Re: Rollback?

Sorry for the very late answer, for an unknown reason I did not see your po=
st.

> Well, I can forbid that for the main database of my application.
>  =

>> - optimistic locking: you'll get notifications when saving changes,
> =

> How does this work?

I was thinking of a delegate method being called by saveChanges() when it n=
otices that changes have happened in the database since the last time the D=
B was queried (meaning that someone else has modified the db).

The delegate will receive a full view of observed modifications: the proper=
ties that have changed (attributes+relationships), objects that have been d=
eleted.  With this information any possible processing is possible: custom =
fusion of local+db modifications, notifying the user of a conflict and aski=
ng him how to solve it, ignoring changes and overriding the db changes, any=
 combination of the previous solutions... In any case, the delegate will de=
cide whether the transaction opened by saveChanges() should be cancelled fo=
r real or re-submitted after conflicts have been solved.

-- S=E9bastien.



Wolfgang Keller wrote:
>> But, given that pessimistic locking locks any data that is going to be =

>> updated, if your application is transaction-intensive updating the same =
data, =

> =

>> you'll get a lot of processes waiting at the same time.
> =

> "Waiting for Godot"
> =

> Or, as users of SAP call it in German; "Sanduhr-Anzeige-Programm" - =

> Hourglass-Display-Program. >:->
>  =

>> it won't even help if the framework had something like a central server =
on =

>> top of the db & shared among different processes since the data still ca=
n =

>> be updated directly at the database level by any other process. =

> =

> Well, I can forbid that for the main database of my application.
>  =

>> - optimistic locking: you'll get notifications when saving changes,
> =

> How does this work?
> =

>> giving you the opportunity to examine the change and, e.g., automaticall=
y =

>> handle them or provide feedback to the user. =

> =

> That would be what I am looking for.
> =

> Sincerely,
> =

> Wolfgang Keller
> =



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