org.apache.juneau.http.Upgrade Maven / Gradle / Ivy
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package org.apache.juneau.http;
import org.apache.juneau.http.annotation.*;
/**
* Represents a parsed Upgrade HTTP request header.
*
*
* Ask the client to upgrade to another protocol.
*
*
Example
*
* Upgrade: HTTP/2.0, HTTPS/1.3, IRC/6.9, RTA/x11, websocket
*
*
* RFC2616 Specification
*
* 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.
*
*
* Upgrade = "Upgrade" ":" 1#product
*
*
*
* For example,
*
* Upgrade: HTTP/2.0, SHTTP/1.3, IRC/6.9, RTA/x11
*
*
*
* 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).
*
*
* 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.
*
*
* 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.
*
*
* 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.
*
*
* 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.
*
*
See Also:
*
* - {@doc RFC2616}
*
*/
@Header("Upgrade")
public final class Upgrade extends HeaderStringArray {
/**
* Constructor.
*
* @param value
*/
public Upgrade(String[] value) {
super(value);
}
/**
* Returns a parsed Upgrade header.
*
* @param value The Upgrade header string.
* @return The parsed Upgrade header, or null 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);
}
}