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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.impl.execchain;
29  
30  import java.io.IOException;
31  
32  import org.apache.http.HttpException;
33  import org.apache.http.client.methods.CloseableHttpResponse;
34  import org.apache.http.client.methods.HttpExecutionAware;
35  import org.apache.http.client.methods.HttpRequestWrapper;
36  import org.apache.http.client.protocol.HttpClientContext;
37  import org.apache.http.conn.routing.HttpRoute;
38  
39  /**
40   * This interface represents an element in the HTTP request execution chain. Each element can
41   * either be a decorator around another element that implements a cross cutting aspect or
42   * a self-contained executor capable of producing a response for the given request.
43   * <p>
44   * Important: please note it is required for decorators that implement post execution aspects
45   * or response post-processing of any sort to release resources associated with the response
46   * by calling {@link CloseableHttpResponse#close()} methods in case of an I/O, protocol or
47   * runtime exception, or in case the response is not propagated to the caller.
48   * </p>
49   *
50   * @since 4.3
51   */
52  public interface ClientExecChain {
53  
54      /**
55       * Executes th request either by transmitting it to the target server or
56       * by passing it onto the next executor in the request execution chain.
57       *
58       * @param route connection route.
59       * @param request current request.
60       * @param clientContext current HTTP context.
61       * @param execAware receiver of notifications of blocking I/O operations.
62       * @return HTTP response either received from the opposite endpoint
63       *   or generated locally.
64       * @throws IOException in case of a I/O error.
65       *   (this type of exceptions are potentially recoverable).
66       * @throws HttpException in case of an HTTP protocol error
67       *   (usually this type of exceptions are non-recoverable).
68       */
69      CloseableHttpResponse execute(
70              HttpRoute route,
71              HttpRequestWrapper request,
72              HttpClientContext clientContext,
73              HttpExecutionAware execAware) throws IOException, HttpException;
74  
75  }