| // *************************************************************************************************************************** |
| // * Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file * |
| // * distributed with this work for additional information regarding copyright ownership. The ASF licenses this file * |
| // * to you under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance * |
| // * with the License. You may obtain a copy of the License at * |
| // * * |
| // * http://www.apache.org/licenses/LICENSE-2.0 * |
| // * * |
| // * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an * |
| // * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the * |
| // * specific language governing permissions and limitations under the License. * |
| // *************************************************************************************************************************** |
| package org.apache.juneau.http; |
| |
| import org.apache.juneau.http.annotation.*; |
| |
| /** |
| * Represents a parsed <l>Warning</l> HTTP request/response header. |
| * |
| * <p> |
| * A general warning about possible problems with the entity body. |
| * |
| * <h5 class='figure'>Example</h5> |
| * <p class='bcode w800'> |
| * Warning: 199 Miscellaneous warning |
| * </p> |
| * |
| * <h5 class='topic'>RFC2616 Specification</h5> |
| * |
| * The Warning general-header field is used to carry additional information about the status or transformation of a |
| * message which might not be reflected in the message. |
| * This information is typically used to warn about a possible lack of semantic transparency from caching operations |
| * or transformations applied to the entity body of the message. |
| * |
| * <p> |
| * Warning headers are sent with responses using: |
| * <p class='bcode w800'> |
| * Warning = "Warning" ":" 1#warning-value |
| * warning-value = warn-code SP warn-agent SP warn-text |
| * [SP warn-date] |
| * warn-code = 3DIGIT |
| * warn-agent = ( host [ ":" port ] ) | pseudonym |
| * ; the name or pseudonym of the server adding |
| * ; the Warning header, for use in debugging |
| * warn-text = quoted-string |
| * warn-date = <"> HTTP-date <"> |
| * </p> |
| * |
| * <p> |
| * A response MAY carry more than one Warning header. |
| * |
| * <p> |
| * The warn-text SHOULD be in a natural language and character set that is most likely to be intelligible to the human |
| * user receiving the response. |
| * This decision MAY be based on any available knowledge, such as the location of the cache or user, the |
| * Accept-Language field in a request, the Content-Language field in a response, etc. |
| * The default language is English and the default character set is ISO-8859-1. |
| * |
| * <p> |
| * If a character set other than ISO-8859-1 is used, it MUST be encoded in the warn-text using the method described in |
| * RFC 2047. |
| * |
| * <p> |
| * Warning headers can in general be applied to any message, however some specific warn-codes are specific to caches |
| * and can only be applied to response messages. |
| * New Warning headers SHOULD be added after any existing Warning headers. |
| * A cache MUST NOT delete any Warning header that it received with a message. |
| * However, if a cache successfully validates a cache entry, it SHOULD remove any Warning headers previously attached |
| * to that entry except as specified for specific Warning codes. |
| * It MUST then add any Warning headers received in the validating response. |
| * In other words, Warning headers are those that would be attached to the most recent relevant response. |
| * |
| * <p> |
| * When multiple Warning headers are attached to a response, the user agent ought to inform the user of as many of them |
| * as possible, in the order that they appear in the response. |
| * If it is not possible to inform the user of all of the warnings, the user agent SHOULD follow these heuristics: |
| * <ul> |
| * <li>Warnings that appear early in the response take priority over those appearing later in the response. |
| * <li>Warnings in the user's preferred character set take priority over warnings in other character sets but with |
| * identical warn-codes and warn-agents. |
| * </ul> |
| * |
| * <p> |
| * Systems that generate multiple Warning headers SHOULD order them with this user agent behavior in mind. |
| * |
| * <p> |
| * Requirements for the behavior of caches with respect to Warnings are stated in section 13.1.2. |
| * |
| * <p> |
| * This is a list of the currently-defined warn-codes, each with a recommended warn-text in English, and a description |
| * of its meaning. |
| * <ul> |
| * <li>110 Response is stale MUST be included whenever the returned response is stale. |
| * <li>111 Revalidation failed MUST be included if a cache returns a stale response because an attempt to revalidate |
| * the response failed, due to an inability to reach the server. |
| * <li>112 Disconnected operation SHOULD be included if the cache is intentionally disconnected from the rest of the |
| * network for a period of time. |
| * <li>113 Heuristic expiration MUST be included if the cache heuristically chose a freshness lifetime greater than |
| * 24 hours and the response's age is greater than 24 hours. |
| * <li>199 Miscellaneous warning The warning text MAY include arbitrary information to be presented to a human user, |
| * or logged. A system receiving this warning MUST NOT take any automated action, besides presenting the warning |
| * to the user. |
| * <li>214 Transformation applied MUST be added by an intermediate cache or proxy if it applies any transformation |
| * changing the content-coding (as specified in the Content-Encoding header) or media-type (as specified in the |
| * Content-Type header) of the response, or the entity-body of the response, unless this Warning code already |
| * appears in the response. |
| * <li>299 Miscellaneous persistent warning The warning text MAY include arbitrary information to be presented to a |
| * human user, or logged. A system receiving this warning MUST NOT take any automated action. |
| * </ul> |
| * |
| * <p> |
| * If an implementation sends a message with one or more Warning headers whose version is HTTP/1.0 or lower, then the |
| * sender MUST include in each warning-value a warn-date that matches the date in the response. |
| * |
| * <p> |
| * If an implementation receives a message with a warning-value that includes a warn-date, and that warn-date is |
| * different from the Date value in the response, then that warning-value MUST be deleted from the message before |
| * storing, forwarding, or using it. |
| * (This prevents bad consequences of naive caching of Warning header fields.) |
| * If all of the warning-values are deleted for this reason, the Warning header MUST be deleted as well. |
| * |
| * <ul class='seealso'> |
| * <li class='extlink'>{@doc RFC2616} |
| * </ul> |
| */ |
| @Header("Warning") |
| public final class Warning extends HeaderString { |
| |
| /** |
| * Returns a parsed <c>Warning</c> header. |
| * |
| * @param value The <c>Warning</c> header string. |
| * @return The parsed <c>Warning</c> header, or <jk>null</jk> if the string was null. |
| */ |
| public static Warning forString(String value) { |
| if (value == null) |
| return null; |
| return new Warning(value); |
| } |
| |
| private Warning(String value) { |
| super(value); |
| } |
| } |
