001// ***************************************************************************************************************************
002// * Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements.  See the NOTICE file *
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006// *                                                                                                                         *
007// *  http://www.apache.org/licenses/LICENSE-2.0                                                                             *
008// *                                                                                                                         *
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012// ***************************************************************************************************************************
013package org.apache.juneau.http;
014
015/**
016 * Represents a parsed <l>Allow</l> HTTP response header.
017 * 
018 * <p>
019 * Valid methods for a specified resource. To be used for a 405 Method not allowed.
020 * 
021 * <h5 class='figure'>Example</h5>
022 * <p class='bcode'>
023 *    Allow: GET, HEAD
024 * </p>
025 * 
026 * <h5 class='topic'>RFC2616 Specification</h5>
027 * 
028 * The Allow entity-header field lists the set of methods supported by the resource identified by the Request-URI.
029 * The purpose of this field is strictly to inform the recipient of valid methods associated with the resource.
030 * An Allow header field MUST be present in a 405 (Method Not Allowed) response.
031 * 
032 * <p class='bcode'>
033 *    Allow   = "Allow" ":" #Method
034 * </p>
035 * 
036 * <p>
037 * Example of use:
038 * <p class='bcode'>
039 *    Allow: GET, HEAD, PUT
040 * </p>
041 * 
042 * <p>
043 * This field cannot prevent a client from trying other methods.
044 * However, the indications given by the Allow header field value SHOULD be followed.
045 * 
046 * <p>
047 * The actual set of allowed methods is defined by the origin server at the time of each request.
048 * 
049 * <p>
050 * The Allow header field MAY be provided with a PUT request to recommend the methods to be supported by the new or
051 * modified resource.
052 * 
053 * <p>
054 * The server is not required to support these methods and SHOULD include an Allow header in the response giving the
055 * actual supported methods.
056 * 
057 * <p>
058 * A proxy MUST NOT modify the Allow header field even if it does not understand all the methods specified, since the
059 * user agent might
060 * have other means of communicating with the origin server.
061 * 
062 * <h5 class='section'>See Also:</h5>
063 * <ul class='doctree'>
064 *    <li class='extlink'><a class='doclink' href='https://www.w3.org/Protocols/rfc2616/rfc2616.html'>Hypertext Transfer Protocol -- HTTP/1.1</a>
065 * </ul>
066 */
067public final class Allow extends HeaderStringArray {
068
069   /**
070    * Returns a parsed <code>Allow</code> header.
071    * 
072    * @param value The <code>Allow</code> header string.
073    * @return The parsed <code>Allow</code> header, or <jk>null</jk> if the string was null.
074    */
075   public static Allow forString(String value) {
076      if (value == null)
077         return null;
078      return new Allow(value);
079   }
080
081   private Allow(String value) {
082      super(value);
083   }
084}