Re: [hibernate-dev] OpenJDK proposal: JDK 9 modules and reflection

I'll try to jump in. I'm mainly providing an external point of view though, since I didn't seriously follow the progress of Java 9. If I understood correctly, modules containing entities would not need to be weak; they *could* be, as a quick solution to migrating to Java 9, but ultimately the clean way of (re-)writing them would be: module foo.bar { exports private com.foo.bar.model; // Exports to anyone, including hibernate.* requires javax.jpa; } (Assuming all classes needed by Hibernate are in `com.foo.bar.model`) Then public classes of package `com.foo.bar.model` would be exported to any module, and additionally package-protected classes from this package could be made accessible by anyone using `AccessibleObject::setAccessible`. Which seems to solve the issue at least in principle. What I'm not sure about is if it couldn't be even stricter by using a qualified export : module foo.bar { exports private com.foo.bar.model to hibernate.entitymanager; exports private com.foo.bar.model to hibernate.core; requires javax.jpa; } It has the advantage of not disclosing private code to the entire world, but the disadvantage of referring to the JPA implementation explicitely, which is a shame. In an ideal world, it would be awesome to be able to not reference Hibernate at all (as below) and still reduce the visibility of the "private" package to only a select few modules. It doesn't seem to be possible, and I guess the syntax below is wrong for many reasons. Not the least being that there's no way for the JVM to connect the dots between JPA and Hibernate. module foo.bar { exports private com.foo.bar.model to javax.jpa; // Won't work requires javax.jpa; } In the end, isn't the issue also about the lack of a concept of "module interface", which "implementation modules" may implement? I mean, here, a developer may not want to say "I'm using Hibernate", just "I'm using JPA", and let the consumer of the module choose the actual JPA implementation. It would be a bit like the `uses` and `provides` keywords, except we would be referring to entire modules instead of classes. I guess that, of course, the full definition of such a feature might get quite complex depending on what it provides exactly. Yoann Rodière <yoann(a)hibernate.org&gt; Hibernate NoORM Team On 16 September 2016 at 19:27, Emmanuel Bernard <emmanuel(a)hibernate.org&gt; wrote: