1   /*
    2    * $HeadURL: https://svn.apache.org/repos/asf/httpcomponents/httpcore/tags/4.0.1/httpcore/src/main/java/org/apache/http/protocol/HttpExpectationVerifier.java $
    3    * $Revision: 744532 $
    4    * $Date: 2009-02-14 18:12:18 +0100 (Sat, 14 Feb 2009) $
    5    *
    6    * ====================================================================
    7    * Licensed to the Apache Software Foundation (ASF) under one
    8    * or more contributor license agreements.  See the NOTICE file
    9    * distributed with this work for additional information
   10    * regarding copyright ownership.  The ASF licenses this file
   11    * to you under the Apache License, Version 2.0 (the
   12    * "License"); you may not use this file except in compliance
   13    * with the License.  You may obtain a copy of the License at
   14    *
   15    *   http://www.apache.org/licenses/LICENSE-2.0
   16    *
   17    * Unless required by applicable law or agreed to in writing,
   18    * software distributed under the License is distributed on an
   19    * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
   20    * KIND, either express or implied.  See the License for the
   21    * specific language governing permissions and limitations
   22    * under the License.
   23    * ====================================================================
   24    *
   25    * This software consists of voluntary contributions made by many
   26    * individuals on behalf of the Apache Software Foundation.  For more
   27    * information on the Apache Software Foundation, please see
   28    * <http://www.apache.org/>.
   29    *
   30    */
   31   
   32   package org.apache.http.protocol;
   33   
   34   import org.apache.http.HttpException;
   35   import org.apache.http.HttpRequest;
   36   import org.apache.http.HttpResponse;
   37   
   38   /**
   39    * Defines an interface to verify whether an incoming HTTP request meets 
   40    * the target server's expectations. 
   41    *<p>
   42    * The Expect request-header field is used to indicate that particular
   43    * server behaviors are required by the client.
   44    *</p>
   45    *<pre>
   46    *    Expect       =  "Expect" ":" 1#expectation
   47    *
   48    *    expectation  =  "100-continue" | expectation-extension
   49    *    expectation-extension =  token [ "=" ( token | quoted-string )
   50    *                             *expect-params ]
   51    *    expect-params =  ";" token [ "=" ( token | quoted-string ) ]
   52    *</pre>
   53    *<p>
   54    * A server that does not understand or is unable to comply with any of
   55    * the expectation values in the Expect field of a request MUST respond
   56    * with appropriate error status. The server MUST respond with a 417
   57    * (Expectation Failed) status if any of the expectations cannot be met
   58    * or, if there are other problems with the request, some other 4xx
   59    * status.
   60    *</p>
   61    *
   62    *
   63    * @version $Revision: 744532 $
   64    * 
   65    * @since 4.0
   66    */
   67   public interface HttpExpectationVerifier {
   68   
   69       /**
   70        * Verifies whether the given request meets the server's expectations. 
   71        * <p>
   72        * If the request fails to meet particular criteria, this method can
   73        * trigger a terminal response back to the client by setting the status
   74        * code of the response object to a value greater or equal to 
   75        * <code>200</code>. In this case the client will not have to transmit 
   76        * the request body. If the request meets expectations this method can 
   77        * terminate without modifying the response object. Per default the status 
   78        * code of the response object will be set to <code>100</code>.
   79        * 
   80        * @param request the HTTP request.
   81        * @param response the HTTP response.
   82        * @param context the HTTP context.
   83        * @throws HttpException in case of an HTTP protocol violation.
   84        */
   85       void verify(HttpRequest request, HttpResponse response, HttpContext context)
   86               throws HttpException;
   87       
   88   }