Hi Ashley,
On Jul 13, 2004, at 12:00 PM, Ashley Aitken wrote:
> 1. Regarding the new "Level 3 - Cross-VM Cache Sharing" Is that like
> the change notification frameworks that are available for
> EOF/WebObjects but implemented at a lower level?
Architecturally it is probably similar to EOF change notifications
framework originally created by David Neumann. The reason for that is
that the access stack has some similarities, so refreshing it works in
a similar way. Of course in Cayenne change notifications configuration
is supported in the Modeler.
> Is this implemented using the "Generic Multithreaded and Distributed
> Events Mechanism"?
Correct.
> 2. How does Cayenne handle updating to-many relationships (as you may
> know "refreshing" an object in EOF/WebObjects doesn't refresh any of
> it's to-may relationships)? Is this an easy or difficult, expensive
> or cheap thing to do in Cayenne?
SnapshotEvent has something called "indirectlyModifiedIds". This is a
way of telling that while an object itself hasn't changed, its
relationships have to be invalidated. This is kind of automatic.
> 3. Does Cayenne modeller do the right thing regarding maintenance of
> single table inheritance, i.e. if you modify the super-entity all the
> sub-entities definitions are updated (in the Cayenne modeller this is,
> not in the code or the running application)?
Ok, let me try it... Yes, all changes from the "super" entity are
visible immediately.
> 4. It seems that with Data Views and DVModeler (not that I have looked
> closely) you now have a good two-tier (client-server) Java solution
> as well. Is that true? Has Cayenne been used in many two-tier
> solutions?
From what I know there are more than a few two-tier systems done with
Cayenne. I wish more people would share with us their uses of Cayenne,
so that I could tell "how many". DataViews are probably not used as
widely (yet), as they lacked documentation and examples. I am planning
to include my recent DataViews example
(http://www.objectstyle.org/cayenne/lists/cayenne-user/2004/06/
0127.html) in the examples download soon.
> Have you thought of building a three-tier (Web) solution? Or does
> Cayenne just work so well with Tapestry (and perhaps other Web
> frameworks that it is not necessary)?
If you are asking if I wanted to do another web framework - the answer
is no. Tapestry is as good as it can get. On the other hand we've
discussed a distributed DataContext (ala D2JC) - this will be needed
for the three-tier rich UI systems.
> Finally, it seems to me that you are taking Cayenne to some places
> that EOF hasn't gone (for one reason or another). This is great to
> see and makes Cayenne more and more interesting every release.
Oh yeah, this has always been the goal. I could never understand open
source projects that stated their goal as being a feature-for-feature
rewrite of some commercial tool (except for the cases of providing free
implementation of some widely accepted standard, like JVM). One of the
main reasons to get involved with Cayenne (at least for me), was that
we are building this great platform where we are not restrained in
changing/adding things. Seems like a great recipe for innovation.
Andrus
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