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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.HttpRequest;
31  import org.apache.http.HttpResponse;
32  import org.apache.http.concurrent.Cancellable;
33  
34  /**
35   * {@code HttpAsyncExchange} represents a server-side HTTP message exchange
36   * where an HTTP response can be deferred without blocking the I/O event thread
37   * and triggered asynchronously at a later point of later time.
38   *
39   * @since 4.2
40   */
41  public interface HttpAsyncExchange {
42  
43      /**
44       * Returns the received HTTP request message.
45       *
46       * @return received HTTP request message.
47       */
48      HttpRequest getRequest();
49  
50      /**
51       * Returns the default HTTP response message. Once ready the response
52       * message can submitted using {@link #submitResponse()} method.
53       *
54       * @return default HTTP response message.
55       */
56      HttpResponse getResponse();
57  
58      /**
59       * Submits the default HTTP response and completed the message exchange.
60       * If the response encloses an {@link org.apache.http.HttpEntity} instance
61       * the entity is also expected to implement the
62       * {@link org.apache.http.nio.entity.HttpAsyncContentProducer }
63       * interface for efficient content streaming to a non-blocking HTTP
64       * connection.
65       *
66       * @throws IllegalStateException if a response has already been submitted.
67       */
68      void submitResponse();
69  
70      /**
71       * Submits an HTTP response using a custom
72       * {@link HttpAsyncResponseProducer}.
73       *
74       * @throws IllegalStateException if a response has already been submitted.
75       */
76      void submitResponse(HttpAsyncResponseProducer responseProducer);
77  
78      /**
79       * Determines whether or not the message exchange has been completed.
80       *
81       * @return {@code true} if the message exchange has been completed,
82       * {@code false} otherwise.
83       */
84      boolean isCompleted();
85  
86      /**
87       * Sets {@link Cancellable} callback to be invoked in case the underlying
88       * connection times out or gets terminated prematurely by the client. This
89       * callback can be used to cancel a long running response generating
90       * process if a response is no longer needed.
91       */
92      void setCallback(Cancellable cancellable);
93  
94      /**
95       * Sets timeout for this message exchange.
96       */
97      void setTimeout(int timeout);
98  
99      /**
100      * Returns timeout for this message exchange.
101      */
102     int getTimeout();
103 
104 }