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013package org.apache.juneau.http;
014
015/**
016 * Represents a parsed <l>Max-Forwards</l> HTTP request header.
017 * 
018 * <p>
019 * Limit the number of times the message can be forwarded through proxies or gateways.
020 * 
021 * <h5 class='figure'>Example</h5>
022 * <p class='bcode'>
023 *    Max-Forwards: 10
024 * </p>
025 * 
026 * <h5 class='topic'>RFC2616 Specification</h5>
027 * 
028 * The Max-Forwards request-header field provides a mechanism with the TRACE (section 9.8) and OPTIONS (section 9.2)
029 * methods to limit the number of proxies or gateways that can forward the request to the next inbound server.
030 * This can be useful when the client is attempting to trace a request chain which appears to be failing or looping in
031 * mid-chain.
032 * 
033 * <p class='bcode'>
034 *    Max-Forwards   = "Max-Forwards" ":" 1*DIGIT
035 * </p>
036 * 
037 * <p>
038 * The Max-Forwards value is a decimal integer indicating the remaining number of times this request message may be
039 * forwarded.
040 * 
041 * <p>
042 * Each proxy or gateway recipient of a TRACE or OPTIONS request containing a Max-Forwards header field MUST check and
043 * update its value prior to forwarding the request.
044 * If the received value is zero (0), the recipient MUST NOT forward the request; instead, it MUST respond as the final
045 * recipient.
046 * If the received Max-Forwards value is greater than zero, then the forwarded message MUST contain an updated
047 * Max-Forwards field with a value decremented by one (1).
048 * 
049 * <p>
050 * The Max-Forwards header field MAY be ignored for all other methods defined by this specification and for any
051 * extension methods for which it is not explicitly referred to as part of that method definition.
052 * 
053 * <h5 class='section'>See Also:</h5>
054 * <ul class='doctree'>
055 *    <li class='extlink'><a class='doclink' href='https://www.w3.org/Protocols/rfc2616/rfc2616.html'>Hypertext Transfer Protocol -- HTTP/1.1</a>
056 * </ul>
057 */
058public final class MaxForwards extends HeaderInteger {
059
060   /**
061    * Returns a parsed <code>Max-Forwards</code> header.
062    * 
063    * @param value The <code>Max-Forwards</code> header string.
064    * @return The parsed <code>Max-Forwards</code> header, or <jk>null</jk> if the string was null.
065    */
066   public static MaxForwards forString(String value) {
067      if (value == null)
068         return null;
069      return new MaxForwards(value);
070   }
071
072   private MaxForwards(String value) {
073      super(value);
074   }
075}