001/*
002 * ====================================================================
003 * Licensed to the Apache Software Foundation (ASF) under one
004 * or more contributor license agreements.  See the NOTICE file
005 * distributed with this work for additional information
006 * regarding copyright ownership.  The ASF licenses this file
007 * to you under the Apache License, Version 2.0 (the
008 * "License"); you may not use this file except in compliance
009 * with the License.  You may obtain a copy of the License at
010 *
011 *   http://www.apache.org/licenses/LICENSE-2.0
012 *
013 * Unless required by applicable law or agreed to in writing,
014 * software distributed under the License is distributed on an
015 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
016 * KIND, either express or implied.  See the License for the
017 * specific language governing permissions and limitations
018 * under the License.
019 * ====================================================================
020 *
021 * This software consists of voluntary contributions made by many
022 * individuals on behalf of the Apache Software Foundation.  For more
023 * information on the Apache Software Foundation, please see
024 * <http://www.apache.org/>.
025 *
026 */
027
028package org.apache.http.protocol;
029
030import org.apache.http.HttpException;
031import org.apache.http.HttpRequest;
032import org.apache.http.HttpResponse;
033
034/**
035 * Defines an interface to verify whether an incoming HTTP request meets
036 * the target server's expectations.
037 *<p>
038 * The Expect request-header field is used to indicate that particular
039 * server behaviors are required by the client.
040 *</p>
041 *<pre>
042 *    Expect       =  "Expect" ":" 1#expectation
043 *
044 *    expectation  =  "100-continue" | expectation-extension
045 *    expectation-extension =  token [ "=" ( token | quoted-string )
046 *                             *expect-params ]
047 *    expect-params =  ";" token [ "=" ( token | quoted-string ) ]
048 *</pre>
049 *<p>
050 * A server that does not understand or is unable to comply with any of
051 * the expectation values in the Expect field of a request MUST respond
052 * with appropriate error status. The server MUST respond with a 417
053 * (Expectation Failed) status if any of the expectations cannot be met
054 * or, if there are other problems with the request, some other 4xx
055 * status.
056 *</p>
057 *
058 * @since 4.0
059 */
060public interface HttpExpectationVerifier {
061
062    /**
063     * Verifies whether the given request meets the server's expectations.
064     * <p>
065     * If the request fails to meet particular criteria, this method can
066     * trigger a terminal response back to the client by setting the status
067     * code of the response object to a value greater or equal to
068     * {@code 200}. In this case the client will not have to transmit
069     * the request body. If the request meets expectations this method can
070     * terminate without modifying the response object. Per default the status
071     * code of the response object will be set to {@code 100}.
072     *
073     * @param request the HTTP request.
074     * @param response the HTTP response.
075     * @param context the HTTP context.
076     * @throws HttpException in case of an HTTP protocol violation.
077     */
078    void verify(HttpRequest request, HttpResponse response, HttpContext context)
079            throws HttpException;
080
081}