Jmx4r metaprogramming

Ruby
1

Hi,

I am attempting to use the jmx4r library to set an MBean attribute.

From here: JMX the Ruby way with jmx4r

It looks like jmx4r uses metaprogramming techniques which disposes
with JMX method calls.

However, I am receiving a

method_missing': undefined method active =’

exception, when I attempt to set the attribute.

require ‘rubygems’
require ‘jmx4r’

include JMX
MBean.establish_connection :host => “xxxxx”, :port => 8999
standby_mbean = MBean.find_by_name
“xxx.jmx.monitors:name=hydra.planb.cps,type=JmsQueueStatsMBeanFactory”
standby_mbean.active # == true
begin
standby_mbean.active = false
ensure
MBean.remove_connection
end

Do I need to explicitly invoke an operation?

Thanks

Aidy

2

aidy wrote:

Hi,

I am attempting to use the jmx4r library to set an MBean attribute.

method_missing': undefined methodactive =’

exception, when I attempt to set the attribute.

This error is strange, there should not be a white space between
‘active’ and ‘=’. The method to set the value should be ‘active=’, not
‘active =’

This may be due to an error in the description of the MBean.
What you can do:

  • check what attributes are exposed by the jmx4r mbean
    irb> standby_mbean.attributes
  • check what is exposed by the Real JMX MBean object:
    irb> JMX::MBean.pretty_print
    “xxx.jmx.monitors:name=hydra.planb.cps,type=JmsQueueStatsMBeanFactory”

In you case, you should see a “Value” attribute which is both readable
and writable.

hope that helps,
jeff

3

Hi Jeff

jmx4r is a pretty useful library.

This error is strange, there should not be a white space between
‘active’ and ‘=’. The method to set the value should be ‘active=’, not
‘active =’

That is a typo, apologies.

This may be due to an error in the description of the MBean.
What you can do:

  • check what attributes are exposed by the jmx4r mbean
    irb> standby_mbean.attributes

standby_mbean.attributes.each { |a | puts a.grep /^ac/ }

=> active

  • check what is exposed by the Real JMX MBean object:
    irb> JMX::MBean.pretty_print
    “xxx.jmx.monitors:name=hydra.planb.cps,type=JmsQueueStatsMBeanFactory”

very nice

In you case, you should see a “Value” attribute which is both readable
and writable.

writable is false and I am an idiot.

I then successfully invoked a JMX operation on the object returned
with MBean#find_by_name

Thanks

Aidy