[hibernate-dev] Processing mapping information followup

[Steve Ebersole]

Wanted to start a follow up discussion to the conversation we had at the 
IRC meeting on 6/13 with regards to changing the way we process mapping 
information to follow dependencies in the various types of information.

What we do currently (in the metamodel code) is essentially the same as 
the legacy code.  That is to say we process through a mapping source in 
full and then move on to the next one, saving off "second passes" 
whenever we encounter information on which we have to wait.  The second 
passes in the new metamodel code are isolated I guess (so far) to 
org.hibernate.metamodel.source.internal.EntityReferenceResolver

What I proposed instead is quite different, more like what I did for the 
rest of the MetadataImpl constructor code in terms of defining 
dependencies and processing stuff in an order that makes sure to avoid 
the need for second passes.

Here is the initial swab at the levels of information:
1) entity - basic entity information such as name, hierarchy
2) identifiers - normal identifiers could almost be handled in the first 
level.  key-many-to-one still needs some form of delayed queuing.
3) secondary tables
4) attributes
5) associations

The dependencies flow downward; (2) depends on (1); (3) depends on (2); etc.

I liked handling (3) secondary tables separately because they basically 
expand the possible set of columns available for (4) and (5).

-- 
Steve Ebersole <steve at hibernate.org>
http://hibernate.org