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From "Leo Simons" <m...@leosimons.com>
Subject RE: MBeanComponentManager ???
Date Thu, 14 Jun 2001 05:56:29 GMT
> > > At 11:11 PM 6/12/01 -0600, Mircea Toma wrote:
> > > >The ComponentManager will use internally a MBeanServer to lookup
> MBean-s
> > > >using role names which in this case will be the MBean's object
> > > name. Also it
> > > >uses the MBeanServer to manage Component/MBean lifecycle by calling
> > > >mBeanServer.isInstaceOf(...) in order to learn what to do with it.
> >
> > I'm all for filling gaps in Java specs, but this sounds like a
> > 'modification'
> > which is probably not something we should do here at Apache. But that's
> not
> > my primary concern.
> >
> > Conceptually, the MBeanServer is there to expose a management interface
> > to humans / console apps / cronjobs / init scripts / whatever. the JMX
> > impl(s) are written to support this. When you use an MBeanSever as the
> > component manager, you loose inversion of control (probably),
> ......why??

The MBeanServer manages MBeans, which are not Components. Using it to
manage Components is a 'hack'.

> > The ComponentManager needs to be speedy, JMX isn't (doesn't have to be).
> .....yes, but it will be a distributed ComponentManager if the
> MBeanServer is
> distributed.

In distributed envs it will definately be useful. It's still better to
code your DistributedComponentManager from scratch tho =)

> > I think that what should be exposed for management (by phoenix) are
> > ServerApplications. Finer graining is inappropriate here. And of course,
> > life cycle management for those could be handled with a MBeanServer
> > (something we've talked about but have yet to decide on).
> >
> > Finally, making the assumption {MBean object name} == {role name} may
> > cause problems in some apps; it probably violates some
> framework contract.
> ......then maybe the framework contracts are to tight!

I don't think so. We don't specify dots as separators yet, the JMX spec
does. I have to look up the details but it seems possible to have role names
that the MBeanServer won't expect.

Conclusion: if you need a distributed system, using JMX definately saves you
a lot of time (but it still feels 'hacky' to me). Phoenix is usually
as lower level than that, so it should not use JMX for comp management.


Leo Simons

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