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//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later
// version.
//
// This library 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 Lesser General Public License for more
// details.
//
// You should have received a copy of the GNU Lesser General
// Public License along with this library; if not, write to the
//
// Free Software Foundation, Inc.,
// 59 Temple Place, Suite 330,
// Boston, MA
// 02111-1307 USA
//
// The Initial Developer of the Original Code is Charles W. Rapp.
// Portions created by Charles W. Rapp are
// Copyright 2012, 2013, 2016. Charles W. Rapp
// All Rights Reserved.
//

package net.sf.eBusx.monitor;

import java.io.Serializable;
import java.util.Formatter;
import net.sf.eBus.messages.EFieldInfo;
import net.sf.eBus.messages.ENotificationMessage;

/**
 * Reports the {@link Monitor#register(Monitorable) registration}
 * or {@link Monitor#deregister(Monitorable) deregistration} or
 * a {@link Monitorable} instance. The {@link #instance} field
 * contains the monitored object unique identifier and
 * {@link #updateFlag} is {@code true} if the object registered
 * and {@code false} if the object deregistered.
 * 
 * In order to receive this notification message, subscribe to:
 * {@code net.sf.eBusx.monitor.MonitorUpdate}:{@link Monitor#MONITOR_UPDATE_SUBJECT}.
 *
 * @see ApplicationInfo
 * @see Monitor
 *
 * @author Charles Rapp
 */

@EFieldInfo(fields={"instance", "updateFlag"})
public final class MonitorUpdate
    extends ENotificationMessage
    implements Serializable
{
//---------------------------------------------------------------
// Member methods.
//

    //-----------------------------------------------------------
    // Constructors.
    //

    /**
     * Creates a new MonitorUpdate instance for the given
     * instance and flag.
     * @param subject the notification subject.
     * @param inst the updated monitored instance.
     * @param flag the update type.
     * @exception IllegalArgumentException
     * if {@code inst} is {@code null}.
     */
    public MonitorUpdate(final String subject,
                         final MonitorId inst,
                         final boolean flag)
        throws IllegalArgumentException
    {
        this (subject,
              System.currentTimeMillis(),
              inst,
              flag);
    } // end of MonitorUpdate(String, MonitorId, boolean)

    /**
     * Deserialization constructor.
     * @param subject the notification subject.
     * @param timestamp the message timestamp.
     * @param inst updated instance.
     * @param flag update type.
     * @exception IllegalArgumentException
     * if {@code inst} is {@code null}.
     */
    public MonitorUpdate(final String subject,
                         final long timestamp,
                         final MonitorId inst,
                         final boolean flag)
        throws IllegalArgumentException
    {
        super (subject, timestamp);

        if (inst == null)
        {
            throw (new IllegalArgumentException("null inst"));
        }

        instance = inst;
        updateFlag = flag;
    } // end of MonitorUpdate(String, long, MonitorId, boolean)

    //
    // end of Constructors.
    //-----------------------------------------------------------

    //-----------------------------------------------------------
    // Object Method Overrides.
    //

    @Override
    public String toString()
    {
        final Formatter retval = new Formatter();

        retval.format("%s%n               instance: %s%n",
                      super.toString(),
                      instance);
        retval.format("                 update: %b",
                      updateFlag);

        return (retval.toString());
    } // end of toString()

    //
    // end of Object Method Overrides.
    //-----------------------------------------------------------

//---------------------------------------------------------------
// Member data.
//

    /**
     * This monitored object was either added or removed.
     */
    public final MonitorId instance;

    /**
     * {@code true} if added and {@code false} if removed.
     */
    public final boolean updateFlag;

    //-----------------------------------------------------------
    // Constants.
    //

    /**
     * Serialization version identifier.
     */
    private static final long serialVersionUID = 0x060100L;
} // end of class MonitorUpdate