aries:services is also a JNDI lookup scheme, it works much the same way as osgi:service, but osgi:service returns a proxy to the target object which switches out the target if it changes. aries:services does not proxy, you get e raw object so it is a little bit less dynamic and safe.
Alasdair Nottingham On 17 Sep 2010, at 03:10, Bengt Rodehav <[email protected]> wrote: > Have I misunderstood when I use "aries:" instead of "osgi:" or is it just > different prefixes to the same namespace? In the JPA samples I cannot see in > the persistence descriptor what namespace "aries:" actually refers to. > > /Bengt > > 2010/9/17 Timothy Ward <[email protected]> > > Hi Harald, > > The Aries project aims to provide a managed programming model, and as such > the Aries JPA runtime is not an implementation of the JPA service > specification. > > As a result I'm afraid my first answer is no, Aries JPA cannot be used to get > unmanaged JPA support, however if you declare your persistence units to use > RESOURCE_LOCAL transactions then there shouldn't be a need for OpenJPA to > load any JTA classes. Please let me know if OpenJPA continues to complain > about the lack of JTA interfaces for RESOURCE_LOCAL persistence units and > I'll try to get that fixed. > > For your requirements you should need two bundles from the Aries JPA project, > the Aries JPA API bundle and the Aries JPA container bundle. You will also > need the Aries Util bundle, which the JPA project uses. > > For reference, the JPA container bundles provide the following support: > > jpa-api :- Core interfaces used by the Aries JPA runtime and > Service providers > jpa-container :- The core JPA container, provides managed > EntityManager factories for use in Application-Managed JPA > jpa-container-context :- JPA managed persistence context support, allows for > bundles to be registered as clients of a managed persistence context > jpa-blueprint-aries :- Integration with the aries blueprint service > providing a custom namespace for JPA resource injection > > > The Aries JPA container is loosely coupled, so it is entirely possible to > pick the bundles you need for the support you want, though each piece of > support builds upon the previous one, so it doesn't make much sense to have > managed persistence context support without managed persistence unit support. > > There's no need to use blueprint, Declarative Services is perfectly capable > of retrieving EntityManagerFactory services from the service registry. > > How data sources are discovered depends upon how they are configured, if you > use the <jta-data-source> or <non-jta-data-source> tag, then the Aries JPA > container will use JNDI to get the resource registered with that JNDI name. > In most cases you actually want to access a DataSource object in the service > registry, which means you need the Aries JNDI support (available as a single > bundle, or as separate core and URL handler bundles) which provides the osgi: > namespace. > > If you want to specify database driver class names in the <properties> > section of the persistence unit then the JPA provider needs to be able to > load those drivers. I do not know whether OpenJPA has support for the OSGi > JDBC service specification, or whether they will simply try to load the > driver classes, and so this may not work. > > I hope this message has been helpful, and I agree that there is insufficient > documentation in this area. I would be more than happy for any Aries users to > contribute information that they find useful so that better documentation can > be built. > > Regards, > > Tim > > ---------------------------------------- > > From: [email protected] > > To: [email protected] > > Date: Thu, 16 Sep 2010 20:31:48 +0200 > > Subject: OSGi JPA and JDBC Services > > > > I'm currently trying to make OpenJPA 2.0.1 work in an OSGi environment, and > > while looking for examples, I found a pointer to Apache Aries on the > > OpenJPA Users' mailing list. > > > > So I had a look at the Aries website, checked out the latest code from > > trunk, played around with it for a couple of hours and was left with no > > usable result - it sort of feels like being offered a four course meal when > > all you were asking for was a plate of soup, and you don't even get a > > spoon... > > > > All I want to do is use OpenJPA in plain old unmanaged mode and have it > > discover my persistence units and load classes from my application bundles > > without DynamicImport-Package, buddy policies or fragments. I am currently > > perfectly happy with Declarative Services and have no intention of > > converting my application to Blueprint. > > > > Can Aries be used to achieve just that? If so, what is the minimum set of > > Aries bundles I need to include in my application? > > > > I got as far as having my persistence unit discovered, but on creating an > > EntityManagerFactory, OpenJPA always complained about missing JTA support. > > Does Aries implement unmanaged JPA at all? (It is supported by the OSGi JPA > > spec, at any rate.) I can only see a call of > > PersistenceProvider.createContainerEntityManagerFactory() in Aries and no > > occurrence of createEntityManagerFactory(). On the OpenJPA side, there is > > some code related to OSGi classloaders, but again, this is just used for > > the managed factories and not for the unmanaged ones. > > > > Another question: how does the Persistence Provider discover the data > > source - where does the magic happen so that the lookup of > > osgi:service:/javax.sql.DataSource will work? Is that done by Aries alone, > > or does the persistence provider need to be OSGi aware in this respect? > > > > Thanks in advance for any hints! > > > > Best regards, > > Harald > >
