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From Noah Vihinen <nvihi...@maven.net>
Subject Re: Observation within a Cluster
Date Wed, 07 Mar 2007 13:45:16 GMT
We can leverage "isExternal()" in the short-term.  Are there any  
plans in place to implement the "deliver-exactly-once"  
functionality?  Most use-cases I can think of for JCR observation  
(other than JCR implementation internals such as cluster node cache  
synchronization) would work more efficiently with the "deliver- 
exactly-once" functionality.

Thanks,
Noah

On Mar 7, 2007, at 1:46 AM, Dominique Pfister wrote:

> Hi again,
>
> Sorry, I made a mistake: of course, isExternal() returns "true" for
> all but one cluster node, namely the active one.
>
> Kind regards
> Dominique
>
> On 3/7/07, Dominique Pfister <dominique.pfister@day.com> wrote:
>> Hi Noah,
>>
>> Jackrabbit's implementation of javax.jcr.observation.Event, namely
>>
>>   org.apache.jackrabbit.core.observation.EventImpl
>>
>> has a public method called "isExternal()" that will return "true" if
>> your EventListener is registered in the "active" cluster node, i.e.
>> the one making the change, and "false" for all the passive ones. May
>> be that helps?
>>
>> Apart from that, it is currently not possible to register a
>> "deliver-exactly-once" EventListener in a cluster.
>>
>> Kind regards
>> Dominique
>>
>> On 3/6/07, Noah Vihinen <nvihinen@maven.net> wrote:
>> > Suppose I would like to construct an EventListener that makes some
>> > persistent change to the repository as a result of some type of  
>> node
>> > being added.  For example, the event listener may create a new node
>> > of a different type, or set some properties.  How do I ensure that
>> > only one JCR server within the cluster processes the NODE_ADDED
>> > event, so the resultant persistent change only happens once?
>> >
>> > Is the only solution to add logic to my event listener to determine
>> > whether or not it should proceed with the persistent change?
>> > Further, if this is the case, are there any plans to make event
>> > handling more efficient in the future, so only one node in the
>> > cluster will receive notification of a particular event?
>> >
>> > Thanks,
>> > Noah
>> >
>>


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