EVALUATION

Cascading is a special case of a more general notion, that of constructing a hierarchy of MBeanServers.  The idea is that within an MBeanServer mbs1, you can specify that another MBeanServer mbs2 appears as "mbs2//", for example.  So if you do mbs1.getAttribute("mbs2//d:k=v", "Foo"), that ends up calling mbs2.getAttribute("d:k=v").  mbs2 can be any object that implements the MBeanServer interface.  It can be a reference to a remote MBeanServer via a connector, which is the basis for building cascading.  It can be an object that constructs the referenced MBeans on demand, which is the basis for Virtual MBeans (see CR 5108739).

"mbs2//" is called a "namespace", and is created by registering an MBean of the class JMXNamespace (or a subclass), with the special ObjectName "mbs2//:type=JMXNamespace".  The JMXNamespace MBean is given an instance of MBeanServer that is the MBeanServer that appears as "mbs2//...", mbs2 in the example.

The characters "//" in the domain part of an ObjectName indicate a path in the hierarchy.  Previously, mbs1.getAttribute("mbs2//d:k=v", "Foo") just looked for an MBean of that name in mbs1.  Now, it looks for a namespace called "mbs2//" and does getAttribute("d:k=v", "Foo") within it.

The meaning of * in an ObjectName is adjusted so that it does not match the separator "//".  Therefore if you call mbs1.queryNames(new ObjectName("*:*"), null), you will not see the MBeans within mbs2, whose names begin with "mbs2//".  On the other hand, if you call mbs1.queryNames(new ObjectName("mbs2//*:*"), null), you *will* see those MBeans, for example "mbs2//d:k=v".

For further details, consult the documentation of package javax.management.namespaces in the documentation reachable from the JSR 255 pages at <http://jcp.org/en/jsr/detail?id=255>.
                                     

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Support "mounting" one or more subagents into a master agent.