[hibernate-dev] Processing mapping information followup

[Max Rydahl Andersen]

>>> In the new terminology, what we are discussing is the process for handling "metadata sources" (o.h.metamodel.source).  What you describe is really a parallel source (o.h.metamodel.source.jdbc???).  So it is going to be completely up to the developer of that code how the binding of source information to metamodel works.
>> 
>> jdbc sources is just for reverse engineering.
>> 
>> If you are using the xml as your source that is the source for code generation that needs to be lazy.
> 
> Again non resolution of the domain classes is already handled.  Or should be.  That has been a consistent mantra as we have developed this new metamodel code.  As for types...

Okey - is Components covered by this ?

Those are also code generated, or at least is for H3.
As I recall Components were modelled by the same mechanism that UserTypes uses.

>>> We will strive to make sure nothing requires the domain classes to be present.  However, please not that in developing this new code I made a distinction.  Specifically, I believe this principal does *not* extend to types, identifier generators, etc.  Entity classes, component classes.. anything that is actually part of the domain model though we will strive to make not required to build this metadmodel.  You specifically asked about "model classes and types"; just wanted to highlight the difference in my mind.
>> 
>> Yes, understood - custom types are required, just the call to .getReturnedClass() that should be avoided if .getReturnedClassName() or .getReturnedEntityName() can suffice ;)
> 
> Again, I disagree with this use case.  Even going back and thinking through the case of enums.  Right now I totally see no benefit to making types non-resolvable in any form/fashion with regards to their typing information (jdbc and java).  So I plan on having type resolution to both JDBC type code(s) and java type (Class) be available.

Ok - I guess we'll just have to wait and see.

>> i.e. a related "dream" of mine is that the metamodel is so decoupled that independent of the source of the mappings I can inject my own understanding
>> of entities - and provide the reflection without actually having classes, i.e. base it on the model eclipse JDT has about classes and make it possible to work
>> with non-compilable classes to be able to use hibernate core to validate the overall mappings.
> 
> org.hibernate.metamodel.Metadata is an interface.  You are free to build that in any way you see fit.  Today, the stuff contained within Metadata is not, though I am certainly open to such a discussion if you think it makes sense for your use cases.  

The usecase I was thinking of is so I can delegate the class metadata and construction of instances. I actually think H3 had most of this, except it wasn't easy to override the defaults globally and thus you
had to thoroughly massage the model to make it happen - leaving behind the biggest issue, that classloading of entities/types were not bound by a sessionfactory so you ended up having class cast problems when running in Eclipse/osgi.

> This is THE reason I wanted your input and eyes on this design.  The earlier we address this stuff the better it would have been.

As far as I know I already given this feedback multiple times. 

Unfortunately I don't have time to attempt to migrate hibernate tools usecases. We are trying to do that now but awaiting actual code that we can try it against.

Any git branches/forks where Configuration is removed or a test is present that doesn't use the "old " Configuration approach and i'll try and take a new look.

/max
http://about.me/maxandersen