001/*
002 *  Licensed to the Apache Software Foundation (ASF) under one
003 *  or more contributor license agreements.  See the NOTICE file
004 *  distributed with this work for additional information
005 *  regarding copyright ownership.  The ASF licenses this file
006 *  to you under the Apache License, Version 2.0 (the
007 *  "License"); you may not use this file except in compliance
008 *  with the License.  You may obtain a copy of the License at
009 *
010 *    http://www.apache.org/licenses/LICENSE-2.0
011 *
012 *  Unless required by applicable law or agreed to in writing,
013 *  software distributed under the License is distributed on an
014 *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 *  KIND, either express or implied.  See the License for the
016 *  specific language governing permissions and limitations
017 *  under the License.
018 *
019 */
020package org.apache.mina.statemachine.annotation;
021
022import java.lang.annotation.ElementType;
023import java.lang.annotation.Retention;
024import java.lang.annotation.RetentionPolicy;
025import java.lang.annotation.Target;
026
027import org.apache.mina.statemachine.StateMachine;
028import org.apache.mina.statemachine.event.Event;
029
030/**
031 * Annotation used on methods to indicate that the method handles a specific
032 * kind of event when in a specific state.
033 *
034 * @author <a href="http://mina.apache.org">Apache MINA Project</a>
035 */
036@Retention(RetentionPolicy.RUNTIME)
037@Target(ElementType.METHOD)
038@TransitionAnnotation(Transitions.class)
039public @interface Transition {
040    public static final String SELF = "__self__";
041
042    /**
043     * Specifies the ids of one or more events handled by the annotated method. If
044     * not specified the handler method will be executed for any event.
045     * 
046     * @return the ids of the handled events
047     */
048    String[] on() default Event.WILDCARD_EVENT_ID;
049
050    /**
051     * The id of the state or states that this handler applies to. Must be
052     * specified.
053     * 
054     * @return the ids of the handled states
055     */
056    String[] in();
057
058    /**
059     * The id of the state the {@link StateMachine} should move to next after
060     * executing the annotated method. If not specified the {@link StateMachine}
061     * will remain in the same state.
062     * 
063     * @return the id of the next state
064     */
065    String next() default SELF;
066
067    /**
068     * The weight used to order handler annotations which match the same event 
069     * in the same state. Transitions with lower weight will be matched first. The
070     * default weight is 0.
071     * 
072     * @return the weight used to order the handler
073     */
074    int weight() default 0;
075}