/*
 * @(#)ActivationMonitor.java	1.12 00/02/02
 *
 * Copyright 1997-2000 Sun Microsystems, Inc. All Rights Reserved.
 * 
 * This software is the proprietary information of Sun Microsystems, Inc.  
 * Use is subject to license terms.
 * 
 */

package java.rmi.activation;

import java.rmi.MarshalledObject;
import java.rmi.activation.UnknownObjectException;
import java.rmi.activation.UnknownGroupException;
import java.rmi.Remote;
import java.rmi.RemoteException;

/**
 * An <code>ActivationMonitor</code> is specific to an
 * <code>ActivationGroup</code> and is obtained when a group is
 * reported active via a call to
 * <code>ActivationSystem.activeGroup</code> (this is done
 * internally). An activation group is responsible for informing its
 * <code>ActivationMonitor</code> when either: its objects become active or
 * inactive, or the group as a whole becomes inactive.
 *
 * @author 	Ann Wollrath
 * @version	1.12, 02/02/00
 * @see		Activator
 * @see		ActivationSystem
 * @see 	ActivationGroup
 * @since	1.2
 */
public interface ActivationMonitor extends Remote {

   /**
     * An activation group calls its monitor's
     * <code>inactiveObject</code> method when an object in its group
     * becomes inactive (deactivates).  An activation group discovers
     * that an object (that it participated in activating) in its VM
     * is no longer active, via calls to the activation group's
     * <code>inactiveObject</code> method. <p>
     *
     * The <code>inactiveObject</code> call informs the
     * <code>ActivationMonitor</code> that the remote object reference
     * it holds for the object with the activation identifier,
     * <code>id</code>, is no longer valid. The monitor considers the
     * reference associated with <code>id</code> as a stale reference.
     * Since the reference is considered stale, a subsequent
     * <code>activate</code> call for the same activation identifier
     * results in re-activating the remote object.<p>
     *
     * @param id the object's activation identifier
     * @exception UnknownObjectException if object is unknown
     * @exception RemoteException if remote call fails
     * @since 1.2
     */
    public void inactiveObject(ActivationID id)
 	throws UnknownObjectException, RemoteException;

    /**
     * Informs that an object is now active. An <code>ActivationGroup</code>
     * informs its monitor if an object in its group becomes active by
     * other means than being activated directly (i.e., the object
     * is registered and "activated" itself).
     *
     * @param id the active object's id
     * @param obj the marshalled form of the object's stub
     * @exception UnknownObjectException if object is unknown
     * @exception RemoteException if remote call fails
     * @since 1.2
     */
    public void activeObject(ActivationID id, MarshalledObject obj)
	throws UnknownObjectException, RemoteException;

    /**
     * Informs that the group is now inactive. The group will be
     * recreated upon a subsequent request to activate an object
     * within the group. A group becomes inactive when all objects
     * in the group report that they are inactive.
     *
     * @param id the group's id
     * @param incarnation the group's incarnation number
     * @exception UnknownGroupException if group is unknown
     * @exception RemoteException if remote call fails
     * @since 1.2
     */
    public void inactiveGroup(ActivationGroupID id,
			      long incarnation)
	throws UnknownGroupException, RemoteException;

}