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 * Copyright (c) 1999, 2008, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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 */

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();
 }
 }
}