Hi Andrus,
On Monday, September 2, 2002, at 08:29 , Andrus wrote:
> thanks a lot for offering help ;-). Like I said we need it, especially
> from people who really understand the underlying concepts.
I don't know if I qualify, but my pleasure in any case.
> I would suggest that invocation of validation methods should be
> external to DataObject. If we are talking about persistence for
> arbitrary classes in the future, we don't want to force yet another
> interface on the class implementors.
Yes. That is what I was thinking: a totally generic validation mechanism.
> Maybe the object being validated may implement "validateXProperty"
> methods (without implementing any particular interface), but the actual
> invocation code should be in a separate class.
Yep. When I mentioned NSValidation, it was more in regard to the default
implementation, not about yet another interface.
> Same with EOValidation-like functionality for insert/delete/update.
Yes, but that's a little bit more specific. And could be also handled
through "self delegation" perhaps: something like willInsert(),
validateForInsert(), didInsert() and so on. I'm always missing all the
"will" and "did" callback in EOF.
>
> I wonder if something like Jakarta DynaBeans would be a good starting
> point for such implementation?
I will check it out. But I have much of the infrastructure already in
place. Will see.
> - delegates that are notified *before* something is about to happen, so
> that they can affect the flow
I have a little implementation of NSInvocation. Very handy for handling
delegation. Let me know if you are interested.
> - notifications that are sent to observers about various events after
> the fact. This is where your notification center might be needed. What
> do you use for distributed notifications? HTTP? Sockets? Multicast?
Multicast.
> We may also look into other ways for distributed notifications. I
> think TopLink uses JMS for that. Cause if we ever get into cache
> synchronization, message flow will be overwhelming.
Multicast is pretty lightweight. But I agree that having a JMS compliant
notification center would be ideal. In the meantime, multicast is very
straightforward.
>
> In any event, I guess we may start with defining the events needed.
Yep. The more the merrier :-)
Cheers,
PA.
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