[hibernate-dev] HSEARCH-3000 Pick Jigsaw Automatic Module names for all published modules

[Sanne Grinovero]

Picking automatic module names for Hibernate Search isn't going to be
straight-forward as our two main jars (hibernate-search-engine &
hibernate-search-orm) suffer from split package among them.

We can't really fix the split package problem without breaking all
users, so if we want to consider that, we can debate it but that will
need to happen at another round as we're doing a minor release, so
let's focus on:
 # Which names to pick
 # Should we pick the names at all
 # Which modules should have a name

For a great background on the possible strategies and pitfalls I
recommend reading Stephen Colebourne's blog on this subject [1].
He persuaded me there are good reasons to use the "reverse DNS, the
top level package", however since we have the split package problem we
can't simply go with that.

Still, we can respect the principles he recommends with a small
variation. It's fair to assume that the `org.hibernate.search` prefix
is "ours"; since the nature of the suggestion is focused on making
sure there are no misunderstandings in the community about which names
you can choose - as there is no central authority making sure module
names aren't clashing - we should be fine within Hibernate projects
with any `org.hibernate.X` prefix, as long as we coordinate and reach
an agreement on this list.

So, I propose we use:

Engine module:
 - org.hibernate.search.engine

ORM integration module:
 - org.hibernate.search.orm

JGroups, JMS backends:
  [ no automatic module name ? Excepting some "guidelines" in the JMS
module, these are not public API so nobody would benefit from it -
also we think we might want to phase out the name "backend" in the
future ]

Elasticsearch integration module [hibernate-search-elasticsearch.jar]:
 - org.hibernate.search.elasticsearch

Elasticsearch / AWS security integration:
 [ no automatic module name: no public API ]

Serialization / Avro
 [ no automatic module name: no public API ]

WDYT?

We could also pick names for the ones which I've listed as "no public
API" but I see no point: as we're only assigning an "Automatic Module
Name" we won't be able to explicitly state that the other modules
depend on these. So nobody will use them, and things are a bit in flux
anyway in this area because of Hibernate Search 6 plans.

Another optional altogether: since we have split packages which we'll
have to resolve before we can actually transform these into fully
fledged modules, I think an acceptable position is also to say we
won't be publishing any automatic module name yet. Personally I'm
inclined to go with the names suggested above, at least some others
can start making baby steps, even if it's not all there.

# What I don't like:
For one, that the typical application will need to import both
`org.hibernate.search.engine` and `org.hibernate.search.orm`, and
likely more as well (e.g. Elasticsearch API, Lucene API module is
coming, ..).

Maybe similar to BOM's today we could publish a module which
statically imports multiple of these, that could be nicer to use but
we risk needing to publish (and document) one for each of a selection
of combinations. So let's not start with such things yet.

Thanks,
Sanne

[1] http://blog.joda.org/2017/05/java-se-9-jpms-automatic-modules.html