[hibernate-dev] 6.0 - design question: "model navigation" exposed as an API?

[Christian Beikov]

In that case I'd say let's do it if it makes sense :)


Mit freundlichen Grüßen,
------------------------------------------------------------------------
*Christian Beikov*
Am 10.03.2017 um 00:14 schrieb Steve Ebersole:
>
> That's basically exactly what @Incubating means - we are exposing this 
> new API/SPI but users should fully expect the contracts to change.  
> Basically the annotated API/SPI is not held to our normal 
> compatibility rules - this is a new thing and we assume it will evolve 
> in use
>
>
> On Thu, Mar 9, 2017, 3:16 PM Christian Beikov 
> <christian.beikov at gmail.com <mailto:christian.beikov at gmail.com>> wrote:
>
>     Is there a definition to what @Incubating means? I'd rather not
>     make it
>     an API until we played a little with it for new features.
>
>
>     Mit freundlichen Grüßen,
>     ------------------------------------------------------------------------
>     *Christian Beikov*
>     Am 09.03.2017 um 17:35 schrieb Steve Ebersole:
>     > Currently in 6.0 we have the notion of a Navigable which models
>     any "piece"
>     > of the application's domain model[1].  We also have the notion of
>     > a NavigableVisitationStrategy which defines the strategy for
>     handling the
>     > visitation of the nodes in a Navigable tree.  In other words,
>     Hibernate
>     > defines a common visitor for how to walk the application's
>     mapped domain
>     > model and the NavigableVisitationStrategy implementation
>     controls which
>     > sub-trees are walked; e.g. we'd use this to apply JPA
>     EntityGraphs or to
>     > stop joining joinable Navigables after we have reached the
>     > `max_fetch_depth` setting value.
>     >
>     > It is important to note that this is very, very different from
>     JPA's model
>     > and walking it.  JPA's model essentially precludes those model
>     nodes from
>     > defining relational mappings as part of its type system in any
>     sane way;
>     > this is due to various reasons because of the model's
>     design[2].  This
>     > Navigable walking would walk the real/full relational mapping model.
>     >
>     > The design question is whether we want to expose this "domain
>     mode walking"
>     > as a general public API feature.  This has been requested
>     before; Max once
>     > asked for it although I forget why.
>     >
>     > Making this an API means exposing quite a few things. Typical
>     visitor
>     > pattern, the visitor (NavigableVisitationStrategy) exposes
>     "handle" methods
>     > based on specific Navigable sub-types.  Those sub-types would
>     need to be
>     > moved to API.  I don't have a particular concern with that, just
>     mentioning
>     > it.
>     >
>     > Opinions on whether this should become an API?
>     >
>     > For sure we'd mark it @Incubating, if we decide to do it.
>     >
>     > [1] Short synopsis: Navigables include things like EntityPersister,
>     > CollectionPersister, EmbeddedPersister, PersistentAttribute,
>     > CollectionIndex, CollectionElement.  A Navigable is always
>     relative to a
>     > NaviagbleSource.  NaviagbleSources are any domain Navigable
>     > (NavigableSource extends Navigable) which includes things like
>     > EntityPersister, EmbeddedPersister, SingularPersistentAttribute,
>     > CollectionElementEntity, CollectionElementEmbedded, etc .  The
>     > NaviagbleSource will be null in the case of EntityPersister (as
>     a root),
>     > but in all other cases the NaviagbleSource is non-null.
>     >
>     > [2] I won't get into the reasons here, but we can certainly
>     follow up if
>     > anyone challenges that assertion.
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