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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.common;
21  
22  /**
23   * An {@link IoFuture} for {@link IoSession#read() asynchronous read requests}. 
24   *
25   * <h3>Example</h3>
26   * <pre>
27   * IoSession session = ...;
28   * // useReadOperation must be enabled to use read operation.
29   * session.getConfig().setUseReadOperation(true);
30   * 
31   * ReadFuture future = session.read();
32   * // Wait until a message is received.
33   * future.await();
34   * try {
35   *     Object message = future.getMessage();
36   * } catch (Exception e) {
37   *     ...
38   * }
39   * </pre>
40   *
41   * @author The Apache MINA Project (dev@mina.apache.org)
42   * @version $Rev: 594477 $, $Date: 2007-11-13 03:42:03 -0700 (Tue, 13 Nov 2007) $
43   */
44  public interface ReadFuture extends IoFuture {
45      
46      /**
47       * Returns the received message.  It returns <tt>null</tt> if this
48       * future is not ready or the associated {@link IoSession} has been closed. 
49       * 
50       * @throws RuntimeException if read or any relevant operation has failed.
51       */
52      Object getMessage();
53      
54      /**
55       * Returns <tt>true</tt> if a message was received successfully.
56       */
57      boolean isRead();
58      
59      /**
60       * Returns <tt>true</tt> if the {@link IoSession} associated with this
61       * future has been closed.
62       */
63      boolean isClosed();
64      
65      /**
66       * Returns the cause of the read failure if and only if the read
67       * operation has failed due to an {@link Exception}.  Otherwise,
68       * <tt>null</tt> is returned.
69       */
70      Throwable getException();
71  
72      /**
73       * Sets the message is written, and notifies all threads waiting for
74       * this future.  This method is invoked by MINA internally.  Please do
75       * not call this method directly.
76       */
77      void setRead(Object message);
78      
79      /**
80       * Sets the associated {@link IoSession} is closed.  This method is invoked
81       * by MINA internally.  Please do not call this method directly.
82       */
83      void setClosed();
84      
85      /**
86       * Sets the cause of the read failure, and notifies all threads waiting
87       * for this future.  This method is invoked by MINA internally.  Please
88       * do not call this method directly.
89       */
90      void setException(Throwable cause);
91  
92      ReadFuture await() throws InterruptedException;
93  
94      ReadFuture awaitUninterruptibly();
95  
96      ReadFuture addListener(IoFutureListener<?> listener);
97  
98      ReadFuture removeListener(IoFutureListener<?> listener);
99  }