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1   /*
2    *  Licensed to the Apache Software Foundation (ASF) under one
3    *  or more contributor license agreements.  See the NOTICE file
4    *  distributed with this work for additional information
5    *  regarding copyright ownership.  The ASF licenses this file
6    *  to you under the Apache License, Version 2.0 (the
7    *  "License"); you may not use this file except in compliance
8    *  with the License.  You may obtain a copy of the License at
9    *
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.context;
21  
22  import org.apache.mina.statemachine.State;
23  import org.apache.mina.statemachine.StateMachine;
24  
25  /**
26   * {@link StateContext} objects are used to store the current {@link State} and
27   * any application specific attributes for a specific client of a 
28   * {@link StateMachine}. Since {@link StateMachine}s are singletons and shared
29   * by all clients using the {@link StateMachine} this is where client specific
30   * data needs to be stored.
31   *
32   * @author <a href="http://mina.apache.org">Apache MINA Project</a>
33   */
34  public interface StateContext {
35      /**
36       * Returns the current {@link State}. This is only meant for internal use.
37       * 
38       * @return the current {@link State}.
39       */
40      State getCurrentState();
41  
42      /**
43       * Sets the current {@link State}. This is only meant for internal use.
44       * Don't call it directly!
45       * 
46       * @param state the new current {@link State}.
47       */
48      void setCurrentState(State state);
49  
50      /**
51       * Returns the value of the attribute with the specified key or 
52       * <code>null</code>if not found.
53       * 
54       * @param key the key.
55       * @return the value or <code>null</code>.
56       */
57      Object getAttribute(Object key);
58  
59      /**
60       * Sets the value of the attribute with the specified key.
61       * 
62       * @param key the key.
63       * @param value the value.
64       */
65      void setAttribute(Object key, Object value);
66  }