001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements.  See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License.  You may obtain a copy of the License at
008     *
009     *     http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the License for the specific language governing permissions and
015     * limitations under the License.
016     */
017    package org.apache.commons.scxml;
018    
019    import org.apache.commons.scxml.model.Transition;
020    import org.apache.commons.scxml.model.TransitionTarget;
021    
022    /**
023     * Listener interface for observable entities in the SCXML model.
024     * Observable entities include {@link org.apache.commons.scxml.model.SCXML}
025     * instances (subscribe to all entry, exit and transition notifications),
026     * {@link org.apache.commons.scxml.model.State} instances (subscribe to
027     * particular entry and exit notifications) and
028     * {@link org.apache.commons.scxml.model.Transition} instances (subscribe to
029     * particular transitions).
030     *
031     */
032    public interface SCXMLListener {
033    
034        /**
035         * Handle the entry into a TransitionTarget.
036         *
037         * @param state The TransitionTarget entered
038         */
039        void onEntry(TransitionTarget state);
040    
041        /**
042         * Handle the exit out of a TransitionTarget.
043         *
044         * @param state The TransitionTarget exited
045         */
046        void onExit(TransitionTarget state);
047    
048        /**
049         * Handle the transition.
050         *
051         * @param from The source TransitionTarget
052         * @param to The destination TransitionTarget
053         * @param transition The Transition taken
054         */
055        void onTransition(TransitionTarget from, TransitionTarget to,
056                Transition transition);
057    
058    }
059