
5. This is then reused in all the components using the same
persistence
unit.
Persistence context is trickier. Entity manager AFAIK are
thread unsafe
and mostly bound to transactions. Hence, either we will
have to proxy
this or use some sort of instance pooling and thread
confinement in our
component management. I think, proxying would be simpler. I
plan to get
at least the EMF side working by end of this week, if I can get the
build going.
Ta
Meeraj
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