/*
 * Copyright (c) 2005, 2006, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */
 
package com.sun.org.glassfish.gmbal ;

import java.lang.annotation.Documented ;
import java.lang.annotation.Target ;
import java.lang.annotation.ElementType ;
import java.lang.annotation.Retention ;
import java.lang.annotation.RetentionPolicy ;

/** This annotation defines an attribute in either CompositeData (ManagedData) or 
 * an open MBean (ManagedObject).  An attribute may be read/write (has a setter
 * and a getter), read only (only has a getter),
 * or write only (only has a setter) depending on the declared methods in the class.  
 * <p> 
 * A method defines a getter if it returns a non-void type and takes no argument types.
 * Likewise a method defines a setter if it return void and takes exactly one
 * argument.  
 * <p>An id is derived from a method name as follows:
 * <ol>
 * <li>If the method is a getter, and has a name of the form getXXX, the derived
 * id is xXX (note the initial lower case change).
 * <li>If the method is a getter with a boolean return type, and has a name of 
 * the form isXXX, the derived id is xXX
 * <li>If the method is a setter, and has a name of the form setXXX, the
 * detived id is xXX.
 * <li>Otherwise the derived ID is the method name.
 * </ol>
 * <p>
 * In certain cases, a field annotated with @ManagedAttribute 
 * may also represent a read-only attribute.
 * The field must be final, and its type must be one of:
 * <ol>
 * <li>A primitive type (boolean, byte, short, char, int, long, float, double)
 * <li>A primitive type wrapper (Boolean, Byte, Short, Character, Integer, 
 * Long, Float, Double)
 * <li>A String
 * <li>A BigDecimal or BigInteger
 * <li>A java.util.Date
 * <li>An ObjectName
 * <li>An enum (which is translated to its ordinal name)
 * </ol>
 * Any such field can be accessed safely by multiple threads, because its value
 * cannot change after an instance of the containing class has completed its
 * constructor.  Note that Date is not truly immutable (it should be!), but it's
 * one of the Open MBean simple types, so it is included here.
 */
@Documented 
@Target({ElementType.METHOD,ElementType.FIELD})
@Retention(RetentionPolicy.RUNTIME)
public @interface ManagedAttribute {
    /** The id of the attribute.  Defaults to value derived from method name.
     * @return The id (default "").
     */
    String id() default "" ;
}
