public void testAttributeHasCorrespondingOperations() throws Exception {
    ModelMBeanInfo info = getMBeanInfoFromAssembler();

    ModelMBeanOperationInfo get = info.getOperation("getName");
    assertNotNull("get operation should not be null", get);
    assertEquals(
        "get operation should have visibility of four",
        (Integer) get.getDescriptor().getFieldValue("visibility"),
        new Integer(4));
    assertEquals(
        "get operation should have role \"getter\"",
        "getter",
        get.getDescriptor().getFieldValue("role"));

    ModelMBeanOperationInfo set = info.getOperation("setName");
    assertNotNull("set operation should not be null", set);
    assertEquals(
        "set operation should have visibility of four",
        (Integer) set.getDescriptor().getFieldValue("visibility"),
        new Integer(4));
    assertEquals(
        "set operation should have role \"setter\"",
        "setter",
        set.getDescriptor().getFieldValue("role"));
  }
  public Object invoke(String method, Object[] arguments, String[] params)
      throws MBeanException, ReflectionException {
    if (method == null)
      throw new RuntimeOperationsException(
          new IllegalArgumentException(
              LocalizedStrings.MX4JModelMBean_METHOD_NAME_CANNOT_BE_NULL.toLocalizedString()));
    if (arguments == null) arguments = new Object[0];
    if (params == null) params = new String[0];

    Logger logger = getLogger();

    // Find operation descriptor
    ModelMBeanInfo info = getModelMBeanInfo();
    if (info == null)
      throw new MBeanException(
          new ServiceNotFoundException(
              LocalizedStrings.MX4JModelMBean_MODELMBEANINFO_IS_NULL.toLocalizedString()));
    if (logger.isEnabledFor(Logger.DEBUG)) logger.debug("ModelMBeanInfo is: " + info);

    // This is a clone, we use it read only
    ModelMBeanOperationInfo operInfo = info.getOperation(method);
    if (operInfo == null)
      throw new MBeanException(
          new ServiceNotFoundException(
              LocalizedStrings.MX4JModelMBean_CANNOT_FIND_MODELMBEANOPERATIONINFO_FOR_OPERATION_0
                  .toLocalizedString(method)));
    if (logger.isEnabledFor(Logger.DEBUG)) logger.debug("Operation info is: " + operInfo);

    // This descriptor is a clone
    Descriptor operationDescriptor = operInfo.getDescriptor();
    if (operationDescriptor == null)
      throw new MBeanException(
          new ServiceNotFoundException(
              LocalizedStrings.MX4JModelMBean_OPERATION_DESCRIPTOR_FOR_OPERATION_0_CANNOT_BE_NULL
                  .toLocalizedString(method)));
    String role = (String) operationDescriptor.getFieldValue("role");
    if (role == null || !role.equals("operation"))
      throw new MBeanException(
          new ServiceNotFoundException(
              LocalizedStrings
                  .MX4JModelMBean_OPERATION_DESCRIPTOR_FIELD_ROLE_MUST_BE_OPERATION_NOT_0
                  .toLocalizedString(role)));
    if (logger.isEnabledFor(Logger.DEBUG))
      logger.debug("Operation descriptor is: " + operationDescriptor);

    // This returns a clone of the mbean descriptor, we use it read only
    Descriptor mbeanDescriptor = info.getMBeanDescriptor();
    if (mbeanDescriptor == null)
      throw new MBeanException(
          new ServiceNotFoundException(
              LocalizedStrings.MX4JModelMBean_MBEAN_DESCRIPTOR_CANNOT_BE_NULL.toLocalizedString()));
    if (logger.isEnabledFor(Logger.DEBUG)) logger.debug("MBean descriptor is: " + mbeanDescriptor);

    Object returnValue = null;

    String lastUpdateField = "lastReturnedTimeStamp";

    // Check if the method should be invoked given the cache settings
    int staleness = getStaleness(operationDescriptor, mbeanDescriptor, lastUpdateField);

    if (staleness == ALWAYS_STALE || staleness == STALE) {
      if (logger.isEnabledFor(Logger.TRACE)) logger.trace("Value is stale");

      // Find parameters classes
      Class[] parameters = null;
      try {
        parameters = Utils.loadClasses(Thread.currentThread().getContextClassLoader(), params);
      } catch (ClassNotFoundException x) {
        logger.error(LocalizedStrings.MX4JModelMBean_CANNOT_FIND_OPERATIONS_PARAMETER_CLASSES, x);
        throw new ReflectionException(x);
      }

      if (logger.isEnabledFor(Logger.TRACE)) logger.trace("Invoking operation...");

      // Find target object
      Object target = resolveTargetObject(operationDescriptor);
      returnValue = invokeMethod(target, method, parameters, arguments);

      if (logger.isEnabledFor(Logger.DEBUG)) logger.debug("Returned value is: " + returnValue);

      if (returnValue != null) {
        Class parameter = returnValue.getClass();
        Class declared = loadClassWithContextClassLoader(operInfo.getReturnType());

        checkAssignability(parameter, declared);
      }

      // Cache the new value only if caching is needed
      if (staleness != ALWAYS_STALE) {
        operationDescriptor.setField("lastReturnedValue", returnValue);
        operationDescriptor.setField(lastUpdateField, Long.valueOf(System.currentTimeMillis()));
        if (logger.isEnabledFor(Logger.TRACE)) {
          logger.trace("Returned value has been cached");
        }

        // And now replace the descriptor with the updated clone
        info.setDescriptor(operationDescriptor, "operation");
      }

      if (logger.isEnabledFor(Logger.DEBUG))
        logger.debug("invoke for operation " + method + " returns invoked value: " + returnValue);
    } else {
      // Return cached value
      returnValue = operationDescriptor.getFieldValue("lastReturnedValue");

      if (returnValue != null) {
        Class parameter = returnValue.getClass();
        Class declared = loadClassWithContextClassLoader(operInfo.getReturnType());

        checkAssignability(parameter, declared);
      }

      if (logger.isEnabledFor(Logger.DEBUG))
        logger.debug("invoke for operation " + method + " returns cached value: " + returnValue);
    }

    // As an extension, persist this model mbean also after operation invocation, but using only
    // settings provided in the operation descriptor, without falling back to defaults set in
    // the MBean descriptor
    boolean persistNow = shouldPersistNow(operationDescriptor, null, lastUpdateField);
    int impact = operInfo.getImpact();
    if (persistNow && impact != MBeanOperationInfo.INFO) {
      if (logger.isEnabledFor(Logger.TRACE)) logger.trace("Persisting this ModelMBean...");
      try {
        store();
        if (logger.isEnabledFor(Logger.TRACE)) logger.trace("ModelMBean persisted successfully");
      } catch (Exception x) {
        logger.error(
            LocalizedStrings.MX4JModelMBean_CANNOT_STORE_MODELMBEAN_AFTER_OPERATION_INVOCATION, x);
        if (x instanceof MBeanException) throw (MBeanException) x;
        else throw new MBeanException(x);
      }
    }

    return returnValue;
  }