[jboss-dev-forums] [Design of JBossCache] - Re: Custom data versions

[bstansberry@jboss.com]

"manik.surtani at jboss.com" wrote : As a workaround, you could use a NonBlockingDataVersion in an option for ALL calls that touch any nodes in the OptimisticCacheProvider. 

If that results in all created-as-a-side effect parent nodes also getting the NonBlockingDataVersion, on both the local node and any remote node, that should work fine. :)

"manik.surtani at jboss.com" wrote : 
  | I think the DataVersionProvider concept should not be developed if DataVersions themselves are a deprecated concept.  
  | 
  | Metadata is a different story though - there is a JIRA about exposing node metadata as a single object that can be persisted, shipped around - which would include stuff like whether nodes are resident, whether data and child maps are ordered (potentially - this is in discussion), and some transient information like node validity, whether data and/or children are loaded, etc.
  | 

So would this include something like the "Provider" concept -- i.e. a solution to setting metadata on created-as-a-side-affect parent nodes that is different from the final child node?

Also, even if DataVersion is deprecated, IMHO as long as it exists it should be included in any general solution to problems; e.g. if there were a NodeMetaData and NodeMetaDataProvider, NodeMetaData should include the data version as a property.

As far as the Hibernate 2LC use case and JBC 3.0.0 goes, I have a hacky solution already for this problem. I'd like to get rid of it. Probably your solution of passing NonBlockingDataVersion will take care of it. If not, perhaps getting rid of it could mean "don't use OPTIMISTIC in your cache, use MVCC."  Perhaps a general solution to metadata handling will take care of it, either in 3.0.0 or some later 3.x release.  But at this point I don't see any reason this is a critical issue for 3.0.0. Doesn't seem like anything we are talking about would produce an incompatible change; i.e. something that has to go in the major release. It will probably be Q4 before we really start attacking a Hibernate/JBC3 integration in earnest anyway.


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