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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 java.io.Closeable;
31  import java.io.IOException;
32  
33  import org.apache.http.HttpException;
34  import org.apache.http.HttpRequest;
35  import org.apache.http.HttpResponse;
36  import org.apache.http.concurrent.Cancellable;
37  import org.apache.http.nio.ContentDecoder;
38  import org.apache.http.nio.ContentEncoder;
39  import org.apache.http.nio.IOControl;
40  
41  /**
42   * {@code HttpAsyncClientExchangeHandler} represents a callback interface whose
43   * methods get invoked when executing one or multiple HTTP message exchanges
44   * on the client side.
45   * <p>
46   * Individual {@code HttpAsyncClientExchangeHandler} are expected to make use of
47   * a {@link org.apache.http.protocol.HttpProcessor} to generate mandatory protocol
48   * headers for all outgoing messages and apply common, cross-cutting message
49   * transformations to all incoming and outgoing messages.
50   * {@code HttpAsyncClientExchangeHandler}s can delegate implementation
51   * of application specific content generation and processing to
52   * a {@link HttpAsyncRequestProducer} and a {@link HttpAsyncResponseConsumer}.
53   *
54   * @since 4.3
55   */
56  public interface HttpAsyncClientExchangeHandler extends Closeable, Cancellable {
57  
58      /**
59       * Invoked to generate a HTTP request message head. The message is expected
60       * to implement the {@link org.apache.http.HttpEntityEnclosingRequest} interface if it is
61       * to enclose a content entity. The {@link #produceContent(ContentEncoder,
62       * IOControl)} method will not be invoked if
63       * {@link org.apache.http.HttpEntityEnclosingRequest#getEntity()} returns
64       * {@code null}.
65       *
66       * @return HTTP request message.
67       * @throws HttpException in case of HTTP protocol violation
68       * @throws IOException in case of an I/O error
69       */
70      HttpRequest generateRequest() throws IOException, HttpException;
71  
72      /**
73       * Invoked to write out a chunk of content to the {@link ContentEncoder}.
74       * The {@link IOControl} interface can be used to suspend output event
75       * notifications if the producer is temporarily unable to produce more content.
76       * <p>
77       * When all content is finished, the producer <b>MUST</b> call
78       * {@link ContentEncoder#complete()}. Failure to do so may cause the entity
79       * to be incorrectly delimited.
80       * <p>
81       * Please note that the {@link ContentEncoder} object is not thread-safe and
82       * should only be used within the context of this method call.
83       * The {@link IOControl} object can be shared and used on other thread
84       * to resume output event notifications when more content is made available.
85       *
86       * @param encoder content encoder.
87       * @param ioctrl I/O control of the underlying connection.
88       * @throws IOException in case of an I/O error
89       */
90      void produceContent(ContentEncoder encoder, IOControl ioctrl) throws IOException;
91  
92      /**
93       * Invoked to signal that the request has been fully written out.
94       */
95      void requestCompleted();
96  
97      /**
98       * Invoked when a HTTP response message is received. Please note
99       * that the {@link #consumeContent(ContentDecoder, IOControl)} method
100      * will be invoked only if the response messages has a content entity
101      * enclosed.
102      *
103      * @param response HTTP response message.
104      * @throws HttpException in case of HTTP protocol violation
105      * @throws IOException in case of an I/O error
106      */
107     void responseReceived(HttpResponse response) throws IOException, HttpException;
108 
109     /**
110      * Invoked to process a chunk of content from the {@link ContentDecoder}.
111      * The {@link IOControl} interface can be used to suspend input event
112      * notifications if the consumer is temporarily unable to process content.
113      * <p>
114      * The consumer can use the {@link ContentDecoder#isCompleted()} method
115      * to find out whether or not the message content has been fully consumed.
116      * <p>
117      * Please note that the {@link ContentDecoder} object is not thread-safe and
118      * should only be used within the context of this method call.
119      * The {@link IOControl} object can be shared and used on other thread
120      * to resume input event notifications when the consumer is capable of
121      * processing more content.
122      *
123      * @param decoder content decoder.
124      * @param ioctrl I/O control of the underlying connection.
125      * @throws IOException in case of an I/O error
126      */
127     void consumeContent(ContentDecoder decoder, IOControl ioctrl) throws IOException;
128 
129     /**
130      * Invoked to signal that the response has been fully processed.
131      */
132     void responseCompleted() throws IOException, HttpException;
133 
134     /**
135      * Invoked to signal that the connection has been terminated prematurely
136      * by the opposite end.
137      */
138     void inputTerminated();
139 
140     /**
141      * Invoked to signal that the response processing terminated abnormally.
142      *
143      * @param ex exception
144      */
145     void failed(Exception ex);
146 
147     /**
148      * Determines whether or not the response processing completed.
149      */
150     boolean isDone();
151 
152 }