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
027/**
028 * Annotation used to define the states in a state machine. Only applies to
029 * <code>static final String</code> fields. The value of the string will be used
030 * as state id. 
031 *
032 * @author <a href="http://mina.apache.org">Apache MINA Project</a>
033 */
034@Retention(RetentionPolicy.RUNTIME)
035@Target(ElementType.FIELD)
036public @interface State {
037    public static final String ROOT = "__root__";
038
039    /**
040     * Sets the id of the parent state. The default is no parent.
041     * 
042     * @return the id of the parent state
043     */
044    String value() default ROOT;
045}