[hibernate-dev] nested ServiceRegistry ?

[Steve Ebersole]

ServiceRegistry itself has worked out great imo, but I am starting to run into 
difficulties in migrating certain things to be services.  Specifically I had 
issues with both event listeners and Statistics.  In each case the issue was 
slightly different, but both were solveable by having a notion of the 
ServiceRegistry being scoped by the SessionFactory.  That is not the ideal 
general solution though since many services do not care about or need the 
SessionFactory.  The only real solution I have thought of is to have the 
concept of a set of nested registries.  In the simpliest case, I think 2.. a 
basic service registry and a session factory scoped one where the session 
factory scoped one knows about the basic one (typical parent delegation).

But I am looking for any other suggestions.

Another option is that maybe listeners and stats are just not services in the 
ServiceRegistry sense.  

So what were the specific problems?  I guess that is useful to formulate 
suggestions ;)

In the case of statistics, its merely a case that it needs a reference to the 
SessionFactory to be able to answer questions like "getEntityNames, 
"getCollectionRoleNames", etc.

In the case of listeners it is not a simple explanation.  It really comes down 
to scoping of the listeners and timing in regards to how stuff happens at the 
moment because of the "freeness" of Configuration.  The end result was 
different for each listener set.  jpa, envers, bean validation, search each 
had unique set of problems; even the default listeners had issues.

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