org.apache.juneau.http.Expect Maven / Gradle / Ivy
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package org.apache.juneau.http;
/**
* Represents a parsed Expect HTTP request header.
*
*
* Indicates that particular server behaviors are required by the client.
*
*
Example
*
* Expect: 100-continue
*
*
* RFC2616 Specification
*
* The Expect request-header field is used to indicate that particular server behaviors are required by the client.
*
* Expect = "Expect" ":" 1#expectation
* expectation = "100-continue" | expectation-extension
* expectation-extension = token [ "=" ( token | quoted-string )
* *expect-params ]
* expect-params = ";" token [ "=" ( token | quoted-string ) ]
*
*
*
* A server that does not understand or is unable to comply with any of the expectation values in the Expect field of a
* request MUST respond with appropriate error status.
* The server MUST respond with a 417 (Expectation Failed) status if any of the expectations cannot be met or, if there
* are other problems with the request, some other 4xx status.
*
*
* This header field is defined with extensible syntax to allow for future extensions.
* If a server receives a request containing an Expect field that includes an expectation-extension that it does not
* support, it MUST respond with a 417 (Expectation Failed) status.
*
*
* Comparison of expectation values is case-insensitive for unquoted tokens (including the 100-continue token), and is
* case-sensitive for quoted-string expectation-extensions.
*
*
* The Expect mechanism is hop-by-hop: that is, an HTTP/1.1 proxy MUST return a 417 (Expectation Failed) status if it
* receives a request with an expectation that it cannot meet.
* However, the Expect request-header itself is end-to-end; it MUST be forwarded if the request is forwarded.
*
*
* Many older HTTP/1.0 and HTTP/1.1 applications do not understand the Expect header.
*
*
* See section 8.2.3 for the use of the 100 (continue) status.
*
*
Additional Information
*
*/
public final class Expect extends HeaderString {
/**
* Returns a parsed Expect header.
*
* @param value The Expect header string.
* @return The parsed Expect header, or null if the string was null.
*/
public static Expect forString(String value) {
if (value == null)
return null;
return new Expect(value);
}
private Expect(String value) {
super(value);
}
}