JSR262 (JMX over WS-Management) public review

If you care about exposing or accessing MBeans via WS-Management, now is a good time to read the public review draft of the JSR262 spec.

JSR262 is very much on the “manageability” side of the “manageability vs. management integration” chasm, which is not the most exciting side to me. But more commonality in manageability protocols is good, I guess, and this falls inside the WS-Management window of opportunity so it may help tip the balance.

There is also a nice white paper which does a nice job of retracing the history from JMX to JMX Remote API to JSR 262 and the different efforts along the way to provide access to the JMX API from outside of the local JVM. The white paper is actually too accurate for its own good: it explains well that models and protocols should be orthogonal (there is a section titled “The Holy Grail of Management: Model, Data and Protocol Independence”) which only highlights the shortcomings of JSR262 in that regard.

In a what looks from the outside like a wonderful exercise of “when you have a hammer” (and also “when you work in a hammer factory” like the JCP), this whole Java app management effort has been API-driven rather than model-driven. What we don’t get out of all this is a clearly defined metamodel and a set of model elements for Java apps with an XML serialization that can be queried and updated. What we do get is a mapping of “WS-Management protocol operations to MBean and MBean server operations” that “exposes JMX technology MBeans as WS-Management resources”.

Yes it now goes over HTTP so it can more easily fool firewalls, but I am yet to see such a need in manageability scenarios (other than from hackers who I am sure are very encouraged by the development). Yes it is easier for a non-Java endpoint to interact with a JSR262 endpoint than before but this is an incremental improvement above the previous JMX over RMI over IIOP because the messages involved still reflect the underlying API.

Maybe that’s all ok. There may very well not be much management integration possible at the level of details provided by JMX APIs. Management integration is probably better served at the SCA and OSGi levels anyway. Having JSR262 just provide incremental progress towards easier Java manageability by HP OVO and the like may be all we should ask of it. I told some of the JSR262 guys, back when they were creating their own XML over HTTP protocol to skirt the WS-Management vs. WSDM debate, that they should build on WS-Management and I am glad they took that route (no idea how much influence my opinion had on this). I just can’t get really excited about the whole thing.

All the details on the current status of JSR262 on Jean-Francois Denise’s blog.