On the SDN JMX forum thread HtmlAdaptorServer Available with Java 6 JMX 1.4 Reference Implementation?, Daniel Fuchs pointed out that the optional HTML/HTTP adapter formerly available with the JMX 1.2 reference implementation is now available as part of the Project OpenDMK.
The HtmlAdaptorServer is not the only optional JMX feature included with Project OpenDMK. Another useful feature is OpenDMK's support for the JMXMP Connector (implemented in
jmxremote_optional.jar). As documented in the Java API documentation for package
javax.management.remote, the JMXMP Connector is an optional part of the JMX Remote API specification and is thus not included in the Java SE 6 JMX offerings.
An an alternate JMX implementation, MX4J also offers some of the optional features in the Java Management Extensions specifications.