[hibernate-dev] Compatibility Considerations wiki

[Gunnar Morling]

2014-08-18 13:12 GMT+02:00 Sanne Grinovero <sanne at hibernate.org>:

> I won't speak for Steve's reasons, but I agree with the granularity
> problem.
>
> For example you might not want to refactor the code to promote an SPI
> to API (or simply fix a mistake), or viceversa demote an API to SPI,
> as you moving the packages around would break backwards compatibility.
>

Yes, it's not so much about mixing API/SPI types in one package (maybe
there is even an overlap in some cases) but it's public (i.e. API + SPI)
vs. internal parts which I don't think should be in one package.


> Essentially this means you can only fix the packages in that short
> time in which you're in Alpha/Beta phase for a new major release,
> which is a short period in which usually the team has other
> priorities.


But shouldn't you really know about that nature of an exposed type after a
Beta phase? There is still the possibility to mark API/SPI members as
incubating (we have an annotation @Experimental for this in OGM, not sure
about others) if it's something still evolving. And the document reserves
the right to fix "errors" anyways.

>
> The best example is ORM itself in it's current shape: we all know that
> some classes should be moved into SPI or Impl, but we can't touch
> them.
>

Agreed on SPI (see above), but is there really a problem with moving an
accidentally exposed type to an "impl" package? It has not been designed to
be accessed publicly, so ideally there should be no public users anyways.
But if there are and we want to avoid breaking them, then it's actually a
public contract by its nature and it should be maintained, no?

To me, something is either public (then we need to keep compatibility in
mind when changing it) or its internal (then we can change it as we like),
but I don't think there is something in between. Having an internal type
which we cannot touch seems like a paradox to me.

If your goal is to publish a nice set of javadocs for users which has
> API only, annotations would allow to do this.
>

It's more the public vs. private API distinction of e.g. OSGi I have in
mind and its way for making sure only public parts are ever consumed by
clients.

Sanne
>
>
> On 18 August 2014 08:14, Gunnar Morling <gunnar at hibernate.org> wrote:
> > Hi Steve,
> >
> > Thanks for writing up these rules. That's very valuable information for
> > users and us as well.
> >
> > Only two remarks on the following:
> >
> >> The use of package names for this is unfortunately not granular enough
> > oftentimes.
> >> Ultimately I would envision a better solution (annotations?)
> >
> > In which cases is it not granular enough? Can such case not always be
> > circumvented by refactoring code into separate classes within separate
> > packages?
> >
> > I'm fearing issues with e.g. distinguishing between public (API/SPI) vs.
> > internal parts on a finer level than the package, as that's what OSGi but
> > also JBoss Modules rely on. We cannot fully leverage the ability of these
> > module systems to "hide" internal parts of a module in that case.
> >
> > Also I think annotations are easier to "miss" than package names when
> > importing classes into an application, thus I'm concerned about
> accidental
> > referencing internal classes.
> >
> >> SPI contracts should be considered stable within a release family, not
> > necessarily across different release families.
> >
> > A specific example, similar to the API section, would be nice, e.g.: "If
> > you implement an application against an integration point from Hibernate
> > ORM 4.3.0, the expectation is that it works without changes when updating
> > to ORM 4.3.1. It should also continue to work when updating to ORM 4.4.x
> in
> > the very most cases, but that's not guaranteed."
> >
> > --Gunnar
> >
> >
> > 2014-08-09 16:55 GMT+02:00 Steve Ebersole <steve at hibernate.org>:
> >
> >> There was a discussion in regards to our view on backwards
> compatibility in
> >> reference to HHH-9316.  I realized that we talk about this amongst
> >> ourselves, but that I have never written these down.  So I did that:
> >>
> >>
> >>
> https://github.com/hibernate/hibernate-orm/wiki/Compatibility-Considerations
> >>
> >> This is a first draft.  Let me know what you think.
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> >>
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