Committed rev 1 of this feature under revision 981719. Includes base support for an instrumentation manager, instrumentation providers, and instruments. In addition, there are the beginnings of instruments for data cache, query cache, and prepared query cache and a JMX platform MBean provider. Updates, fixes, doc and more tests to follow...
@Pinaki - I answered your questions several days ago, but the comment didn't get make it into the JIRA for whatever reason.
1) Platform MBean supported included with the JDK provides remote connectivity with a very small amount of configuration. The JMX provider I'm working on is based on that. A provider for another remote-able technology could be plugged in as well.
2) Initially, the goal will be to provide simple callable MBean API interfaces. A control or widget can use standard JMX calls to get metrics from various sources.
3) The base "enablement" will go into OpenJPA. Tools built on top of the instrumentation should go elsewhere. Most likely devtools.