| // *************************************************************************************************************************** |
| // * 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>Upgrade</l> HTTP request header. |
| * |
| * <p> |
| * Ask the client to upgrade to another protocol. |
| * |
| * <h5 class='figure'>Example</h5> |
| * <p class='bcode w800'> |
| * Upgrade: HTTP/2.0, HTTPS/1.3, IRC/6.9, RTA/x11, websocket |
| * </p> |
| * |
| * <h5 class='topic'>RFC2616 Specification</h5> |
| * |
| * The Upgrade general-header allows the client to specify what additional communication protocols it supports and |
| * would like to use if the server finds it appropriate to switch protocols. |
| * The server MUST use the Upgrade header field within a 101 (Switching Protocols) response to indicate which |
| * protocol(s) are being switched. |
| * |
| * <p class='bcode w800'> |
| * Upgrade = "Upgrade" ":" 1#product |
| * </p> |
| * |
| * <p> |
| * For example, |
| * <p class='bcode w800'> |
| * Upgrade: HTTP/2.0, SHTTP/1.3, IRC/6.9, RTA/x11 |
| * </p> |
| * |
| * <p> |
| * The Upgrade header field is intended to provide a simple mechanism for transition from HTTP/1.1 to some other, |
| * incompatible protocol. |
| * It does so by allowing the client to advertise its desire to use another protocol, such as a later version of HTTP |
| * with a higher major version number, even though the current request has been made using HTTP/1.1. |
| * This eases the difficult transition between incompatible protocols by allowing the client to initiate a request in |
| * the more commonly supported protocol while indicating to the server that it would like to use a "better" protocol if |
| * available (where "better" is determined by the server, possibly according to the nature of the method and/or resource |
| * being requested). |
| * |
| * <p> |
| * The Upgrade header field only applies to switching application-layer protocols upon the existing transport-layer |
| * connection. |
| * Upgrade cannot be used to insist on a protocol change; its acceptance and use by the server is optional. |
| * The capabilities and nature of the application-layer communication after the protocol change is entirely dependent |
| * upon the new protocol chosen, although the first action after changing the protocol MUST be a response to the initial |
| * HTTP request containing the Upgrade header field. |
| * |
| * <p> |
| * The Upgrade header field only applies to the immediate connection. |
| * Therefore, the upgrade keyword MUST be supplied within a Connection header field (section 14.10) whenever Upgrade is |
| * present in an HTTP/1.1 message. |
| * |
| * <p> |
| * The Upgrade header field cannot be used to indicate a switch to a protocol on a different connection. |
| * For that purpose, it is more appropriate to use a 301, 302, 303, or 305 redirection response. |
| * |
| * <p> |
| * This specification only defines the protocol name "HTTP" for use by the family of Hypertext Transfer Protocols, as |
| * defined by the HTTP version rules of section 3.1 and future updates to this specification. |
| * Any token can be used as a protocol name; however, it will only be useful if both the client and server associate |
| * the name with the same protocol. |
| * |
| * <ul class='seealso'> |
| * <li class='extlink'>{@doc RFC2616} |
| * </ul> |
| */ |
| @Header("Upgrade") |
| public final class Upgrade extends HeaderStringArray { |
| |
| /** |
| * Constructor. |
| * |
| * @param value The value for this header. |
| */ |
| public Upgrade(String[] value) { |
| super(value); |
| } |
| |
| /** |
| * Returns a parsed <c>Upgrade</c> header. |
| * |
| * @param value The <c>Upgrade</c> header string. |
| * @return The parsed <c>Upgrade</c> header, or <jk>null</jk> if the string was null. |
| */ |
| public static Upgrade forString(String value) { |
| if (value == null) |
| return null; |
| return new Upgrade(value); |
| } |
| |
| private Upgrade(String value) { |
| super(value); |
| } |
| } |