[vbox-dev] IEvent not triggering on some events ... ?

Klaus Espenlaub klaus.espenlaub at oracle.com
Fri Mar 25 13:11:20 GMT 2011

Hi Joe,

see comments inline

On 24.03.2011 20:23, Nikolay Igotti wrote:
> Hi Joseph,
> I think you just hit an issue (aka bug) in VirtualBox - certain events
> not triggered when they should or could be triggered.
> The only solution is to implement those.
> Klaus, what do you think about when shall events firing happen, do you
> have bit of time to look on that?
> Thanks,
> Nikolay
> 24.03.2011 17:45, Joseph Smith пишет:
>> Hi,
>> Was wondering if anyone has had an opportunity to give this some
>> thought and maybe have some suggestions or ideas to offer.
>> Thanks,
>> Joe
>> ------------------------------------------------------------------------
>> *From:* Joseph Smith <joseph1962smith at yahoo.com>
>> *To:* vbox-dev at virtualbox.org
>> *Sent:* Sat, March 19, 2011 11:11:12 PM
>> *Subject:* [vbox-dev] IEvent not triggering on some events ... ?
>> VBox Ver: 4.0.0 and 4.0.4
>> Hosts: Win XP, openSuSE 11.2, Mac OS 10.6
>> Guests: various
>> I am using the VirtualBox webservice PHP APIs (via
>> vboxServiceWrappers.php). With the release of 4.0.x, I shifted my
>> solution approach from a heavy polling approach to the light-weight
>> IEvent approach.
>> It appears there are some key events that are not being triggered. For
>> example, I do not receive the IMediumChanged and IMediumRegistered
>> events among some lesser important events that I don't quite need just
>> yet (e.g: IRuntimeErrorEvent).

IMediumRegistered (an IVirtualBox event) indeed is never triggered. Will 
look into getting this fixed for 4.0.6. No promises.

IMediumChanged (an IConsole event) is triggered, but only when a VM is 
running. You need to register with the Console object of the running VM, 
not with the local Console object which is associated with every session...

I can see no problem with IRuntimeErrorEvent (also an IConsole event) 
either, it should be fired for every runtime error encountered by a 
running VM. Sure you're using the right Console object?

>> I do consistently receive the OnMachineRegistered,
>> OnMachineDataChanged, OnMachineStateChanged, OnGuestPropertyChanged,
>> OnEventSourceChanged, OnSessionStateChagned events and a few others.
>> When I register the listner (EventSource::RegisterListener), I listen
>> for 'Any' events as described in the documentation and after handling
>> each event, I call EventSource::EventProcessed.
>> Does ver 4.0.x fire IMedium events ? Any suggestions of what I might
>> be able to look for to determine what I might be doing incorrectly?

Half of them yes, half of them no.

>> Oh ... my application runs for weeks at a time without being restarted
>> and polls about every 3 seconds for events. There are never any events
>> that are not processed. Of the events I listed above, I continue to
>> receive those events when actions trigger them ... just not getting
>> many of the others listed in the enumerated VBoxEvent Type.

Again sounds like a description of the symptoms of not registering with 
the Console events correctly. They do not show up for the VirtualBox 
event source.


>> Any suggestions are welcome.
>> Thanks,
>> Joe
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>> vbox-dev at virtualbox.org
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