[hibernate-dev] Using Hibernate ORM as automatic JPMS modules

[Steve Ebersole]

I created a Jira to track this:
https://hibernate.atlassian.net/browse/HHH-12188

On Fri, Dec 22, 2017 at 5:33 AM Steve Ebersole <steve at hibernate.org> wrote:

> Thanks for investigating this Gunnar.
>
> Some thoughts inline...
>
> On Wed, Dec 20, 2017 at 3:54 PM Gunnar Morling <gunnar at hibernate.org>
> wrote:
>
>
>> * JDK 9 comes with an incomplete JTA module (java.transaction), so a
>> complete one must be provided via --upgrade-module-path (I'm using the
>> 2.0.0.Alpha1 version Tomaz Cerar has created for that purpose)
>>
>
> Do you know if there is a plan to fix this in Java 9?  Seems bizarre that
> Java 9 expects all kinds of strict modularity from libraries and
> applications when the JDK itself can't follow that..
>
>
>
>> * hibernate-jpa-2.1-api-1.0.0.Final.jar can't be used as an automatic
>> module, as the automatic naming algorithm stumples upon the numbers (2.1)
>> within the module name it derives; I'm therefore using my ModiTect
>> tooling (
>> https://github.com/moditect/moditect/) to convert the JPA API JAR into an
>> explicit module on the fly
>>
>
> We actually no longer use that artifact as a dependency.  Since JPA 2.2,
> the EG publishes a "blessed" API jar which is what we use as a dependency.
>
>
>
>> * When using ByteBuddy as the byte code provider, a reads relationship
>> must
>> be added from the user's module towards hibernate.core ("requires
>> hibernate.core"). This is due to the usage of
>> org.hibernate.proxy.ProxyConfiguration within the generated proxy classes.
>> Ideally no dependence to the JPA provider should be needed when solely
>> working with the JPA API (as this demo does), but I'm not sure whether
>> this
>> can be avoided when using proxies (or could we construct proxies in a way
>> not requiring this dependence?).
>>
>
> I'm not sure what a decent solution would be here.  Ultimately the runtime
> needs to be able to communicate with the generated proxies - how else would
> you suggest this happen?
>
>
> * When using ByteBuddy as the byte code provider, I still needed to have
>> Javassist around, as it's used in ClassFileArchiveEntryHandler. I
>> understand that eventually this should be using Jandex, but I'm wondering
>> whether we could (temporarily) change it to use ASM instead of Javassist
>> (at least when using ByteBuddy as byte code provider, which is based on
>> ASM), so people don't need to have Javassist *and* ByteBuddy when using
>> the
>> latter as byte code provider? This seems desirable esp. once we move to
>> ByteBuddy by default.
>>
>
> Yes, Sanne brought this up in Paris and it is something I will look at
> prior to a 5.3.0.Final
>
>
> * Multiple methods in ReflectHelper call setAccessible() without checking
>> whether the method/field/constructor already is accessible. If we changed
>> that to only call setAccessible() if actually needed, people would have to
>> be a little bit less permissive in their module descriptor. It'd suffice
>> for them to declare "exports com.example.entities to hibernate.core"
>> instead of "opens com.example.entities to hibernate.core", unless they
>> mandate (private) field access for their entities.
>>
>
> Can you open a Jira for that?
>
>
>
>> The demo is very simple (insert and load of an entity with a lazy
>> association). If there's anything else you'd like to try out when using
>> ORM
>> as JPMS modules, let me know or just fork the demo and try it out yourself
>>
>
> IIUC for jars targeting both Java 8 and Java 9 we cannot include a
> module-info file.  But we need to set the module names - you mentioned
> there was a "hinting" process.  From what I could glean from searching
> (which was oddly not many hits), this is achieved by adding a
> `Automatic-Module-Name` entry in the JAR's MANIFEST.MF.  Correct?
>
> Also, IIRC we agreed with `org.hibernate.orm` as the base for all ORM
> module names, so we'd have:
>
>    - org.hibernate.orm.c3p0
>    - org.hibernate.orm.core
>    - ...
>
>
>
>
>