package org.tanukisoftware.wrapper.event;

/*
 * Copyright (c) 1999, 2008 Tanuki Software, Inc.
 * http://www.tanukisoftware.com
 * All rights reserved.
 *
 * This software is the proprietary information of Tanuki Software.
 * You shall use it only in accordance with the terms of the
 * license agreement you entered into with Tanuki Software.
 * http://wrapper.tanukisoftware.org/doc/english/licenseOverview.html
 */

/**
 * WrapperEventListeners can be registered with the WrapperManager class
 *  to receive WrapperEvents.
 *
 * @author Leif Mortenson <leif@tanukisoftware.com>
 */
public interface WrapperEventListener
{
    /**
     * Enabling service events will cause the listener to receive
     *  WrapperServiceEvents.  These events pertain to the Wrapper as a
     *  service.
     */
    static long EVENT_FLAG_SERVICE = 0x1;
    
    /**
     * Enabling control events will cause the listener to receive
     *  WrapperControlEvents.  There events are thrown whenever the
     *  Java process receives control events from the system.  These
     *  include CTRL-C, HALT, TERM signals etc.
     */
    static long EVENT_FLAG_CONTROL = 0x2;
    
    /**
     * Enabling core events will cause the listener to receive
     *  WrapperCoreEvents. These events provide information on the internal
     *  timing of the Wrapper.
     * <p>
     * WARNING - Great care should be taken when receiving events of this type.
     *  They are sent from within the Wrapper's internal timing thread.  If the
     *  listner takes too much time working with the event, Wrapper performance
     *  could be adversely affected.  If unsure, it is recommended that events
     *  of this type not be included.
     */
    static long EVENT_FLAG_CORE = 0xf000000000000000L;
    
    /**
     * Called whenever a WrapperEvent is fired.  The exact set of events that a
     *  listener will receive will depend on the mask supplied when
     *  WrapperManager.addWrapperEventListener was called to register the
     *  listener.
     * <p>
     * Listener implementations should never assume that they will only receive
     *  events of a particular type.   To assure that events added to future
     *  versions of the Wrapper do not cause problems with user code, events
     *  should always be tested with "if ( event instanceof {EventClass} )"
     *  before casting it to a specific event type.
     *
     * @param event WrapperEvent which was fired.
     */
    void fired( WrapperEvent event );
}
