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.transition; 021 022import org.apache.mina.statemachine.State; 023import org.apache.mina.statemachine.StateMachine; 024import org.apache.mina.statemachine.event.Event; 025 026/** 027 * The interface implemented by classes which need to react on transitions 028 * between states. 029 * 030 * @author <a href="http://mina.apache.org">Apache MINA Project</a> 031 */ 032public interface Transition { 033 /** 034 * Executes this {@link Transition}. It is the responsibility of this 035 * {@link Transition} to determine whether it actually applies for the 036 * specified {@link Event}. If this {@link Transition} doesn't apply 037 * nothing should be executed and <tt>false</tt> must be returned. 038 * 039 * @param event the current {@link Event}. 040 * @return <tt>true</tt> if the {@link Transition} was executed, 041 * <tt>false</tt> otherwise. 042 */ 043 boolean execute(Event event); 044 045 /** 046 * @return the {@link State} which the {@link StateMachine} should move to 047 * if this {@link Transition} is taken and {@link #execute(Event)} returns 048 * <tt>true</tt>. <code>null</code> if this {@link Transition} is a loopback 049 * {@link Transition}. 050 */ 051 State getNextState(); 052}