RE: [Springframework-developer] Spring JMX Query

[Keith D. <kd...@cs...>]

>As for defining the mgmt interface in code - aren't 
>we getting into the realms of recreating what JMX does already?

No, JMX employs different strategies for getting to the same thing; that is,
a configured management descriptor (MBeanInfo) describing a manageable
object.

As you know, one of these strategies is reflection: you have your bean
implement a "*MBean" interface and JMX uses reflection to generate a new
MBeanInfo descriptor when your bean is registered with the MBeanServer.  But
this has limitations: there is only so much you can find out from
reflection.  And MBeanInfos are not shared.

Another strategy involves creating populated MBeanInfo instances ahead of
time, to support dynamic mbeans and model mbeans.  You specify the
descriptor separately and at runtime a DynamicMBean or RequiredModelMBean
proxy connects the descriptor with the managed bean instance.  In these
cases you're not required to define a strongly typed management interface at
all.

I prefer strongly typed POJO management interfaces combined with
descriptive, configurable management metadata that can be shared between
POJO implementations that are of the same _logical type_.  For example,
let's say we have a logical type, like the JSR-77 "Service".  Such a type
can be expressed via a POJO management interface -- Service --, with methods
like start(), and stop().  Such an interface might also extend a base
management interface used by all managed entities, like
"ManagedSystemElement".

In this example, I'd prefer my POJOs to implement Service, and I'd prefer to
have a shared "Service MBeanInfo" instance providing metadata about the
attributes, operations, and notifications instrumented by all services.  At
runtime, I'd expect my MBean adapter to note my bean is a "Service" and
locate the right MBeanInfo descriptor for registration in an MBeanServer as
a ModelMBean.

One way of providing MBeanInfo information is XML, but I'd just assume have
it defined in java-code using annotations---cutting out the need for
reflection.

My only caveat with such a solution is many times you want a much more
generically typed management model exposed to _clients_: e.g with strings,
primitives, object names, and generic tabular/composite data structure types
ONLY, while the _interal_ workings of your managed beans want a richly typed
model to work with.  This is because you can't often make the assumption all
your management clients have access to your classes, or that they're even
all java.  So I can see a need for our JMX support to create translators
that map between a richly typed model to a more generic management model.

Keith


Keith

-----Original Message-----
From: spr...@li...
[mailto:spr...@li...] On Behalf Of
Rob Harrop
Sent: Monday, November 29, 2004 11:44 AM
To: spr...@li...
Subject: Re: [Springframework-developer] Spring JMX Query

Keith,

I have a passing familiarity with Commons Modeler and I understand what 
you mean about the inheritance. However, it should be more than possible 
to allow for mgmt interface inheritance using XML - there is no reason 
it couldn't be done. As for defining the mgmt interface in code - aren't 
we getting into the realms of recreating what JMX does already? Add to 
that I'm not sure how all the different metadata utils such as Commons 
Attributes handle inheritance - I'll need to check that out.

Rob

Keith Donald wrote:

>Rob,
>
>Commons-modeler has such a format for defining model mbean metadata in XML,
>and an associated Registry allowing MBeanInfo definitions to be indexed by
>'type' (essentially a logical management class identifier) and shared
>between different MBean instances (perhaps backed by different POJO
>implementations.)
>
>In my experience where the format breaks down is with MBean inheritance.
It
>would extremely helpful if you could define base management interfaces with
>metadata and be able to extend to derive more specific management types.
>For anyone whose ever done any network management work, this is important.
>Look at JSR-77, it's basically defines a management hierarchy as well.
>
>Do we have the ability to define management interfaces in java code (with
an
>inheritance hierarchy), markup those interfaces with management metadata,
>and generate corresponding MBeanInfos at runtime that can be shared?  I
>wonder if that would work.  I'd much rather apply attributes to the
>management interfaces than the managed beans themselves...
>
>Keith
>
>-----Original Message-----
>From: spr...@li...
>[mailto:spr...@li...] On Behalf Of
>Rob Harrop
>Sent: Monday, November 29, 2004 11:18 AM
>To: spr...@li...
>Subject: [Springframework-developer] Spring JMX Query
>
>All,
>
>I have raised a new issue on JIRA related to Spring JMX and I would like 
>your input: http://opensource.atlassian.com/projects/spring/browse/SPR-498.
>
>Rob
>
>
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