JMX support for Clojure

Usage
  (require '[clojure.java.jmx :as jmx])

What beans do I have?

  (jmx/mbean-names "*:*")
  -> #<HashSet [java.lang:type=MemoryPool,name=CMS Old Gen,
                java.lang:type=Memory, ...]

What attributes does a bean have?

  (jmx/attribute-names "java.lang:type=Memory")
  -> (:Verbose :ObjectPendingFinalizationCount
      :HeapMemoryUsage :NonHeapMemoryUsage)

What is the value of an attribute?

  (jmx/read "java.lang:type=Memory" :ObjectPendingFinalizationCount)
  -> 0
  (jmx/read "java.lang:type=Memory" [:HeapMemoryUsage :NonHeapMemoryUsage])
  ->
  {:NonHeapMemoryUsage
    {:used 16674024, :max 138412032, :init 24317952, :committed 24317952},
   :HeapMemoryUsage
    {:used 18619064, :max 85393408, :init 0, :committed 83230720}}

Can't I just have *all* the attributes in a Clojure map?

  (jmx/mbean "java.lang:type=Memory")
  -> {:NonHeapMemoryUsage
       {:used 16674024, :max 138412032, :init 24317952, :committed 24317952},
      :HeapMemoryUsage
       {:used 18619064, :max 85393408, :init 0, :committed 83230720},
      :ObjectPendingFinalizationCount 0,
      :Verbose false}

Can I find and invoke an operation?

  (jmx/operation-names "java.lang:type=Memory")
  -> (:gc)
  (jmx/invoke "java.lang:type=Memory" :gc)
  -> nil

What about some other process? Just run *any* of the above code
inside a with-connection:

  (jmx/with-connection {:host "localhost", :port 3000}
    (jmx/mbean "java.lang:type=Memory"))
  -> {:ObjectPendingFinalizationCount 0,
      :HeapMemoryUsage ... etc.}

Can I serve my own beans?  Sure, just drop a Clojure ref
into an instance of clojure.java.jmx.Bean, and the bean
will expose read-only attributes for every key/value pair
in the ref:

  (jmx/register-mbean
     (create-bean
     (ref {:string-attribute "a-string"}))
     "my.namespace:name=Value")