Hi Alasdair,
Am Donnerstag, den 07.07.2011, 22:25 +0100 schrieb Alasdair Nottingham:
> On 5 July 2011 13:15, Felix Meschberger <[email protected]> wrote:
>
> > Hi,
> >
> > Am Dienstag, den 05.07.2011, 12:50 +0100 schrieb Alasdair Nottingham:
> > > Hi,
> > >
> > > This is amazing timing. I've hit exactly this problem while writing the
> > code
> > > for ARIES-686.
> >
> > ;-)
> >
> > >
> > > I agree with your proposal, although when you describe 2 when you say
> > you'll
> > > look to see if the MBean implements a *MBean interface do you mean you
> > will
> > > use reflection, or look at the interfaces published into the service
> > > registry? I think I'd like it to be the latter.
> >
> > If I drop the "(objectClass=*MBean)" term from the filter, I don't care
> > for what is actually registered and the only means remaining is the
> > jmx.objectname service property.
> >
> > Thus I use reflection.
> >
> > In any case, it seems to be essential to not require the *MBean
> > interface to be exported by the MBean bundles (and consequently not to
> > import them in the Whiteboard support bundle.
> >
> > But I could live well with using "(objectClass=*MBean)" (instead of
> > (jmx.objectname=*)) as the filter and inspect the objectClass for the
> > MBean interface. This would be closer to my original code ;-)
> >
> >
> I'm wondering if we should look at the objectClass parameter in combination.
> I might be worrying about a weird edge case, but I could see this happening.
> Imagine the following object:
>
> class MyManageableObject implements PoolingMBean, LifecycleMBean
> {
> }
>
> this, I think, is not normal for StandardMBeans, but with the current 702
> fix MyManageableObject could be registered using PoolingMBean, and we
> publish using LifecycleMBean. I'm just mainly thinking about using
> objectClass to aid disambiguation. What do you think?
Good point. How about combining these approaches ?
* inspect objectClass property and if there is an *MBean in
there use it
* otherwise revert to reflection
On the other hand, if neither PoolingMean nor LifecycleMBean extend the
DynamicMBean interface it looks kind of weird anyway .. To my knowledge
JMX only supports a single *MBean interface and does not combine,
right ?
Regards
Felix
>
> Alasdair
>
>
> > Regards
> > Felix
>
>
> > >
> > > Thanks
> > > Alasdair
> > >
> > > On 5 July 2011 08:03, Felix Meschberger <[email protected]> wrote:
> > >
> > > > Hi,
> > > >
> > > > I think I missed a problematic point: Standard MBeans registered with
> > > > the <classname>MBean pattern require that the implementation and the
> > > > MBean interface reside in the same package. Not very practical for OSGi
> > > > where the MBean interface of course must be exposed.
> > > >
> > > > So, I think we should probably drop the requirement for the MBean to
> > > > exposed with an interface matching "*MBean".
> > > >
> > > > I still don't like to require the MBeanRegistration interface to be
> > used
> > > > in the registration. It is kind of like a helper interface not
> > > > identifying the primary purpose of the MBean.
> > > >
> > > > How about changing the filter to just be (jmx.objectname=*). If the
> > > > actual property is an empty string (or is not a single-value String),
> > > > the object is expected to implement the MBeanRegistration interface. If
> > > > not, an ERROR level message is logged and the service ignored.
> > > >
> > > > Now for the actual service object being registered:
> > > > 1 if the service implements the DynamicMBean interface, use it
> > > > right away as the object to register
> > > > 2 otherwise see whether the object implements an interface whose
> > > > name matches the <simple-class-name>MBean pattern. If so, wrap
> > > > the object with a StandardMBean class using the interface as
> > > > the MBean interface (and log this at INFO level)
> > > > 3 otherwise log an ERROR level message and ignore the service
> > > >
> > > > Note that using the simple-class-name in the second step is a deviation
> > > > from the JMX Spec which requires the MBean interface to reside in the
> > > > same package as the MBean object.
> > > >
> > > > To make this work, the mbeanTracker ServiceTracker must be modified to
> > > > actually track all services (this is a generic bug to be fixed,
> > > > ARIES-700).
> > > >
> > > > Regards
> > > > Felix
> > > >
> > > > Am Montag, den 27.06.2011, 20:45 +0100 schrieb Alasdair Nottingham:
> > > > > On 27 June 2011 20:19, Felix Meschberger <[email protected]> wrote:
> > > > >
> > > > > > Hi,
> > > > > >
> > > > > > Am Montag, den 27.06.2011, 20:07 +0100 schrieb Alasdair Nottingham:
> > > > > > > Hi,
> > > > > > >
> > > > > > > I've been looking at the way the whiteboard implementation works
> > and
> > > > I
> > > > > > was
> > > > > > > wondering if it would make sense to change the way it detects
> > mbeans.
> > > > > > > Currently it detects them by looking for:
> > > > > > >
> > > > > > > (objectClass=*MBean). The impl then needs to either have a
> > > > jmx.objectname
> > > > > > > property, or it needs to be javax.management.MBeanRegistration
> > > > extension.
> > > > > > I
> > > > > >
> > > > > > My idea for requiring some MBean interface is that it makes
> > > > registration
> > > > > > extremely easy:
> > > > > >
> > > > >
> > > > > I agree with this goal.
> > > > >
> > > > >
> > > > > >
> > > > > > - either it is a DynamicMBean (or some extension thereof) service
> > > > > > - or it is an interface with MBean suffix which as per the spec
> > > > > > defines the MBean interface for the bean
> > > > > >
> > > > >
> > > > > OK.
> > > > >
> > > > >
> > > > > >
> > > > > > For the registration then only an ObjectName is required which can
> > be
> > > > > > provided as a service registration property or by implementing the
> > > > > > MBeanRegistration interface (which is also similarly used in the
> > spec
> > > > > > IIRC).
> > > > > >
> > > > > >
> > > > > > > think it would make more sense for a service filter like this:
> > > > > > >
> > > > > > >
> > (|(objectClass=javax.management.MBeanRegistration)(jmx.objectname=))
> > > > > > >
> > > > > > > what do people think?
> > > > > >
> > > > > > By going that way, you will solve the second issue with the filter
> > but
> > > > > > you then have an MBean where you have to find out how to be able to
> > > > > > register (or I may be missing something in more recent JMX specs).
> > > > > >
> > > > > > But then, I don't think we should require the MBeanRegistration
> > > > > > interface as a service interface. Sounds kind of incorrect.
> > > > > >
> > > > >
> > > > > I think if it needs to be an MBeanRegistration then we should require
> > the
> > > > > object to be advertised as an MBeanRegistration. Not putting
> > > > > MBeanRegistration on a service and then relying on it being one is
> > dodgy
> > > > in
> > > > > OSGi. Sure in most cases it'll work, but if someone decides to use
> > > > service
> > > > > hooks to insert a proxy they will probably get this wrong, also you
> > can't
> > > > > make use of the service registry to get the class space consistency.
> > > > >
> > > > > Overall based on this I think a more correct filter would be this:
> > > > >
> > > > >
> > > >
> > (&(objectClass=*MBean)(|(objectClass=javax.management.MBeanRegistration)(jmx.objectname=)))
> > > > >
> > > > >
> > > > > >
> > > > > > All in all, I think the original filter sounds more correct.
> > > > > >
> > > > > > Regards
> > > > > > Felix
> > > > > >
> > > > > > > Alasdair
> > > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > >
> > > > >
> > > >
> > > >
> > > >
> > >
> > >
> >
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> >
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>
