001/* PersistentMBean.java -- Interface for beans that should persist.
002   Copyright (C) 2007 Free Software Foundation, Inc.
003
004This file is part of GNU Classpath.
005
006GNU Classpath is free software; you can redistribute it and/or modify
007it under the terms of the GNU General Public License as published by
008the Free Software Foundation; either version 2, or (at your option)
009any later version.
010
011GNU Classpath is distributed in the hope that it will be useful, but
012WITHOUT ANY WARRANTY; without even the implied warranty of
013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014General Public License for more details.
015
016You should have received a copy of the GNU General Public License
017along with GNU Classpath; see the file COPYING.  If not, write to the
018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
01902110-1301 USA.
020
021Linking this library statically or dynamically with other modules is
022making a combined work based on this library.  Thus, the terms and
023conditions of the GNU General Public License cover the whole
024combination.
025
026As a special exception, the copyright holders of this library give you
027permission to link this library with independent modules to produce an
028executable, regardless of the license terms of these independent
029modules, and to copy and distribute the resulting executable under
030terms of your choice, provided that you also meet, for each linked
031independent module, the terms and conditions of the license of that
032module.  An independent module is a module which is not derived from
033or based on this library.  If you modify this library, you may extend
034this exception to your version of the library, but you are not
035obligated to do so.  If you do not wish to do so, delete this
036exception statement from your version. */
037
038package javax.management;
039
040/**
041 * Beans may implement this interface in order to become
042 * persistent.  The {@link #load()} method should be
043 * called on construction in order to reload the stored
044 * state.  The {@link #store()} method should be called
045 * sometime during the bean's lifetime in order to create
046 * a persistent copy of the bean's instance data.  This
047 * method may also be called by the {@link MBeanServer}
048 * as a result of the {@link Descriptor} of an
049 * {@link javax.management.modelmbean.ModelMBean}.
050 *
051 * @author Andrew John Hughes (gnu_andrew@member.fsf.org)
052 * @since 1.5
053 */
054public interface PersistentMBean
055{
056
057  /**
058   * Instantiates the bean with the data previously stored
059   * using a call to {@link #store()}.  The data stored can
060   * include values held by attributes as well as those returned
061   * by operations.  This method should be called during
062   * construction or initialisation of the bean, before
063   * it becomes registered with an {@link MBeanServer}.
064   *
065   * @throws MBeanException if persistence is not supported,
066   *                        or another exception is thrown
067   *                        (which this then wraps).
068   * @throws RuntimeOperationsException if the persistence
069   *                                    mechanism throws an
070   *                                    exception.
071   * @throws InstanceNotFoundException if the bean can not
072   *                                   be found in the
073   *                                   persistent store.
074   */
075  void load()
076    throws MBeanException, RuntimeOperationsException,
077           InstanceNotFoundException;
078
079  /**
080   * <p>
081   * Captures the current state of the bean and stores it
082   * for future retrieval by the {@link #load()} method.
083   * The data stored can include values held by attributes
084   * as well as those returned by operations.
085   * </p>
086   * <p>
087   * Whether the state is stored or not depends on the
088   * <code>persistPolicy</code> field of the MBean/attribute
089   * descriptor.  The state should be stored if the policy
090   * is set to any of the following:
091   * </p>
092   * <ul>
093   * <li><code>always</code></li>
094   * <li><code>onTimer</code> and <code>now</code> is
095   * greater than or equal to <code>lastPersistTime +
096   * persistPeriod</code>.</li>
097   * <li><code>noMoreOftenThan</code> and <code>now</code> is
098   * greater than or equal to <code>lastPersistTime +
099   * persistPeriod</code>.</li>
100   * <li>onUnregister</li>
101   * </ul>
102   * <p>If the policy is set to any of the following, the state
103   * should not be stored:</p>
104   * <ul>
105   * <li><code>never</code></li>
106   * <li><code>onUpdate</code></li>
107   * <li><code>onTimer</code> and <code>now</code> is
108   * less than <code>lastPersistTime + persistPeriod</code>.
109   * </li>
110   * </ul>
111   *
112   * @throws MBeanException if persistence is not supported,
113   *                        or another exception is thrown
114   *                        (which this then wraps).
115   * @throws RuntimeOperationsException if the persistence
116   *                                    mechanism throws an
117   *                                    exception.
118   * @throws InstanceNotFoundException if the persistent
119   *                                   store can not be found
120   *                                   or accessed.
121   */
122  void store()
123    throws MBeanException, RuntimeOperationsException,
124           InstanceNotFoundException;
125
126}