/*

 * Copyright (c) 1999, 2008, 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 javax.management;

import java.io.IOException;

import java.io.ObjectInputStream;

import java.io.ObjectOutputStream;

import java.io.ObjectStreamField;

import java.util.EventObject;

import java.security.AccessController;

import com.sun.jmx.mbeanserver.GetPropertyAction;

/**

 * <p>The Notification class represents a notification emitted by an

 * MBean.  It contains a reference to the source MBean: if the

 * notification has been forwarded through the MBean server, and the

 * original source of the notification was a reference to the emitting

 * MBean object, then the MBean server replaces it by the MBean's

 * ObjectName.  If the listener has registered directly with the

 * MBean, this is either the object name or a direct reference to the

 * MBean.</p>

 *

 * <p>It is strongly recommended that notification senders use the

 * object name rather than a reference to the MBean object as the

 * source.</p>

 *

 * <p>The <b>serialVersionUID</b> of this class is <code>-7516092053498031989L</code>.

 *

 * @since 1.5

 */

@SuppressWarnings("serial")  // serialVersionUID is not constant

public class Notification extends EventObject {

    // Serialization compatibility stuff:

    // Two serial forms are supported in this class. The selected form depends

    // on system property "jmx.serial.form":

    //  - "1.0" for JMX 1.0

    //  - any other value for JMX 1.1 and higher

    //

    // Serial version for old serial form

    private static final long oldSerialVersionUID = 1716977971058914352L;

    //

    // Serial version for new serial form

    private static final long newSerialVersionUID = -7516092053498031989L;

    //

    // Serializable fields in old serial form

    private static final ObjectStreamField[] oldSerialPersistentFields =

    {

        new ObjectStreamField("message", String.class),

        new ObjectStreamField("sequenceNumber", Long.TYPE),

        new ObjectStreamField("source", Object.class),

        new ObjectStreamField("sourceObjectName", ObjectName.class),

        new ObjectStreamField("timeStamp", Long.TYPE),

        new ObjectStreamField("type", String.class),

        new ObjectStreamField("userData", Object.class)

    };

    //

    // Serializable fields in new serial form

    private static final ObjectStreamField[] newSerialPersistentFields =

    {

        new ObjectStreamField("message", String.class),

        new ObjectStreamField("sequenceNumber", Long.TYPE),

        new ObjectStreamField("source", Object.class),

        new ObjectStreamField("timeStamp", Long.TYPE),

        new ObjectStreamField("type", String.class),

        new ObjectStreamField("userData", Object.class)

    };

    //

    // Actual serial version and serial form

    private static final long serialVersionUID;

    /**

     * @serialField type String The notification type.

     *              A string expressed in a dot notation similar to Java properties.

     *              An example of a notification type is network.alarm.router

     * @serialField sequenceNumber long The notification sequence number.

     *              A serial number which identify particular instance

     *              of notification in the context of the notification source.

     * @serialField timeStamp long The notification timestamp.

     *              Indicating when the notification was generated

     * @serialField userData Object The notification user data.

     *              Used for whatever other data the notification

     *              source wishes to communicate to its consumers

     * @serialField message String The notification message.

     * @serialField source Object The object on which the notification initially occurred.

     */

    private static final ObjectStreamField[] serialPersistentFields;

    private static boolean compat = false;

    static {

        try {

            GetPropertyAction act = new GetPropertyAction("jmx.serial.form");

            String form = AccessController.doPrivileged(act);

            compat = (form != null && form.equals("1.0"));

        } catch (Exception e) {

            // OK: exception means no compat with 1.0, too bad

        }

        if (compat) {

            serialPersistentFields = oldSerialPersistentFields;

            serialVersionUID = oldSerialVersionUID;

        } else {

            serialPersistentFields = newSerialPersistentFields;

            serialVersionUID = newSerialVersionUID;

        }

    }

    //

    // END Serialization compatibility stuff

    /**

     * @serial The notification type.

     *         A string expressed in a dot notation similar to Java properties.

     *         An example of a notification type is network.alarm.router

     */

    private String type;

    /**

     * @serial The notification sequence number.

     *         A serial number which identify particular instance

     *         of notification in the context of the notification source.

     */

    private long sequenceNumber;

    /**

     * @serial The notification timestamp.

     *         Indicating when the notification was generated

     */

    private long timeStamp;

    /**

     * @serial The notification user data.

     *         Used for whatever other data the notification

     *         source wishes to communicate to its consumers

     */

    private Object userData = null;

    /**

     * @serial The notification message.

     */

    private String message  = "";

    /**

     * <p>This field hides the {@link EventObject#source} field in the

     * parent class to make it non-transient and therefore part of the

     * serialized form.</p>

     *

     * @serial The object on which the notification initially occurred.

     */

    protected Object source = null;

    /**

     * Creates a Notification object.

     * The notification timeStamp is set to the current date.

     *

     * @param type The notification type.

     * @param source The notification source.

     * @param sequenceNumber The notification sequence number within the source object.

     *

     */

    public Notification(String type, Object source, long sequenceNumber) {

        super (source) ;

        this.source = source;

        this.type = type;

        this.sequenceNumber = sequenceNumber ;

        this.timeStamp = (new java.util.Date()).getTime() ;

    }

    /**

     * Creates a Notification object.

     * The notification timeStamp is set to the current date.

     *

     * @param type The notification type.

     * @param source The notification source.

     * @param sequenceNumber The notification sequence number within the source object.

     * @param message The detailed message.

     *

     */

    public Notification(String type, Object source, long sequenceNumber, String message) {

        super (source) ;

        this.source = source;

        this.type = type;

        this.sequenceNumber = sequenceNumber ;

        this.timeStamp = (new java.util.Date()).getTime() ;

        this.message = message ;

    }

    /**

     * Creates a Notification object.

     *

     * @param type The notification type.

     * @param source The notification source.

     * @param sequenceNumber The notification sequence number within the source object.

     * @param timeStamp The notification emission date.

     *

     */

    public Notification(String type, Object source, long sequenceNumber, long timeStamp) {

        super (source) ;

        this.source = source;

        this.type = type ;

        this.sequenceNumber = sequenceNumber ;

        this.timeStamp = timeStamp ;

    }

    /**

     * Creates a Notification object.

     *

     * @param type The notification type.

     * @param source The notification source.

     * @param sequenceNumber The notification sequence number within the source object.

     * @param timeStamp The notification emission date.

     * @param message The detailed message.

     *

     */

    public Notification(String type, Object source, long sequenceNumber, long timeStamp, String message) {

        super (source) ;

        this.source = source;

        this.type = type ;

        this.sequenceNumber = sequenceNumber ;

        this.timeStamp = timeStamp ;

        this.message = message ;

    }

    /**

     * Sets the source.

     *

     * @param source the new source for this object.

     *

     * @see EventObject#getSource

     */

    public void setSource(Object source) {

        super.source = source;

        this.source = source;

    }

    /**

     * Get the notification sequence number.

     *

     * @return The notification sequence number within the source object. It's a serial number

     * identifying a particular instance of notification in the context of the notification source.

     * The notification model does not assume that notifications will be received in the same order

     * that they are sent. The sequence number helps listeners to sort received notifications.

     *

     * @see #setSequenceNumber

     */

    public long getSequenceNumber() {

        return sequenceNumber ;

    }

    /**

     * Set the notification sequence number.

     *

     * @param sequenceNumber The notification sequence number within the source object. It is

     * a serial number identifying a particular instance of notification in the

     * context of the notification source.

     *

     * @see #getSequenceNumber

     */

    public void setSequenceNumber(long sequenceNumber) {

        this.sequenceNumber = sequenceNumber;

    }

    /**

     * Get the notification type.

     *

     * @return The notification type. It's a string expressed in a dot notation

     * similar to Java properties. It is recommended that the notification type

     * should follow the reverse-domain-name convention used by Java package

     * names.  An example of a notification type is com.example.alarm.router.

     */

    public String getType() {

        return type ;

    }

    /**

     * Get the notification timestamp.

     *

     * @return The notification timestamp.

     *

     * @see #setTimeStamp

     */

    public long getTimeStamp() {

        return timeStamp ;

    }

    /**

     * Set the notification timestamp.

     *

     * @param timeStamp The notification timestamp. It indicates when the notification was generated.

     *

     * @see #getTimeStamp

     */

    public void setTimeStamp(long timeStamp) {

        this.timeStamp = timeStamp;

    }

    /**

     * Get the notification message.

     *

     * @return The message string of this notification object.

     *

     */

    public String getMessage() {

        return message ;

    }

    /**

     * Get the user data.

     *

     * @return The user data object. It is used for whatever data

     * the notification source wishes to communicate to its consumers.

     *

     * @see #setUserData

     */

    public Object getUserData() {

        return userData ;

    }

    /**

     * Set the user data.

     *

     * @param userData The user data object. It is used for whatever data

     * the notification source wishes to communicate to its consumers.

     *

     * @see #getUserData

     */

    public void setUserData(Object userData) {

        this.userData = userData ;

    }

    /**

     * Returns a String representation of this notification.

     *

     * @return A String representation of this notification.

     */

    @Override

    public String toString() {

        return super.toString()+"[type="+type+"][message="+message+"]";

    }

    /**

     * Deserializes a {@link Notification} from an {@link ObjectInputStream}.

     */

    private void readObject(ObjectInputStream in)

            throws IOException, ClassNotFoundException {

      // New serial form ignores extra field "sourceObjectName"

      in.defaultReadObject();

      super.source = source;

    }

    /**

     * Serializes a {@link Notification} to an {@link ObjectOutputStream}.

     */

    private void writeObject(ObjectOutputStream out)

            throws IOException {

        if (compat) {

            // Serializes this instance in the old serial form

            //

            ObjectOutputStream.PutField fields = out.putFields();

            fields.put("type", type);

            fields.put("sequenceNumber", sequenceNumber);

            fields.put("timeStamp", timeStamp);

            fields.put("userData", userData);

            fields.put("message", message);

            fields.put("source", source);

            out.writeFields();

        } else {

            // Serializes this instance in the new serial form

            //

            out.defaultWriteObject();

        }

    }

}