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1   /*
2    * ====================================================================
3    * Licensed to the Apache Software Foundation (ASF) under one
4    * or more contributor license agreements.  See the NOTICE file
5    * distributed with this work for additional information
6    * regarding copyright ownership.  The ASF licenses this file
7    * to you under the Apache License, Version 2.0 (the
8    * "License"); you may not use this file except in compliance
9    * with the License.  You may obtain a copy of the License at
10   *
11   *   http://www.apache.org/licenses/LICENSE-2.0
12   *
13   * Unless required by applicable law or agreed to in writing,
14   * software distributed under the License is distributed on an
15   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
16   * KIND, either express or implied.  See the License for the
17   * specific language governing permissions and limitations
18   * under the License.
19   * ====================================================================
20   *
21   * This software consists of voluntary contributions made by many
22   * individuals on behalf of the Apache Software Foundation.  For more
23   * information on the Apache Software Foundation, please see
24   * <http://www.apache.org/>.
25   *
26   */
27  
28  package org.apache.http.nio.protocol;
29  
30  import org.apache.http.HttpEntity;
31  import org.apache.http.HttpRequest;
32  import org.apache.http.HttpResponse;
33  import org.apache.http.concurrent.Cancellable;
34  import org.apache.http.nio.entity.HttpAsyncContentProducer;
35  
36  /**
37   * <tt>HttpAsyncExchange</tt> represents a server-side HTTP message exchange
38   * where an HTTP response can be deferred without blocking the I/O event thread
39   * and triggered asynchronously at a later point of later time.
40   *
41   * @since 4.2
42   */
43  public interface HttpAsyncExchange {
44  
45      /**
46       * Returns the received HTTP request message.
47       *
48       * @return received HTTP request message.
49       */
50      HttpRequest getRequest();
51  
52      /**
53       * Returns the default HTTP response message. Once ready the response
54       * message can submitted using {@link #submitResponse()} method.
55       *
56       * @return default HTTP response message.
57       */
58      HttpResponse getResponse();
59  
60      /**
61       * Submits the default HTTP response and completed the message exchange.
62       * If the response encloses an {@link HttpEntity} instance the entity is
63       * also expected to implement the {@link HttpAsyncContentProducer}
64       * interface for efficient content streaming to a non-blocking HTTP
65       * connection.
66       *
67       * @throws IllegalStateException if a response has already been submitted.
68       */
69      void submitResponse();
70  
71      /**
72       * Submits an HTTP response using a custom
73       * {@link HttpAsyncResponseProducer}.
74       *
75       * @throws IllegalStateException if a response has already been submitted.
76       */
77      void submitResponse(HttpAsyncResponseProducer responseProducer);
78  
79      /**
80       * Determines whether or not the message exchange has been completed.
81       *
82       * @return <code>true</code> if the message exchange has been completed,
83       * <code>false</code> otherwise.
84       */
85      boolean isCompleted();
86  
87      /**
88       * Sets {@link Cancellable} callback to be invoked in case the underlying
89       * connection times out or gets terminated prematurely by the client. This
90       * callback can be used to cancel a long running response generating
91       * process if a response is no longer needed.
92       *
93       * @param cancellable
94       */
95      void setCallback(Cancellable cancellable);
96  
97      /**
98       * Sets timeout for this message exchange.
99       */
100     void setTimeout(int timeout);
101 
102     /**
103      * Returns timeout for this message exchange.
104      */
105     int getTimeout();
106 
107 }