[Hibernate-devel] pulling a few different threads together:

[Gavin_King/Cirrus%<CI...@ci...>]

As a logical extension to some of the stuff we've talked about and also
bringing in some other things people have asked about, I think I can
start to see a new approach to the whole relationship between sessions
and connections. We have already considered changing the commit()/cancel()
process to the more fine grained:

Session.flush()
Session.connection().commit()
Session.connection().rollback()
Session.close()

Now, to support a much more useable "optimistic locking with versioning"
scheme, we could add the following:

Session.disconnect()
Session.reconnect()

disconnect would return the connection to the pool and reconnect would
grab a new connection. This is (a) more efficient than and (b) more
useable than the suggested approach in the documentation which is to do
some selects with Connection.setAutocommit(true) and then start a
transaction to do the updates.

Session.disconnect() would relinquish any read locks (by releasing the
connection) and would need to be proceeded by a connection().commit()
if any updates had been performed.

Updates performed subsequent to a Session.reconnect() would depend upon
the checking of version numbers to maintain consistency. Write locks
could easily be re-obtained by using Session.lock() (which also, in
the current implementation, checks the version number).

How I envisage this stuff would be used is, for example, in a stateful
session bean where we can't keep a connection (or transaction) open
between invocations from the UI. The bean would disconnect the session
at the end of each operation and reconnect at the start. Currently you
would need a new Session each time which would force you to reload a
versioned object, even if all you were going to do was update it.

So the session would come to represent a real business transaction that
might span multiple database transactions (using optimistic locking
with versioning to enforce consistency).

I'm *really* keen on this approch, so shoot me down if necessary....