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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.protocol;
29  
30  import org.apache.http.HttpException;
31  import org.apache.http.HttpRequest;
32  import org.apache.http.HttpResponse;
33  
34  /**
35   * Defines an interface to verify whether an incoming HTTP request meets
36   * the target server's expectations.
37   *<p>
38   * The Expect request-header field is used to indicate that particular
39   * server behaviors are required by the client.
40   *</p>
41   *<pre>
42   *    Expect       =  "Expect" ":" 1#expectation
43   *
44   *    expectation  =  "100-continue" | expectation-extension
45   *    expectation-extension =  token [ "=" ( token | quoted-string )
46   *                             *expect-params ]
47   *    expect-params =  ";" token [ "=" ( token | quoted-string ) ]
48   *</pre>
49   *<p>
50   * A server that does not understand or is unable to comply with any of
51   * the expectation values in the Expect field of a request MUST respond
52   * with appropriate error status. The server MUST respond with a 417
53   * (Expectation Failed) status if any of the expectations cannot be met
54   * or, if there are other problems with the request, some other 4xx
55   * status.
56   *</p>
57   *
58   * @since 4.0
59   */
60  public interface HttpExpectationVerifier {
61  
62      /**
63       * Verifies whether the given request meets the server's expectations.
64       * <p>
65       * If the request fails to meet particular criteria, this method can
66       * trigger a terminal response back to the client by setting the status
67       * code of the response object to a value greater or equal to
68       * {@code 200}. In this case the client will not have to transmit
69       * the request body. If the request meets expectations this method can
70       * terminate without modifying the response object. Per default the status
71       * code of the response object will be set to {@code 100}.
72       *
73       * @param request the HTTP request.
74       * @param response the HTTP response.
75       * @param context the HTTP context.
76       * @throws HttpException in case of an HTTP protocol violation.
77       */
78      void verify(HttpRequest request, HttpResponse response, HttpContext context)
79              throws HttpException;
80  
81  }