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From Carsten Ziegeler <cziege...@apache.org>
Subject Re: EventAdmin Asynchronous/Parallel EventHandler
Date Tue, 24 Jan 2012 09:55:15 GMT
Hi,

we haven't implemented this feature yet but will do once the final
spec is publically available.

I've written a new implementation of the event admin which is in the
felix sandbox atm, this one is significanlty faster than the old
implementation from trunk.

Regards
Carsten

2012/1/18 DBinSD <cdiebner@gmail.com>:
>
> Thanks Holger, this is exactly the info I was looking for.  It sounds like
> the Async Unordered Events might get me the performance I was looking for
> (though the implications of 'unordered' events might be a problem in some
> applications).  I will keep an eye out for an implementation of this
> feature.
>
> Thanks again
> Chris
>
>
>
> Holger Hoffstätte-4 wrote:
>>
>> On 18.01.2012 03:35, DBinSD wrote:
>>> Does the felix implementation of the EventAdmin service support the
>>> delivery
>>> of events, asynchronously and in parallel to multiple listeners at once?
>>> It
>>
>> This was addressed as part of RFC 157 ("Updates to EventAdmin") sometime
>> in 2010 and accepted, though I don't remember offhand what the
>> implementation status was/is. IIRC it was part of 4.3.
>>
>> The solution added a set of constants that express basic delivery
>> behaviour/expectations. Not really enforceable end-to-end QoS constraints
>> (which are impossible in Java anyway) but better than nothing.
>>
>> --snip--
>>
>> 5.2    Asynchronous Unordered Events
>>
>> The following constants are added to EventConstants. This allows an Event
>> Handler to indicate that it is willing to relax the event ordering
>> requirements so that Event Admin can optimize delivery.
>>
>> String EVENT_DELIVERY = "event.delivery"
>> Service Registration property specifying the delivery qualities requested
>> by an Event Handler service.
>>
>> Event handlers MAY be registered with this property. Each value of this
>> property is a string specifying a delivery quality for the Event handler.
>>
>> The value of this property must be of type String, String[], or
>> Collection<String>.
>>
>> Since:
>>         1.3
>> See Also:
>>         DELIVERY_ASYNC_ORDERED
>>         DELIVERY_ASYNC_UNORDERED
>>
>> String DELIVERY_ASYNC_ORDERED = "async.ordered"
>> Event Handler delivery quality value specifying the Event Handler requires
>> asynchronously delivered events be delivered in order. Ordered delivery is
>> the default for asynchronously delivered events.
>>
>> This delivery quality value is mutually exclusive with
>> DELIVERY_ASYNC_UNORDERED. However, if both this value and
>> DELIVERY_ASYNC_UNORDERED are specifed for an event handler, this value
>> takes precedence.
>>
>> Since:
>>         1.3
>> See Also:
>>         EVENT_DELIVERY
>>
>> String DELIVERY_ASYNC_UNORDERED = "async.unordered"
>> Event Handler delivery quality value specifying the Event Handler does not
>> require asynchronously delivered events be delivered in order. This may
>> allow an Event Admin implementation to optimize asynchronous event
>> delivery by relaxing ordering requirements.
>>
>> This delivery quality value is mutually exclusive with
>> DELIVERY_ASYNC_ORDERED. However, if both this value and
>> DELIVERY_ASYNC_ORDERED are specifed for an event handler,
>> DELIVERY_ASYNC_ORDERED takes precedence.
>>
>> Since:
>>         1.3
>>
>> See Also:
>>         EVENT_DELIVERY
>>
>> --snip--
>>
>> Also see
>> http://stackoverflow.com/questions/7018762/when-to-use-osgi-eventadmin-and-when-not
>> for BJ's official answer.
>>
>> hope this helps
>> Holger
>>
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>>
>>
>
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>
>
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-- 
Carsten Ziegeler
cziegeler@apache.org

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