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From Armin Waibel <arm...@apache.org>
Subject Re: Detecting Metadata Changes
Date Tue, 14 Sep 2004 14:39:08 GMT
Hi Brian,

Brian McCallister wrote:
> I am working on a distributed cache implementation which transmits 
> dirties only, and transmits just the table and pk information (over JMS 
> (using ActiveCluster)) so that non-OJB clients can dirty caches.
> 
> A problem I am having is how to detect runtime changes of metadata. 

Think I don't get your point. In 1.1 OJB use several cache if necessary. 
So if e.g. someone use the same connection with different 
metadata-model, OJB use different cache instances and transmit dirties 
autonomous. The caches register each other as 'InvalidationListener' and 
if cache A update an object it invalidates this object in cache B (and 
vice versa).

So your Distributed ObjectCache implementation shouldn't have to think 
about it.

regards,
Armin


> Searching the entire repository for every dirty even received is a 
> terrible option, imho, but caching the descriptor information is risky 
> as heck as there is no mechanism for detecting runtime metadata changes 
> of which I am aware.
> 
> Is there one I don't know about?
> 
> If not the workaround is simply to tell anyone using this cache that 
> they need to call a static method (which will broadcast the change 
> notification) when they make runtime metadata changes if they are using 
> this cache.
> 
> Thanks,
> 
> Brian
> 
> 
> 
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