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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.IOException;
31  
32  import org.apache.http.HttpException;
33  import org.apache.http.HttpRequest;
34  import org.apache.http.protocol.HttpContext;
35  
36  /**
37   * <tt>HttpAsyncRequestHandler</tt> represents a routine for asynchronous
38   * processing of a specific group of non-blocking HTTP requests. Protocol
39   * handlers are designed to take care of protocol specific aspects, whereas
40   * individual request handlers are expected to take care of application
41   * specific HTTP processing. The main purpose of a request handler is to
42   * generate a response object with a content entity to be sent back to
43   * the client in response to the given request.
44   *
45   * @since 4.2
46   */
47  public interface HttpAsyncRequestHandler<T> {
48  
49      /**
50       * Triggered when an incoming request is received. This method should
51       * return a {@link HttpAsyncRequestConsumer} that will be used to process
52       * the request and consume message content if enclosed. The consumer
53       * can optionally parse or transform the message content into a structured
54       * object which is then passed onto
55       * the {@link #handle(Object, HttpAsyncExchange, HttpContext)}
56       * method for further processing.
57       *
58       * @param request the entity enclosing request.
59       * @param context the execution context.
60       * @return request consumer.
61       * @throws IOException in case of an I/O error.
62       * @throws HttpException in case of HTTP protocol violation or a processing
63       *   problem.
64       */
65      HttpAsyncRequestConsumer<T> processRequest(
66              HttpRequest request,
67              HttpContext context) throws HttpException, IOException;
68  
69      /**
70       * Triggered to complete request processing and to initiate the process of
71       * generating a response. This method does not have to submit a response
72       * immediately. It can defer transmission of an HTTP response back to
73       * the client without blocking the I/O thread by delegating the process
74       * of request handling to another service or a worker thread. HTTP response
75       * can be submitted as a later a later point of time using
76       * {@link HttpAsyncExchange} once response content becomes available.
77       *
78       * @param data request data returned by the request consumer.
79       * @param httpExchange HTTP exchange.
80       * @param context HTTP execution context.
81       * @throws IOException in case of an I/O error.
82       * @throws HttpException in case of HTTP protocol violation or a processing
83       *   problem.
84       */
85      void handle(
86              T data,
87              HttpAsyncExchange httpExchange,
88              HttpContext context) throws HttpException, IOException;
89  
90  }