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006// *                                                                                                                         *
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012// ***************************************************************************************************************************
013package org.apache.juneau.http;
014
015import org.apache.juneau.annotation.*;
016import org.apache.juneau.http.annotation.*;
017
018/**
019 * Represents a parsed <l>Connection</l> HTTP request header.
020 *
021 * <p>
022 * Control options for the current connection and list of hop-by-hop request fields.
023 *
024 * <h5 class='figure'>Example</h5>
025 * <p class='bcode w800'>
026 *    Connection: keep-alive
027 *    Connection: Upgrade
028 * </p>
029 *
030 * <h5 class='topic'>RFC2616 Specification</h5>
031 *
032 * The Connection general-header field allows the sender to specify options that are desired for that particular
033 * connection and MUST NOT be communicated by proxies over further connections.
034 *
035 * <p>
036 * The Connection header has the following grammar:
037 * <p class='bcode w800'>
038 *    Connection = "Connection" ":" 1#(connection-token)
039 *    connection-token  = token
040 * </p>
041 *
042 * <p>
043 * HTTP/1.1 proxies MUST parse the Connection header field before a message is forwarded and, for each connection-token
044 * in this field, remove any header field(s) from the message with the same name as the connection-token.
045 * Connection options are signaled by the presence of a connection-token in the Connection header field, not by any
046 * corresponding additional header field(s), since the additional header field may not be sent if there are no
047 * parameters associated with that connection option.
048 *
049 * <p>
050 * Message headers listed in the Connection header MUST NOT include end-to-end headers, such as Cache-Control.
051 *
052 * <p>
053 * HTTP/1.1 defines the "close" connection option for the sender to signal that the connection will be closed after
054 * completion of the response.
055 * For example...
056 * <p class='bcode w800'>
057 *    Connection: close
058 * </p>
059 * <p>
060 * ...in either the request or the response header fields indicates that the connection SHOULD NOT be considered
061 * `persistent' (section 8.1) after the current request/response is complete.
062 *
063 * <p>
064 * HTTP/1.1 applications that do not support persistent connections MUST include the "close" connection option in
065 * every message.
066 *
067 * <p>
068 * A system receiving an HTTP/1.0 (or lower-version) message that includes a Connection header MUST, for each
069 * connection-token in this field, remove and ignore any header field(s) from the message with the same name as the
070 * connection-token.
071 * This protects against mistaken forwarding of such header fields by pre-HTTP/1.1 proxies.
072 * See section 19.6.2.
073 *
074 * <ul class='seealso'>
075 *    <li class='extlink'>{@doc RFC2616}
076 * </ul>
077 */
078@Header("Connection")
079@BeanIgnore
080public final class Connection extends HeaderString {
081
082   /**
083    * Returns a parsed <c>Connection</c> header.
084    *
085    * @param value The <c>Connection</c> header string.
086    * @return The parsed <c>Connection</c> header, or <jk>null</jk> if the string was null.
087    */
088   public static Connection forString(String value) {
089      if (value == null)
090         return null;
091      return new Connection(value);
092   }
093
094
095   private Connection(String value) {
096      super(value);
097   }
098
099   /**
100    * Returns <jk>true</jk> if the header value is <c>close</c>.
101    *
102    * @return <jk>true</jk> if the header value is <c>close</c>.
103    */
104   public boolean isClose() {
105      return eqIC("close");
106   }
107
108   /**
109    * Returns <jk>true</jk> if the header value is <c>keep-alive</c>.
110    *
111    * @return <jk>true</jk> if the header value is <c>keep-alive</c>.
112    */
113   public boolean isKeepAlive() {
114      return eqIC("keep-alive");
115   }
116
117   /**
118    * Returns <jk>true</jk> if the header value is <c>upgrade</c>.
119    *
120    * @return <jk>true</jk> if the header value is <c>upgrade</c>.
121    */
122   public boolean isUpgrade() {
123      return eqIC("upgrade");
124   }
125}