private synchronized NameValueMap getCachedAttributes(ObjectName objName, Set<String> attrNames)
     throws InstanceNotFoundException, ReflectionException, IOException {
   NameValueMap values = cachedValues.get(objName);
   if (values != null && values.keySet().containsAll(attrNames)) {
     return values;
   }
   attrNames = new TreeSet<String>(attrNames);
   Set<String> oldNames = cachedNames.get(objName);
   if (oldNames != null) {
     attrNames.addAll(oldNames);
   }
   values = new NameValueMap();
   final AttributeList attrs =
       conn.getAttributes(objName, attrNames.toArray(new String[attrNames.size()]));
   for (Attribute attr : attrs.asList()) {
     values.put(attr.getName(), attr.getValue());
   }
   cachedValues.put(objName, values);
   cachedNames.put(objName, attrNames);
   return values;
 }
  private static boolean test(String proto, MBeanServer mbs, ObjectName on) throws Exception {
    System.out.println("Testing for protocol " + proto);

    JMXConnectorServer cs;
    JMXServiceURL url = new JMXServiceURL(proto, null, 0);
    try {
      cs = JMXConnectorServerFactory.newJMXConnectorServer(url, null, mbs);
    } catch (MalformedURLException e) {
      System.out.println("System does not recognize URL: " + url + "; ignoring");
      return true;
    }
    cs.start();
    JMXServiceURL addr = cs.getAddress();
    JMXConnector client = JMXConnectorFactory.connect(addr);
    MBeanServerConnection mbsc = client.getMBeanServerConnection();
    Object getAttributeExotic = mbsc.getAttribute(on, "Exotic");
    AttributeList getAttrs = mbsc.getAttributes(on, new String[] {"Exotic"});
    AttributeList setAttrs = new AttributeList();
    setAttrs.add(new Attribute("Exotic", new Exotic()));
    setAttrs = mbsc.setAttributes(on, setAttrs);
    Object invokeExotic = mbsc.invoke(on, "anExotic", new Object[] {}, new String[] {});
    MBeanInfo exoticMBI = mbsc.getMBeanInfo(on);

    mbsc.setAttribute(on, new Attribute("Exception", Boolean.TRUE));
    Exception getAttributeException, setAttributeException, invokeException;
    try {
      try {
        mbsc.getAttribute(on, "Exotic");
        throw noException("getAttribute");
      } catch (Exception e) {
        getAttributeException = e;
      }
      try {
        mbsc.setAttribute(on, new Attribute("Exotic", new Exotic()));
        throw noException("setAttribute");
      } catch (Exception e) {
        setAttributeException = e;
      }
      try {
        mbsc.invoke(on, "anExotic", new Object[] {}, new String[] {});
        throw noException("invoke");
      } catch (Exception e) {
        invokeException = e;
      }
    } finally {
      mbsc.setAttribute(on, new Attribute("Exception", Boolean.FALSE));
    }
    client.close();
    cs.stop();

    boolean ok = true;

    ok &= checkAttrs("getAttributes", getAttrs);
    ok &= checkAttrs("setAttributes", setAttrs);

    ok &= checkType("getAttribute", getAttributeExotic, Exotic.class);
    ok &= checkType("getAttributes", attrValue(getAttrs), Exotic.class);
    ok &= checkType("setAttributes", attrValue(setAttrs), Exotic.class);
    ok &= checkType("invoke", invokeExotic, Exotic.class);
    ok &= checkType("getMBeanInfo", exoticMBI, ExoticMBeanInfo.class);

    ok &= checkExceptionType("getAttribute", getAttributeException, ExoticException.class);
    ok &= checkExceptionType("setAttribute", setAttributeException, ExoticException.class);
    ok &= checkExceptionType("invoke", invokeException, ExoticException.class);

    if (ok) System.out.println("Test passes for protocol " + proto);
    return ok;
  }