Re: WHChangeNotification Question
Re: WHChangeNotification Question
- Subject: Re: WHChangeNotification Question
- From: Alan Ward <email@hidden>
- Date: Fri, 31 Mar 2006 12:54:57 -0700
On Mar 31, 2006, at 12:49 PM, Chuck Hill wrote:
I think this was originally a framework from David Neumann who
worked at Apple.
and still does.
Alan
So in a way... I will say that I have never used this framework.
I have always found ways to maintain data freshness using the tools
provided in EOF. I don't think that one way is always better than
the other. The EOF way may produce more DB reads that are needed.
The notification framework will pass a lot messages around about
data not relevant to an instance. Certainly, adding the
notification framework is the less effort way of handling this.
Chuck
On Mar 31, 2006, at 11:39 AM, James Cicenia wrote:
Wow... confusion reigns... You would think this is one place where
Apple would have stepped in.
On Mar 31, 2006, at 1:23 PM, Jean-François Veillette wrote:
Beware that the wonder implementation distribute changes snapshot
and tries to apply them to the database cache.
Unfortunately, under load, you will realise that this is causing
a deadlock.
I haven't got to the point where I was able to debug this
strategy. Maybe you just need another lock somewhere in the eo
stack to prevent the dead lock, I do not know at that point.
Maybe someone can look at this.
Anyway, I started with wonder's code and used a different
strategy that I had seen already and was talked numerously here
on the mailing list, which is to publish globalID of changed eo
(and not diffs), and simply invalidate eos based on those
globalIDs at the subscriber's end.
We didn't have any locking problem since !
- jfv
Le 06-03-31, à 14:09, Ken Anderson a écrit :
No, not really. I personally really like how lightweight
WHChangeNotification is. I'm using a modified version of it
because I already have a pub/sub system that my apps are
participating in. It really depends on your Wonder threshold :)
Ken
On Mar 31, 2006, at 2:02 PM, James Cicenia wrote:
Ok -
So you are saying that I *should* use the Wonder version
instead? If so, is it stand alone, or, do I need ERX my classes
etc.?
- James
On Mar 31, 2006, at 12:56 PM, Ken Anderson wrote:
James,
You need to configure it to know what instances you have, and
what classes you want distributed.
I believe the version available uses direct connect, so you'll
have to make sure that it's enabled.
There have been some concerns about issues with the direct
connect transport mechanism... it's suggested that you use
some other type of transport like JMS. I also believe that
project wonder has something similar to WHChangeNotification
that already uses JMS.
Ken
On Mar 31, 2006, at 12:28 PM, James Cicenia wrote:
Hello -
Now that we went multiple instances, we are having refresh
problems and since this is a multi-user type application our
customer are now complaining. Basically, changes in one
instance are not reflected in the other.
So, I perused the list and found WHChangeNotification as the
magic answer. I downloaded it, made it into a framework in
Eclipse, and imported it, set the configurations carefully,
and have uploaded it to dev for testing.
No change in behavior!
Is there a magic step I am missing?
Thanks
James Cicenia
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