01: /*
02: * Licensed to the Apache Software Foundation (ASF) under one
03: * or more contributor license agreements. See the NOTICE file
04: * distributed with this work for additional information
05: * regarding copyright ownership. The ASF licenses this file
06: * to you under the Apache License, Version 2.0 (the
07: * "License"); you may not use this file except in compliance
08: * with the License. You may obtain a copy of the License at
09: *
10: * http://www.apache.org/licenses/LICENSE-2.0
11: *
12: * Unless required by applicable law or agreed to in writing,
13: * software distributed under the License is distributed on an
14: * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15: * KIND, either express or implied. See the License for the
16: * specific language governing permissions and limitations
17: * under the License.
18: *
19: */
20: package org.apache.mina.statemachine.transition;
21:
22: import org.apache.mina.statemachine.State;
23: import org.apache.mina.statemachine.StateMachine;
24: import org.apache.mina.statemachine.event.Event;
25:
26: /**
27: * The interface implemented by classes which need to react on transitions
28: * between states.
29: *
30: * @author The Apache MINA Project (dev@mina.apache.org)
31: * @version $Rev: 586695 $, $Date: 2007-10-20 04:01:17 -0600 (Sat, 20 Oct 2007) $
32: */
33: public interface Transition {
34: /**
35: * Executes this {@link Transition}. It is the responsibility of this
36: * {@link Transition} to determine whether it actually applies for the
37: * specified {@link Event}. If this {@link Transition} doesn't apply
38: * nothing should be executed and <code>false</code> must be returned.
39: *
40: * @param event the current {@link Event}.
41: * @return <code>true</code> if the {@link Transition} was executed,
42: * <code>false</code> otherwise.
43: */
44: boolean execute(Event event);
45:
46: /**
47: * Returns the {@link State} which the {@link StateMachine} should move to
48: * if this {@link Transition} is taken and {@link #execute(Event)} returns
49: * <code>true</code>.
50: *
51: * @return the next {@link State} or <code>null</code> if this
52: * {@link Transition} is a loopback {@link Transition}.
53: */
54: State getNextState();
55: }
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