[Modeling-users] Optimistic Locking

[Ernesto R. <er...@si...>]

I agree with Fede that this should be one of the priorities, cause it =
has so many positive effects:
we can let modeling run in a 'heavy client', although this is not an =
approach that I like, because I want the business logic on the server, =
but....
we can do load balancing with more servers, we can use different editing =
contexts for each session, as already done with Zope, and detect easily =
any update collisions. Each application should handle collisions on it's =
own way.

I don't agree with Heinz on the fetch problem, because:
* the probability we hack on the same data over and over again is very =
high. This is a matter of natural work.
* it may be normal to fetch the objects in several steps, although it is =
more probable to get the objects through object traversal.
* as S=E9bastien said, you can use ec.dispose()
* we definetly need some refresh mechanism. I don't know if the strategy =
to only reread data if write collisions are detected is better than =
doing a refresh on some fetch. Just a comment: I think ZEO (Zope =
Enterprise Objects) use notifications to invalid objects, yes, the =
server sends messages to the client to invalidate data. This does not =
consume much bandwith as there are not many objects that change. (But =
this may not be the same context in RDBMS.)

Erny