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From Raman Gupta <rocketra...@gmail.com>
Subject Re: RFC on proposal to allow hooks into Karaf shutdown
Date Sun, 02 Dec 2012 20:05:42 GMT
On 12/02/2012 02:44 PM, Guillaume Nodet wrote:
> As I explained, I don't think that's possible.
> The Main class is only responsible for shutting the framework when using
> the bin/stop script and it does not have anything to do when shutting down
> the framework from the inside using osgi:shutdown (or anything calling stop
> on the system bundle).

It's not possible or its not optimal? Presumably, each place in the
Karaf source that initiates a framework shutdown could place a
"FrameworkShutdownStarted" event onto the OSGi EventAdmin?

Perhaps this is also an opportunity to refactor the shutdown code and
move all the framework shutdown related stuff into one place.

> Another way to ensure that the listener will be called first would be to
> give to its bundle a very low start level so that it's listener will be
> registered first.

True, but this is a bit messy. The bundle that I want to act on the
event uses Spring-DM, so I can't start it before Spring-DM. I could
pull out just this functionality into a separate bundle, but its a bit
messy. Nevertheless, it seems to be the only option now.

Regards,
Raman


> 
> On Sun, Dec 2, 2012 at 5:47 PM, Raman Gupta <rocketraman@gmail.com> wrote:
> 
>> On 11/30/2012 01:56 AM, Jean-Baptiste Onofré wrote:
>>> On 11/30/2012 05:15 AM, Raman Gupta wrote:
>>>> I sent this to the users mailing list, but it probably belongs more on
>>>> dev. I'd like to hook into the Karaf shutdown process at a higher
>>>> level than the OSGi bundle shutdown. The bundle shutdown starts
>>>> prematurely shutting down services and such that are necessary for
>>>> work in progress to complete.
>>>
>>> it's more or less already available. I'm not against enhancement
>>> around that, but, maybe it's redundant with the following.
>>>
>>> You can more or less already do something like this using a
>>> SynchronousBundleListener (you will received the STOPPING event on
>>> bundleId 0, so the framework), or a FrameworkListener (to hook on
>>> the framework).
>>
>> I think there might still be some room for improvement here...
>>
>> The problem I'm having is that Spring-DM also hooks a
>> SynchronousBundleListener into the OSGi framework. Because Spring-DM's
>> listener is registered first, and executes first, it goes ahead and
>> shuts down all my bundles *before* my listener gets a chance to do
>> anything useful.
>>
>> (As an aside, for a STOPPING/STOPPED event, IMO it would make sense to
>> execute listeners in reverse order i.e. the higher level listeners
>> registered later should be executed first, rather than last. However,
>> I guess this wasn't specified in the OSGi spec so nothing can be done
>> there. There also appears to be no way specified to control the order
>> explicitly.)
>>
>> So... I still think it would be useful if Karaf provided an event or
>> hook for just before a shutdown begins. Thoughts?
>>
>> Regards,
>> Raman
>>

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