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 ioControl I/O control of the underlying connection.
88 * @throws IOException in case of an I/O error
89 */
90 void produceContent(ContentEncoder encoder, IOControl ioControl) 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 ioControl I/O control of the underlying connection.
125 * @throws IOException in case of an I/O error
126 */
127 void consumeContent(ContentDecoder decoder, IOControl ioControl) 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 }