[hibernate-dev] hibernate-osgi JPA bootstrap & classloader

[Brett Meyer]

> I would fully expect hibernate-osgi to not directly use Bootstrap to build
> an EntityManagerFactoryBuilder.  Bootstrap is geared toward users wanting
> to leverage 2-phase JPA bootstrapping, not our components.  I would have
> expected Enterprise OSGi support to instead directly build (and possibly
> override) EntityManagerFactoryBuilderImpl.  I'll add that as a task for
> post-5.0.

+1, makes sense.  I should have done that to begin with...

> Because I think that is a first step in being able to better
> manage bundles coming and going.  Please correct me if I am wrong.

At first glance, supporting bundles being activated/deactivated at runtime may just be limited to OsgiClassLoader and an impl of OSGi's "BundleListener".  HibernateBundleActivator would simply register that listener during startup (BundleContext#addBundleListener), which would receive the events.  As bundles are added/removed from the runtime, they'd just be added/removed from OsgiClassLoader#bundles.

> Also I'd like to start making sure that we fully support (certain) OSGi services
> being replaced.  Especially thinking of TransactionManagers and DataSources.

+1

> 
> 
> On Tue, May 26, 2015 at 10:44 AM, Brett Meyer <brmeyer at redhat.com> wrote:
> 
> > IIRC:
> >
> > OsgiPersistenceProvider and OsgiSessionFactoryService both need *some* way
> > to build the OsgiClassLoader and pass it into Hibernate bootstrapping.  For
> > the SF, that's easy: just hand OSGiClassLoaderServiceImpl to
> > BootstrapServiceRegistryBuilder.  For EMF, it looks like I mistakenly
> > overrode those Bootstrap methods -- I missed that PersistenceUnitDescriptor
> > included the CL.  So you're probably right -- presumably you could strip
> > 'em out and somehow use the descriptor, but you might still need the
> > overridden method in HibernatePersistenceProvider so that
> > OsgiPersistenceProvider can give you the OsgiClassLoader to use.
> >
> > > Additionally, this ClassLoader is ultimately just used to build the
> > > ClassLoaderService which hibernate-osgi overrides anyway.
> >
> > Right, assuming you're talking about
> > 'ClassLoaderHelper.overridenClassLoader'.  But the intention there was to
> > remove that whole class ASAP -- that was just a temporary hack for ORM 4,
> > since CL handling was still really static.  But admittedly, I'm a bit out
> > of touch with ORM 5, so I'm not sure if that's feasible yet.
> >
> > ----- Original Message -----
> > > From: "Steve Ebersole" <steve at hibernate.org>
> > > To: "hibernate-dev" <hibernate-dev at lists.jboss.org>
> > > Sent: Saturday, May 23, 2015 1:49:50 PM
> > > Subject: [hibernate-dev] hibernate-osgi JPA bootstrap & classloader
> > >
> > > Brett,
> > >
> > > As part of HHH-7527 (Enterprise OSGi support) you had changed
> > > the org.hibernate.jpa.boot.spi.Bootstrap contract to basically overload
> > > each method to additional accept a "providedClassLoader".
> > >
> > > Every one of those methods however, also accepts
> > > a org.hibernate.jpa.boot.spi.PersistenceUnitDescriptor which exposes 2
> > > ClassLoader already.
> > >
> > > Additionally, this ClassLoader is ultimately just used to build the
> > > ClassLoaderService which hibernate-osgi overrides anyway.
> > >
> > > Just curious if I missed something.  Unless I did, it seems to me that we
> > > really do not need these overloads on Bootstrap to support Enterprise
> > > OSGi.  This dove-tails with a discussion from the Karaf user list
> > > ultimately discussing OsgiClassLoaderService and "holding bundles" that
> > are
> > > being re-installed or upgraded.  Ultimately I am thinking through ways to
> > > support being able to release OSGI bundle references from the
> > > OsgiClassLoaderService...
> > > _______________________________________________
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> > >
> >
>