001    // This file is part of the program FRYSK.
002    //
003    // Copyright 2005, Red Hat Inc.
004    //
005    // FRYSK is free software; you can redistribute it and/or modify it
006    // under the terms of the GNU General Public License as published by
007    // the Free Software Foundation; version 2 of the License.
008    //
009    // FRYSK is distributed in the hope that it will be useful, but
010    // WITHOUT ANY WARRANTY; without even the implied warranty of
011    // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
012    // General Public License for more details.
013    // 
014    // You should have received a copy of the GNU General Public License
015    // along with FRYSK; if not, write to the Free Software Foundation,
016    // Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
017    // 
018    // In addition, as a special exception, Red Hat, Inc. gives You the
019    // additional right to link the code of FRYSK with code not covered
020    // under the GNU General Public License ("Non-GPL Code") and to
021    // distribute linked combinations including the two, subject to the
022    // limitations in this paragraph. Non-GPL Code permitted under this
023    // exception must only link to the code of FRYSK through those well
024    // defined interfaces identified in the file named EXCEPTION found in
025    // the source code files (the "Approved Interfaces"). The files of
026    // Non-GPL Code may instantiate templates or use macros or inline
027    // functions from the Approved Interfaces without causing the
028    // resulting work to be covered by the GNU General Public
029    // License. Only Red Hat, Inc. may make changes or additions to the
030    // list of Approved Interfaces. You must obey the GNU General Public
031    // License in all respects for all of the FRYSK code and other code
032    // used in conjunction with FRYSK except the Non-GPL Code covered by
033    // this exception. If you modify this file, you may extend this
034    // exception to your version of the file, but you are not obligated to
035    // do so. If you do not wish to provide this exception without
036    // modification, you must delete this exception statement from your
037    // version and license this file solely under the GPL without
038    // exception.
039    
040    package frysk.proc;
041    
042    /**
043     * Root Observer interface.
044     */
045    
046    public interface Observer
047    {
048        /**
049         * Acknowledge the request to add this Observer from Object's set
050         * of observers was successful.
051         */
052        void addedTo (Object observable);
053    
054        /**
055         * Notify that the attempt to add to the specified observer failed.
056         */
057        void addFailed (Object observable, Throwable w);
058    
059        /**
060         * Acknowledge the request to delete this Observer from Object's
061         * set of observers was successful (or that the Observer was
062         * spontaneously deleted, e.g., due to a task exit).
063         */
064        void deletedFrom (Object observable);
065    }